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1<?xml version="1.0" encoding="UTF-8"?>
2<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
3<html xmlns="http://www.w3.org/1999/xhtml"><head><meta http-equiv="Content-Type" content="text/html; charset=UTF-8" /><title></title><link rel="stylesheet" href="mega-style.css" type="text/css" /><meta name="generator" content="DocBook XSL Stylesheets V1.75.2" /></head><body><div xml:lang="en" class="book" lang="en"><div class="titlepage"><hr /></div>
4
5 <div class="article"><div class="titlepage"><hr /></div><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 90px"><td align="right"><img src="figures/yocto-project-transp.png" align="right" width="135" /></td></tr></table><div class="section" title="1. The Yocto Project Quick Start"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="fake-title"></a>1. The Yocto Project Quick Start</h2></div></div></div><p>Copyright © 2010-2012 Linux Foundation</p></div><div class="section" title="2. Welcome!"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="welcome"></a>2. Welcome!</h2></div></div></div><p>
6 Welcome to the Yocto Project!
7 The Yocto Project is an open-source collaboration project focused on embedded Linux
8 developers.
9 Among other things, the Yocto Project uses a build system based on the Poky project
10 to construct complete Linux images.
11 The Poky project, in turn, draws from and contributes back to the OpenEmbedded project.
12 </p><p>
13 If you don't have a system that runs Linux and you want to give the Yocto Project a test run,
14 you might consider using the Yocto Project Build Appliance.
15 The Build Appliance allows you to build and boot a custom embedded Linux image with the Yocto
16 Project using a non-Linux development system.
17 See the <a class="ulink" href="http://www.yoctoproject.org/documentation/build-appliance" target="_top">Yocto
18 Project Build Appliance</a> for more information.
19 </p><p>
20 On the other hand, if you know all about open-source development, Linux development environments,
21 Git source repositories and the like and you just want some quick information that lets you try out
22 the Yocto Project on your Linux system, skip right to the
23 "<a class="link" href="#super-user" title="6. Super User">Super User</a>" section at the end of this quick start.
24 </p><p>
25 For the rest of you, this short document will give you some basic information about the environment and
26 let you experience it in its simplest form.
27 After reading this document, you will have a basic understanding of what the Yocto Project is
28 and how to use some of its core components.
29 This document steps you through a simple example showing you how to build a small image
30 and run it using the Quick EMUlator (QEMU emulator).
31 </p><p>
32 For more detailed information on the Yocto Project, you should check out these resources:
33 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Website:</em></span> The <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project Website</a>
34 provides the latest builds, breaking news, full development documentation, and a rich Yocto
35 Project Development Community into which you can tap.
36 </p></li><li class="listitem"><p><span class="emphasis"><em>FAQs:</em></span> Lists commonly asked Yocto Project questions and answers.
37 You can find two FAQs: <a class="ulink" href="https://wiki.yoctoproject.org/wiki/FAQ" target="_top">Yocto Project FAQ</a> on
38 a wiki, and the
39 <a class="link" href="#faq" target="_top">FAQ</a> chapter in
40 the Yocto Project Reference Manual.
41 </p></li><li class="listitem"><p><span class="emphasis"><em>Developer Screencast:</em></span> The
42 <a class="ulink" href="http://vimeo.com/36450321" target="_top">Getting Started with the Yocto Project - New
43 Developer Screencast Tutorial</a> provides a 30-minute video for the user
44 new to the Yocto Project but familiar with Linux build systems.</p></li></ul></div><p>
45 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
46 Due to production processes, there could be differences between the Yocto Project
47 documentation bundled in a released tarball and the
48 Yocto Project Quick Start on
49 the <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project</a> website.
50 For the latest version of this manual, see the manual on the website.
51 </div></div><div class="section" title="3. Introducing the Yocto Project Development Environment"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="yp-intro"></a>3. Introducing the Yocto Project Development Environment</h2></div></div></div><p>
52 The Yocto Project through the OpenEmbedded build system provides an open source development
53 environment targeting the ARM, MIPS, PowerPC and x86 architectures for a variety of
54 platforms including x86-64 and emulated ones.
55 You can use components from the Yocto Project to design, develop, build, debug, simulate,
56 and test the complete software stack using Linux, the X Window System, GNOME Mobile-based
57 application frameworks, and Qt frameworks.
58 </p><div class="mediaobject" align="center"><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="100%"><tr><td align="center"><img src="figures/yocto-environment.png" align="middle" width="100%" /></td></tr></table><div class="caption"><p>The Yocto Project Development Environment</p></div></div><p>
59 Here are some highlights for the Yocto Project:
60 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Provides a recent Linux kernel along with a set of system commands and libraries suitable for the embedded environment.</p></li><li class="listitem"><p>Makes available system components such as X11, Matchbox, GTK+, Pimlico, Clutter,
61 GuPNP and Qt (among others) so you can create a richer user interface experience on
62 devices that use displays or have a GUI.
63 For devices that don't have a GUI or display, you simply would not employ these
64 components.</p></li><li class="listitem"><p>Creates a focused and stable core compatible with the OpenEmbedded
65 project with which you can easily and reliably build and develop.</p></li><li class="listitem"><p>Fully supports a wide range of hardware and device emulation through the QEMU
66 Emulator.</p></li></ul></div><p>
67 The Yocto Project can generate images for many kinds of devices.
68 However, the standard example machines target QEMU full-system emulation for x86, x86-64, ARM, MIPS,
69 and PPC-based architectures as well as specific hardware such as the
70 <span class="trademark">Intel</span>® Desktop Board DH55TC.
71 Because an image developed with the Yocto Project can boot inside a QEMU emulator, the
72 development environment works nicely as a test platform for developing embedded software.
73 </p><p>
74 Another important Yocto Project feature is the Sato reference User Interface.
75 This optional GNOME mobile-based UI, which is intended for devices with
76 restricted screen sizes, sits neatly on top of a device using the
77 GNOME Mobile Stack and provides a well-defined user experience.
78 Implemented in its own layer, it makes it clear to developers how they can implement
79 their own user interface on top of a Linux image created with the Yocto Project.
80 </p></div><div class="section" title="4. What You Need and How You Get It"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="yp-resources"></a>4. What You Need and How You Get It</h2></div></div></div><p>
81 You need these things to develop in the Yocto Project environment:
82 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>A host system running a supported Linux distribution (i.e. recent releases of
83 Fedora, openSUSE, CentOS, and Ubuntu).
84 If the host system supports multiple cores and threads, you can configure the
85 Yocto Project build system to decrease the time needed to build images
86 significantly.
87 </p></li><li class="listitem"><p>The right packages.</p></li><li class="listitem"><p>A release of the Yocto Project.</p></li></ul></div><div class="section" title="4.1. The Linux Distribution"><div class="titlepage"><div><div><h3 class="title"><a id="the-linux-distro"></a>4.1. The Linux Distribution</h3></div></div></div><p>
88 The Yocto Project team is continually verifying more and more Linux
89 distributions with each release.
90 In general, if you have the current release minus one of the following
91 distributions you should have no problems.
92 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Ubuntu</p></li><li class="listitem"><p>Fedora</p></li><li class="listitem"><p>openSUSE</p></li><li class="listitem"><p>CentOS</p></li></ul></div><p>
93 For a list of the distributions under validation and their status, see the
94 <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Distribution_Support" target="_top">Distribution
95 Support</a> wiki page.
96 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
97 For notes about using the Yocto Project on a RHEL 4-based host, see the
98 <a class="ulink" href="https://wiki.yoctoproject.org/wiki/BuildingOnRHEL4" target="_top">BuildingOnRHEL4</a>
99 wiki page.
100 </div><p>
101 </p><p>
102 The OpenEmbedded build system should be able to run on any modern distribution with Python 2.6 or 2.7.
103 Earlier releases of Python are known to not work and the system does not support Python 3 at this time.
104 This document assumes you are running one of the previously noted distributions on your Linux-based
105 host systems.
106 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
107 If you attempt to use a distribution not in the above list, you may or may not have success - you
108 are venturing into untested territory.
109 Refer to
110 <a class="ulink" href="http://www.openembedded.org/index.php?title=OEandYourDistro&amp;action=historysubmit&amp;diff=4309&amp;okdid=4225" target="_top">OE and Your Distro</a> and
111 <a class="ulink" href="http://www.openembedded.org/index.php?title=Required_software&amp;action=historysubmit&amp;diff=4311&amp;oldid=4251" target="_top">Required Software</a>
112 for information for other distributions used with the OpenEmbedded project, which might be
113 a starting point for exploration.
114 If you go down this path, you should expect problems.
115 When you do, please go to <a class="ulink" href="http://bugzilla.yoctoproject.org" target="_top">Yocto Project Bugzilla</a>
116 and submit a bug.
117 We are interested in hearing about your experience.
118 </p></div></div><div class="section" title="4.2. The Packages"><div class="titlepage"><div><div><h3 class="title"><a id="packages"></a>4.2. The Packages</h3></div></div></div><p>
119 Packages and package installation vary depending on your development system.
120 In general, you need to have root access and then install the required packages.
121 The next few sections show you how to get set up with the right packages for
122 Ubuntu, Fedora, openSUSE, and CentOS.
123 </p><div class="section" title="4.2.1. Ubuntu"><div class="titlepage"><div><div><h4 class="title"><a id="ubuntu"></a>4.2.1. Ubuntu</h4></div></div></div><p>
124 The packages you need for a supported Ubuntu distribution are shown in the following command:
125 </p><pre class="literallayout">
126 $ sudo apt-get install sed wget subversion git-core coreutils \
127 unzip texi2html texinfo libsdl1.2-dev docbook-utils fop gawk \
128 python-pysqlite2 diffstat make gcc build-essential xsltproc \
129 g++ desktop-file-utils chrpath libgl1-mesa-dev libglu1-mesa-dev \
130 autoconf automake groff libtool xterm libxml-parser-perl dblatex
131 </pre></div><div class="section" title="4.2.2. Fedora"><div class="titlepage"><div><div><h4 class="title"><a id="fedora"></a>4.2.2. Fedora</h4></div></div></div><p>
132 The packages you need for a supported Fedora distribution are shown in the following
133 commands:
134 </p><pre class="literallayout">
135 $ sudo yum groupinstall "development tools"
136 $ sudo yum install python m4 make wget curl ftp tar bzip2 gzip \
137 unzip perl texinfo texi2html diffstat openjade \
138 docbook-style-dsssl sed docbook-style-xsl docbook-dtds fop libxslt \
139 docbook-utils sed bc eglibc-devel ccache pcre pcre-devel quilt \
140 groff linuxdoc-tools patch cmake \
141 perl-ExtUtils-MakeMaker tcl-devel gettext chrpath ncurses apr \
142 SDL-devel mesa-libGL-devel mesa-libGLU-devel gnome-doc-utils \
143 autoconf automake libtool xterm dblatex
144 </pre></div><div class="section" title="4.2.3. openSUSE"><div class="titlepage"><div><div><h4 class="title"><a id="opensuse"></a>4.2.3. openSUSE</h4></div></div></div><p>
145 The packages you need for a supported openSUSE distribution are shown in the following
146 command:
147 </p><pre class="literallayout">
148 $ sudo zypper install python gcc gcc-c++ libtool fop \
149 subversion git chrpath automake make wget xsltproc \
150 diffstat texinfo freeglut-devel libSDL-devel dblatex
151 </pre></div><div class="section" title="4.2.4. CentOS"><div class="titlepage"><div><div><h4 class="title"><a id="centos"></a>4.2.4. CentOS</h4></div></div></div><p>
152 The packages you need for a supported CentOS distribution are shown in the following
153 commands:
154 </p><pre class="literallayout">
155 $ sudo yum -y groupinstall "development tools"
156 $ sudo yum -y install tetex gawk sqlite-devel vim-common redhat-lsb xz \
157 m4 make wget curl ftp tar bzip2 gzip python-devel \
158 unzip perl texinfo texi2html diffstat openjade zlib-devel \
159 docbook-style-dsssl sed docbook-style-xsl docbook-dtds \
160 docbook-utils bc glibc-devel pcre pcre-devel \
161 groff linuxdoc-tools patch cmake \
162 tcl-devel gettext ncurses apr \
163 SDL-devel mesa-libGL-devel mesa-libGLU-devel gnome-doc-utils \
164 autoconf automake libtool xterm dblatex
165 </pre><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
166 Depending on the CentOS version you are using, other requirements and dependencies
167 might exist.
168 For details, you should look at the CentOS sections on the
169 <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Poky/GettingStarted/Dependencies" target="_top">Poky/GettingStarted/Dependencies</a>
170 wiki page.
171 </p></div></div></div><div class="section" title="4.3. Yocto Project Release"><div class="titlepage"><div><div><h3 class="title"><a id="releases"></a>4.3. Yocto Project Release</h3></div></div></div><p>
172 You can download the latest Yocto Project release by going to the
173 <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">Yocto Project Download page</a>.
174 Just go to the page and click the "Yocto Downloads" link found in the "Download"
175 navigation pane to the right to view all available Yocto Project releases.
176 Then, click the "Yocto Release" link for the release you want from the list to
177 begin the download.
178 Nightly and developmental builds are also maintained at
179 <a class="ulink" href="http://autobuilder.yoctoproject.org/nightly/" target="_top">http://autobuilder.yoctoproject.org/nightly/</a>.
180 However, for this document a released version of Yocto Project is used.
181 </p><p>
182 You can also get the Yocto Project files you need by setting up (cloning in Git terms)
183 a local copy of the <code class="filename">poky</code> Git repository on your host development
184 system.
185 Doing so allows you to contribute back to the Yocto Project project.
186 For information on how to get set up using this method, see the
187 "<a class="link" href="#local-yp-release" target="_top">Yocto
188 Project Release</a>" item in the Yocto Project Development Manual.
189 </p></div></div><div class="section" title="5. A Quick Test Run"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="test-run"></a>5. A Quick Test Run</h2></div></div></div><p>
190 Now that you have your system requirements in order, you can give the Yocto Project a try.
191 This section presents some steps that let you do the following:
192 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Build an image and run it in the QEMU emulator</p></li><li class="listitem"><p>Use a pre-built image and run it in the QEMU emulator</p></li></ul></div><div class="section" title="5.1. Building an Image"><div class="titlepage"><div><div><h3 class="title"><a id="building-image"></a>5.1. Building an Image</h3></div></div></div><p>
193 In the development environment you will need to build an image whenever you change hardware
194 support, add or change system libraries, or add or change services that have dependencies.
195 </p><div class="mediaobject" align="center"><img src="figures/building-an-image.png" align="middle" /><div class="caption"><p>Building an Image</p></div></div><p>
196 Use the following commands to build your image.
197 The OpenEmbedded build process creates an entire Linux distribution, including the toolchain,
198 from source.
199 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
200 The build process using Sato currently consumes about 50GB of disk space.
201 To allow for variations in the build process and for future package expansion, we
202 recommend having at least 100GB of free disk space.
203 </p></div><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
204 By default, the build process searches for source code using a pre-determined order
205 through a set of locations.
206 If you encounter problems with the build process finding and downloading source code, see the
207 "<a class="link" href="#how-does-the-yocto-project-obtain-source-code-and-will-it-work-behind-my-firewall-or-proxy-server" target="_top">How does the OpenEmbedded build system obtain source code and will it work behind my
208 firewall or proxy server?</a>" in the Yocto Project Reference Manual.
209 </p></div><p>
210 </p><pre class="literallayout">
211 $ wget http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/poky-1.2+snapshot-8.0.tar.bz2
212 $ tar xjf poky-1.2+snapshot-8.0.tar.bz2
213 $ source poky-1.2+snapshot-8.0/oe-init-build-env poky-1.2+snapshot-8.0-build
214 </pre><p>
215 </p><div class="tip" title="Tip" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Tip</h3><p>
216 To help conserve disk space during builds, you can add the following statement
217 to your project's configuration file, which for this example
218 is <code class="filename">poky-1.2+snapshot-8.0-build/conf/local.conf</code>.
219 Adding this statement deletes the work directory used for building a package
220 once the package is built.
221 </p><pre class="literallayout">
222 INHERIT += "rm_work"
223 </pre><p>
224 </p></div><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>In the previous example, the first command retrieves the Yocto Project
225 release tarball from the source repositories using the
226 <code class="filename">wget</code> command.
227 Alternatively, you can go to the
228 <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">Yocto Project website's Downloads page</a>
229 to retrieve the tarball.</p></li><li class="listitem"><p>The second command extracts the files from the tarball and places
230 them into a directory named <code class="filename">poky-1.2+snapshot-8.0</code> in the current
231 directory.</p></li><li class="listitem"><p>The third command runs the Yocto Project environment setup script.
232 Running this script defines OpenEmbedded build environment settings needed to
233 complete the build.
234 The script also creates the
235 <a class="link" href="#build-directory" target="_top">build directory</a>,
236 which is <code class="filename">poky-1.2+snapshot-8.0-build</code> in this case.
237 After the script runs, your current working directory is set
238 to the build directory.
239 Later, when the build completes, the build directory contains all the files
240 created during the build.
241 </p></li></ul></div><p>
242 Take some time to examine your <code class="filename">local.conf</code> file
243 in your project's configuration directory.
244 The defaults in that file should work fine.
245 However, there are some variables of interest at which you might look.
246 </p><p>
247 By default, the target architecture for the build is <code class="filename">qemux86</code>,
248 which produces an image that can be used in the QEMU emulator and is targeted at an
249 <span class="trademark">Intel</span>® 32-bit based architecture.
250 To change this default, edit the value of the <code class="filename">MACHINE</code> variable
251 in the configuration file before launching the build.
252 </p><p>
253 Another couple of variables of interest are the
254 <a class="link" href="#var-BB_NUMBER_THREADS" target="_top"><code class="filename">BB_NUMBER_THREADS</code></a> and the
255 <a class="link" href="#var-PARALLEL_MAKE" target="_top"><code class="filename">PARALLEL_MAKE</code></a> variables.
256 By default, these variables are commented out.
257 However, if you have a multi-core CPU you might want to uncomment
258 the lines and set both variables equal to twice the number of your
259 host's processor cores.
260 Setting these variables can significantly shorten your build time.
261 </p><p>
262 Another consideration before you build is the package manager used when creating
263 the image.
264 By default, the OpenEmbedded build system uses the RPM package manager.
265 You can control this configuration by using the
266 <code class="filename"><a class="link" href="#var-PACKAGE_CLASSES" target="_top"><code class="filename">PACKAGE_CLASSES</code></a></code> variable.
267 For additional package manager selection information, see
268 "<a class="link" href="#ref-classes-package" target="_top">Packaging - <code class="filename">package*.bbclass</code></a>"
269 in the Yocto Project Reference Manual.
270 </p><p>
271 Continue with the following command to build an OS image for the target, which is
272 <code class="filename">core-image-sato</code> in this example.
273 For information on the <code class="filename">-k</code> option use the
274 <code class="filename">bitbake --help</code> command or see the
275 "<a class="link" href="#usingpoky-components-bitbake" target="_top">BitBake</a>" section in
276 the Yocto Project Reference Manual.
277 </p><pre class="literallayout">
278 $ bitbake -k core-image-sato
279 </pre><p>
280 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
281 BitBake requires Python 2.6 or 2.7. For more information on this requirement,
282 see the
283 <a class="link" href="#faq" target="_top">FAQ</a> in the Yocto Project Reference
284 Manual.
285 </p></div><p>
286 The final command runs the image:
287 </p><pre class="literallayout">
288 $ runqemu qemux86
289 </pre><p>
290 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
291 Depending on the number of processors and cores, the amount or RAM, the speed of your
292 Internet connection and other factors, the build process could take several hours the first
293 time you run it.
294 Subsequent builds run much faster since parts of the build are cached.
295 </p></div><p>
296 </p></div><div class="section" title="5.2. Using Pre-Built Binaries and QEMU"><div class="titlepage"><div><div><h3 class="title"><a id="using-pre-built"></a>5.2. Using Pre-Built Binaries and QEMU</h3></div></div></div><p>
297 If hardware, libraries and services are stable, you can get started by using a pre-built binary
298 of the filesystem image, kernel, and toolchain and run it using the QEMU emulator.
299 This scenario is useful for developing application software.
300 </p><div class="mediaobject" align="center"><img src="figures/using-a-pre-built-image.png" align="middle" /><div class="caption"><p>Using a Pre-Built Image</p></div></div><p>
301 For this scenario, you need to do several things:
302 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Install the appropriate stand-alone toolchain tarball.</p></li><li class="listitem"><p>Download the pre-built image that will boot with QEMU.
303 You need to be sure to get the QEMU image that matches your target machine’s
304 architecture (e.g. x86, ARM, etc.).</p></li><li class="listitem"><p>Download the filesystem image for your target machine's architecture.
305 </p></li><li class="listitem"><p>Set up the environment to emulate the hardware and then start the QEMU emulator.
306 </p></li></ul></div><div class="section" title="5.2.1. Installing the Toolchain"><div class="titlepage"><div><div><h4 class="title"><a id="installing-the-toolchain"></a>5.2.1. Installing the Toolchain</h4></div></div></div><p>
307 You can download a tarball with the pre-built toolchain, which includes the
308 <code class="filename">runqemu</code>
309 script and support files, from the appropriate directory under
310 <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/toolchain/" target="_top">http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/toolchain/</a>.
311 Toolchains are available for 32-bit and 64-bit development systems from the
312 <code class="filename">i686</code> and <code class="filename">x86-64</code> directories, respectively.
313 Each type of development system supports five target architectures.
314 The names of the tarballs are such that a string representing the host system appears
315 first in the filename and then is immediately followed by a string representing
316 the target architecture.
317 </p><pre class="literallayout">
318 poky-eglibc-&lt;<span class="emphasis"><em>host_system</em></span>&gt;-&lt;<span class="emphasis"><em>arch</em></span>&gt;-toolchain-gmae-&lt;<span class="emphasis"><em>release</em></span>&gt;.tar.bz2
319
320 Where:
321 &lt;<span class="emphasis"><em>host_system</em></span>&gt; is a string representing your development system:
322 i686 or x86_64.
323
324 &lt;<span class="emphasis"><em>arch</em></span>&gt; is a string representing the target architecture:
325 i586, x86_64, powerpc, mips, or arm.
326
327 &lt;<span class="emphasis"><em>release</em></span>&gt; is the version of Yocto Project.
328 </pre><p>
329 For example, the following toolchain tarball is for a 64-bit development
330 host system and a 32-bit target architecture:
331 </p><pre class="literallayout">
332 poky-eglibc-x86_64-i586-toolchain-gmae-1.3.tar.bz2
333 </pre><p>
334 The toolchain tarballs are self-contained and must be installed into <code class="filename">/opt/poky</code>.
335 The following commands show how you install the toolchain tarball given a 64-bit development
336 host system and a 32-bit target architecture.
337 The example assumes the toolchain tarball is located in <code class="filename">~/toolchains/</code>.
338 You must have your working directory set to root before unpacking the tarball:
339 </p><p>
340 </p><pre class="literallayout">
341 $ cd /
342 $ sudo tar -xvjf ~/toolchains/poky-eglibc-x86_64-i586-toolchain-gmae-1.3.tar.bz2
343 </pre><p>
344 </p><p>
345 For more information on how to install tarballs, see the
346 "<a class="link" href="#using-an-existing-toolchain-tarball" target="_top">Using a Cross-Toolchain Tarball</a>" and
347 "<a class="link" href="#using-the-toolchain-from-within-the-build-tree" target="_top">Using BitBake and the Build Directory</a>" sections in the Yocto Project Application Developer's Guide.
348 </p></div><div class="section" title="5.2.2. Downloading the Pre-Built Linux Kernel"><div class="titlepage"><div><div><h4 class="title"><a id="downloading-the-pre-built-linux-kernel"></a>5.2.2. Downloading the Pre-Built Linux Kernel</h4></div></div></div><p>
349 You can download the pre-built Linux kernel suitable for running in the QEMU emulator from
350 <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/qemu" target="_top">http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/qemu</a>.
351 Be sure to use the kernel that matches the architecture you want to simulate.
352 Download areas exist for the five supported machine architectures:
353 <code class="filename">qemuarm</code>, <code class="filename">qemumips</code>, <code class="filename">qemuppc</code>,
354 <code class="filename">qemux86</code>, and <code class="filename">qemux86-64</code>.
355 </p><p>
356 Most kernel files have one of the following forms:
357 </p><pre class="literallayout">
358 *zImage-qemu&lt;<span class="emphasis"><em>arch</em></span>&gt;.bin
359 vmlinux-qemu&lt;<span class="emphasis"><em>arch</em></span>&gt;.bin
360
361 Where:
362 &lt;<span class="emphasis"><em>arch</em></span>&gt; is a string representing the target architecture:
363 x86, x86-64, ppc, mips, or arm.
364 </pre><p>
365 </p><p>
366 You can learn more about downloading a Yocto Project kernel in the
367 "<a class="link" href="#local-kernel-files" target="_top">Yocto Project Kernel</a>"
368 bulleted item in the Yocto Project Development Manual.
369 </p></div><div class="section" title="5.2.3. Downloading the Filesystem"><div class="titlepage"><div><div><h4 class="title"><a id="downloading-the-filesystem"></a>5.2.3. Downloading the Filesystem</h4></div></div></div><p>
370 You can also download the filesystem image suitable for your target architecture from
371 <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/qemu" target="_top">http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/qemu</a>.
372 Again, be sure to use the filesystem that matches the architecture you want
373 to simulate.
374 </p><p>
375 The filesystem image has two tarball forms: <code class="filename">ext3</code> and
376 <code class="filename">tar</code>.
377 You must use the <code class="filename">ext3</code> form when booting an image using the
378 QEMU emulator.
379 The <code class="filename">tar</code> form can be flattened out in your host development system
380 and used for build purposes with the Yocto Project.
381 </p><pre class="literallayout">
382 core-image-&lt;<span class="emphasis"><em>profile</em></span>&gt;-qemu&lt;<span class="emphasis"><em>arch</em></span>&gt;.ext3
383 core-image-&lt;<span class="emphasis"><em>profile</em></span>&gt;-qemu&lt;<span class="emphasis"><em>arch</em></span>&gt;.tar.bz2
384
385 Where:
386 &lt;<span class="emphasis"><em>profile</em></span>&gt; is the filesystem image's profile:
387 lsb, lsb-dev, lsb-sdk, lsb-qt3, minimal, minimal-dev, sato, sato-dev, or sato-sdk.
388 For information on these types of image profiles, see the
389 "<a class="link" href="#ref-images" target="_top">Images</a>" chapter
390 in the Yocto Project Reference Manual.
391
392 &lt;<span class="emphasis"><em>arch</em></span>&gt; is a string representing the target architecture:
393 x86, x86-64, ppc, mips, or arm.
394 </pre><p>
395 </p></div><div class="section" title="5.2.4. Setting Up the Environment and Starting the QEMU Emulator"><div class="titlepage"><div><div><h4 class="title"><a id="setting-up-the-environment-and-starting-the-qemu-emulator"></a>5.2.4. Setting Up the Environment and Starting the QEMU Emulator</h4></div></div></div><p>
396 Before you start the QEMU emulator, you need to set up the emulation environment.
397 The following command form sets up the emulation environment.
398 </p><pre class="literallayout">
399 $ source /opt/poky/1.3/environment-setup-&lt;<span class="emphasis"><em>arch</em></span>&gt;-poky-linux-&lt;<span class="emphasis"><em>if</em></span>&gt;
400
401 Where:
402 &lt;<span class="emphasis"><em>arch</em></span>&gt; is a string representing the target architecture:
403 i586, x86_64, ppc603e, mips, or armv5te.
404
405 &lt;<span class="emphasis"><em>if</em></span>&gt; is a string representing an embedded application binary interface.
406 Not all setup scripts include this string.
407 </pre><p>
408 </p><p>
409 Finally, this command form invokes the QEMU emulator
410 </p><pre class="literallayout">
411 $ runqemu &lt;<span class="emphasis"><em>qemuarch</em></span>&gt; &lt;<span class="emphasis"><em>kernel-image</em></span>&gt; &lt;<span class="emphasis"><em>filesystem-image</em></span>&gt;
412
413 Where:
414 &lt;<span class="emphasis"><em>qemuarch</em></span>&gt; is a string representing the target architecture: qemux86, qemux86-64,
415 qemuppc, qemumips, or qemuarm.
416
417 &lt;<span class="emphasis"><em>kernel-image</em></span>&gt; is the architecture-specific kernel image.
418
419 &lt;<span class="emphasis"><em>filesystem-image</em></span>&gt; is the .ext3 filesystem image.
420
421 </pre><p>
422 </p><p>
423 Continuing with the example, the following two commands setup the emulation
424 environment and launch QEMU.
425 This example assumes the root filesystem (<code class="filename">.ext3</code> file) and
426 the pre-built kernel image file both reside in your home directory.
427 The kernel and filesystem are for a 32-bit target architecture.
428 </p><pre class="literallayout">
429 $ cd $HOME
430 $ source /opt/poky/1.3/environment-setup-i586-poky-linux
431 $ runqemu qemux86 bzImage-qemux86.bin \
432 core-image-sato-qemux86.ext3
433 </pre><p>
434 </p><p>
435 The environment in which QEMU launches varies depending on the filesystem image and on the
436 target architecture.
437 For example, if you source the environment for the ARM target
438 architecture and then boot the minimal QEMU image, the emulator comes up in a new
439 shell in command-line mode.
440 However, if you boot the SDK image, QEMU comes up with a GUI.
441 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Booting the PPC image results in QEMU launching in the same shell in
442 command-line mode.</div><p>
443 </p></div></div></div><div class="section" title="6. Super User"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="super-user"></a>6. Super User
444</h2></div></div></div><p>
445 This section
446 <sup>[<a id="id1482592" href="#ftn.id1482592" class="footnote">1</a>]</sup>
447 gives you a very fast description of how to use the Yocto Project to build images
448 for a BeagleBoard xM starting from scratch.
449 The steps were performed on a 64-bit Ubuntu 10.04 system.
450 </p><div class="section" title="6.1. Getting the Yocto Project"><div class="titlepage"><div><div><h3 class="title"><a id="getting-yocto"></a>6.1. Getting the Yocto Project</h3></div></div></div><p>
451 Set up your <a class="link" href="#source-directory" target="_top">source directory</a>
452 one of two ways:
453 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Tarball:</em></span>
454 Use if you want the latest stable release:
455 </p><pre class="literallayout">
456 $ wget http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/poky-1.2+snapshot-8.0.tar.bz2
457 $ tar xvjf poky-1.2+snapshot-8.0.tar.bz2
458 </pre></li><li class="listitem"><p><span class="emphasis"><em>Git Repository:</em></span>
459 Use if you want to work with cutting edge development content:
460 </p><pre class="literallayout">
461 $ git clone git://git.yoctoproject.org/poky
462 </pre></li></ul></div><p>
463 The remainder of the section assumes the Git repository method.
464 </p></div><div class="section" title="6.2. Setting Up Your Host"><div class="titlepage"><div><div><h3 class="title"><a id="setting-up-your-host"></a>6.2. Setting Up Your Host</h3></div></div></div><p>
465 You need some packages for everything to work.
466 Rather than duplicate them here, look at the "<a class="link" href="#packages" title="4.2. The Packages">The Packages</a>"
467 section earlier in this quick start.
468 </p></div><div class="section" title="6.3. Initializing the Build Environment"><div class="titlepage"><div><div><h3 class="title"><a id="initializing-the-build-environment"></a>6.3. Initializing the Build Environment</h3></div></div></div><p>
469 From the parent directory of local source directory, initialize your environment
470 and provide a meaningful
471 <a class="link" href="#build-directory" target="_top">build directory</a>
472 name:
473 </p><pre class="literallayout">
474 $ source poky/oe-init-build-env mybuilds
475 </pre><p>
476 At this point, the <code class="filename">mybuilds</code> directory has been created for you
477 and it is now your current working directory.
478 If you don't provide your own directory name it defaults to <code class="filename">build</code>.
479 </p></div><div class="section" title="6.4. Configuring the local.conf File"><div class="titlepage"><div><div><h3 class="title"><a id="configuring-the-local.conf-file"></a>6.4. Configuring the local.conf File</h3></div></div></div><p>
480 Initializing the build environment creates a <code class="filename">conf/local.conf</code> configuration file
481 in the build directory.
482 You need to manually edit this file to specify the machine you are building and to optimize
483 your build time.
484 Here are the minimal changes to make:
485 </p><pre class="literallayout">
486 BB_NUMBER_THREADS = "8"
487 PARALLEL_MAKE = "-j 8"
488 MACHINE ?= "beagleboard"
489 </pre><p>
490 Briefly, set <a class="link" href="#var-BB_NUMBER_THREADS" target="_top"><code class="filename">BB_NUMBER_THREADS</code></a>
491 and <a class="link" href="#var-PARALLEL_MAKE" target="_top"><code class="filename">PARALLEL_MAKE</code></a> to
492 twice your host processor's number of cores.
493 </p><p>
494 A good deal that goes into a Yocto Project build is simply downloading all of the source
495 tarballs.
496 Maybe you have been working with another build system (OpenEmbedded, Angstrom, etc) for which
497 you've built up a sizable directory of source tarballs.
498 Or perhaps someone else has such a directory for which you have read access.
499 If so, you can save time by adding the <code class="filename">PREMIRRORS</code>
500 statement to your configuration file so that local directories are first checked for existing
501 tarballs before running out to the net:
502 </p><pre class="literallayout">
503 PREMIRRORS_prepend = "\
504 git://.*/.* file:///home/you/dl/ \n \
505 svn://.*/.* file:///home/you/dl/ \n \
506 cvs://.*/.* file:///home/you/dl/ \n \
507 ftp://.*/.* file:///home/you/dl/ \n \
508 http://.*/.* file:///home/you/dl/ \n \
509 https://.*/.* file:///home/you/dl/ \n"
510 </pre><p>
511 </p></div><div class="section" title="6.5. Building the Image"><div class="titlepage"><div><div><h3 class="title"><a id="building-the-image"></a>6.5. Building the Image</h3></div></div></div><p>
512 At this point, you need to select an image to build for the BeagleBoard xM.
513 If this is your first build using the Yocto Project, you should try the smallest and simplest
514 image:
515 </p><pre class="literallayout">
516 $ bitbake core-image-minimal
517 </pre><p>
518 Now you just wait for the build to finish.
519 </p><p>
520 Here are some variations on the build process that could be helpful:
521 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Fetch all the necessary sources without starting the build:
522 </p><pre class="literallayout">
523 $ bitbake -c fetchall core-image-minimal
524 </pre><p>
525 This variation guarantees that you have all the sources for that BitBake target
526 should you to disconnect from the net and want to do the build later offline.
527 </p></li><li class="listitem"><p>Specify to continue the build even if BitBake encounters an error.
528 By default, BitBake aborts the build when it encounters an error.
529 This command keeps a faulty build going:
530 </p><pre class="literallayout">
531 $ bitbake -k core-image-minimal
532 </pre></li></ul></div><p>
533 </p><p>
534 Once you have your image, you can take steps to load and boot it on the target hardware.
535 </p></div></div><div class="footnotes"><br /><hr width="100" align="left" /><div class="footnote"><p><sup>[<a id="ftn.id1482592" href="#id1482592" class="para">1</a>] </sup>
536 Kudos and thanks to Robert P. J. Day of
537 <a class="ulink" href="http://www.crashcourse.ca" target="_top">CrashCourse</a> for providing the basis
538 for this "expert" section with information from one of his
539 <a class="ulink" href="http://www.crashcourse.ca/wiki/index.php/Yocto_Project_Quick_Start" target="_top">wiki</a>
540 pages.
541 </p></div></div></div>
542
543<table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="100%"><tr><td align="left"><img src="figures/dev-title.png" align="left" width="100%" /></td></tr></table>
544
545 <div xml:lang="en" class="book" lang="en"><div class="titlepage"><div><div><h1 class="title"><a id="dev-manual"></a></h1></div><div><div class="authorgroup">
546 <div class="author"><h3 class="author"><span class="firstname">Scott</span> <span class="surname">Rifenbark</span></h3><div class="affiliation">
547 <span class="orgname">Intel Corporation<br /></span>
548 </div><code class="email">&lt;<a class="email" href="mailto:scott.m.rifenbark@intel.com">scott.m.rifenbark@intel.com</a>&gt;</code></div>
549 </div></div><div><p class="copyright">Copyright © 2010-2012 Linux Foundation</p></div><div><div class="legalnotice" title="Legal Notice"><a id="id1482939"></a>
550 <p>
551 Permission is granted to copy, distribute and/or modify this document under
552 the terms of the <a class="ulink" href="http://creativecommons.org/licenses/by-sa/2.0/uk/" target="_top">
553 Creative Commons Attribution-Share Alike 2.0 UK: England &amp; Wales</a> as published by
554 Creative Commons.
555 </p>
556
557 <div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
558 Due to production processes, there could be differences between the Yocto Project
559 documentation bundled in the release tarball and the
560 Yocto Project Development Manual on
561 the <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project</a> website.
562 For the latest version of this manual, see the manual on the website.
563 </div>
564 </div></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr>
565 <tr><td align="left">Revision 1.1</td><td align="left">6 October 2011</td></tr><tr><td align="left" colspan="2">The initial document released with the Yocto Project 1.1 Release.</td></tr>
566 <tr><td align="left">Revision 1.2</td><td align="left">April 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.2 Release.</td></tr>
567 <tr><td align="left">Revision 1.3</td><td align="left">Sometime in 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.3 Release.</td></tr>
568 </table></div></div></div><hr /></div>
569
570
571 <div class="chapter" title="Chapter 1. The Yocto Project Development Manual"><div class="titlepage"><div><div><h2 class="title"><a id="dev-manual-intro"></a>Chapter 1. The Yocto Project Development Manual</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#intro">1.1. Introduction</a></span></dt><dt><span class="section"><a href="#what-this-manual-provides">1.2. What this Manual Provides</a></span></dt><dt><span class="section"><a href="#what-this-manual-does-not-provide">1.3. What this Manual Does Not Provide</a></span></dt><dt><span class="section"><a href="#other-information">1.4. Other Information</a></span></dt></dl></div><div class="section" title="1.1. Introduction"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="intro"></a>1.1. Introduction</h2></div></div></div><p>
572 Welcome to the Yocto Project Development Manual!
573 This manual gives you an idea of how to use the Yocto Project to develop embedded Linux
574 images and user-space applications to run on targeted devices.
575 Reading this manual gives you an overview of image, kernel, and user-space application development
576 using the Yocto Project.
577 Because much of the information in this manual is general, it contains many references to other
578 sources where you can find more detail.
579 For example, detailed information on Git, repositories and open source in general
580 can be found in many places.
581 Another example is how to get set up to use the Yocto Project, which our Yocto Project
582 Quick Start covers.
583 </p><p>
584 The Yocto Project Development Manual, however, does provide detailed examples on how to create a
585 Board Support Package (BSP), change the kernel source code, and reconfigure the kernel.
586 You can find this information in the appendices of the manual.
587 </p></div><div class="section" title="1.2. What this Manual Provides"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="what-this-manual-provides"></a>1.2. What this Manual Provides</h2></div></div></div><p>
588 The following list describes what you can get from this guide:
589 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Information that lets you get set
590 up to develop using the Yocto Project.</p></li><li class="listitem"><p>Information to help developers who are new to the open source environment
591 and to the distributed revision control system Git, which the Yocto Project
592 uses.</p></li><li class="listitem"><p>An understanding of common end-to-end development models and tasks.</p></li><li class="listitem"><p>Development case overviews for both system development and user-space
593 applications.</p></li><li class="listitem"><p>An overview and understanding of the emulation environment used with
594 the Yocto Project (QEMU).</p></li><li class="listitem"><p>An understanding of basic kernel architecture and concepts.</p></li><li class="listitem"><p>Many references to other sources of related information.</p></li></ul></div><p>
595 </p></div><div class="section" title="1.3. What this Manual Does Not Provide"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="what-this-manual-does-not-provide"></a>1.3. What this Manual Does Not Provide</h2></div></div></div><p>
596 This manual will not give you the following:
597 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Step-by-step instructions if those instructions exist in other Yocto
598 Project documentation.
599 For example, the Yocto Project Development Manual contains detailed
600 instruction on how to obtain and configure the
601 <span class="trademark">Eclipse</span>™ Yocto Plug-in.</p></li><li class="listitem"><p>Reference material.
602 This type of material resides in an appropriate reference manual.
603 For example, system variables are documented in the
604 Yocto Project Reference Manual.</p></li><li class="listitem"><p>Detailed public information that is not specific to the Yocto Project.
605 For example, exhaustive information on how to use Git is covered better through the
606 Internet than in this manual.</p></li></ul></div><p>
607 </p></div><div class="section" title="1.4. Other Information"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="other-information"></a>1.4. Other Information</h2></div></div></div><p>
608 Because this manual presents overview information for many different topics, you will
609 need to supplement it with other information.
610 The following list presents other sources of information you might find helpful:
611 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>The <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project Website</a>:
612 </em></span> The home page for the Yocto Project provides lots of information on the project
613 as well as links to software and documentation.</p></li><li class="listitem"><p><span class="emphasis"><em>
614 Yocto Project Quick Start:</em></span> This short document lets you get started
615 with the Yocto Project quickly and start building an image.</p></li><li class="listitem"><p><span class="emphasis"><em>
616 Yocto Project Reference Manual:</em></span> This manual is a reference
617 guide to the OpenEmbedded build system known as "Poky."
618 The manual also contains a reference chapter on Board Support Package (BSP)
619 layout.</p></li><li class="listitem"><p><span class="emphasis"><em>
620 Yocto Project Application Developer's Guide:</em></span>
621 This guide provides information that lets you get going with the Application
622 Development Toolkit (ADT) and stand-alone cross-development toolchains to
623 develop projects using the Yocto Project.</p></li><li class="listitem"><p><span class="emphasis"><em>
624 Yocto Project Board Support Package (BSP) Developer's Guide:</em></span>
625 This guide defines the structure for BSP components.
626 Having a commonly understood structure encourages standardization.</p></li><li class="listitem"><p><span class="emphasis"><em>
627 Yocto Project Kernel Architecture and Use Manual:</em></span>
628 This manual describes the architecture of the Yocto Project kernel and provides
629 some work flow examples.</p></li><li class="listitem"><p><span class="emphasis"><em>
630 <a class="ulink" href="http://www.youtube.com/watch?v=3ZlOu-gLsh0" target="_top">
631 Eclipse IDE Yocto Plug-in</a>:</em></span> A step-by-step instructional video that
632 demonstrates how an application developer uses Yocto Plug-in features within
633 the Eclipse IDE.</p></li><li class="listitem"><p><span class="emphasis"><em>
634 <a class="ulink" href="https://wiki.yoctoproject.org/wiki/FAQ" target="_top">FAQ</a>:</em></span>
635 A list of commonly asked questions and their answers.</p></li><li class="listitem"><p><span class="emphasis"><em>
636 <a class="ulink" href="http://www.yoctoproject.org/download/yocto/yocto-project-1.1-release-notes-poky-8.0" target="_top">
637 Release Notes</a>:</em></span> Features, updates and known issues for the current
638 release of the Yocto Project.</p></li><li class="listitem"><p><span class="emphasis"><em>
639 <a class="ulink" href="http://www.yoctoproject.org/projects/hob" target="_top">
640 Hob</a>:</em></span> A graphical user interface for BitBake.
641 Hob's primary goal is to enable a user to perform common tasks more easily.</p></li><li class="listitem"><p><span class="emphasis"><em>
642 <a class="ulink" href="http://www.yoctoproject.org/documentation/build-appliance" target="_top">
643 Build Appliance</a>:</em></span> A bootable custom embedded Linux image you can
644 either build using a non-Linux development system (VMware applications) or download
645 from the Yocto Project website.
646 See the <a class="ulink" href="http://www.yoctoproject.org/documentation/build-appliance" target="_top">Build Appliance</a>
647 page for more information.</p></li><li class="listitem"><p><span class="emphasis"><em>
648 <a class="ulink" href="http://bugzilla.yoctoproject.org" target="_top">Bugzilla</a>:</em></span>
649 The bug tracking application the Yocto Project uses.
650 If you find problems with the Yocto Project, you should report them using this
651 application.</p></li><li class="listitem"><p><span class="emphasis"><em>
652 Yocto Project Mailing Lists:</em></span> To subscribe to the Yocto Project mailing
653 lists, click on the following URLs and follow the instructions:
654 </p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p><a class="ulink" href="http://lists.yoctoproject.org/listinfo/yocto" target="_top">http://lists.yoctoproject.org/listinfo/yocto</a> for a
655 Yocto Project Discussions mailing list.</p></li><li class="listitem"><p><a class="ulink" href="http://lists.yoctoproject.org/listinfo/poky" target="_top">http://lists.yoctoproject.org/listinfo/poky</a> for a
656 Yocto Project Discussions mailing list about the Poky build system.</p></li><li class="listitem"><p><a class="ulink" href="http://lists.yoctoproject.org/listinfo/yocto-announce" target="_top">http://lists.yoctoproject.org/listinfo/yocto-announce</a>
657 for a mailing list to receive official Yocto Project announcements for developments and
658 as well as Yocto Project milestones.</p></li></ul></div></li><li class="listitem"><p><span class="emphasis"><em>Internet Relay Chat (IRC):</em></span>
659 Two IRC channels on freenode are available
660 for Yocto Project and Poky discussions: <code class="filename">#yocto</code> and
661 <code class="filename">#poky</code>, respectively.</p></li><li class="listitem"><p><span class="emphasis"><em>
662 <a class="ulink" href="http://o-hand.com" target="_top">OpenedHand</a>:</em></span>
663 The company that initially developed the Poky project, which is the basis
664 for the OpenEmbedded build system used by the Yocto Project.
665 OpenedHand was acquired by Intel Corporation in 2008.</p></li><li class="listitem"><p><span class="emphasis"><em>
666 <a class="ulink" href="http://www.intel.com/" target="_top">Intel Corporation</a>:</em></span>
667 A multinational semiconductor chip manufacturer company whose Software and
668 Services Group created and supports the Yocto Project.
669 Intel acquired OpenedHand in 2008.</p></li><li class="listitem"><p><span class="emphasis"><em>
670 <a class="ulink" href="http://www.openembedded.org" target="_top">OpenEmbedded</a>:</em></span>
671 The build system used by the Yocto Project.
672 This project is the upstream, generic, embedded distribution from which the Yocto
673 Project derives its build system (Poky) from and to which it contributes.</p></li><li class="listitem"><p><span class="emphasis"><em>
674 <a class="ulink" href="http://developer.berlios.de/projects/bitbake/" target="_top">
675 BitBake</a>:</em></span> The tool used by the OpenEmbedded build system
676 to process project metadata.</p></li><li class="listitem"><p><span class="emphasis"><em>
677 <a class="ulink" href="http://docs.openembedded.org/bitbake/html/" target="_top">
678 BitBake User Manual</a>:</em></span> A comprehensive guide to the BitBake tool.
679 </p></li><li class="listitem"><p><span class="emphasis"><em>
680 <a class="ulink" href="http://wiki.qemu.org/Index.html" target="_top">QEMU</a>:
681 </em></span> An open-source machine emulator and virtualizer.</p></li></ul></div><p>
682 </p></div></div>
683
684 <div class="chapter" title="Chapter 2. Getting Started with the Yocto Project"><div class="titlepage"><div><div><h2 class="title"><a id="dev-manual-start"></a>Chapter 2. Getting Started with the Yocto Project</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#introducing-the-yocto-project">2.1. Introducing the Yocto Project</a></span></dt><dt><span class="section"><a href="#getting-setup">2.2. Getting Set Up</a></span></dt><dt><span class="section"><a href="#building-images">2.3. Building Images</a></span></dt><dt><span class="section"><a href="#using-pre-built-binaries-and-qemu">2.4. Using Pre-Built Binaries and QEMU</a></span></dt></dl></div><p>
685 This chapter introduces the Yocto Project and gives you an idea of what you need to get started.
686 You can find enough information to set up your development host and build or use images for
687 hardware supported by the Yocto Project by reading the
688 Yocto Project Quick Start.
689</p><p>
690 The remainder of this chapter summarizes what is in the Yocto Project Quick Start and provides
691 some higher-level concepts you might want to consider.
692</p><div class="section" title="2.1. Introducing the Yocto Project"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="introducing-the-yocto-project"></a>2.1. Introducing the Yocto Project</h2></div></div></div><p>
693 The Yocto Project is an open-source collaboration project focused on embedded Linux development.
694 The project currently provides a build system, which is
695 referred to as the OpenEmbedded build system in the Yocto Project documentation.
696 The Yocto Project provides various ancillary tools suitable for the embedded developer
697 and also features the Sato reference User Interface, which is optimized for
698 stylus driven, low-resolution screens.
699 </p><p>
700 You can use the OpenEmbedded build system, which uses
701 <a class="ulink" href="http://docs.openembedded.org/bitbake/html/" target="_top">BitBake</a>, to develop complete Linux
702 images and associated user-space applications for architectures based on ARM, MIPS, PowerPC,
703 x86 and x86-64.
704 While the Yocto Project does not provide a strict testing framework,
705 it does provide or generate for you artifacts that let you perform target-level and
706 emulated testing and debugging.
707 Additionally, if you are an <span class="trademark">Eclipse</span>™
708 IDE user, you can install an Eclipse Yocto Plug-in to allow you to
709 develop within that familiar environment.
710 </p></div><div class="section" title="2.2. Getting Set Up"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="getting-setup"></a>2.2. Getting Set Up</h2></div></div></div><p>
711 Here is what you need to get set up to use the Yocto Project:
712 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Host System:</em></span> You should have a reasonably current
713 Linux-based host system.
714 You will have the best results with a recent release of Fedora,
715 OpenSUSE, Ubuntu, or CentOS as these releases are frequently tested against the Yocto Project
716 and officially supported.
717 You should also have about 100 gigabytes of free disk space for building images.
718 </p></li><li class="listitem"><p><span class="emphasis"><em>Packages:</em></span> The OpenEmbedded build system
719 requires certain packages exist on your development system (e.g. Python 2.6 or 2.7).
720 See "<a class="link" href="#packages" target="_top">The Packages</a>"
721 section in the Yocto Project Quick Start for the exact package
722 requirements and the installation commands to install them
723 for the supported distributions.</p></li><li class="listitem"><p><a id="local-yp-release"></a><span class="emphasis"><em>Yocto Project Release:</em></span>
724 You need a release of the Yocto Project.
725 You set up a with local <a class="link" href="#source-directory">source directory</a>
726 one of two ways depending on whether you
727 are going to contribute back into the Yocto Project or not.
728 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
729 Regardless of the method you use, this manual refers to the resulting local
730 hierarchical set of files as the "source directory."
731 </div><p>
732 </p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p><span class="emphasis"><em>Tarball Extraction:</em></span> If you are not going to contribute
733 back into the Yocto Project, you can simply download a Yocto Project release you want
734 from the website’s <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">download page</a>.
735 Once you have the tarball, just extract it into a directory of your choice.</p><p>For example, the following command extracts the Yocto Project 1.3
736 release tarball
737 into the current working directory and sets up the local source directory
738 with a top-level folder named <code class="filename">poky-1.2+snapshot-8.0</code>:
739 </p><pre class="literallayout">
740 $ tar xfj poky-1.2+snapshot-8.0.tar.bz2
741 </pre><p>This method does not produce a local Git repository.
742 Instead, you simply end up with a snapshot of the release.</p></li><li class="listitem"><p><span class="emphasis"><em>Git Repository Method:</em></span> If you are going to be contributing
743 back into the Yocto Project or you simply want to keep up
744 with the latest developments, you should use Git commands to set up a local
745 Git repository of the upstream <code class="filename">poky</code> source repository.
746 Doing so creates a repository with a complete history of changes and allows
747 you to easily submit your changes upstream to the project.
748 Because you cloned the repository, you have access to all the Yocto Project development
749 branches and tag names used in the upstream repository.</p><p>The following transcript shows how to clone the <code class="filename">poky</code>
750 Git repository into the current working directory.
751 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>You can view the Yocto Project Source Repositories at
752 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a></div><p>
753 The command creates the local repository in a directory named <code class="filename">poky</code>.
754 For information on Git used within the Yocto Project, see the
755 "<a class="link" href="#git" title="3.6. Git">Git</a>" section.
756 </p><pre class="literallayout">
757 $ git clone git://git.yoctoproject.org/poky
758 Initialized empty Git repository in /home/scottrif/poky/.git/
759 remote: Counting objects: 141863, done.
760 remote: Compressing objects: 100% (38624/38624), done.
761 remote: Total 141863 (delta 99661), reused 141816 (delta 99614)
762 Receiving objects: 100% (141863/141863), 76.64 MiB | 126 KiB/s, done.
763 Resolving deltas: 100% (99661/99661), done.
764 </pre><p>For another example of how to set up your own local Git repositories, see this
765 <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Transcript:_from_git_checkout_to_meta-intel_BSP" target="_top">
766 wiki page</a>, which describes how to create both <code class="filename">poky</code>
767 and <code class="filename">meta-intel</code> Git repositories.</p></li></ul></div></li><li class="listitem"><p><a id="local-kernel-files"></a><span class="emphasis"><em>Yocto Project Kernel:</em></span>
768 If you are going to be making modifications to a supported Yocto Project kernel, you
769 need to establish local copies of the source.
770 You can find Git repositories of supported Yocto Project Kernels organized under
771 "Yocto Project Linux Kernel" in the Yocto Project Source Repositories at
772 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a>.</p><p>This setup involves creating a bare clone of the Yocto Project kernel and then
773 copying that cloned repository.
774 You can create the bare clone and the copy of the bare clone anywhere you like.
775 For simplicity, it is recommended that you create these structures outside of the
776 source directory (usually <code class="filename">poky</code>).</p><p>As an example, the following transcript shows how to create the bare clone
777 of the <code class="filename">linux-yocto-3.2</code> kernel and then create a copy of
778 that clone.
779 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>When you have a local Yocto Project kernel Git repository, you can
780 reference that repository rather than the upstream Git repository as
781 part of the <code class="filename">clone</code> command.
782 Doing so can speed up the process.</div><p>In the following example, the bare clone is named
783 <code class="filename">linux-yocto-3.2.git</code>, while the
784 copy is named <code class="filename">my-linux-yocto-3.2-work</code>:
785 </p><pre class="literallayout">
786 $ git clone --bare git://git.yoctoproject.org/linux-yocto-3.2 linux-yocto-3.2.git
787 Initialized empty Git repository in /home/scottrif/linux-yocto-3.2.git/
788 remote: Counting objects: 2468027, done.
789 remote: Compressing objects: 100% (392255/392255), done.
790 remote: Total 2468027 (delta 2071693), reused 2448773 (delta 2052498)
791 Receiving objects: 100% (2468027/2468027), 530.46 MiB | 129 KiB/s, done.
792 Resolving deltas: 100% (2071693/2071693), done.
793 </pre><p>Now create a clone of the bare clone just created:
794 </p><pre class="literallayout">
795 $ git clone linux-yocto-3.2.git my-linux-yocto-3.2-work
796 Initialized empty Git repository in /home/scottrif/my-linux-yocto-3.2-work/.git/
797 Checking out files: 100% (37619/37619), done.
798 </pre></li><li class="listitem"><p><a id="poky-extras-repo"></a><span class="emphasis"><em>
799 The <code class="filename">poky-extras</code> Git Repository</em></span>:
800 The <code class="filename">poky-extras</code> Git repository contains metadata needed
801 only if you are modifying and building the kernel image.
802 In particular, it contains the kernel BitBake append (<code class="filename">.bbappend</code>)
803 files that you
804 edit to point to your locally modified kernel source files and to build the kernel
805 image.
806 Pointing to these local files is much more efficient than requiring a download of the
807 kernel's source files from upstream each time you make changes to the kernel.</p><p>You can find the <code class="filename">poky-extras</code> Git Repository in the
808 "Yocto Metadata Layers" area of the Yocto Project Source Repositories at
809 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a>.
810 It is good practice to create this Git repository inside the source directory.</p><p>Following is an example that creates the <code class="filename">poky-extras</code> Git
811 repository inside the source directory, which is named <code class="filename">poky</code>
812 in this case:
813 </p><pre class="literallayout">
814 $ git clone git://git.yoctoproject.org/poky-extras poky-extras
815 Initialized empty Git repository in /home/scottrif/poky/poky-extras/.git/
816 remote: Counting objects: 618, done.
817 remote: Compressing objects: 100% (558/558), done.
818 remote: Total 618 (delta 192), reused 307 (delta 39)
819 Receiving objects: 100% (618/618), 526.26 KiB | 111 KiB/s, done.
820 Resolving deltas: 100% (192/192), done.
821 </pre></li><li class="listitem"><p><a id="supported-board-support-packages-(bsps)"></a><span class="emphasis"><em>Supported Board
822 Support Packages (BSPs):</em></span>
823 The Yocto Project provides a layer called <code class="filename">meta-intel</code> and
824 it is maintained in its own separate Git repository.
825 The <code class="filename">meta-intel</code> layer contains many supported
826 <a class="link" href="#bsp-layers" target="_top">BSP Layers</a>.</p><p>Similar considerations exist for setting up the <code class="filename">meta-intel</code>
827 layer.
828 You can get set up for BSP development one of two ways: tarball extraction or
829 with a local Git repository.
830 It is a good idea to use the same method that you used to set up the source directory.
831 Regardless of the method you use, the Yocto Project uses the following BSP layer
832 naming scheme:
833 </p><pre class="literallayout">
834 meta-&lt;BSP_name&gt;
835 </pre><p>
836 where &lt;BSP_name&gt; is the recognized BSP name.
837 Here are some examples:
838 </p><pre class="literallayout">
839 meta-crownbay
840 meta-emenlow
841 meta-n450
842 </pre><p>
843 See the
844 "<a class="link" href="#bsp-layers" target="_top">BSP Layers</a>"
845 section in the Yocto Project Board Support Package (BSP) Developer's Guide for more
846 information on BSP Layers.
847 </p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p><span class="emphasis"><em>Tarball Extraction:</em></span> You can download any released
848 BSP tarball from the same
849 <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">download site</a> used
850 to get the Yocto Project release.
851 Once you have the tarball, just extract it into a directory of your choice.
852 Again, this method just produces a snapshot of the BSP layer in the form
853 of a hierarchical directory structure.</p></li><li class="listitem"><p><span class="emphasis"><em>Git Repository Method:</em></span> If you are working
854 with a local Git repository for your source directory, you should also use this method
855 to set up the <code class="filename">meta-intel</code> Git repository.
856 You can locate the <code class="filename">meta-intel</code> Git repository in the
857 "Yocto Metadata Layers" area of the Yocto Project Source Repositories at
858 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a>.</p><p>Typically, you set up the <code class="filename">meta-intel</code> Git repository inside
859 the source directory.
860 For example, the following transcript shows the steps to clone the
861 <code class="filename">meta-intel</code>
862 Git repository inside the local <code class="filename">poky</code> Git repository.
863 </p><pre class="literallayout">
864 $ git clone git://git.yoctoproject.org/meta-intel.git
865 Initialized empty Git repository in /home/scottrif/poky/meta-intel/.git/
866 remote: Counting objects: 3380, done.
867 remote: Compressing objects: 100% (2750/2750), done.
868 remote: Total 3380 (delta 1689), reused 227 (delta 113)
869 Receiving objects: 100% (3380/3380), 1.77 MiB | 128 KiB/s, done.
870 Resolving deltas: 100% (1689/1689), done.
871 </pre><p>The same
872 <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Transcript:_from_git_checkout_to_meta-intel_BSP" target="_top">
873 wiki page</a> referenced earlier covers how to
874 set up the <code class="filename">meta-intel</code> Git repository.</p></li></ul></div></li><li class="listitem"><p><span class="emphasis"><em>Eclipse Yocto Plug-in:</em></span> If you are developing
875 applications using the Eclipse Integrated Development Environment (IDE),
876 you will need this plug-in.
877 See the
878 "<a class="link" href="#setting-up-the-eclipse-ide" title="5.2.2.1. Setting Up the Eclipse IDE">Setting up the Eclipse IDE</a>"
879 section for more information.</p></li></ul></div><p>
880 </p></div><div class="section" title="2.3. Building Images"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="building-images"></a>2.3. Building Images</h2></div></div></div><p>
881 The build process creates an entire Linux distribution, including the toolchain, from source.
882 For more information on this topic, see the
883 "<a class="link" href="#building-image" target="_top">Building an Image</a>"
884 section in the Yocto Project Quick Start.
885 </p><p>
886 The build process is as follows:
887 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Make sure you have set up the source directory described in the
888 previous section.</p></li><li class="listitem"><p>Initialize the build environment by sourcing a build environment
889 script.</p></li><li class="listitem"><p>Optionally ensure the <code class="filename">conf/local.conf</code> configuration file,
890 which is found in the
891 <a class="link" href="#build-directory">build directory</a>,
892 is set up how you want it.
893 This file defines many aspects of the build environment including
894 the target machine architecture through the
895 <code class="filename"><a class="link" href="#var-MACHINE" target="_top">MACHINE</a></code> variable,
896 the development machine's processor use through the
897 <code class="filename"><a class="link" href="#var-BB_NUMBER_THREADS" target="_top">BB_NUMBER_THREADS</a></code> and
898 <code class="filename"><a class="link" href="#var-PARALLEL_MAKE" target="_top">PARALLEL_MAKE</a></code> variables, and
899 a centralized tarball download directory through the
900 <code class="filename"><a class="link" href="#var-DL_DIR" target="_top">DL_DIR</a></code> variable.</p></li><li class="listitem"><p>Build the image using the <code class="filename">bitbake</code> command.
901 If you want information on BitBake, see the user manual at
902 <a class="ulink" href="http://docs.openembedded.org/bitbake/html" target="_top">http://docs.openembedded.org/bitbake/html</a>.</p></li><li class="listitem"><p>Run the image either on the actual hardware or using the QEMU
903 emulator.</p></li></ol></div><p>
904 </p></div><div class="section" title="2.4. Using Pre-Built Binaries and QEMU"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="using-pre-built-binaries-and-qemu"></a>2.4. Using Pre-Built Binaries and QEMU</h2></div></div></div><p>
905 Another option you have to get started is to use pre-built binaries.
906 The Yocto Project provides many types of binaries with each release.
907 See the <a class="link" href="#ref-images" target="_top">Images</a>
908 chapter in the Yocto Project Reference Manual
909 for descriptions of the types of binaries that ship with a Yocto Project
910 release.
911 </p><p>
912 Using a pre-built binary is ideal for developing software applications to run on your
913 target hardware.
914 To do this, you need to be able to access the appropriate cross-toolchain tarball for
915 the architecture on which you are developing.
916 If you are using an SDK type image, the image ships with the complete toolchain native to
917 the architecture.
918 If you are not using an SDK type image, you need to separately download and
919 install the stand-alone Yocto Project cross-toolchain tarball.
920 </p><p>
921 Regardless of the type of image you are using, you need to download the pre-built kernel
922 that you will boot in the QEMU emulator and then download and extract the target root
923 filesystem for your target machine’s architecture.
924 You can get architecture-specific binaries and filesystem from
925 <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines" target="_top">machines</a>.
926 You can get stand-alone toolchains from
927 <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/toolchain/" target="_top">toolchains</a>.
928 Once you have all your files, you set up the environment to emulate the hardware
929 by sourcing an environment setup script.
930 Finally, you start the QEMU emulator.
931 You can find details on all these steps in the
932 "<a class="link" href="#using-pre-built" target="_top">Using Pre-Built Binaries and QEMU</a>"
933 section of the Yocto Project Quick Start.
934 </p><p>
935 Using QEMU to emulate your hardware can result in speed issues
936 depending on the target and host architecture mix.
937 For example, using the <code class="filename">qemux86</code> image in the emulator
938 on an Intel-based 32-bit (x86) host machine is fast because the target and
939 host architectures match.
940 On the other hand, using the <code class="filename">qemuarm</code> image on the same Intel-based
941 host can be slower.
942 But, you still achieve faithful emulation of ARM-specific issues.
943 </p><p>
944 To speed things up, the QEMU images support using <code class="filename">distcc</code>
945 to call a cross-compiler outside the emulated system.
946 If you used <code class="filename">runqemu</code> to start QEMU, and the
947 <code class="filename">distccd</code> application is present on the host system, any
948 BitBake cross-compiling toolchain available from the build system is automatically
949 used from within QEMU simply by calling <code class="filename">distcc</code>.
950 You can accomplish this by defining the cross-compiler variable
951 (e.g. <code class="filename">export CC="distcc"</code>).
952 Alternatively, if you are using a suitable SDK image or the appropriate
953 stand-alone toolchain is present in <code class="filename">/opt/poky</code>,
954 the toolchain is also automatically used.
955 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
956 Several mechanisms exist that let you connect to the system running on the
957 QEMU emulator:
958 <div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>QEMU provides a framebuffer interface that makes standard
959 consoles available.</p></li><li class="listitem"><p>Generally, headless embedded devices have a serial port.
960 If so, you can configure the operating system of the running image
961 to use that port to run a console.
962 The connection uses standard IP networking.</p></li><li class="listitem"><p>SSH servers exist in some QEMU images.
963 The <code class="filename">core-image-sato</code> QEMU image has a Dropbear secure
964 shell (ssh) server that runs with the root password disabled.
965 The <code class="filename">core-image-basic</code> and <code class="filename">core-image-lsb</code> QEMU images
966 have OpenSSH instead of Dropbear.
967 Including these SSH servers allow you to use standard <code class="filename">ssh</code> and
968 <code class="filename">scp</code> commands.
969 The <code class="filename">core-image-minimal</code> QEMU image, however, contains no ssh
970 server.</p></li><li class="listitem"><p>You can use a provided, user-space NFS server to boot the QEMU session
971 using a local copy of the root filesystem on the host.
972 In order to make this connection, you must extract a root filesystem tarball by using the
973 <code class="filename">runqemu-extract-sdk</code> command.
974 After running the command, you must then point the <code class="filename">runqemu</code>
975 script to the extracted directory instead of a root filesystem image file.</p></li></ul></div></div></div></div>
976
977 <div class="chapter" title="Chapter 3. The Yocto Project Open Source Development Environment"><div class="titlepage"><div><div><h2 class="title"><a id="dev-manual-newbie"></a>Chapter 3. The Yocto Project Open Source Development Environment</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#open-source-philosophy">3.1. Open Source Philosophy</a></span></dt><dt><span class="section"><a href="#usingpoky-changes-collaborate">3.2. Using the Yocto Project in a Team Environment</a></span></dt><dt><span class="section"><a href="#yocto-project-repositories">3.3. Yocto Project Source Repositories</a></span></dt><dt><span class="section"><a href="#yocto-project-terms">3.4. Yocto Project Terms</a></span></dt><dt><span class="section"><a href="#licensing">3.5. Licensing</a></span></dt><dt><span class="section"><a href="#git">3.6. Git</a></span></dt><dd><dl><dt><span class="section"><a href="#repositories-tags-and-branches">3.6.1. Repositories, Tags, and Branches</a></span></dt><dt><span class="section"><a href="#basic-commands">3.6.2. Basic Commands</a></span></dt></dl></dd><dt><span class="section"><a href="#workflows">3.7. Workflows</a></span></dt><dt><span class="section"><a href="#tracking-bugs">3.8. Tracking Bugs</a></span></dt><dt><span class="section"><a href="#how-to-submit-a-change">3.9. How to Submit a Change</a></span></dt><dd><dl><dt><span class="section"><a href="#pushing-a-change-upstream">3.9.1. Using Scripts to Push a Change Upstream and Request a Pull</a></span></dt><dt><span class="section"><a href="#submitting-a-patch">3.9.2. Using Email to Submit a Patch</a></span></dt></dl></dd></dl></div><p>
978 This chapter helps you understand the Yocto Project as an open source development project.
979 In general, working in an open source environment is very different from working in a
980 closed, proprietary environment.
981 Additionally, the Yocto Project uses specific tools and constructs as part of its development
982 environment.
983 This chapter specifically addresses open source philosophy, licensing issues, code repositories,
984 the open source distributed version control system Git, and best practices using the Yocto Project.
985</p><div class="section" title="3.1. Open Source Philosophy"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="open-source-philosophy"></a>3.1. Open Source Philosophy</h2></div></div></div><p>
986 Open source philosophy is characterized by software development directed by peer production
987 and collaboration through an active community of developers.
988 Contrast this to the more standard centralized development models used by commercial software
989 companies where a finite set of developers produces a product for sale using a defined set
990 of procedures that ultimately result in an end product whose architecture and source material
991 are closed to the public.
992 </p><p>
993 Open source projects conceptually have differing concurrent agendas, approaches, and production.
994 These facets of the development process can come from anyone in the public (community) that has a
995 stake in the software project.
996 The open source environment contains new copyright, licensing, domain, and consumer issues
997 that differ from the more traditional development environment.
998 In an open source environment, the end product, source material, and documentation are
999 all available to the public at no cost.
1000 </p><p>
1001 A benchmark example of an open source project is the Linux Kernel, which was initially conceived
1002 and created by Finnish computer science student Linus Torvalds in 1991.
1003 Conversely, a good example of a non-open source project is the
1004 <span class="trademark">Windows</span>® family of operating
1005 systems developed by <span class="trademark">Microsoft</span>® Corporation.
1006 </p><p>
1007 Wikipedia has a good historical description of the Open Source Philosophy
1008 <a class="ulink" href="http://en.wikipedia.org/wiki/Open_source" target="_top">here</a>.
1009 You can also find helpful information on how to participate in the Linux Community
1010 <a class="ulink" href="http://ldn.linuxfoundation.org/book/how-participate-linux-community" target="_top">here</a>.
1011 </p></div><div class="section" title="3.2. Using the Yocto Project in a Team Environment"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-changes-collaborate"></a>3.2. Using the Yocto Project in a Team Environment</h2></div></div></div><p>
1012 It might not be immediately clear how you can use the Yocto Project in a team environment,
1013 or scale it for a large team of developers.
1014 The specifics of any situation determine the best solution.
1015 Granted that the Yocto Project offers immense flexibility regarding this, practices do exist
1016 that experience has shown work well.
1017 </p><p>
1018 The core component of any development effort with the Yocto Project is often an
1019 automated build and testing framework along with an image generation process.
1020 You can use these core components to check that the metadata can be built,
1021 highlight when commits break the build, and provide up-to-date images that
1022 allow developers to test the end result and use it as a base platform for further
1023 development.
1024 Experience shows that buildbot is a good fit for this role.
1025 What works well is to configure buildbot to make two types of builds:
1026 incremental and full (from scratch).
1027 See <a class="ulink" href="http://autobuilder.yoctoproject.org:8010/" target="_top">the buildbot for the
1028 Yocto Project</a> for an example implementation that uses buildbot.
1029 </p><p>
1030 You can tie incremental builds to a commit hook that triggers the build
1031 each time a commit is made to the metadata.
1032 This practice results in useful acid tests that determine whether a given commit
1033 breaks the build in some serious way.
1034 Associating a build to a commit can catch a lot of simple errors.
1035 Furthermore, the tests are fast so developers can get quick feedback on changes.
1036 </p><p>
1037 Full builds build and test everything from the ground up.
1038 These types of builds usually happen at predetermined times like during the
1039 night when the machine load is low.
1040 </p><p>
1041 Most teams have many pieces of software undergoing active development at any given time.
1042 You can derive large benefits by putting these pieces under the control of a source
1043 control system that is compatible (i.e. Git or Subversion (SVN)) with the OpenEmbeded
1044 build system that the Yocto Project uses.
1045 You can then set the autobuilder to pull the latest revisions of the packages
1046 and test the latest commits by the builds.
1047 This practice quickly highlights issues.
1048 The build system easily supports testing configurations that use both a
1049 stable known good revision and a floating revision.
1050 The build system can also take just the changes from specific source control branches.
1051 This capability allows you to track and test specific changes.
1052 </p><p>
1053 Perhaps the hardest part of setting this up is defining the software project or
1054 the metadata policies that surround the different source control systems.
1055 Of course circumstances will be different in each case.
1056 However, this situation reveals one of the Yocto Project's advantages -
1057 the system itself does not
1058 force any particular policy on users, unlike a lot of build systems.
1059 The system allows the best policies to be chosen for the given circumstances.
1060 </p></div><div class="section" title="3.3. Yocto Project Source Repositories"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="yocto-project-repositories"></a>3.3. Yocto Project Source Repositories</h2></div></div></div><p>
1061 The Yocto Project team maintains complete source repositories for all Yocto Project files
1062 at <a class="ulink" href="http://git.yoctoproject.org/cgit/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit/cgit.cgi</a>.
1063 This web-based source code browser is organized into categories by function such as
1064 IDE Plugins, Matchbox, Poky, Yocto Linux Kernel, and so forth.
1065 From the interface, you can click on any particular item in the "Name" column and
1066 see the URL at the bottom of the page that you need to set up a Git repository for
1067 that particular item.
1068 Having a local Git repository of the source directory (poky) allows you to
1069 make changes, contribute to the history, and ultimately enhance the Yocto Project's
1070 tools, Board Support Packages, and so forth.
1071 </p><p>
1072 Conversely, if you are a developer that is not interested in contributing back to the
1073 Yocto Project, you have the ability to simply download and extract release tarballs
1074 and use them within the Yocto Project environment.
1075 All that is required is a particular release of the Yocto Project and
1076 your application source code.
1077 </p><p>
1078 For any supported release of Yocto Project, you can go to the Yocto Project website’s
1079 <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">download page</a> and get a
1080 tarball of the release.
1081 You can also go to this site to download any supported BSP tarballs.
1082 Unpacking the tarball gives you a hierarchical source directory that lets you develop
1083 using the Yocto Project.
1084 </p><p>
1085 Once you are set up through either tarball extraction or creation of Git repositories,
1086 you are ready to develop.
1087 </p><p>
1088 In summary, here is where you can get the project files needed for development:
1089 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><a id="source-repositories"></a><span class="emphasis"><em><a class="ulink" href="http://git.yoctoproject.org/cgit/cgit.cgi" target="_top">Source Repositories:</a></em></span>
1090 This area contains IDE Plugins, Matchbox, Poky, Poky Support, Tools, Yocto Linux Kernel, and Yocto
1091 Metadata Layers.
1092 You can create local copies of Git repositories for each of these areas.</p><p>
1093 </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 360px"><td align="center"><img src="figures/source-repos.png" align="middle" width="540" /></td></tr></table><p>
1094 </p></li><li class="listitem"><p><a id="index-downloads"></a><span class="emphasis"><em><a class="ulink" href="http://downloads.yoctoproject.org/releases/" target="_top">Index of /releases:</a></em></span>
1095 This area contains index releases such as
1096 the <span class="trademark">Eclipse</span>™
1097 Yocto Plug-in, miscellaneous support, poky, pseudo, cross-development toolchains,
1098 and all released versions of Yocto Project in the form of images or tarballs.
1099 Downloading and extracting these files does not produce a local copy of the
1100 Git repository but rather a snapshot of a particular release or image.</p><p>
1101 </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 360px"><td align="center"><img src="figures/index-downloads.png" align="middle" width="540" /></td></tr></table><p>
1102 </p></li><li class="listitem"><p><span class="emphasis"><em><a class="ulink" href="http://www.yoctoproject.org/download" target="_top">Yocto Project Download Page</a></em></span>
1103 This page on the Yocto Project website allows you to download any Yocto Project
1104 release or Board Support Package (BSP) in tarball form.
1105 The tarballs are similar to those found in the
1106 <a class="ulink" href="http://downloads.yoctoproject.org/releases/" target="_top">Index of /releases:</a> area.</p><p>
1107 </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 360px"><td align="center"><img src="figures/yp-download.png" align="middle" width="540" /></td></tr></table><p>
1108 </p></li></ul></div><p>
1109 </p></div><div class="section" title="3.4. Yocto Project Terms"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="yocto-project-terms"></a>3.4. Yocto Project Terms</h2></div></div></div><p>
1110 Following is a list of terms and definitions users new to the Yocto Project development
1111 environment might find helpful.
1112 While some of these terms are universal, the list includes them just in case:
1113 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Append Files:</em></span> Files that append build information to
1114 a recipe file.
1115 Append files are known as BitBake append files and <code class="filename">.bbappend</code> files.
1116 The OpenEmbedded build system expects every append file to have a corresponding and
1117 underlying recipe (<code class="filename">.bb</code>) file.
1118 Furthermore, the append file and the underlying recipe must have the same root filename.
1119 The filenames can differ only in the file type suffix used (e.g.
1120 <code class="filename">formfactor_0.0.bb</code> and <code class="filename">formfactor_0.0.bbappend</code>).
1121 </p><p>Information in append files overrides the information in the similarly-named recipe file.
1122 For examples of <code class="filename">.bbappend</code> file in use, see the
1123 "<a class="link" href="#using-bbappend-files" title="4.1.4. Using .bbappend Files">Using .bbappend Files</a>" and
1124 "<a class="link" href="#changing-recipes-kernel" title="A.5.2.4. Changing  recipes-kernel">Changing <code class="filename">recipes-kernel</code></a>"
1125 sections.</p></li><li class="listitem"><p><span class="emphasis"><em>BitBake:</em></span> The task executor and scheduler used by
1126 the OpenEmbedded build system to build images.
1127 For more information on BitBake, see the <a class="ulink" href="http://docs.openembedded.org/bitbake/html/" target="_top">
1128 BitBake documentation</a>.</p></li><li class="listitem"><p><a id="build-directory"></a><span class="emphasis"><em>Build Directory:</em></span>
1129 This term refers to the area used by the OpenEmbedded build system for builds.
1130 The area is created when you <code class="filename">source</code> the setup
1131 environment script that is found in the source directory
1132 (i.e. <code class="filename">oe-init-build-env</code>).
1133 The <a class="link" href="#var-TOPDIR" target="_top"><code class="filename">TOPDIR</code></a>
1134 variable points to the build directory.</p><p>You have a lot of flexibility when creating the build directory.
1135 Following are some examples that show how to create the directory:
1136 </p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p>Create the build directory in your current working directory
1137 and name it <code class="filename">build</code>.
1138 This is the default behavior.
1139 </p><pre class="literallayout">
1140 $ source oe-init-build-env
1141 </pre></li><li class="listitem"><p>Provide a directory path and specifically name the build
1142 directory.
1143 This next example creates a build directory named <code class="filename">YP-8.0</code>
1144 in your home directory within the directory <code class="filename">mybuilds</code>.
1145 If <code class="filename">mybuilds</code> does not exist, the directory is created for you:
1146 </p><pre class="literallayout">
1147 $ source poky-1.2+snapshot-8.0/oe-init-build-env $HOME/mybuilds/YP-8.0
1148 </pre></li><li class="listitem"><p>Provide an existing directory to use as the build directory.
1149 This example uses the existing <code class="filename">mybuilds</code> directory
1150 as the build directory.
1151 </p><pre class="literallayout">
1152 $ source poky-1.2+snapshot-8.0/oe-init-build-env $HOME/mybuilds/
1153 </pre></li></ul></div><p>
1154 </p></li><li class="listitem"><p><span class="emphasis"><em>Build System:</em></span> In the context of the Yocto Project
1155 this term refers to the OpenEmbedded build system used by the project.
1156 This build system is based on the project known as "Poky."
1157 For some historical information about Poky, see the
1158 <a class="link" href="#poky">poky</a> term further along in this section.
1159 </p></li><li class="listitem"><p><span class="emphasis"><em>Classes:</em></span> Files that provide for logic encapsulation
1160 and inheritance allowing commonly used patterns to be defined once and easily used
1161 in multiple recipes.
1162 Class files end with the <code class="filename">.bbclass</code> filename extension.
1163 </p></li><li class="listitem"><p><span class="emphasis"><em>Configuration File:</em></span> Configuration information in various
1164 <code class="filename">.conf</code> files provides global definitions of variables.
1165 The <code class="filename">conf/local.conf</code> configuration file in the
1166 <a class="link" href="#build-directory">build directory</a>
1167 contains user-defined variables that affect each build.
1168 The <code class="filename">meta-yocto/conf/distro/poky.conf</code> configuration file
1169 defines Yocto ‘distro’ configuration
1170 variables used only when building with this policy.
1171 Machine configuration files, which
1172 are located throughout the
1173 <a class="link" href="#source-directory">source directory</a>, define
1174 variables for specific hardware and are only used when building for that target
1175 (e.g. the <code class="filename">machine/beagleboard.conf</code> configuration file defines
1176 variables for the Texas Instruments ARM Cortex-A8 development board).
1177 Configuration files end with a <code class="filename">.conf</code> filename extension.
1178 </p></li><li class="listitem"><p><span class="emphasis"><em>Cross-Development Toolchain:</em></span>
1179 A collection of software development
1180 tools and utilities that allow you to develop software for targeted architectures.
1181 This toolchain contains cross-compilers, linkers, and debuggers that are specific to
1182 an architecture.
1183 You can use the OpenEmbedded build system to build cross-development toolchains in tarball
1184 form that, when
1185 unpacked, contain the development tools you need to cross-compile and test your software.
1186 The Yocto Project ships with images that contain toolchains for supported architectures
1187 as well.
1188 Sometimes this toolchain is referred to as the meta-toolchain.</p></li><li class="listitem"><p><span class="emphasis"><em>Image:</em></span> An image is the result produced when
1189 BitBake processes a given collection of recipes and related metadata.
1190 Images are the binary output that run on specific hardware and for specific
1191 use cases.
1192 For a list of the supported image types that the Yocto Project provides, see the
1193 "<a class="link" href="#ref-images" target="_top">Images</a>"
1194 chapter in the Yocto Project Reference Manual.</p></li><li class="listitem"><p><a id="layer"></a><span class="emphasis"><em>Layer:</em></span> A collection of recipes representing the core,
1195 a BSP, or an application stack.
1196 For a discussion on BSP Layers, see the
1197 "<a class="link" href="#bsp-layers" target="_top">BSP Layers</a>"
1198 section in the Yocto Project Board Support Packages (BSP) Developer's Guide.</p></li><li class="listitem"><p><a id="metadata"></a><span class="emphasis"><em>Metadata:</em></span> The files that BitBake parses when
1199 building an image.
1200 Metadata includes recipes, classes, and configuration files.</p></li><li class="listitem"><p><span class="emphasis"><em>OE-Core:</em></span> A core set of metadata originating
1201 with OpenEmbedded (OE) that is shared between OE and the Yocto Project.
1202 This metadata is found in the <code class="filename">meta</code> directory of the source
1203 directory.</p></li><li class="listitem"><p><span class="emphasis"><em>Package:</em></span> The packaged output from a baked recipe.
1204 A package is generally the compiled binaries produced from the recipe's sources.
1205 You ‘bake’ something by running it through BitBake.</p></li><li class="listitem"><p><a id="poky"></a><span class="emphasis"><em>Poky:</em></span> The term "poky" can mean several things.
1206 In its most general sence, it is an open-source project that was initially developed
1207 by OpenedHand. With OpenedHand, poky was developed off of the existing OpenEmbedded
1208 build system becoming a build system for embedded images.
1209 After Intel Corporation aquired OpenedHand, the project poky became the basis for
1210 the Yocto Project's build system.
1211 Within the Yocto Project source repositories, poky exists as a separate Git repository
1212 that can be cloned to yield a local copy on the host system.
1213 Thus, "poky" can refer to the local copy of the source directory used to develop within
1214 the Yocto Project.</p></li><li class="listitem"><p><span class="emphasis"><em>Recipe:</em></span> A set of instructions for building packages.
1215 A recipe describes where you get source code and which patches to apply.
1216 Recipes describe dependencies for libraries or for other recipes, and they
1217 also contain configuration and compilation options.
1218 Recipes contain the logical unit of execution, the software/images to build, and
1219 use the <code class="filename">.bb</code> file extension.</p></li><li class="listitem"><p><a id="source-directory"></a><span class="emphasis"><em>Source Directory:</em></span>
1220 This term refers to the directory structure created as a result of either downloading
1221 and unpacking a Yocto Project release tarball or creating a local copy of
1222 <code class="filename">poky</code> Git repository <code class="filename">git://git.yoctoproject.org/poky</code>.
1223 Sometimes you might here the term "poky directory" used to refer to this
1224 directory structure.</p><p>The source directory contains BitBake, Documentation, metadata and
1225 other files that all support the Yocto Project.
1226 Consequently, you must have the source directory in place on your development
1227 system in order to do any development using the Yocto Project.</p><p>For tarball expansion, the name of the top-level directory of the source directory
1228 is derived from the Yocto Project release tarball.
1229 For example, downloading and unpacking <code class="filename">poky-1.2+snapshot-8.0.tar.bz2</code>
1230 results in a source directory whose top-level folder is named
1231 <code class="filename">poky-1.2+snapshot-8.0</code>.
1232 If you create a local copy of the Git repository, then you can name the repository
1233 anything you like.
1234 Throughout much of the documentation, <code class="filename">poky</code> is used as the name of
1235 the top-level folder of the local copy of the poky Git repository.
1236 So, for example, cloning the <code class="filename">poky</code> Git repository results in a
1237 local Git repository whose top-level folder is also named <code class="filename">poky</code>.</p><p>It is important to understand the differences between the source directory created
1238 by unpacking a released tarball as compared to cloning
1239 <code class="filename">git://git.yoctoproject.org/poky</code>.
1240 When you unpack a tarball, you have an exact copy of the files based on the time of
1241 release - a fixed release point.
1242 Any changes you make to your local files in the source directory are on top of the release.
1243 On the other hand, when you clone the <code class="filename">poky</code> Git repository, you have an
1244 active development repository.
1245 In this case, any local changes you make to the source directory can be later applied
1246 to active development branches of the upstream <code class="filename">poky</code> Git
1247 repository.</p><p>Finally, if you want to track a set of local changes while starting from the same point
1248 as a release tarball, you can create a local Git branch that
1249 reflects the exact copy of the files at the time of their release.
1250 You do this using Git tags that are part of the repository.</p><p>For more information on concepts around Git repositories, branches, and tags,
1251 see the
1252 "<a class="link" href="#repositories-tags-and-branches" title="3.6.1. Repositories, Tags, and Branches">Repositories, Tags, and Branches</a>"
1253 section.</p></li><li class="listitem"><p><span class="emphasis"><em>Tasks:</em></span> Arbitrary groups of software Recipes.
1254 You simply use Tasks to hold recipes that, when built, usually accomplish a single task.
1255 For example, a task could contain the recipes for a company’s proprietary or value-add software.
1256 Or, the task could contain the recipes that enable graphics.
1257 A task is really just another recipe.
1258 Because task files are recipes, they end with the <code class="filename">.bb</code> filename
1259 extension.</p></li><li class="listitem"><p><span class="emphasis"><em>Upstream:</em></span> A reference to source code or repositories
1260 that are not local to the development system but located in a master area that is controlled
1261 by the maintainer of the source code.
1262 For example, in order for a developer to work on a particular piece of code, they need to
1263 first get a copy of it from an "upstream" source.</p></li></ul></div><p>
1264 </p></div><div class="section" title="3.5. Licensing"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="licensing"></a>3.5. Licensing</h2></div></div></div><p>
1265 Because open source projects are open to the public, they have different licensing structures in place.
1266 License evolution for both Open Source and Free Software has an interesting history.
1267 If you are interested in this history, you can find basic information here:
1268 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><a class="ulink" href="http://en.wikipedia.org/wiki/Open-source_license" target="_top">Open source license history</a>
1269 </p></li><li class="listitem"><p><a class="ulink" href="http://en.wikipedia.org/wiki/Free_software_license" target="_top">Free software license
1270 history</a></p></li></ul></div><p>
1271 </p><p>
1272 In general, the Yocto Project is broadly licensed under the Massachusetts Institute of Technology
1273 (MIT) License.
1274 MIT licensing permits the reuse of software within proprietary software as long as the
1275 license is distributed with that software.
1276 MIT is also compatible with the GNU General Public License (GPL).
1277 Patches to the Yocto Project follow the upstream licensing scheme.
1278 You can find information on the MIT license at
1279 <a class="ulink" href="http://www.opensource.org/licenses/mit-license.php" target="_top">here</a>.
1280 You can find information on the GNU GPL <a class="ulink" href="http://www.opensource.org/licenses/LGPL-3.0" target="_top">
1281 here</a>.
1282 </p><p>
1283 When you build an image using Yocto Project, the build process uses a known list of licenses to
1284 ensure compliance.
1285 You can find this list in the Yocto Project files directory at
1286 <code class="filename">meta/files/common-licenses</code>.
1287 Once the build completes, the list of all licenses found and used during that build are
1288 kept in the
1289 <a class="link" href="#build-directory">build directory</a> at
1290 <code class="filename">tmp/deploy/images/licenses</code>.
1291 </p><p>
1292 If a module requires a license that is not in the base list, the build process
1293 generates a warning during the build.
1294 These tools make it easier for a developer to be certain of the licenses with which
1295 their shipped products must comply.
1296 However, even with these tools it is still up to the developer to resolve potential licensing issues.
1297 </p><p>
1298 The base list of licenses used by the build process is a combination of the Software Package
1299 Data Exchange (SPDX) list and the Open Source Initiative (OSI) projects.
1300 <a class="ulink" href="http://spdx.org" target="_top">SPDX Group</a> is a working group of the Linux Foundation
1301 that maintains a specification
1302 for a standard format for communicating the components, licenses, and copyrights
1303 associated with a software package.
1304 <a class="ulink" href="http://opensource.org" target="_top">OSI</a> is a corporation dedicated to the Open Source
1305 Definition and the effort for reviewing and approving licenses that are OSD-conformant.
1306 </p><p>
1307 You can find a list of the combined SPDX and OSI licenses that the Yocto Project uses
1308 <a class="ulink" href="http://git.yoctoproject.org/cgit/cgit.cgi/poky/tree/meta/files/common-licenses" target="_top">here</a>.
1309 This wiki page discusses the license infrastructure used by the Yocto Project.
1310 </p></div><div class="section" title="3.6. Git"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="git"></a>3.6. Git</h2></div></div></div><p>
1311 The Yocto Project uses Git, which is a free, open source distributed version control system.
1312 Git supports distributed development, non-linear development, and can handle large projects.
1313 It is best that you have some fundamental understanding of how Git tracks projects and
1314 how to work with Git if you are going to use Yocto Project for development.
1315 This section provides a quick overview of how Git works and provides you with a summary
1316 of some essential Git commands.
1317 </p><p>
1318 For more information on Git, see
1319 <a class="ulink" href="http://git-scm.com/documentation" target="_top">http://git-scm.com/documentation</a>.
1320 If you need to download Git, go to <a class="ulink" href="http://git-scm.com/download" target="_top">http://git-scm.com/download</a>.
1321 </p><div class="section" title="3.6.1. Repositories, Tags, and Branches"><div class="titlepage"><div><div><h3 class="title"><a id="repositories-tags-and-branches"></a>3.6.1. Repositories, Tags, and Branches</h3></div></div></div><p>
1322 As mentioned earlier in section
1323 "<a class="link" href="#yocto-project-repositories" title="3.3. Yocto Project Source Repositories">Yocto Project Source Repositories</a>",
1324 the Yocto Project maintains source repositories at
1325 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a>.
1326 If you look at this web-interface of the repositories, each item is a separate
1327 Git repository.
1328 </p><p>
1329 Git repositories use branching techniques that track content change (not files)
1330 within a project (e.g. a new feature or updated documentation).
1331 Creating a tree-like structure based on project divergence allows for excellent historical
1332 information over the life of a project.
1333 This methodology also allows for an environment in which you can do lots of
1334 local experimentation on a project as you develop changes or new features.
1335 </p><p>
1336 A Git repository represents all development efforts for a given project.
1337 For example, the Git repository <code class="filename">poky</code> contains all changes
1338 and developments for Poky over the course of its entire life.
1339 That means that all changes that make up all releases are captured.
1340 The repository maintains a complete history of changes.
1341 </p><p>
1342 You can create a local copy of any repository by "cloning" it with the Git
1343 <code class="filename">clone</code> command.
1344 When you clone a Git repository, you end up with an identical copy of the
1345 repository on your development system.
1346 Once you have a local copy of a repository, you can take steps to develop locally.
1347 For examples on how to clone Git repositories, see the section
1348 "<a class="link" href="#getting-setup" title="2.2. Getting Set Up">Getting Set Up</a>" earlier in this manual.
1349 </p><p>
1350 It is important to understand that Git tracks content change and not files.
1351 Git uses "branches" to organize different development efforts.
1352 For example, the <code class="filename">poky</code> repository has
1353 <code class="filename">laverne</code>, <code class="filename">bernard</code>,
1354 <code class="filename">edison</code>, <code class="filename">denzil</code> and
1355 <code class="filename">master</code> branches among
1356 others.
1357 You can see all the branches by going to
1358 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/poky/" target="_top">http://git.yoctoproject.org/cgit.cgi/poky/</a> and
1359 clicking on the
1360 <code class="filename"><a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/poky/refs/heads" target="_top">[...]</a></code>
1361 link beneath the "Branch" heading.
1362 </p><p>
1363 Each of these branches represents a specific area of development.
1364 The <code class="filename">master</code> branch represents the current or most recent
1365 development.
1366 All other branches represent off-shoots of the <code class="filename">master</code>
1367 branch.
1368 </p><p>
1369 When you create a local copy of a Git repository, the copy has the same set
1370 of branches as the original.
1371 This means you can use Git to create a local working area (also called a branch)
1372 that tracks a specific development branch from the source Git repository.
1373 in other words, you can define your local Git environment to work on any development
1374 branch in the repository.
1375 To help illustrate, here is a set of commands that creates a local copy of the
1376 <code class="filename">poky</code> Git repository and then creates and checks out a local
1377 Git branch that tracks the Yocto Project 1.3 Release (1.2+snapshot) development:
1378 </p><pre class="literallayout">
1379 $ cd ~
1380 $ git clone git://git.yoctoproject.org/poky
1381 $ cd poky
1382 $ git checkout -b 1.2+snapshot origin/1.2+snapshot
1383 </pre><p>
1384 In this example, the name of the top-level directory of your local Yocto Project
1385 Files Git repository is <code class="filename">poky</code>,
1386 and the name of the local working area (or local branch) you have created and checked
1387 out is <code class="filename">1.2+snapshot</code>.
1388 The files in your repository now reflect the same files that are in the
1389 <code class="filename">1.2+snapshot</code> development branch of the Yocto Project's
1390 <code class="filename">poky</code> repository.
1391 It is important to understand that when you create and checkout a
1392 local working branch based on a branch name,
1393 your local environment matches the "tip" of that development branch
1394 at the time you created your local branch, which could be
1395 different than the files at the time of a similarly named release.
1396 In other words, creating and checking out a local branch based on the
1397 <code class="filename">1.2+snapshot</code> branch name is not the same as creating and
1398 checking out a local branch based on the <code class="filename">1.2+snapshot-1.3</code>
1399 release.
1400 Keep reading to see how you create a local snapshot of a Yocto Project Release.
1401 </p><p>
1402 Git uses "tags" to mark specific changes in a repository.
1403 Typically, a tag is used to mark a special point such as the final change
1404 before a project is released.
1405 You can see the tags used with the <code class="filename">poky</code> Git repository
1406 by going to <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/poky/" target="_top">http://git.yoctoproject.org/cgit.cgi/poky/</a> and
1407 clicking on the
1408 <code class="filename"><a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/poky/refs/tags" target="_top">[...]</a></code>
1409 link beneath the "Tag" heading.
1410 </p><p>
1411 Some key tags are <code class="filename">laverne-4.0</code>, <code class="filename">bernard-5.0</code>,
1412 and <code class="filename">1.2+snapshot-8.0</code>.
1413 These tags represent Yocto Project releases.
1414 </p><p>
1415 When you create a local copy of the Git repository, you also have access to all the
1416 tags.
1417 Similar to branches, you can create and checkout a local working Git branch based
1418 on a tag name.
1419 When you do this, you get a snapshot of the Git repository that reflects
1420 the state of the files when the change was made associated with that tag.
1421 The most common use is to checkout a working branch that matches a specific
1422 Yocto Project release.
1423 Here is an example:
1424 </p><pre class="literallayout">
1425 $ cd ~
1426 $ git clone git://git.yoctoproject.org/poky
1427 $ cd poky
1428 $ git checkout -b my-1.2+snapshot-8.0 1.2+snapshot-8.0
1429 </pre><p>
1430 In this example, the name of the top-level directory of your local Yocto Project
1431 Files Git repository is <code class="filename">poky</code>.
1432 And, the name of the local branch you have created and checked out is
1433 <code class="filename">my-1.2+snapshot-8.0</code>.
1434 The files in your repository now exactly match the Yocto Project 1.3
1435 Release tag (<code class="filename">1.2+snapshot-8.0</code>).
1436 It is important to understand that when you create and checkout a local
1437 working branch based on a tag, your environment matches a specific point
1438 in time and not a development branch.
1439 </p></div><div class="section" title="3.6.2. Basic Commands"><div class="titlepage"><div><div><h3 class="title"><a id="basic-commands"></a>3.6.2. Basic Commands</h3></div></div></div><p>
1440 Git has an extensive set of commands that lets you manage changes and perform
1441 collaboration over the life of a project.
1442 Conveniently though, you can manage with a small set of basic operations and workflows
1443 once you understand the basic philosophy behind Git.
1444 You do not have to be an expert in Git to be functional.
1445 A good place to look for instruction on a minimal set of Git commands is
1446 <a class="ulink" href="http://git-scm.com/documentation" target="_top">here</a>.
1447 If you need to download Git, you can do so
1448 <a class="ulink" href="http://git-scm.com/download" target="_top">here</a>.
1449 </p><p>
1450 If you don’t know much about Git, we suggest you educate
1451 yourself by visiting the links previously mentioned.
1452 </p><p>
1453 The following list briefly describes some basic Git operations as a way to get started.
1454 As with any set of commands, this list (in most cases) simply shows the base command and
1455 omits the many arguments they support.
1456 See the Git documentation for complete descriptions and strategies on how to use these commands:
1457 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em><code class="filename">git init</code>:</em></span> Initializes an empty Git repository.
1458 You cannot use Git commands unless you have a <code class="filename">.git</code> repository.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git clone</code>:</em></span> Creates a clone of a repository.
1459 During collaboration, this command allows you to create a local repository that is on
1460 equal footing with a fellow developer’s repository.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git add</code>:</em></span> Adds updated file contents
1461 to the index that
1462 Git uses to track changes.
1463 You must add all files that have changed before you can commit them.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git commit</code>:</em></span> Creates a “commit” that documents
1464 the changes you made.
1465 Commits are used for historical purposes, for determining if a maintainer of a project
1466 will allow the change, and for ultimately pushing the change from your local Git repository
1467 into the project’s upstream (or master) repository.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git status</code>:</em></span> Reports any modified files that
1468 possibly need to be added and committed.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git checkout &lt;branch-name&gt;</code>:</em></span> Changes
1469 your working branch.
1470 This command is analogous to “cd”.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git checkout –b &lt;working-branch&gt;</code>:</em></span> Creates
1471 a working branch on your local machine where you can isolate work.
1472 It is a good idea to use local branches when adding specific features or changes.
1473 This way if you don’t like what you have done you can easily get rid of the work.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git branch</code>:</em></span> Reports existing branches and
1474 tells you which branch in which you are currently working.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git branch -D &lt;branch-name&gt;</code>:</em></span>
1475 Deletes an existing branch.
1476 You need to be in a branch other than the one you are deleting
1477 in order to delete &lt;branch-name&gt;.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git pull</code>:</em></span> Retrieves information
1478 from an upstream Git
1479 repository and places it in your local Git repository.
1480 You use this command to make sure you are synchronized with the repository
1481 from which you are basing changes (.e.g. the master repository).</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git push</code>:</em></span> Sends all your local changes you
1482 have committed to an upstream Git repository (e.g. a contribution repository).
1483 The maintainer of the project draws from these repositories when adding your changes to the
1484 project’s master repository.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git merge</code>:</em></span> Combines or adds changes from one
1485 local branch of your repository with another branch.
1486 When you create a local Git repository, the default branch is named “master”.
1487 A typical workflow is to create a temporary branch for isolated work, make and commit your
1488 changes, switch to your local master branch, merge the changes from the temporary branch into the
1489 local master branch, and then delete the temporary branch.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git cherry-pick</code>:</em></span> Choose and apply specific
1490 commits from one branch into another branch.
1491 There are times when you might not be able to merge all the changes in one branch with
1492 another but need to pick out certain ones.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">gitk</code>:</em></span> Provides a GUI view of the branches
1493 and changes in your local Git repository.
1494 This command is a good way to graphically see where things have diverged in your
1495 local repository.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git log</code>:</em></span> Reports a history of your changes to the
1496 repository.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">git diff</code>:</em></span> Displays line-by-line differences
1497 between your local working files and the same files in the upstream Git repository that your
1498 branch currently tracks.</p></li></ul></div><p>
1499 </p></div></div><div class="section" title="3.7. Workflows"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="workflows"></a>3.7. Workflows</h2></div></div></div><p>
1500 This section provides some overview on workflows using Git.
1501 In particular, the information covers basic practices that describe roles and actions in a
1502 collaborative development environment.
1503 Again, if you are familiar with this type of development environment, you might want to just
1504 skip this section.
1505 </p><p>
1506 The Yocto Project files are maintained using Git in a "master" branch whose Git history
1507 tracks every change and whose structure provides branches for all diverging functionality.
1508 Although there is no need to use Git, many open source projects do so.
1509 For the Yocto Project, a key individual called the "maintainer" is responsible for the "master"
1510 branch of the Git repository.
1511 The "master" branch is the “upstream” repository where the final builds of the project occur.
1512 The maintainer is responsible for allowing changes in from other developers and for
1513 organizing the underlying branch structure to reflect release strategies and so forth.
1514 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>You can see who is the maintainer for Yocto Project files by examining the
1515 <code class="filename">distro_tracking_fields.inc</code> file in the Yocto Project
1516 <code class="filename">meta/conf/distro/include</code> directory.</div><p>
1517 </p><p>
1518 The project also has contribution repositories known as “contrib” areas.
1519 These areas temporarily hold changes to the project that have been submitted or committed
1520 by the Yocto Project development team and by community members that contribute to the project.
1521 The maintainer determines if the changes are qualified to be moved from the "contrib" areas
1522 into the "master" branch of the Git repository.
1523 </p><p>
1524 Developers (including contributing community members) create and maintain cloned repositories
1525 of the upstream "master" branch.
1526 These repositories are local to their development platforms and are used to develop changes.
1527 When a developer is satisfied with a particular feature or change, they “push” the changes
1528 to the appropriate "contrib" repository.
1529 </p><p>
1530 Developers are responsible for keeping their local repository up-to-date with "master".
1531 They are also responsible for straightening out any conflicts that might arise within files
1532 that are being worked on simultaneously by more than one person.
1533 All this work is done locally on the developer’s machine before anything is pushed to a
1534 "contrib" area and examined at the maintainer’s level.
1535 </p><p>
1536 A somewhat formal method exists by which developers commit changes and push them into the
1537 "contrib" area and subsequently request that the maintainer include them into "master"
1538 This process is called “submitting a patch” or “submitting a change.”
1539 </p><p>
1540 To summarize the environment: we have a single point of entry for changes into the project’s
1541 "master" branch of the Git repository, which is controlled by the project’s maintainer.
1542 And, we have a set of developers who independently develop, test, and submit changes
1543 to "contrib" areas for the maintainer to examine.
1544 The maintainer then chooses which changes are going to become a permanent part of the project.
1545 </p><p>
1546 </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 270px"><td align="left"><img src="figures/git-workflow.png" align="left" height="270" /></td></tr></table><p>
1547 </p><p>
1548 While each development environment is unique, there are some best practices or methods
1549 that help development run smoothly.
1550 The following list describes some of these practices.
1551 For more information about Git workflows, see the workflow topics in the
1552 <a class="ulink" href="http://book.git-scm.com" target="_top">Git Community Book</a>.
1553 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Make Small Changes:</em></span> It is best to keep the changes you commit
1554 small as compared to bundling many disparate changes into a single commit.
1555 This practice not only keeps things manageable but also allows the maintainer
1556 to more easily include or refuse changes.</p><p>It is also good practice to leave the repository in a state that allows you to
1557 still successfully build your project. In other words, do not commit half of a feature,
1558 then add the other half in a separate, later commit.
1559 Each commit should take you from one buildable project state to another
1560 buildable state.</p></li><li class="listitem"><p><span class="emphasis"><em>Use Branches Liberally:</em></span> It is very easy to create, use, and
1561 delete local branches in your working Git repository.
1562 You can name these branches anything you like.
1563 It is helpful to give them names associated with the particular feature or change
1564 on which you are working.
1565 Once you are done with a feature or change, simply discard the branch.</p></li><li class="listitem"><p><span class="emphasis"><em>Merge Changes:</em></span> The <code class="filename">git merge</code>
1566 command allows you to take the
1567 changes from one branch and fold them into another branch.
1568 This process is especially helpful when more than a single developer might be working
1569 on different parts of the same feature.
1570 Merging changes also automatically identifies any collisions or “conflicts”
1571 that might happen as a result of the same lines of code being altered by two different
1572 developers.</p></li><li class="listitem"><p><span class="emphasis"><em>Manage Branches:</em></span> Because branches are easy to use, you should
1573 use a system where branches indicate varying levels of code readiness.
1574 For example, you can have a “work” branch to develop in, a “test” branch where the code or
1575 change is tested, a “stage” branch where changes are ready to be committed, and so forth.
1576 As your project develops, you can merge code across the branches to reflect ever-increasing
1577 stable states of the development.</p></li><li class="listitem"><p><span class="emphasis"><em>Use Push and Pull:</em></span> The push-pull workflow is based on the
1578 concept of developers “pushing” local commits to a remote repository, which is
1579 usually a contribution repository.
1580 This workflow is also based on developers “pulling” known states of the project down into their
1581 local development repositories.
1582 The workflow easily allows you to pull changes submitted by other developers from the
1583 upstream repository into your work area ensuring that you have the most recent software
1584 on which to develop.
1585 The Yocto Project has two scripts named <code class="filename">create-pull-request</code> and
1586 <code class="filename">send-pull-request</code> that ship with the release to facilitate this
1587 workflow.
1588 You can find these scripts in the local Yocto Project files Git repository in
1589 the <code class="filename">scripts</code> directory.</p></li><li class="listitem"><p><span class="emphasis"><em>Patch Workflow:</em></span> This workflow allows you to notify the
1590 maintainer through an email that you have a change (or patch) you would like considered
1591 for the "master" branch of the Git repository.
1592 To send this type of change you format the patch and then send the email using the Git commands
1593 <code class="filename">git format-patch</code> and <code class="filename">git send-email</code>.
1594 You can find information on how to submit later in this chapter.</p></li></ul></div><p>
1595 </p></div><div class="section" title="3.8. Tracking Bugs"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="tracking-bugs"></a>3.8. Tracking Bugs</h2></div></div></div><p>
1596 The Yocto Project uses its own implementation of
1597 <a class="ulink" href="http://www.bugzilla.org/about/" target="_top">Bugzilla</a> to track bugs.
1598 Implementations of Bugzilla work well for group development because they track bugs and code
1599 changes, can be used to communicate changes and problems with developers, can be used to
1600 submit and review patches, and can be used to manage quality assurance.
1601 The home page for the Yocto Project implementation of Bugzilla is
1602 <a class="ulink" href="http://bugzilla.yoctoproject.org" target="_top">http://bugzilla.yoctoproject.org</a>.
1603 </p><p>
1604 Sometimes it is helpful to submit, investigate, or track a bug against the Yocto Project itself
1605 such as when discovering an issue with some component of the build system that acts contrary
1606 to the documentation or your expectations.
1607 Following is the general procedure for submitting a new bug using the Yocto Project
1608 Bugzilla.
1609 You can find more information on defect management, bug tracking, and feature request
1610 processes all accomplished through the Yocto Project Bugzilla on the wiki page
1611 <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Bugzilla_Configuration_and_Bug_Tracking" target="_top">here</a>.
1612 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Always use the Yocto Project implementation of Bugzilla to submit
1613 a bug.</p></li><li class="listitem"><p>When submitting a new bug, be sure to choose the appropriate
1614 Classification, Product, and Component for which the issue was found.
1615 Defects for Yocto Project fall into one of four classifications: Yocto Projects,
1616 Infrastructure, Poky, and Yocto Metadata Layers.
1617 Each of these Classifications break down into multiple Products and, in some
1618 cases, multiple Components.</p></li><li class="listitem"><p>Use the bug form to choose the correct Hardware and Architecture
1619 for which the bug applies.</p></li><li class="listitem"><p>Indicate the Yocto Project version you were using when the issue
1620 occurred.</p></li><li class="listitem"><p>Be sure to indicate the Severity of the bug.
1621 Severity communicates how the bug impacted your work.</p></li><li class="listitem"><p>Provide a brief summary of the issue.
1622 Try to limit your summary to just a line or two and be sure to capture the
1623 essence of the issue.</p></li><li class="listitem"><p>Provide a detailed description of the issue.
1624 You should provide as much detail as you can about the context, behavior, output,
1625 and so forth that surround the issue.
1626 You can even attach supporting files for output or log by using the "Add an attachment"
1627 button.</p></li><li class="listitem"><p>Submit the bug by clicking the "Submit Bug" button.</p></li></ol></div><p>
1628 </p></div><div class="section" title="3.9. How to Submit a Change"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="how-to-submit-a-change"></a>3.9. How to Submit a Change</h2></div></div></div><p>
1629 Contributions to the Yocto Project and OpenEmbedded are very welcome.
1630 Because the system is extremely configurable and flexible, we recognize that developers
1631 will want to extend, configure or optimize it for their specific uses.
1632 You should send patches to the appropriate mailing list so that they
1633 can be reviewed and merged by the appropriate maintainer.
1634 For a list of the Yocto Project and related mailing lists, see the
1635 "<a class="link" href="#resources-mailinglist" target="_top">Mailing lists</a>" section in
1636 the Yocto Project Reference Manual.
1637 </p><p>
1638 The following is some guidance on which mailing list to use for what type of change:
1639 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>For changes to the core metadata, send your patch to the
1640 <a class="ulink" href="http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-core" target="_top">openembedded-core</a> mailing list.
1641 For example, a change to anything under the <code class="filename">meta</code> or
1642 <code class="filename">scripts</code> directories
1643 should be sent to this mailing list.</p></li><li class="listitem"><p>For changes to BitBake (anything under the <code class="filename">bitbake</code>
1644 directory), send your patch to the
1645 <a class="ulink" href="http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/bitbake-devel" target="_top">bitbake-devel</a> mailing list.</p></li><li class="listitem"><p>For changes to <code class="filename">meta-yocto</code>, send your patch to the
1646 <a class="ulink" href="http://lists.yoctoproject.org/listinfo/poky" target="_top">poky</a> mailing list.</p></li><li class="listitem"><p>For changes to other layers hosted on yoctoproject.org (unless the
1647 layer's documentation specifies otherwise), tools, and Yocto Project
1648 documentation, use the
1649 <a class="ulink" href="http://lists.yoctoproject.org/listinfo/yocto" target="_top">yocto</a> mailing list.</p></li><li class="listitem"><p>For additional recipes that do not fit into the core metadata,
1650 you should determine which layer the recipe should go into and submit the
1651 change in the manner recommended by the documentation (e.g. README) supplied
1652 with the layer. If in doubt, please ask on the
1653 <a class="ulink" href="http://lists.yoctoproject.org/listinfo/yocto" target="_top">yocto</a> or
1654 <a class="ulink" href="http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-devel" target="_top">openembedded-devel</a>
1655 mailing lists.</p></li></ul></div><p>
1656 </p><p>
1657 When you send a patch, be sure to include a "Signed-off-by:"
1658 line in the same style as required by the Linux kernel.
1659 Adding this line signifies that you, the submitter, have agreed to the Developer's Certificate of Origin 1.1
1660 as follows:
1661 </p><pre class="literallayout">
1662 Developer's Certificate of Origin 1.1
1663
1664 By making a contribution to this project, I certify that:
1665
1666 (a) The contribution was created in whole or in part by me and I
1667 have the right to submit it under the open source license
1668 indicated in the file; or
1669
1670 (b) The contribution is based upon previous work that, to the best
1671 of my knowledge, is covered under an appropriate open source
1672 license and I have the right under that license to submit that
1673 work with modifications, whether created in whole or in part
1674 by me, under the same open source license (unless I am
1675 permitted to submit under a different license), as indicated
1676 in the file; or
1677
1678 (c) The contribution was provided directly to me by some other
1679 person who certified (a), (b) or (c) and I have not modified
1680 it.
1681
1682 (d) I understand and agree that this project and the contribution
1683 are public and that a record of the contribution (including all
1684 personal information I submit with it, including my sign-off) is
1685 maintained indefinitely and may be redistributed consistent with
1686 this project or the open source license(s) involved.
1687 </pre><p>
1688 </p><p>
1689 In a collaborative environment, it is necessary to have some sort of standard
1690 or method through which you submit changes.
1691 Otherwise, things could get quite chaotic.
1692 One general practice to follow is to make small, controlled changes.
1693 Keeping changes small and isolated aids review, makes merging/rebasing easier
1694 and keeps the change history clean when anyone needs to refer to it in future.
1695 </p><p>
1696 When you make a commit, you must follow certain standards established by the
1697 OpenEmbedded and Yocto Project development teams.
1698 For each commit, you must provide a single-line summary of the change and you
1699 should almost always provide a more detailed description of what you did (i.e.
1700 the body of the commit message).
1701 The only exceptions for not providing a detailed description would be if your
1702 change is a simple, self-explanatory change that needs no description.
1703 Here are the guidelines for composing a commit message:
1704 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Provide a single-line, short summary of the change.
1705 This summary is typically viewable in the "shortlist" of changes.
1706 Thus, providing something short and descriptive that gives the reader
1707 a summary of the change is useful when viewing a list of many commits.
1708 This should be prefixed by the recipe name (if changing a recipe), or
1709 else the short form path to the file being changed.
1710 </p></li><li class="listitem"><p>For the body of the commit message, provide detailed information
1711 that describes what you changed, why you made the change, and the approach
1712 you used. It may also be helpful if you mention how you tested the change.
1713 Provide as much detail as you can in the body of the commit message.
1714 </p></li><li class="listitem"><p>If the change addresses a specific bug or issue that is
1715 associated with a bug-tracking ID, include a reference to that ID in
1716 your detailed description.
1717 For example, the Yocto Project uses a specific convention for bug
1718 references - any commit that addresses a specific bug should include the
1719 bug ID in the description (typically at the beginning) as follows:
1720 </p><pre class="literallayout">
1721 [YOCTO #&lt;bug-id&gt;]
1722
1723 &lt;detailed description of change&gt;
1724 </pre></li></ul></div><p>
1725 </p><p>
1726 You can find more guidance on creating well-formed commit messages at this OpenEmbedded
1727 wiki page:
1728 <a class="ulink" href="http://www.openembedded.org/wiki/Commit_Patch_Message_Guidelines" target="_top">http://www.openembedded.org/wiki/Commit_Patch_Message_Guidelines</a>.
1729 </p><p>
1730 Following are general instructions for both pushing changes upstream and for submitting
1731 changes as patches.
1732 </p><div class="section" title="3.9.1. Using Scripts to Push a Change Upstream and Request a Pull"><div class="titlepage"><div><div><h3 class="title"><a id="pushing-a-change-upstream"></a>3.9.1. Using Scripts to Push a Change Upstream and Request a Pull</h3></div></div></div><p>
1733 The basic flow for pushing a change to an upstream "contrib" Git repository is as follows:
1734 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Make your changes in your local Git repository.</p></li><li class="listitem"><p>Stage your changes by using the <code class="filename">git add</code>
1735 command on each file you changed.</p></li><li class="listitem"><p>Commit the change by using the <code class="filename">git commit</code>
1736 command and push it to the "contrib" repository.
1737 Be sure to provide a commit message that follows the project’s commit message standards
1738 as described earlier.</p></li><li class="listitem"><p>Notify the maintainer that you have pushed a change by making a pull
1739 request.
1740 The Yocto Project provides two scripts that conveniently let you generate and send
1741 pull requests to the Yocto Project.
1742 These scripts are <code class="filename">create-pull-request</code> and
1743 <code class="filename">send-pull-request</code>.
1744 You can find these scripts in the <code class="filename">scripts</code> directory of the
1745 Yocto Project file structure.</p><p>Using these scripts correctly formats the requests without introducing any
1746 whitespace or HTML formatting.
1747 The maintainer that receives your patches needs to be able to save and apply them
1748 directly from your emails.
1749 Using these scripts is the preferred method for sending patches.</p><p>For help on using these scripts, simply provide the
1750 <code class="filename">-h</code> argument as follows:
1751 </p><pre class="literallayout">
1752 $ ~/poky/scripts/create-pull-request -h
1753 $ ~/poky/scripts/send-pull-request -h
1754 </pre></li></ul></div><p>
1755 </p><p>
1756 You can find general Git information on how to push a change upstream in the
1757 <a class="ulink" href="http://book.git-scm.com/3_distributed_workflows.html" target="_top">Git Community Book</a>.
1758 </p></div><div class="section" title="3.9.2. Using Email to Submit a Patch"><div class="titlepage"><div><div><h3 class="title"><a id="submitting-a-patch"></a>3.9.2. Using Email to Submit a Patch</h3></div></div></div><p>
1759 You can submit patches without using the <code class="filename">create-pull-request</code> and
1760 <code class="filename">send-pull-request</code> scripts described in the previous section.
1761 Keep in mind, the preferred method is to use the scripts, however.
1762 </p><p>
1763 Depending on the components changed, you need to submit the email to a specific
1764 mailing list.
1765 For some guidance on which mailing list to use, see the list in the
1766 "<a class="link" href="#how-to-submit-a-change" title="3.9. How to Submit a Change">How to Submit a Change</a>" section
1767 earlier in this manual.
1768 For a description of the available mailing lists, see
1769 "<a class="link" href="#resources-mailinglist" target="_top">Mailing Lists</a>"
1770 section in the Yocto Project Reference Manual.
1771 </p><p>
1772 Here is the general procedure on how to submit a patch through email without using the
1773 scripts:
1774 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Make your changes in your local Git repository.</p></li><li class="listitem"><p>Stage your changes by using the <code class="filename">git add</code>
1775 command on each file you changed.</p></li><li class="listitem"><p>Commit the change by using the
1776 <code class="filename">git commit --signoff</code> command.
1777 Using the <code class="filename">--signoff</code> option identifies you as the person
1778 making the change and also satisfies the Developer's Certificate of
1779 Origin (DCO) shown earlier.</p><p>When you form a commit you must follow certain standards established by the
1780 Yocto Project development team.
1781 See the earlier section
1782 "<a class="link" href="#how-to-submit-a-change" title="3.9. How to Submit a Change">How to Submit a Change</a>"
1783 for Yocto Project commit message standards.</p></li><li class="listitem"><p>Format the commit into an email message.
1784 To format commits, use the <code class="filename">git format-patch</code> command.
1785 When you provide the command, you must include a revision list or a number of patches
1786 as part of the command.
1787 For example, these two commands each take the most recent single commit and
1788 format it as an email message in the current directory:
1789 </p><pre class="literallayout">
1790 $ git format-patch -1
1791 $ git format-patch HEAD~
1792 </pre><p>After the command is run, the current directory contains a
1793 numbered <code class="filename">.patch</code> file for the commit.</p><p>If you provide several commits as part of the command,
1794 the <code class="filename">git format-patch</code> command produces a numbered
1795 series of files in the current directory – one for each commit.
1796 If you have more than one patch, you should also use the
1797 <code class="filename">--cover</code> option with the command, which generates a
1798 cover letter as the first "patch" in the series.
1799 You can then edit the cover letter to provide a description for
1800 the series of patches.
1801 For information on the <code class="filename">git format-patch</code> command,
1802 see <code class="filename">GIT_FORMAT_PATCH(1)</code> displayed using the
1803 <code class="filename">man git-format-patch</code> command.</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>If you are or will be a frequent contributor to the Yocto Project
1804 or to OpenEmbedded, you might consider requesting a contrib area and the
1805 necessary associated rights.</div></li><li class="listitem"><p>Import the files into your mail client by using the
1806 <code class="filename">git send-email</code> command.
1807 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>In order to use <code class="filename">git send-email</code>, you must have the
1808 the proper Git packages installed.
1809 For Ubuntu and Fedora the package is <code class="filename">git-email</code>.</div><p>The <code class="filename">git send-email</code> command sends email by using a local
1810 or remote Mail Transport Agent (MTA) such as
1811 <code class="filename">msmtp</code>, <code class="filename">sendmail</code>, or through a direct
1812 <code class="filename">smtp</code> configuration in your Git <code class="filename">config</code>
1813 file.
1814 If you are submitting patches through email only, it is very important
1815 that you submit them without any whitespace or HTML formatting that
1816 either you or your mailer introduces.
1817 The maintainer that receives your patches needs to be able to save and
1818 apply them directly from your emails.
1819 A good way to verify that what you are sending will be applicable by the
1820 maintainer is to do a dry run and send them to yourself and then
1821 save and apply them as the maintainer would.</p><p>The <code class="filename">git send-email</code> command is the preferred method
1822 for sending your patches since there is no risk of compromising whitespace
1823 in the body of the message, which can occur when you use your own mail client.
1824 The command also has several options that let you
1825 specify recipients and perform further editing of the email message.
1826 For information on how to use the <code class="filename">git send-email</code> command,
1827 use the <code class="filename">man git-send-email</code> command.</p></li></ul></div><p>
1828 </p></div></div></div>
1829
1830 <div class="chapter" title="Chapter 4. Common Tasks"><div class="titlepage"><div><div><h2 class="title"><a id="extendpoky"></a>Chapter 4. Common Tasks</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#understanding-and-creating-layers">4.1. Understanding and Creating Layers</a></span></dt><dd><dl><dt><span class="section"><a href="#yocto-project-layers">4.1.1. Layers</a></span></dt><dt><span class="section"><a href="#creating-your-own-layer">4.1.2. Creating Your Own Layer</a></span></dt><dt><span class="section"><a href="#enabling-your-layer">4.1.3. Enabling Your Layer</a></span></dt><dt><span class="section"><a href="#using-bbappend-files">4.1.4. Using .bbappend Files</a></span></dt><dt><span class="section"><a href="#prioritizing-your-layer">4.1.5. Prioritizing Your Layer</a></span></dt><dt><span class="section"><a href="#managing-layers">4.1.6. Managing Layers</a></span></dt></dl></dd><dt><span class="section"><a href="#usingpoky-extend-customimage">4.2. Customizing Images</a></span></dt><dd><dl><dt><span class="section"><a href="#usingpoky-extend-customimage-custombb">4.2.1. Customizing Images Using Custom .bb Files</a></span></dt><dt><span class="section"><a href="#usingpoky-extend-customimage-customtasks">4.2.2. Customizing Images Using Custom Tasks</a></span></dt><dt><span class="section"><a href="#usingpoky-extend-customimage-imagefeatures">4.2.3. Customizing Images Using Custom <code class="filename">IMAGE_FEATURES</code> and
1831 <code class="filename">EXTRA_IMAGE_FEATURES</code></a></span></dt><dt><span class="section"><a href="#usingpoky-extend-customimage-localconf">4.2.4. Customizing Images Using <code class="filename">local.conf</code></a></span></dt></dl></dd><dt><span class="section"><a href="#usingpoky-extend-addpkg">4.3. Adding a Package</a></span></dt><dd><dl><dt><span class="section"><a href="#usingpoky-extend-addpkg-singlec">4.3.1. Single .c File Package (Hello World!)</a></span></dt><dt><span class="section"><a href="#usingpoky-extend-addpkg-autotools">4.3.2. Autotooled Package</a></span></dt><dt><span class="section"><a href="#usingpoky-extend-addpkg-makefile">4.3.3. Makefile-Based Package</a></span></dt><dt><span class="section"><a href="#splitting-an-application-into-multiple-packages">4.3.4. Splitting an Application into Multiple Packages</a></span></dt><dt><span class="section"><a href="#including-static-library-files">4.3.5. Including Static Library Files</a></span></dt><dt><span class="section"><a href="#usingpoky-extend-addpkg-postinstalls">4.3.6. Post Install Scripts</a></span></dt></dl></dd><dt><span class="section"><a href="#platdev-newmachine">4.4. Adding a New Machine</a></span></dt><dd><dl><dt><span class="section"><a href="#platdev-newmachine-conffile">4.4.1. Adding the Machine Configuration File</a></span></dt><dt><span class="section"><a href="#platdev-newmachine-kernel">4.4.2. Adding a Kernel for the Machine</a></span></dt><dt><span class="section"><a href="#platdev-newmachine-formfactor">4.4.3. Adding a Formfactor Configuration File</a></span></dt></dl></dd><dt><span class="section"><a href="#building-multiple-architecture-libraries-into-one-image">4.5. Combining Multiple Versions of Library Files into One Image</a></span></dt><dd><dl><dt><span class="section"><a href="#preparing-to-use-multilib">4.5.1. Preparing to use Multilib</a></span></dt><dt><span class="section"><a href="#using-multilib">4.5.2. Using Multilib</a></span></dt><dt><span class="section"><a href="#additional-implementation-details">4.5.3. Additional Implementation Details</a></span></dt></dl></dd><dt><span class="section"><a href="#configuring-the-kernel">4.6. Configuring the Kernel</a></span></dt><dd><dl><dt><span class="section"><a href="#using-menuconfig">4.6.1. Using  <code class="filename">menuconfig</code></a></span></dt><dt><span class="section"><a href="#creating-config-fragments">4.6.2. Creating Configuration Fragments</a></span></dt><dt><span class="section"><a href="#fine-tuning-the-kernel-configuration-file">4.6.3. Fine-tuning the Kernel Configuration File</a></span></dt></dl></dd><dt><span class="section"><a href="#usingpoky-changes-updatingimages">4.7. Updating Existing Images</a></span></dt><dt><span class="section"><a href="#usingpoky-changes-prbump">4.8. Incrementing a Package Revision Number</a></span></dt><dt><span class="section"><a href="#usingpoky-configuring-DISTRO_PN_ALIAS">4.9. Handling a Package Name Alias</a></span></dt><dt><span class="section"><a href="#building-software-from-an-external-source">4.10. Building Software from an External Source</a></span></dt><dt><span class="section"><a href="#excluding-recipes-from-the-build">4.11. Excluding Recipes From the Build</a></span></dt><dt><span class="section"><a href="#platdev-appdev-srcrev">4.12. Using an External SCM</a></span></dt><dt><span class="section"><a href="#platdev-gdb-remotedebug">4.13. Debugging With the GNU Project Debugger (GDB) Remotely</a></span></dt><dd><dl><dt><span class="section"><a href="#platdev-gdb-remotedebug-launch-gdbserver">4.13.1. Launching Gdbserver on the Target</a></span></dt><dt><span class="section"><a href="#platdev-gdb-remotedebug-launch-gdb">4.13.2. Launching GDB on the Host Computer</a></span></dt></dl></dd><dt><span class="section"><a href="#platdev-oprofile">4.14. Profiling with OProfile</a></span></dt><dd><dl><dt><span class="section"><a href="#platdev-oprofile-target">4.14.1. Profiling on the Target</a></span></dt><dt><span class="section"><a href="#platdev-oprofile-oprofileui">4.14.2. Using OProfileUI</a></span></dt></dl></dd></dl></div><p>
1832 This chapter describes standard tasks such as adding new
1833 software packages, extending or customizing images, and porting work to
1834 new hardware (adding a new machine).
1835 The chapter also describes how to combine multiple
1836 versions of library files into a single image, how to handle a package name alias, and
1837 gives advice about how to make changes to the Yocto Project to achieve the best results.
1838 </p><div class="section" title="4.1. Understanding and Creating Layers"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="understanding-and-creating-layers"></a>4.1. Understanding and Creating Layers</h2></div></div></div><p>
1839 The OpenEmbedded build system supports organizing <a class="link" href="#metadata">metadata</a>
1840 into multiple layers.
1841 Layers allow you to isolate different types of customizations from each other.
1842 You might find it tempting to keep everything in one layer when working on a single project.
1843 However, the more modular you organize your metadata, the easier it is to cope with future changes.
1844 </p><p>
1845 To illustrate how layers are used to keep things modular, consider machine customizations.
1846 These types of customizations typically reside in a BSP Layer.
1847 Furthermore, the machine customizations should be isolated from recipes and metadata that support
1848 a new GUI environment, for example.
1849 This situation gives you a couple a layers: one for the machine configurations, and one for the
1850 GUI environment.
1851 It is important to understand, however, that the BSP layer can still make machine-specific
1852 additions to recipes within the GUI environment layer without polluting the GUI layer itself
1853 with those machine-specific changes.
1854 You can accomplish this through a recipe that is a BitBake append
1855 (<code class="filename">.bbappend</code>) file, which is described later in this section.
1856 </p><p>
1857 </p><div class="section" title="4.1.1. Layers"><div class="titlepage"><div><div><h3 class="title"><a id="yocto-project-layers"></a>4.1.1. Layers</h3></div></div></div><p>
1858 The source directory contains several layers right out of the box.
1859 You can easily identify a layer in the source directory by its folder name.
1860 Folders that are layers begin with the string <code class="filename">meta</code>.
1861 For example, when you set up the <a class="link" href="#source-directory">source directory</a>
1862 structure, you will see several layers: <code class="filename">meta</code>, <code class="filename">meta-demoapps</code>,
1863 <code class="filename">meta-skeleton</code>, and <code class="filename">meta-yocto</code>.
1864 Each of these folders is a layer.
1865 </p><p>
1866 Furthermore, if you set up a local copy of the <code class="filename">meta-intel</code> Git repository
1867 and then explore that folder, you will discover many BSP layers within the
1868 <code class="filename">meta-intel</code> layer.
1869 For more information on BSP layers, see the
1870 "<a class="link" href="#bsp-layers" target="_top">BSP Layers</a>"
1871 section in the Yocto Project Board Support Package (BSP) Developer's Guide.
1872 </p></div><div class="section" title="4.1.2. Creating Your Own Layer"><div class="titlepage"><div><div><h3 class="title"><a id="creating-your-own-layer"></a>4.1.2. Creating Your Own Layer</h3></div></div></div><p>
1873 It is very easy to create your own layer to use with the OpenEmbedded build system.
1874 Follow these general steps to create your layer:
1875 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Check Existing Layers:</em></span> Before creating a new layer,
1876 you should be sure someone has not already created a layer containing the metadata
1877 you need.
1878 You can see the
1879 <a class="ulink" href="http://www.openembedded.org/wiki/LayerIndex" target="_top"><code class="filename">LayerIndex</code></a>
1880 for a list of layers from the OpenEmbedded community that can be used in the
1881 Yocto Project.</p></li><li class="listitem"><p><span class="emphasis"><em>Create a Directory:</em></span> Create the directory
1882 for your layer.
1883 Traditionally, prepend the name of the folder with the string
1884 <code class="filename">meta</code>.
1885 For example:
1886 </p><pre class="literallayout">
1887 meta-mylayer
1888 meta-GUI_xyz
1889 meta-mymachine
1890 </pre></li><li class="listitem"><p><span class="emphasis"><em>Create a Layer Configuration File:</em></span> Inside your new
1891 layer folder, you need to create a <code class="filename">conf/layer.conf</code> file.
1892 It is easiest to take an existing layer configuration file and copy that to your
1893 layer's <code class="filename">conf</code> directory and then modify the file as needed.</p><p>The <code class="filename">meta-yocto/conf/layer.conf</code> file demonstrates the
1894 required syntax:
1895 </p><pre class="literallayout">
1896 # We have a conf and classes directory, add to BBPATH
1897 BBPATH := "${LAYERDIR}:${BBPATH}"
1898
1899 # We have recipes-* directories, add to BBFILES
1900 BBFILES := "${BBFILES} ${LAYERDIR}/recipes-*/*/*.bb \
1901 ${LAYERDIR}/recipes-*/*/*.bbappend"
1902
1903 BBFILE_COLLECTIONS += "yocto"
1904 BBFILE_PATTERN_yocto := "^${LAYERDIR}/"
1905 BBFILE_PRIORITY_yocto = "5"
1906 </pre><p>In the previous example, the recipes for the layers are added to
1907 <code class="filename"><a class="link" href="#var-BBFILES" target="_top">BBFILES</a></code>.
1908 The
1909 <code class="filename"><a class="link" href="#var-BBFILE_COLLECTIONS" target="_top">BBFILE_COLLECTIONS</a></code>
1910 variable is then appended with the layer name.
1911 The
1912 <code class="filename"><a class="link" href="#var-BBFILE_PATTERN" target="_top">BBFILE_PATTERN</a></code>
1913 variable is set to a regular expression and is used to match files
1914 from <code class="filename">BBFILES</code> into a particular layer.
1915 In this case, immediate expansion of
1916 <code class="filename"><a class="link" href="#var-LAYERDIR" target="_top">LAYERDIR</a></code>
1917 sets <code class="filename">BBFILE_PATTERN</code> to the layer's path.
1918 The
1919 <code class="filename"><a class="link" href="#var-BBFILE_PRIORITY" target="_top">BBFILE_PRIORITY</a></code>
1920 variable then assigns a priority to the layer.
1921 Applying priorities is useful in situations where the same package might appear in multiple
1922 layers and allows you to choose what layer should take precedence.</p><p>Note the use of the
1923 <code class="filename"><a class="link" href="#var-LAYERDIR" target="_top">LAYERDIR</a></code>
1924 variable with the immediate expansion operator.
1925 The <code class="filename">LAYERDIR</code> variable expands to the directory of the current layer and
1926 requires the immediate expansion operator so that BitBake does not wait to expand the variable
1927 when it's parsing a different directory.</p><p>Through the use of the <code class="filename">BBPATH</code> variable,
1928 BitBake locates <code class="filename">.bbclass</code> files, configuration
1929 files, and files that are included with <code class="filename">include</code>
1930 and <code class="filename">require</code> statements.
1931 For these cases, BitBake uses the first file with the matching name found in
1932 <code class="filename">BBPATH</code>.
1933 This is similar to the way the <code class="filename">PATH</code> variable is used for binaries.
1934 We recommend, therefore, that you use unique <code class="filename">.bbclass</code>
1935 and configuration file names in your custom layer.</p></li><li class="listitem"><p><span class="emphasis"><em>Add Content:</em></span> Depending on the type of layer,
1936 add the content.
1937 If the layer adds support for a machine, add the machine configuration in
1938 a <code class="filename">conf/machine/</code> file within the layer.
1939 If the layer adds distro policy, add the distro configuration in a
1940 <code class="filename">conf/distro/</code> file with the layer.
1941 If the layer introduces new recipes, put the recipes you need in
1942 <code class="filename">recipes-*</code> subdirectories within the layer.</p></li></ol></div><p>
1943 </p><p>
1944 To create layers that are easier to maintain, you should consider the following:
1945 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Avoid "overlaying" entire recipes from other layers in your
1946 configuration.
1947 In other words, don't copy an entire recipe into your layer and then modify it.
1948 Use <code class="filename">.bbappend</code> files to override the parts of the
1949 recipe you need to modify.</p></li><li class="listitem"><p>Avoid duplicating include files.
1950 Use <code class="filename">.bbappend</code> files for each recipe that uses an include
1951 file.
1952 Or, if you are introducing a new recipe that requires the included file, use the
1953 path relative to the original layer directory to refer to the file.
1954 For example, use <code class="filename">require recipes-core/somepackage/somefile.inc</code>
1955 instead of <code class="filename">require somefile.inc</code>.
1956 If you're finding you have to overlay the include file, it could indicate a
1957 deficiency in the include file in the layer to which it originally belongs.
1958 If this is the case, you need to address that deficiency instead of overlaying
1959 the include file.
1960 For example, consider how Qt 4 database support plugins are configured.
1961 The source directory does not have
1962 MySQL or PostgreSQL, however OpenEmbedded's
1963 layer <code class="filename">meta-oe</code> does.
1964 Consequently, <code class="filename">meta-oe</code> uses <code class="filename">.bbappend</code>
1965 files to modify the <code class="filename">QT_SQL_DRIVER_FLAGS</code> variable to enable
1966 the appropriate plugins.
1967 This variable was added to the <code class="filename">qt4.inc</code> include file in
1968 the source directory specifically to allow the <code class="filename">meta-oe</code> layer
1969 to be able to control which plugins are built.</p></li></ul></div><p>
1970 </p><p>
1971 We also recommend the following:
1972 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Store custom layers in a Git repository that uses the
1973 <code class="filename">meta-&lt;layer_name&gt;</code> format.</p></li><li class="listitem"><p>Clone the repository alongside other <code class="filename">meta</code>
1974 directories in the
1975 <a class="link" href="#source-directory">source directory</a>.</p></li></ul></div><p>
1976 Following these recommendations keeps your source directory and
1977 its configuration entirely inside the Yocto Project's core base.
1978 </p></div><div class="section" title="4.1.3. Enabling Your Layer"><div class="titlepage"><div><div><h3 class="title"><a id="enabling-your-layer"></a>4.1.3. Enabling Your Layer</h3></div></div></div><p>
1979 Before the OpenEmbedded build system can use your new layer, you need to enable it.
1980 To enable your layer, simply add your layer's path to the
1981 <code class="filename"><a class="link" href="#var-BBLAYERS" target="_top">BBLAYERS</a></code>
1982 variable in your <code class="filename">conf/bblayers.conf</code> file, which is found in the
1983 <a class="link" href="#build-directory">build directory</a>.
1984 The following example shows how to enable a layer named <code class="filename">meta-mylayer</code>:
1985 </p><pre class="literallayout">
1986 LCONF_VERSION = "1"
1987
1988 BBFILES ?= ""
1989 BBLAYERS = " \
1990 /path/to/poky/meta \
1991 /path/to/poky/meta-yocto \
1992 /path/to/poky/meta-mylayer \
1993 "
1994 </pre><p>
1995 </p><p>
1996 BitBake parses each <code class="filename">conf/layer.conf</code> file as specified in the
1997 <code class="filename">BBLAYERS</code> variable within the <code class="filename">conf/bblayers.conf</code>
1998 file.
1999 During the processing of each <code class="filename">conf/layer.conf</code> file, BitBake adds the
2000 recipes, classes and configurations contained within the particular layer to the source
2001 directory.
2002 </p></div><div class="section" title="4.1.4. Using .bbappend Files"><div class="titlepage"><div><div><h3 class="title"><a id="using-bbappend-files"></a>4.1.4. Using .bbappend Files</h3></div></div></div><p>
2003 Recipes used to append metadata to other recipes are called BitBake append files.
2004 BitBake append files use the <code class="filename">.bbappend</code> file type suffix, while
2005 underlying recipes to which metadata is being appended use the
2006 <code class="filename">.bb</code> file type suffix.
2007 </p><p>
2008 A <code class="filename">.bbappend</code> file allows your layer to make additions or
2009 changes to the content of another layer's recipe without having to copy the other
2010 recipe into your layer.
2011 Your <code class="filename">.bbappend</code> file resides in your layer, while the underlying
2012 <code class="filename">.bb</code> recipe file to which you are appending metadata
2013 resides in a different layer.
2014 </p><p>
2015 Append files files must have the same name as the underlying recipe.
2016 For example, the append file <code class="filename">someapp_1.3.bbappend</code> must
2017 apply to <code class="filename">someapp_1.3.bb</code>.
2018 This means the original recipe and append file names are version number specific.
2019 If the underlying recipe is renamed to update to a newer version, the
2020 corresponding <code class="filename">.bbappend</code> file must be renamed as well.
2021 During the build process, BitBake displays an error on starting if it detects a
2022 <code class="filename">.bbappend</code> file that does not have an underlying recipe
2023 with a matching name.
2024 </p><p>
2025 Being able to append information to an existing recipe not only avoids duplication,
2026 but also automatically applies recipe changes in a different layer to your layer.
2027 If you were copying recipes, you would have to manually merge changes as they occur.
2028 </p><p>
2029 As an example, consider the main formfactor recipe and a corresponding formfactor
2030 append file both from the
2031 <a class="link" href="#source-directory">source directory</a>.
2032 Here is the main formfactor recipe, which is named <code class="filename">formfactor_0.0.bb</code> and
2033 located in the meta layer at <code class="filename">meta/recipes-bsp/formfactor</code>:
2034 </p><pre class="literallayout">
2035 DESCRIPTION = "Device formfactor information"
2036 SECTION = "base"
2037 LICENSE = "MIT"
2038 LIC_FILES_CHKSUM = "file://${COREBASE}/LICENSE;md5=3f40d7994397109285ec7b81fdeb3b58 \
2039 file://${COREBASE}/meta/COPYING.MIT;md5=3da9cfbcb788c80a0384361b4de20420"
2040 PR = "r20"
2041
2042 SRC_URI = "file://config file://machconfig"
2043 S = "${WORKDIR}"
2044
2045 PACKAGE_ARCH = "${MACHINE_ARCH}"
2046 INHIBIT_DEFAULT_DEPS = "1"
2047
2048 do_install() {
2049 # Only install file if it has a contents
2050 install -d ${D}${sysconfdir}/formfactor/
2051 install -m 0644 ${S}/config ${D}${sysconfdir}/formfactor/
2052 if [ -s "${S}/machconfig" ]; then
2053 install -m 0644 ${S}/machconfig ${D}${sysconfdir}/formfactor/
2054 fi
2055 }
2056 </pre><p>
2057 Here is the append file, which is named <code class="filename">formfactor_0.0.bbappend</code> and is from the
2058 Crown Bay BSP Layer named <code class="filename">meta-intel/meta-crownbay</code>.
2059 The file is in <code class="filename">recipes-bsp/formfactor</code>:
2060 </p><pre class="literallayout">
2061 FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
2062
2063 PRINC = "1"
2064 </pre><p>
2065 This example adds or overrides files in
2066 <a class="link" href="#var-SRC_URI" target="_top"><code class="filename">SRC_URI</code></a>
2067 within a <code class="filename">.bbappend</code> by extending the path BitBake uses to search for files.
2068 The most reliable way to do this is by prepending the
2069 <code class="filename">FILESEXTRAPATHS</code> variable.
2070 For example, if you have your files in a directory that is named the same as your package
2071 (<a class="link" href="#var-PN" target="_top"><code class="filename">PN</code></a>),
2072 you can add this directory by adding the following to your <code class="filename">.bbappend</code> file:
2073 </p><pre class="literallayout">
2074 FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
2075 </pre><p>
2076 Using the immediate expansion assignment operator <code class="filename">:=</code> is important because
2077 of the reference to <code class="filename">THISDIR</code>.
2078 The trailing colon character is important as it ensures that items in the list remain
2079 colon-separated.
2080 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>BitBake automatically defines the <code class="filename">THISDIR</code> variable.
2081 You should never set this variable yourself.
2082 Using <code class="filename">_prepend</code> ensures your path will be searched prior to other
2083 paths in the final list.
2084 </div><p>
2085 </p><p>
2086 For another example on how to use a <code class="filename">.bbappend</code> file, see the
2087 "<a class="link" href="#changing-recipes-kernel" title="A.5.2.4. Changing  recipes-kernel">Changing <code class="filename">recipes-kernel</code></a>"
2088 section.
2089 </p></div><div class="section" title="4.1.5. Prioritizing Your Layer"><div class="titlepage"><div><div><h3 class="title"><a id="prioritizing-your-layer"></a>4.1.5. Prioritizing Your Layer</h3></div></div></div><p>
2090 Each layer is assigned a priority value.
2091 Priority values control which layer takes precedence if there are recipe files with
2092 the same name in multiple layers.
2093 For these cases, the recipe file from the layer with a higher priority number taking precedence.
2094 Priority values also affect the order in which multiple <code class="filename">.bbappend</code> files
2095 for the same recipe are applied.
2096 You can either specify the priority manually, or allow the build system to calculate it
2097 based on the layer's dependencies.
2098 </p><p>
2099 To specify the layer's priority manually, use the
2100 <a class="link" href="#var-BBFILE_PRIORITY" target="_top"><code class="filename">BBFILE_PRIORITY</code></a>
2101 variable.
2102 For example:
2103 </p><pre class="literallayout">
2104 BBFILE_PRIORITY := "1"
2105 </pre><p>
2106 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>It is possible for a recipe with a lower version number
2107 <a class="link" href="#var-PV" target="_top"><code class="filename">PV</code></a>
2108 in a layer that has a higher priority to take precedence.</p><p>Also, the layer priority does not currently affect the precedence order of
2109 <code class="filename">.conf</code> or <code class="filename">.bbclass</code> files.
2110 Future versions of BitBake might address this.</p></div></div><div class="section" title="4.1.6. Managing Layers"><div class="titlepage"><div><div><h3 class="title"><a id="managing-layers"></a>4.1.6. Managing Layers</h3></div></div></div><p>
2111 You can use the BitBake layer management tool to provide a view into the structure of
2112 recipes across a multi-layer project.
2113 Being able to generate output that reports on configured layers with their paths and
2114 priorities and on <code class="filename">.bbappend</code> files and their applicable recipes
2115 can help to reveal potential problems.
2116 </p><p>
2117 Use the following form when running the layer management tool.
2118 </p><pre class="literallayout">
2119 $ bitbake-layers &lt;command&gt; [arguments]
2120 </pre><p>
2121 The following list describes the available commands:
2122 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename"><span class="emphasis"><em>help:</em></span></code>
2123 Displays general help or help on a specified command.</p></li><li class="listitem"><p><code class="filename"><span class="emphasis"><em>show-layers:</em></span></code>
2124 Show the current configured layers.</p></li><li class="listitem"><p><code class="filename"><span class="emphasis"><em>show-recipes:</em></span></code>
2125 Lists available recipes and the layers that provide them.
2126 </p></li><li class="listitem"><p><code class="filename"><span class="emphasis"><em>show-overlayed:</em></span></code>
2127 Lists overlayed recipes.
2128 A recipe is overlayed when a recipe with the same name exists in another layer
2129 that has a higher layer priority.
2130 </p></li><li class="listitem"><p><code class="filename"><span class="emphasis"><em>show-appends:</em></span></code>
2131 Lists <code class="filename">.bbappend</code> files and the recipe files to which
2132 they apply.</p></li><li class="listitem"><p><code class="filename"><span class="emphasis"><em>flatten:</em></span></code>
2133 Flattens the layer configuration into a separate output directory.
2134 Flattening your layer configuration builds a "flattened" directory that contains
2135 the contents of all layers, with any overlayed recipes removed and any
2136 <code class="filename">.bbappend</code> files appended to the corresponding recipes.
2137 You might have to perform some manual cleanup of the flattened layer as follows:
2138 </p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p>Non-recipe files (such as patches) are overwritten.
2139 The flatten command shows a warning for these files.</p></li><li class="listitem"><p>Anything beyond the normal layer setup has been added to
2140 the <code class="filename">layer.conf</code> file.
2141 Only the lowest priority layer's <code class="filename">layer.conf</code> is used.
2142 </p></li><li class="listitem"><p>Overridden and appended items from <code class="filename">.bbappend</code>
2143 files need to be cleaned up.
2144 The contents of each <code class="filename">.bbappend</code> end up in the
2145 flattened recipe.
2146 However, if there are appended or changed variable values, you need to tidy
2147 these up yourself.
2148 Consider the following example.
2149 Here, the <code class="filename">bitbake-layers</code> command adds the line
2150 <code class="filename">#### bbappended ...</code> so that you know where the following
2151 lines originate:
2152 </p><pre class="literallayout">
2153 ...
2154 DESCRIPTION = "A useful utility"
2155 ...
2156 EXTRA_OECONF = "--enable-something"
2157 ...
2158
2159 #### bbappended from meta-anotherlayer ####
2160
2161 DESCRIPTION = "Customized utility"
2162 EXTRA_OECONF += "--enable-somethingelse"
2163 </pre><p>
2164 Ideally, you would tidy up these utilities as follows:
2165 </p><pre class="literallayout">
2166 ...
2167 DESCRIPTION = "Customized utility"
2168 ...
2169 EXTRA_OECONF = "--enable-something --enable-somethingelse"
2170 ...
2171 </pre></li></ul></div></li></ul></div><p>
2172 </p></div></div><div class="section" title="4.2. Customizing Images"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-extend-customimage"></a>4.2. Customizing Images</h2></div></div></div><p>
2173 You can customize images to satisfy particular requirements.
2174 This section describes several methods and provides guidelines for each.
2175 </p><div class="section" title="4.2.1. Customizing Images Using Custom .bb Files"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-customimage-custombb"></a>4.2.1. Customizing Images Using Custom .bb Files</h3></div></div></div><p>
2176 One way to get additional software into an image is to create a custom image.
2177 The following example shows the form for the two lines you need:
2178 </p><pre class="literallayout">
2179 IMAGE_INSTALL = "task-core-x11-base package1 package2"
2180
2181 inherit core-image
2182 </pre><p>
2183 </p><p>
2184 By creating a custom image, a developer has total control
2185 over the contents of the image.
2186 It is important to use the correct names of packages in the
2187 <code class="filename"><a class="link" href="#var-IMAGE_INSTALL" target="_top">IMAGE_INSTALL</a></code>
2188 variable.
2189 You must use the OpenEmbedded notation and not the Debian notation for the names
2190 (e.g. <code class="filename">eglibc-dev</code> instead of <code class="filename">libc6-dev</code>).
2191 </p><p>
2192 The other method for creating a custom image is to base it on an existing image.
2193 For example, if you want to create an image based on <code class="filename">core-image-sato</code>
2194 but add the additional package <code class="filename">strace</code> to the image,
2195 copy the <code class="filename">meta/recipes-sato/images/core-image-sato.bb</code> to a
2196 new <code class="filename">.bb</code> and add the following line to the end of the copy:
2197 </p><pre class="literallayout">
2198 IMAGE_INSTALL += "strace"
2199 </pre><p>
2200 </p></div><div class="section" title="4.2.2. Customizing Images Using Custom Tasks"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-customimage-customtasks"></a>4.2.2. Customizing Images Using Custom Tasks</h3></div></div></div><p>
2201 For complex custom images, the best approach is to create a custom task package
2202 that is used to build the image or images.
2203 A good example of a tasks package is
2204 <code class="filename">meta/recipes-core/tasks/task-core-boot.bb</code>
2205 The
2206 <code class="filename"><a class="link" href="#var-PACKAGES" target="_top">PACKAGES</a></code>
2207 variable lists the task packages to build along with the complementary
2208 <code class="filename">-dbg</code> and <code class="filename">-dev</code> packages.
2209 For each package added, you can use
2210 <code class="filename"><a class="link" href="#var-RDEPENDS" target="_top">RDEPENDS</a></code>
2211 and
2212 <code class="filename"><a class="link" href="#var-RRECOMMENDS" target="_top">RRECOMMENDS</a></code>
2213 entries to provide a list of packages the parent task package should contain.
2214 Following is an example:
2215 </p><pre class="literallayout">
2216 DESCRIPTION = "My Custom Tasks"
2217
2218 PACKAGES = "\
2219 task-custom-apps \
2220 task-custom-apps-dbg \
2221 task-custom-apps-dev \
2222 task-custom-tools \
2223 task-custom-tools-dbg \
2224 task-custom-tools-dev \
2225 "
2226
2227 RDEPENDS_task-custom-apps = "\
2228 dropbear \
2229 portmap \
2230 psplash"
2231
2232 RDEPENDS_task-custom-tools = "\
2233 oprofile \
2234 oprofileui-server \
2235 lttng-control \
2236 lttng-viewer"
2237
2238 RRECOMMENDS_task-custom-tools = "\
2239 kernel-module-oprofile"
2240 </pre><p>
2241 </p><p>
2242 In the previous example, two task packages are created with their dependencies and their
2243 recommended package dependencies listed: <code class="filename">task-custom-apps</code>, and
2244 <code class="filename">task-custom-tools</code>.
2245 To build an image using these task packages, you need to add
2246 <code class="filename">task-custom-apps</code> and/or
2247 <code class="filename">task-custom-tools</code> to
2248 <code class="filename"><a class="link" href="#var-IMAGE_INSTALL" target="_top">IMAGE_INSTALL</a></code>.
2249 For other forms of image dependencies see the other areas of this section.
2250 </p></div><div class="section" title="4.2.3. Customizing Images Using Custom IMAGE_FEATURES and EXTRA_IMAGE_FEATURES"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-customimage-imagefeatures"></a>4.2.3. Customizing Images Using Custom <code class="filename">IMAGE_FEATURES</code> and
2251 <code class="filename">EXTRA_IMAGE_FEATURES</code></h3></div></div></div><p>
2252 Ultimately users might want to add extra image features to the set by using the
2253 <code class="filename"><a class="link" href="#var-IMAGE_FEATURES" target="_top">IMAGE_FEATURES</a></code>
2254 variable.
2255 To create these features, the best reference is
2256 <code class="filename">meta/classes/core-image.bbclass</code>, which shows how to achieve this.
2257 In summary, the file looks at the contents of the
2258 <code class="filename">IMAGE_FEATURES</code>
2259 variable and then maps that into a set of tasks or packages.
2260 Based on this information the
2261 <code class="filename"><a class="link" href="#var-IMAGE_INSTALL" target="_top"> IMAGE_INSTALL</a></code>
2262 variable is generated automatically.
2263 Users can add extra features by extending the class or creating a custom class for use
2264 with specialized image <code class="filename">.bb</code> files.
2265 You can also add more features by configuring the
2266 <code class="filename"><a class="link" href="#var-EXTRA_IMAGE_FEATURES" target="_top">EXTRA_IMAGE_FEATURES</a></code>
2267 variable in the <code class="filename">local.conf</code> file found in the source directory
2268 located in the build directory.
2269 </p><p>
2270 The Yocto Project ships with two SSH servers you can use in your images:
2271 Dropbear and OpenSSH.
2272 Dropbear is a minimal SSH server appropriate for resource-constrained environments,
2273 while OpenSSH is a well-known standard SSH server implementation.
2274 By default, the <code class="filename">core-image-sato</code> image is configured to use Dropbear.
2275 The <code class="filename">core-image-basic</code> and <code class="filename">core-image-lsb</code>
2276 images both include OpenSSH.
2277 The <code class="filename">core-image-minimal</code> image does not contain an SSH server.
2278 To change these defaults, edit the <code class="filename">IMAGE_FEATURES</code> variable
2279 so that it sets the image you are working with to include
2280 <code class="filename">ssh-server-dropbear</code> or <code class="filename">ssh-server-openssh</code>.
2281 </p></div><div class="section" title="4.2.4. Customizing Images Using local.conf"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-customimage-localconf"></a>4.2.4. Customizing Images Using <code class="filename">local.conf</code></h3></div></div></div><p>
2282 It is possible to customize image contents by using variables from your
2283 local configuration in your <code class="filename">conf/local.conf</code> file.
2284 Because it is limited to local use, this method generally only allows you to
2285 add packages and is not as flexible as creating your own customized image.
2286 When you add packages using local variables this way, you need to realize that
2287 these variable changes affect all images at the same time and might not be
2288 what you require.
2289 </p><p>
2290 The simplest way to add extra packages to all images is by using the
2291 <code class="filename"><a class="link" href="#var-IMAGE_INSTALL" target="_top">IMAGE_INSTALL</a></code>
2292 variable with the <code class="filename">_append</code> operator:
2293 </p><pre class="literallayout">
2294 IMAGE_INSTALL_append = " strace"
2295 </pre><p>
2296 Use of the syntax is important.
2297 Specifically, the space between the quote and the package name, which is
2298 <code class="filename">strace</code> in this example.
2299 This space is required since the <code class="filename">_append</code>
2300 operator does not add the space.
2301 </p><p>
2302 Furthermore, you must use <code class="filename">_append</code> instead of the <code class="filename">+=</code>
2303 operator if you want to avoid ordering issues.
2304 The reason for this is because doing so unconditionally appends to the variable and
2305 avoids ordering problems due to the variable being set in image recipes and
2306 <code class="filename">.bbclass</code> files with operators like <code class="filename">?=</code>.
2307 Using <code class="filename">_append</code> ensures the operation takes affect.
2308 </p><p>
2309 As shown in its simplest use, <code class="filename">IMAGE_INSTALL_append</code> affects
2310 all images.
2311 It is possible to extend the syntax so that the variable applies to a specific image only.
2312 Here is an example:
2313 </p><pre class="literallayout">
2314 IMAGE_INSTALL_append_pn-core-image-minimal = " strace"
2315 </pre><p>
2316 This example adds <code class="filename">strace</code> to <code class="filename">core-image-minimal</code>
2317 only.
2318 </p><p>
2319 You can add packages using a similar approach through the
2320 <code class="filename"><a class="link" href="#var-CORE_IMAGE_EXTRA_INSTALL" target="_top">CORE_IMAGE_EXTRA_INSTALL</a></code>
2321 variable.
2322 If you use this variable, only <code class="filename">core-image-*</code> images are affected.
2323 </p></div></div><div class="section" title="4.3. Adding a Package"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-extend-addpkg"></a>4.3. Adding a Package</h2></div></div></div><p>
2324 To add a package you need to write a recipe for it.
2325 Writing a recipe means creating a <code class="filename">.bb</code> file that sets some
2326 variables.
2327 For information on variables that are useful for recipes and for information about recipe naming
2328 issues, see the
2329 "<a class="link" href="#ref-varlocality-recipe-required" target="_top">Required</a>"
2330 section of the Yocto Project Reference Manual.
2331 </p><p>
2332 Before writing a recipe from scratch, it is often useful to check
2333 whether someone else has written one already.
2334 OpenEmbedded is a good place to look as it has a wider scope and range of packages.
2335 Because the Yocto Project aims to be compatible with OpenEmbedded, most recipes
2336 you find there should work for you.
2337 </p><p>
2338 For new packages, the simplest way to add a recipe is to base it on a similar
2339 pre-existing recipe.
2340 The sections that follow provide some examples that show how to add standard
2341 types of packages.
2342 </p><div class="section" title="4.3.1. Single .c File Package (Hello World!)"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-addpkg-singlec"></a>4.3.1. Single .c File Package (Hello World!)</h3></div></div></div><p>
2343 Building an application from a single file that is stored locally (e.g. under
2344 <code class="filename">files/</code>) requires a recipe that has the file listed in
2345 the
2346 <code class="filename"><a class="link" href="#var-SRC_URI" target="_top">SRC_URI</a></code>
2347 variable.
2348 Additionally, you need to manually write the <code class="filename">do_compile</code> and
2349 <code class="filename">do_install</code> tasks.
2350 The <code class="filename"><a class="link" href="#var-S" target="_top">S</a></code>
2351 variable defines the
2352 directory containing the source code, which is set to
2353 <code class="filename"><a class="link" href="#var-WORKDIR" target="_top">
2354 WORKDIR</a></code> in this case - the directory BitBake uses for the build.
2355 </p><pre class="literallayout">
2356 DESCRIPTION = "Simple helloworld application"
2357 SECTION = "examples"
2358 LICENSE = "MIT"
2359 LIC_FILES_CHKSUM = "file://${COMMON_LICENSE_DIR}/MIT;md5=0835ade698e0bcf8506ecda2f7b4f302"
2360 PR = "r0"
2361
2362 SRC_URI = "file://helloworld.c"
2363
2364 S = "${WORKDIR}"
2365
2366 do_compile() {
2367 ${CC} helloworld.c -o helloworld
2368 }
2369
2370 do_install() {
2371 install -d ${D}${bindir}
2372 install -m 0755 helloworld ${D}${bindir}
2373 }
2374 </pre><p>
2375 </p><p>
2376 By default, the <code class="filename">helloworld</code>, <code class="filename">helloworld-dbg</code>,
2377 and <code class="filename">helloworld-dev</code> packages are built.
2378 For information on how to customize the packaging process, see the
2379 "<a class="link" href="#splitting-an-application-into-multiple-packages" title="4.3.4. Splitting an Application into Multiple Packages">Splitting an Application
2380 into Multiple Packages</a>" section.
2381 </p></div><div class="section" title="4.3.2. Autotooled Package"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-addpkg-autotools"></a>4.3.2. Autotooled Package</h3></div></div></div><p>
2382 Applications that use Autotools such as <code class="filename">autoconf</code> and
2383 <code class="filename">automake</code> require a recipe that has a source archive listed in
2384 <code class="filename"><a class="link" href="#var-SRC_URI" target="_top">SRC_URI</a></code> and
2385 also inherits Autotools, which instructs BitBake to use the
2386 <code class="filename">autotools.bbclass</code> file, which contains the definitions of all the steps
2387 needed to build an Autotool-based application.
2388 The result of the build is automatically packaged.
2389 And, if the application uses NLS for localization, packages with local information are
2390 generated (one package per language).
2391 Following is one example: (<code class="filename">hello_2.3.bb</code>)
2392 </p><pre class="literallayout">
2393 DESCRIPTION = "GNU Helloworld application"
2394 SECTION = "examples"
2395 LICENSE = "GPLv2+"
2396 LIC_FILES_CHKSUM = "file://COPYING;md5=751419260aa954499f7abaabaa882bbe"
2397 PR = "r0"
2398
2399 SRC_URI = "${GNU_MIRROR}/hello/hello-${PV}.tar.gz"
2400
2401 inherit autotools gettext
2402 </pre><p>
2403 </p><p>
2404 The variable
2405 <code class="filename"><a class="link" href="#var-LIC_FILES_CHKSUM" target="_top">LIC_FILES_CHKSUM</a></code>
2406 is used to track source license changes as described in the
2407 "<a class="link" href="#usingpoky-configuring-LIC_FILES_CHKSUM" target="_top">Track License Changes</a>" section.
2408 You can quickly create Autotool-based recipes in a manner similar to the previous example.
2409 </p></div><div class="section" title="4.3.3. Makefile-Based Package"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-addpkg-makefile"></a>4.3.3. Makefile-Based Package</h3></div></div></div><p>
2410 Applications that use GNU <code class="filename">make</code> also require a recipe that has
2411 the source archive listed in
2412 <code class="filename"><a class="link" href="#var-SRC_URI" target="_top">SRC_URI</a></code>.
2413 You do not need to add a <code class="filename">do_compile</code> step since by default BitBake
2414 starts the <code class="filename">make</code> command to compile the application.
2415 If you need additional <code class="filename">make</code> options you should store them in the
2416 <code class="filename"><a class="link" href="#var-EXTRA_OEMAKE" target="_top">EXTRA_OEMAKE</a></code>
2417 variable.
2418 BitBake passes these options into the <code class="filename">make</code> GNU invocation.
2419 Note that a <code class="filename">do_install</code> task is still required.
2420 Otherwise BitBake runs an empty <code class="filename">do_install</code> task by default.
2421 </p><p>
2422 Some applications might require extra parameters to be passed to the compiler.
2423 For example, the application might need an additional header path.
2424 You can accomplish this by adding to the
2425 <code class="filename"><a class="link" href="#var-CFLAGS" target="_top">CFLAGS</a></code> variable.
2426 The following example shows this:
2427 </p><pre class="literallayout">
2428 CFLAGS_prepend = "-I ${S}/include "
2429 </pre><p>
2430 </p><p>
2431 In the following example, <code class="filename">mtd-utils</code> is a makefile-based package:
2432 </p><pre class="literallayout">
2433 DESCRIPTION = "Tools for managing memory technology devices."
2434 SECTION = "base"
2435 DEPENDS = "zlib lzo e2fsprogs util-linux"
2436 HOMEPAGE = "http://www.linux-mtd.infradead.org/"
2437 LICENSE = "GPLv2+"
2438 LIC_FILES_CHKSUM = "file://COPYING;md5=0636e73ff0215e8d672dc4c32c317bb3 \
2439 file://include/common.h;beginline=1;endline=17;md5=ba05b07912a44ea2bf81ce409380049c"
2440
2441 SRC_URI = "git://git.infradead.org/mtd-utils.git;protocol=git;tag=995cfe51b0a3cf32f381c140bf72b21bf91cef1b \
2442 file://add-exclusion-to-mkfs-jffs2-git-2.patch"
2443
2444 S = "${WORKDIR}/git/"
2445
2446 PR = "r1"
2447
2448 EXTRA_OEMAKE = "'CC=${CC}' 'RANLIB=${RANLIB}' 'AR=${AR}' \
2449 'CFLAGS=${CFLAGS} -I${S}/include -DWITHOUT_XATTR' 'BUILDDIR=${S}'"
2450
2451 do_install () {
2452 oe_runmake install DESTDIR=${D} SBINDIR=${sbindir} MANDIR=${mandir} \
2453 INCLUDEDIR=${includedir}
2454 install -d ${D}${includedir}/mtd/
2455 for f in ${S}/include/mtd/*.h; do
2456 install -m 0644 $f ${D}${includedir}/mtd/
2457 done
2458 }
2459
2460 PARALLEL_MAKE = ""
2461
2462 BBCLASSEXTEND = "native"
2463 </pre><p>
2464 </p><p>
2465 If your sources are available as a tarball instead of a Git repository, you
2466 will need to provide the URL to the tarball as well as an
2467 <code class="filename">md5</code> or <code class="filename">sha256</code> sum of
2468 the download.
2469 Here is an example:
2470 </p><pre class="literallayout">
2471 SRC_URI="ftp://ftp.infradead.org/pub/mtd-utils/mtd-utils-1.4.9.tar.bz2"
2472 SRC_URI[md5sum]="82b8e714b90674896570968f70ca778b"
2473 </pre><p>
2474 You can generate the <code class="filename">md5</code> or <code class="filename">sha256</code> sums
2475 by using the <code class="filename">md5sum</code> or <code class="filename">sha256sum</code> commands
2476 with the target file as the only argument.
2477 Here is an example:
2478 </p><pre class="literallayout">
2479 $ md5sum mtd-utils-1.4.9.tar.bz2
2480 82b8e714b90674896570968f70ca778b mtd-utils-1.4.9.tar.bz2
2481 </pre><p>
2482 </p></div><div class="section" title="4.3.4. Splitting an Application into Multiple Packages"><div class="titlepage"><div><div><h3 class="title"><a id="splitting-an-application-into-multiple-packages"></a>4.3.4. Splitting an Application into Multiple Packages</h3></div></div></div><p>
2483 You can use the variables
2484 <code class="filename"><a class="link" href="#var-PACKAGES" target="_top">PACKAGES</a></code> and
2485 <code class="filename"><a class="link" href="#var-FILES" target="_top">FILES</a></code>
2486 to split an application into multiple packages.
2487 </p><p>
2488 Following is an example that uses the <code class="filename">libXpm</code> recipe.
2489 By default, this recipe generates a single package that contains the library along
2490 with a few binaries.
2491 You can modify the recipe to split the binaries into separate packages:
2492 </p><pre class="literallayout">
2493 require xorg-lib-common.inc
2494
2495 DESCRIPTION = "X11 Pixmap library"
2496 LICENSE = "X-BSD"
2497 LIC_FILES_CHKSUM = "file://COPYING;md5=3e07763d16963c3af12db271a31abaa5"
2498 DEPENDS += "libxext libsm libxt"
2499 PR = "r3"
2500 PE = "1"
2501
2502 XORG_PN = "libXpm"
2503
2504 PACKAGES =+ "sxpm cxpm"
2505 FILES_cxpm = "${bindir}/cxpm"
2506 FILES_sxpm = "${bindir}/sxpm"
2507 </pre><p>
2508 </p><p>
2509 In the previous example, we want to ship the <code class="filename">sxpm</code>
2510 and <code class="filename">cxpm</code> binaries in separate packages.
2511 Since <code class="filename">bindir</code> would be packaged into the main
2512 <code class="filename"><a class="link" href="#var-PN" target="_top">PN</a></code>
2513 package by default, we prepend the
2514 <code class="filename"><a class="link" href="#var-PACKAGES" target="_top">PACKAGES</a>
2515 </code> variable so additional package names are added to the start of list.
2516 This results in the extra
2517 <code class="filename"><a class="link" href="#var-FILES" target="_top">FILES</a>_*</code>
2518 variables then containing information that define which files and
2519 directories go into which packages.
2520 Files included by earlier packages are skipped by latter packages.
2521 Thus, the main
2522 <code class="filename"><a class="link" href="#var-PN" target="_top">PN</a></code> package
2523 does not include the above listed files.
2524 </p></div><div class="section" title="4.3.5. Including Static Library Files"><div class="titlepage"><div><div><h3 class="title"><a id="including-static-library-files"></a>4.3.5. Including Static Library Files</h3></div></div></div><p>
2525 If you are building a library and the library offers static linking, you can control
2526 which static library files (<code class="filename">*.a</code> files) get included in the
2527 built library.
2528 </p><p>
2529 The <code class="filename">PACKAGES</code> and <code class="filename">FILES_*</code> variables in the
2530 <code class="filename">meta/conf/bitbake.conf</code> configuration file define how files installed
2531 by the <code class="filename">do_install</code> task are packaged.
2532 By default, the <code class="filename">PACKAGES</code> variable contains
2533 <code class="filename">${PN}-staticdev</code>, which includes all static library files.
2534 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
2535 Previously released versions of the Yocto Project defined the static library files
2536 through <code class="filename">${PN}-dev</code>.
2537 </div><p>
2538 Following, is part of the BitBake configuration file.
2539 You can see where the static library files are defined:
2540 </p><pre class="literallayout">
2541 PACKAGES = "${PN}-dbg ${PN} ${PN}-doc ${PN}-dev ${PN}-staticdev ${PN}-locale"
2542 PACKAGES_DYNAMIC = "${PN}-locale-*"
2543 FILES = ""
2544
2545 FILES_${PN} = "${bindir}/* ${sbindir}/* ${libexecdir}/* ${libdir}/lib*${SOLIBS} \
2546 ${sysconfdir} ${sharedstatedir} ${localstatedir} \
2547 ${base_bindir}/* ${base_sbindir}/* \
2548 ${base_libdir}/*${SOLIBS} \
2549 ${datadir}/${BPN} ${libdir}/${BPN}/* \
2550 ${datadir}/pixmaps ${datadir}/applications \
2551 ${datadir}/idl ${datadir}/omf ${datadir}/sounds \
2552 ${libdir}/bonobo/servers"
2553
2554 FILES_${PN}-doc = "${docdir} ${mandir} ${infodir} ${datadir}/gtk-doc \
2555 ${datadir}/gnome/help"
2556 SECTION_${PN}-doc = "doc"
2557
2558 FILES_${PN}-dev = "${includedir} ${libdir}/lib*${SOLIBSDEV} ${libdir}/*.la \
2559 ${libdir}/*.o ${libdir}/pkgconfig ${datadir}/pkgconfig \
2560 ${datadir}/aclocal ${base_libdir}/*.o"
2561 SECTION_${PN}-dev = "devel"
2562 ALLOW_EMPTY_${PN}-dev = "1"
2563 RDEPENDS_${PN}-dev = "${PN} (= ${EXTENDPKGV})"
2564
2565 FILES_${PN}-staticdev = "${libdir}/*.a ${base_libdir}/*.a"
2566 SECTION_${PN}-staticdev = "devel"
2567 RDEPENDS_${PN}-staticdev = "${PN}-dev (= ${EXTENDPKGV})"
2568 </pre><p>
2569 </p></div><div class="section" title="4.3.6. Post Install Scripts"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-extend-addpkg-postinstalls"></a>4.3.6. Post Install Scripts</h3></div></div></div><p>
2570 To add a post-installation script to a package, add a <code class="filename">pkg_postinst_PACKAGENAME()
2571 </code> function to the <code class="filename">.bb</code> file and use
2572 <code class="filename">PACKAGENAME</code> as the name of the package you want to attach to the
2573 <code class="filename">postinst</code> script.
2574 Normally
2575 <code class="filename"><a class="link" href="#var-PN" target="_top">PN</a></code>
2576 can be used, which automatically expands to <code class="filename">PACKAGENAME</code>.
2577 A post-installation function has the following structure:
2578 </p><pre class="literallayout">
2579 pkg_postinst_PACKAGENAME () {
2580 #!/bin/sh -e
2581 # Commands to carry out
2582 }
2583 </pre><p>
2584 </p><p>
2585 The script defined in the post-installation function is called when the
2586 root filesystem is created.
2587 If the script succeeds, the package is marked as installed.
2588 If the script fails, the package is marked as unpacked and the script is
2589 executed when the image boots again.
2590 </p><p>
2591 Sometimes it is necessary for the execution of a post-installation
2592 script to be delayed until the first boot.
2593 For example, the script might need to be executed on the device itself.
2594 To delay script execution until boot time, use the following structure in the
2595 post-installation script:
2596 </p><pre class="literallayout">
2597 pkg_postinst_PACKAGENAME () {
2598 #!/bin/sh -e
2599 if [ x"$D" = "x" ]; then
2600 # Actions to carry out on the device go here
2601 else
2602 exit 1
2603 fi
2604 }
2605 </pre><p>
2606 </p><p>
2607 The previous example delays execution until the image boots again because the
2608 <code class="filename"><a class="link" href="#var-D" target="_top">D</a></code>
2609 variable points
2610 to the directory containing the image when the root filesystem is created at build time but
2611 is unset when executed on the first boot.
2612 </p></div></div><div class="section" title="4.4. Adding a New Machine"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="platdev-newmachine"></a>4.4. Adding a New Machine</h2></div></div></div><p>
2613 Adding a new machine to the Yocto Project is a straightforward process.
2614 This section provides information that gives you an idea of the changes you must make.
2615 The information covers adding machines similar to those the Yocto Project already supports.
2616 Although well within the capabilities of the Yocto Project, adding a totally new architecture
2617 might require
2618 changes to <code class="filename">gcc/eglibc</code> and to the site information, which is
2619 beyond the scope of this manual.
2620 </p><p>
2621 For a complete example that shows how to add a new machine,
2622 see the
2623 "<a class="link" href="#dev-manual-bsp-appendix" target="_top">BSP Development Example</a>"
2624 in Appendix A.
2625 </p><div class="section" title="4.4.1. Adding the Machine Configuration File"><div class="titlepage"><div><div><h3 class="title"><a id="platdev-newmachine-conffile"></a>4.4.1. Adding the Machine Configuration File</h3></div></div></div><p>
2626 To add a machine configuration you need to add a <code class="filename">.conf</code> file
2627 with details of the device being added to the <code class="filename">conf/machine/</code> file.
2628 The name of the file determines the name the OpenEmbedded build system
2629 uses to reference the new machine.
2630 </p><p>
2631 The most important variables to set in this file are as follows:
2632 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename"><a class="link" href="#var-TARGET_ARCH" target="_top">
2633 TARGET_ARCH</a></code> (e.g. "arm")</p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-PREFERRED_PROVIDER" target="_top">
2634 PREFERRED_PROVIDER</a></code>_virtual/kernel (see below)</p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-MACHINE_FEATURES" target="_top">
2635 MACHINE_FEATURES</a></code> (e.g. "apm screen wifi")</p></li></ul></div><p>
2636 </p><p>
2637 You might also need these variables:
2638 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename"><a class="link" href="#var-SERIAL_CONSOLE" target="_top">
2639 SERIAL_CONSOLE</a></code> (e.g. "115200 ttyS0")</p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-KERNEL_IMAGETYPE" target="_top">
2640 KERNEL_IMAGETYPE</a></code> (e.g. "zImage")</p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-IMAGE_FSTYPES" target="_top">
2641 IMAGE_FSTYPES</a></code> (e.g. "tar.gz jffs2")</p></li></ul></div><p>
2642 </p><p>
2643 You can find full details on these variables in the reference section.
2644 You can leverage many existing machine <code class="filename">.conf</code> files from
2645 <code class="filename">meta/conf/machine/</code>.
2646 </p></div><div class="section" title="4.4.2. Adding a Kernel for the Machine"><div class="titlepage"><div><div><h3 class="title"><a id="platdev-newmachine-kernel"></a>4.4.2. Adding a Kernel for the Machine</h3></div></div></div><p>
2647 The OpenEmbedded build system needs to be able to build a kernel for the machine.
2648 You need to either create a new kernel recipe for this machine, or extend an
2649 existing recipe.
2650 You can find several kernel examples in the
2651 source directory at <code class="filename">meta/recipes-kernel/linux</code>
2652 that you can use as references.
2653 </p><p>
2654 If you are creating a new recipe, normal recipe-writing rules apply for setting
2655 up a
2656 <code class="filename"><a class="link" href="#var-SRC_URI" target="_top">SRC_URI</a></code>.
2657 Thus, you need to specify any necessary patches and set
2658 <code class="filename"><a class="link" href="#var-S" target="_top">S</a></code> to point at the source code.
2659 You need to create a <code class="filename">configure</code> task that configures the
2660 unpacked kernel with a defconfig.
2661 You can do this by using a <code class="filename">make defconfig</code> command or,
2662 more commonly, by copying in a suitable <code class="filename">defconfig</code> file and and then running
2663 <code class="filename">make oldconfig</code>.
2664 By making use of <code class="filename">inherit kernel</code> and potentially some of the
2665 <code class="filename">linux-*.inc</code> files, most other functionality is
2666 centralized and the the defaults of the class normally work well.
2667 </p><p>
2668 If you are extending an existing kernel, it is usually a matter of adding a
2669 suitable defconfig file.
2670 The file needs to be added into a location similar to defconfig files
2671 used for other machines in a given kernel.
2672 A possible way to do this is by listing the file in the
2673 <code class="filename">SRC_URI</code> and adding the machine to the expression in
2674 <code class="filename"><a class="link" href="#var-COMPATIBLE_MACHINE" target="_top">COMPATIBLE_MACHINE</a></code>:
2675 </p><pre class="literallayout">
2676 COMPATIBLE_MACHINE = '(qemux86|qemumips)'
2677 </pre><p>
2678 </p></div><div class="section" title="4.4.3. Adding a Formfactor Configuration File"><div class="titlepage"><div><div><h3 class="title"><a id="platdev-newmachine-formfactor"></a>4.4.3. Adding a Formfactor Configuration File</h3></div></div></div><p>
2679 A formfactor configuration file provides information about the
2680 target hardware for which the image is being built and information that
2681 the build system cannot obtain from other sources such as the kernel.
2682 Some examples of information contained in a formfactor configuration file include
2683 framebuffer orientation, whether or not the system has a keyboard,
2684 the positioning of the keyboard in relation to the screen, and
2685 the screen resolution.
2686 </p><p>
2687 The build system uses reasonable defaults in most cases, but if customization is
2688 necessary you need to create a <code class="filename">machconfig</code> file
2689 in the <code class="filename">meta/recipes-bsp/formfactor/files</code>
2690 directory.
2691 This directory contains directories for specific machines such as
2692 <code class="filename">qemuarm</code> and <code class="filename">qemux86</code>.
2693 For information about the settings available and the defaults, see the
2694 <code class="filename">meta/recipes-bsp/formfactor/files/config</code> file found in the
2695 same area.
2696 Following is an example for qemuarm:
2697 </p><pre class="literallayout">
2698 HAVE_TOUCHSCREEN=1
2699 HAVE_KEYBOARD=1
2700
2701 DISPLAY_CAN_ROTATE=0
2702 DISPLAY_ORIENTATION=0
2703 #DISPLAY_WIDTH_PIXELS=640
2704 #DISPLAY_HEIGHT_PIXELS=480
2705 #DISPLAY_BPP=16
2706 DISPLAY_DPI=150
2707 DISPLAY_SUBPIXEL_ORDER=vrgb
2708 </pre><p>
2709 </p></div></div><div class="section" title="4.5. Combining Multiple Versions of Library Files into One Image"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="building-multiple-architecture-libraries-into-one-image"></a>4.5. Combining Multiple Versions of Library Files into One Image</h2></div></div></div><p>
2710 The build system offers the ability to build libraries with different
2711 target optimizations or architecture formats and combine these together
2712 into one system image.
2713 You can link different binaries in the image
2714 against the different libraries as needed for specific use cases.
2715 This feature is called "Multilib."
2716 </p><p>
2717 An example would be where you have most of a system compiled in 32-bit
2718 mode using 32-bit libraries, but you have something large, like a database
2719 engine, that needs to be a 64-bit application and use 64-bit libraries.
2720 Multilib allows you to get the best of both 32-bit and 64-bit libraries.
2721 </p><p>
2722 While the Multilib feature is most commonly used for 32 and 64-bit differences,
2723 the approach the build system uses facilitates different target optimizations.
2724 You could compile some binaries to use one set of libraries and other binaries
2725 to use other different sets of libraries.
2726 The libraries could differ in architecture, compiler options, or other
2727 optimizations.
2728 </p><p>
2729 This section overviews the Multilib process only.
2730 For more details on how to implement Multilib, see the
2731 <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Multilib" target="_top">Multilib</a> wiki
2732 page.
2733 </p><div class="section" title="4.5.1. Preparing to use Multilib"><div class="titlepage"><div><div><h3 class="title"><a id="preparing-to-use-multilib"></a>4.5.1. Preparing to use Multilib</h3></div></div></div><p>
2734 User-specific requirements drive the Multilib feature,
2735 Consequently, there is no one "out-of-the-box" configuration that likely
2736 exists to meet your needs.
2737 </p><p>
2738 In order to enable Multilib, you first need to ensure your recipe is
2739 extended to support multiple libraries.
2740 Many standard recipes are already extended and support multiple libraries.
2741 You can check in the <code class="filename">meta/conf/multilib.conf</code>
2742 configuration file in the source directory to see how this is
2743 done using the <code class="filename">BBCLASSEXTEND</code> variable.
2744 Eventually, all recipes will be covered and this list will be unneeded.
2745 </p><p>
2746 For the most part, the Multilib class extension works automatically to
2747 extend the package name from <code class="filename">${PN}</code> to
2748 <code class="filename">${MLPREFIX}${PN}</code>, where <code class="filename">MLPREFIX</code>
2749 is the particular multilib (e.g. "lib32-" or "lib64-").
2750 Standard variables such as <code class="filename">DEPENDS</code>,
2751 <code class="filename">RDEPENDS</code>, <code class="filename">RPROVIDES</code>,
2752 <code class="filename">RRECOMMENDS</code>, <code class="filename">PACKAGES</code>, and
2753 <code class="filename">PACKAGES_DYNAMIC</code> are automatically extended by the system.
2754 If you are extending any manual code in the recipe, you can use the
2755 <code class="filename">${MLPREFIX}</code> variable to ensure those names are extended
2756 correctly.
2757 This automatic extension code resides in <code class="filename">multilib.bbclass</code>.
2758 </p></div><div class="section" title="4.5.2. Using Multilib"><div class="titlepage"><div><div><h3 class="title"><a id="using-multilib"></a>4.5.2. Using Multilib</h3></div></div></div><p>
2759 After you have set up the recipes, you need to define the actual
2760 combination of multiple libraries you want to build.
2761 You accomplish this through your <code class="filename">local.conf</code>
2762 configuration file in the
2763 <a class="link" href="#build-directory">build directory</a>.
2764 An example configuration would be as follows:
2765 </p><pre class="literallayout">
2766 MACHINE = "qemux86-64"
2767 require conf/multilib.conf
2768 MULTILIBS = "multilib:lib32"
2769 DEFAULTTUNE_virtclass-multilib-lib32 = "x86"
2770 IMAGE_INSTALL = "lib32-connman"
2771 </pre><p>
2772 This example enables an
2773 additional library named <code class="filename">lib32</code> alongside the
2774 normal target packages.
2775 When combining these "lib32" alternatives, the example uses "x86" for tuning.
2776 For information on this particular tuning, see
2777 <code class="filename">meta/conf/machine/include/ia32/arch-ia32.inc</code>.
2778 </p><p>
2779 The example then includes <code class="filename">lib32-connman</code>
2780 in all the images, which illustrates one method of including a
2781 multiple library dependency.
2782 You can use a normal image build to include this dependency,
2783 for example:
2784 </p><pre class="literallayout">
2785 $ bitbake core-image-sato
2786 </pre><p>
2787 You can also build Multilib packages specifically with a command like this:
2788 </p><pre class="literallayout">
2789 $ bitbake lib32-connman
2790 </pre><p>
2791 </p></div><div class="section" title="4.5.3. Additional Implementation Details"><div class="titlepage"><div><div><h3 class="title"><a id="additional-implementation-details"></a>4.5.3. Additional Implementation Details</h3></div></div></div><p>
2792 Different packaging systems have different levels of native Multilib
2793 support.
2794 For the RPM Package Management System, the following implementation details
2795 exist:
2796 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>A unique architecture is defined for the Multilib packages,
2797 along with creating a unique deploy folder under
2798 <code class="filename">tmp/deploy/rpm</code> in the
2799 <a class="link" href="#build-directory">build directory</a>.
2800 For example, consider <code class="filename">lib32</code> in a
2801 <code class="filename">qemux86-64</code> image.
2802 The possible architectures in the system are "all", "qemux86_64",
2803 "lib32_qemux86_64", and "lib32_x86".</p></li><li class="listitem"><p>The <code class="filename">${MLPREFIX}</code> variable is stripped from
2804 <code class="filename">${PN}</code> during RPM packaging.
2805 The naming for a normal RPM package and a Multilib RPM package in a
2806 <code class="filename">qemux86-64</code> system resolves to something similar to
2807 <code class="filename">bash-4.1-r2.x86_64.rpm</code> and
2808 <code class="filename">bash-4.1.r2.lib32_x86.rpm</code>, respectively.
2809 </p></li><li class="listitem"><p>When installing a Multilib image, the RPM backend first
2810 installs the base image and then installs the Multilib libraries.
2811 </p></li><li class="listitem"><p>The build system relies on RPM to resolve the identical files in the
2812 two (or more) Multilib packages.</p></li></ul></div><p>
2813 </p><p>
2814 For the IPK Package Management System, the following implementation details exist:
2815 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The <code class="filename">${MLPREFIX}</code> is not stripped from
2816 <code class="filename">${PN}</code> during IPK packaging.
2817 The naming for a normal RPM package and a Multilib IPK package in a
2818 <code class="filename">qemux86-64</code> system resolves to something like
2819 <code class="filename">bash_4.1-r2.x86_64.ipk</code> and
2820 <code class="filename">lib32-bash_4.1-rw_x86.ipk</code>, respectively.
2821 </p></li><li class="listitem"><p>The IPK deploy folder is not modified with
2822 <code class="filename">${MLPREFIX}</code> because packages with and without
2823 the Multilib feature can exist in the same folder due to the
2824 <code class="filename">${PN}</code> differences.</p></li><li class="listitem"><p>IPK defines a sanity check for Multilib installation
2825 using certain rules for file comparison, overridden, etc.
2826 </p></li></ul></div><p>
2827 </p></div></div><div class="section" title="4.6. Configuring the Kernel"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="configuring-the-kernel"></a>4.6. Configuring the Kernel</h2></div></div></div><p>
2828 Configuring the Yocto Project kernel consists of making sure the <code class="filename">.config</code>
2829 file has all the right information in it for the image you are building.
2830 You can use the <code class="filename">menuconfig</code> tool and configuration fragments to
2831 make sure your <code class="filename">.config</code> file is just how you need it.
2832 This section describes how to use <code class="filename">menuconfig</code>, create and use
2833 configuration fragments, and how to interactively tweak your <code class="filename">.config</code>
2834 file to create the leanest kernel configuration file possible.
2835 </p><p>
2836 For concepts on kernel configuration, see the
2837 "<a class="link" href="#kernel-configuration" target="_top">Kernel Configuration</a>"
2838 section in the Yocto Project Kernel Architecture and Use Manual.
2839 </p><div class="section" title="4.6.1. Using  menuconfig"><div class="titlepage"><div><div><h3 class="title"><a id="using-menuconfig"></a>4.6.1. Using  <code class="filename">menuconfig</code></h3></div></div></div><p>
2840 The easiest way to define kernel configurations is to set them through the
2841 <code class="filename">menuconfig</code> tool.
2842 For general information on <code class="filename">menuconfig</code>, see
2843 <a class="ulink" href="http://en.wikipedia.org/wiki/Menuconfig" target="_top">http://en.wikipedia.org/wiki/Menuconfig</a>.
2844 </p><p>
2845 To use the <code class="filename">menuconfig</code> tool in the Yocto Project development
2846 environment, you must build the tool using BitBake.
2847 The following commands build and invoke <code class="filename">menuconfig</code> assuming the
2848 source directory top-level folder is <code class="filename">~/poky</code>:
2849 </p><pre class="literallayout">
2850 $ cd ~/poky
2851 $ source oe-init-build-env
2852 $ bitbake linux-yocto -c menuconfig
2853 </pre><p>
2854 Once <code class="filename">menuconfig</code> comes up, its standard interface allows you to
2855 examine and configure all the kernel configuration parameters.
2856 Once you have made your changes, simply exit the tool and save your changes to
2857 create an updated version of the <code class="filename">.config</code> configuration file.
2858 </p><p>
2859 For an example that shows how to change a specific kernel option
2860 using <code class="filename">menuconfig</code>, see the
2861 "<a class="link" href="#changing-the-config-smp-configuration-using-menuconfig" title="B.2.3. Changing the  CONFIG_SMP Configuration Using  menuconfig">Changing
2862 the <code class="filename">CONFIG_SMP</code> Configuration Using <code class="filename">menuconfig</code></a>"
2863 section.
2864 </p></div><div class="section" title="4.6.2. Creating Configuration Fragments"><div class="titlepage"><div><div><h3 class="title"><a id="creating-config-fragments"></a>4.6.2. Creating Configuration Fragments</h3></div></div></div><p>
2865 Configuration fragments are simply kernel options that appear in a file
2866 placed where the OpenEmbedded build system can find and apply them.
2867 Syntactically, the configuration statement is identical to what would appear
2868 in the <code class="filename">.config</code> file, which is in the
2869 <a class="link" href="#build-directory">build directory</a> in
2870 <code class="filename">tmp/work/&lt;arch&gt;-poky-linux/linux-yocto-&lt;release-specific-string&gt;/linux-&lt;arch&gt;-&lt;build-type&gt;</code>.
2871 </p><p>
2872 It is simple to create a configuration fragment.
2873 For example, issuing the following from the shell creates a configuration fragment
2874 file named <code class="filename">my_smp.cfg</code> that enables multi-processor support
2875 within the kernel:
2876 </p><pre class="literallayout">
2877 $ echo "CONFIG_SMP=y" &gt;&gt; my_smp.cfg
2878 </pre><p>
2879 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
2880 All configuration files must use the <code class="filename">.cfg</code> extension in order
2881 for the OpenEmbedded build system to recognize them as a configuration fragment.
2882 </div><p>
2883 </p><p>
2884 Where do you put your configuration files?
2885 You can place these configuration files in the same area pointed to by
2886 <code class="filename">SRC_URI</code>.
2887 The OpenEmbedded build system will pick up the configuration and add it to the
2888 kernel's configuration.
2889 For example, suppose you had a set of configuration options in a file called
2890 <code class="filename">myconfig.cfg</code>.
2891 If you put that file inside a directory named <code class="filename">/linux-yocto</code>
2892 that resides in the same directory as the kernel's append file and then add
2893 a <code class="filename">SRC_URI</code> statement such as the following to the kernel's append file,
2894 those configuration options will be picked up and applied when the kernel is built.
2895 </p><pre class="literallayout">
2896 SRC_URI += "file://myconfig.cfg"
2897 </pre><p>
2898 </p><p>
2899 As mentioned earlier, you can group related configurations into multiple files and
2900 name them all in the <code class="filename">SRC_URI</code> statement as well.
2901 For example, you could group separate configurations specifically for Ethernet and graphics
2902 into their own files and add those by using a <code class="filename">SRC_URI</code> statement like the
2903 following in your append file:
2904 </p><pre class="literallayout">
2905 SRC_URI += "file://myconfig.cfg \
2906 file://eth.cfg \
2907 file://gfx.cfg"
2908 </pre><p>
2909 </p></div><div class="section" title="4.6.3. Fine-tuning the Kernel Configuration File"><div class="titlepage"><div><div><h3 class="title"><a id="fine-tuning-the-kernel-configuration-file"></a>4.6.3. Fine-tuning the Kernel Configuration File</h3></div></div></div><p>
2910 You can make sure the <code class="filename">.config</code> is as lean or efficient as
2911 possible by reading the output of the kernel configuration fragment audit,
2912 noting any issues, making changes to correct the issues, and then repeating.
2913 </p><p>
2914 As part of the kernel build process, the
2915 <code class="filename">kernel_configcheck</code> task runs.
2916 This task validates the kernel configuration by checking the final
2917 <code class="filename">.config</code> file against the input files.
2918 During the check, the task produces warning messages for the following
2919 issues:
2920 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Requested options that did not make the final
2921 <code class="filename">.config</code> file.</p></li><li class="listitem"><p>Configuration items that appear twice in the same
2922 configuration fragment.</p></li><li class="listitem"><p>Configuration items tagged as 'required' were overridden.
2923 </p></li><li class="listitem"><p>A board overrides a non-board specific option.</p></li><li class="listitem"><p>Listed options not valid for the kernel being processed.
2924 In other words, the option does not appear anywhere.</p></li></ul></div><p>
2925 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
2926 The <code class="filename">kernel_configcheck</code> task can also optionally report
2927 if an option is overridden during processing.
2928 </div><p>
2929 </p><p>
2930 For each output warning, a message points to the file
2931 that contains a list of the options and a pointer to the config
2932 fragment that defines them.
2933 Collectively, the files are the key to streamlining the configuration.
2934 </p><p>
2935 To streamline the configuration, do the following:
2936 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Start with a full configuration that you know
2937 works - it builds and boots successfully.
2938 This configuration file will be your baseline.</p></li><li class="listitem"><p>Separately run the <code class="filename">configme</code> and
2939 <code class="filename">kernel_configcheck</code> tasks.</p></li><li class="listitem"><p>Take the resulting list of files from the
2940 <code class="filename">kernel_configcheck</code> task warnings and do the following:
2941 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Drop values that are redefined in the fragment but do not
2942 change the final <code class="filename">.config</code> file.</p></li><li class="listitem"><p>Analyze and potentially drop values from the
2943 <code class="filename">.config</code> file that override required
2944 configurations.</p></li><li class="listitem"><p>Analyze and potentially remove non-board specific options.
2945 </p></li><li class="listitem"><p>Remove repeated and invalid options.</p></li></ul></div></li><li class="listitem"><p>After you have worked through the output of the kernel configuration
2946 audit, you can re-run the <code class="filename">configme</code>
2947 and <code class="filename">kernel_configcheck</code> tasks to see the results of your
2948 changes.
2949 If you have more issues, you can deal with them as described in the
2950 previous step.</p></li></ol></div><p>
2951 </p><p>
2952 Iteratively working through steps two through four eventually yields
2953 a minimal, streamlined configuration file.
2954 Once you have the best <code class="filename">.config</code>, you can build the Linux
2955 Yocto kernel.
2956 </p></div></div><div class="section" title="4.7. Updating Existing Images"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-changes-updatingimages"></a>4.7. Updating Existing Images</h2></div></div></div><p>
2957 Often, rather than re-flashing a new image, you might wish to install updated
2958 packages into an existing running system.
2959 You can do this by first sharing the <code class="filename">tmp/deploy/ipk/</code> directory
2960 through a web server and then by changing <code class="filename">/etc/opkg/base-feeds.conf</code>
2961 to point at the shared server.
2962 Following is an example:
2963 </p><pre class="literallayout">
2964 $ src/gz all http://www.mysite.com/somedir/deploy/ipk/all
2965 $ src/gz armv7a http://www.mysite.com/somedir/deploy/ipk/armv7a
2966 $ src/gz beagleboard http://www.mysite.com/somedir/deploy/ipk/beagleboard
2967 </pre><p>
2968 </p></div><div class="section" title="4.8. Incrementing a Package Revision Number"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-changes-prbump"></a>4.8. Incrementing a Package Revision Number</h2></div></div></div><p>
2969 If a committed change results in changing the package output,
2970 then the value of the
2971 <code class="filename"><a class="link" href="#var-PR" target="_top">PR</a></code>
2972 variable needs to be increased
2973 (or "bumped") as part of that commit.
2974 This means that for new recipes you must be sure to add the <code class="filename">PR</code>
2975 variable and set its initial value equal to "r0".
2976 Failing to define <code class="filename">PR</code> makes it easy to miss when you bump a package.
2977 Note that you can only use integer values following the "r" in the
2978 <code class="filename">PR</code> variable.
2979 </p><p>
2980 If you are sharing a common <code class="filename">.inc</code> file with multiple recipes,
2981 you can also use the
2982 <code class="filename"><a class="link" href="#var-INC_PR" target="_top">INC_PR</a></code>
2983 variable to ensure that
2984 the recipes sharing the <code class="filename">.inc</code> file are rebuilt when the
2985 <code class="filename">.inc</code> file itself is changed.
2986 The <code class="filename">.inc</code> file must set <code class="filename">INC_PR</code>
2987 (initially to "r0"), and all recipes referring to it should set <code class="filename">PR</code>
2988 to "$(INC_PR).0" initially, incrementing the last number when the recipe is changed.
2989 If the <code class="filename">.inc</code> file is changed then its
2990 <code class="filename">INC_PR</code> should be incremented.
2991 </p><p>
2992 When upgrading the version of a package, assuming the
2993 <code class="filename"><a class="link" href="#var-PV" target="_top">PV</a></code>
2994 changes, the <code class="filename">PR</code> variable should be reset to "r0"
2995 (or "$(INC_PR).0" if you are using <code class="filename">INC_PR</code>).
2996 </p><p>
2997 Usually, version increases occur only to packages.
2998 However, if for some reason <code class="filename">PV</code> changes but does not
2999 increase, you can increase the
3000 <code class="filename"><a class="link" href="#var-PE" target="_top">PE</a></code>
3001 variable (Package Epoch).
3002 The <code class="filename">PE</code> variable defaults to "0".
3003 </p><p>
3004 Version numbering strives to follow the
3005 <a class="ulink" href="http://www.debian.org/doc/debian-policy/ch-controlfields.html" target="_top">
3006 Debian Version Field Policy Guidelines</a>.
3007 These guidelines define how versions are compared and what "increasing" a version means.
3008 </p><p>
3009 There are two reasons for following the previously mentioned guidelines.
3010 First, to ensure that when a developer updates and rebuilds, they get all the changes to
3011 the repository and do not have to remember to rebuild any sections.
3012 Second, to ensure that target users are able to upgrade their
3013 devices using package manager commands such as <code class="filename">opkg upgrade</code>
3014 (or similar commands for dpkg/apt or rpm-based systems).
3015 </p><p>
3016 The goal is to ensure the Yocto Project has packages that can be upgraded in all cases.
3017 </p></div><div class="section" title="4.9. Handling a Package Name Alias"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-configuring-DISTRO_PN_ALIAS"></a>4.9. Handling a Package Name Alias</h2></div></div></div><p>
3018 Sometimes a package name you are using might exist under an alias or as a similarly named
3019 package in a different distribution.
3020 The OpenEmbedded build system implements a <code class="filename">distro_check</code>
3021 task that automatically connects to major distributions
3022 and checks for these situations.
3023 If the package exists under a different name in a different distribution, you get a
3024 <code class="filename">distro_check</code> mismatch.
3025 You can resolve this problem by defining a per-distro recipe name alias using the
3026 <code class="filename"><a class="link" href="#var-DISTRO_PN_ALIAS" target="_top">DISTRO_PN_ALIAS</a></code>
3027 variable.
3028 </p><p>
3029 Following is an example that shows how you specify the <code class="filename">DISTRO_PN_ALIAS</code>
3030 variable:
3031 </p><pre class="literallayout">
3032 DISTRO_PN_ALIAS_pn-PACKAGENAME = "distro1=package_name_alias1 \
3033 distro2=package_name_alias2 \
3034 distro3=package_name_alias3 \
3035 ..."
3036 </pre><p>
3037 </p><p>
3038 If you have more than one distribution alias, separate them with a space.
3039 Note that the build system currently automatically checks the
3040 Fedora, OpenSuSE, Debian, Ubuntu,
3041 and Mandriva distributions for source package recipes without having to specify them
3042 using the <code class="filename">DISTRO_PN_ALIAS</code> variable.
3043 For example, the following command generates a report that lists the Linux distributions
3044 that include the sources for each of the recipes.
3045 </p><pre class="literallayout">
3046 $ bitbake world -f -c distro_check
3047 </pre><p>
3048 The results are stored in the <code class="filename">build/tmp/log/distro_check-${DATETIME}.results</code>
3049 file found in the source directory.
3050 </p></div><div class="section" title="4.10. Building Software from an External Source"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="building-software-from-an-external-source"></a>4.10. Building Software from an External Source</h2></div></div></div><p>
3051 By default, the OpenEmbedded build system does its work from within the
3052 <a class="link" href="#build-directory">build directory</a>.
3053 The build process involves fetching the source files, unpacking them, and then patching them
3054 if necessary before the build takes place.
3055 </p><p>
3056 Situations exist where you might want to build software from source files that are external to
3057 and thus outside of the <a class="link" href="#source-directory">source directory</a>.
3058 For example, suppose you have a project that includes a new BSP with a heavily customized
3059 kernel, a very minimal image, and some new user-space recipes.
3060 And, you want to minimize the exposure to the build system to the
3061 development team so that they can focus on their project and maintain everyone's workflow
3062 as much as possible.
3063 In this case, you want a kernel source directory on the development machine where the
3064 development occurs.
3065 You want the recipe's
3066 <a class="link" href="#var-SRC_URI" target="_top"><code class="filename">SRC_URI</code></a>
3067 variable to point to the external directory and use it as is, not copy it.
3068 </p><p>
3069 To build from software that comes from an external source, all you need to do is
3070 change your recipe so that it inherits the
3071 <a class="link" href="#ref-classes-externalsrc" target="_top"><code class="filename">externalsrc.bbclass</code></a>
3072 class and then sets the
3073 <a class="link" href="#var-S" target="_top"><code class="filename">S</code></a>
3074 variable to point to your external source code.
3075 Here are the statements to put in your recipe:
3076 </p><pre class="literallayout">
3077 inherit externalsrc
3078 S = "/some/path/to/your/package/source"
3079 </pre><p>
3080 </p><p>
3081 It is important to know that the <code class="filename">externalsrc.bbclass</code> assumes that the
3082 source directory <code class="filename">S</code> and the build directory
3083 <a class="link" href="#var-B" target="_top"><code class="filename">B</code></a>
3084 are different even though by default these directories are the same.
3085 This assumption is important because it supports building different variants of the recipe
3086 by using the
3087 <a class="link" href="#var-BBCLASSEXTEND" target="_top"><code class="filename">BBCLASSEXTEND</code></a>
3088 variable.
3089 You could allow the build directory to be the same as the source directory but you would
3090 not be able to build more than one variant of the recipe.
3091 Consequently, if you are building multiple variants of the recipe, you need to establish a
3092 build directory that is different than the source directory.
3093 </p></div><div class="section" title="4.11. Excluding Recipes From the Build"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="excluding-recipes-from-the-build"></a>4.11. Excluding Recipes From the Build</h2></div></div></div><p>
3094 You might find that there are groups of recipes you want to filter
3095 out of the build process.
3096 For example, recipes you know you will never use or want should not
3097 be part of the build.
3098 Removing these recipes from parsing speeds up parts of the build.
3099 </p><p>
3100 It is possible to filter or mask out <code class="filename">.bb</code> and
3101 <code class="filename">.bbappend</code> files.
3102 You can do this by providing an expression with the
3103 <code class="filename"><a class="link" href="#var-BBMASK" target="_top">BBMASK</a></code>
3104 variable.
3105 Here is an example:
3106 </p><pre class="literallayout">
3107 BBMASK = ".*/meta-mymachine/recipes-maybe/"
3108 </pre><p>
3109 Here, all <code class="filename">.bb</code> and <code class="filename">.bbappend</code> files
3110 in the directory that match the expression are ignored during the build
3111 process.
3112 </p></div><div class="section" title="4.12. Using an External SCM"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="platdev-appdev-srcrev"></a>4.12. Using an External SCM</h2></div></div></div><p>
3113 If you're working on a recipe that pulls from an external Source Code Manager (SCM), it
3114 is possible to have the OpenEmbedded build system notice new changes added to the
3115 SCM and then build the package that depends on them using the latest version.
3116 This only works for SCMs from which it is possible to get a sensible revision number for changes.
3117 Currently, you can do this with Apache Subversion (SVN), Git, and Bazaar (BZR) repositories.
3118 </p><p>
3119 To enable this behavior, simply add the following to the <code class="filename">local.conf</code>
3120 configuration file found in the
3121 <a class="link" href="#build-directory" target="_top">build directory</a>:
3122 </p><pre class="literallayout">
3123 SRCREV_pn-&lt;PN&gt; = "${AUTOREV}"
3124 </pre><p>
3125 where <code class="filename">PN</code>
3126 is the name of the package for which you want to enable automatic source
3127 revision updating.
3128 </p></div><div class="section" title="4.13. Debugging With the GNU Project Debugger (GDB) Remotely"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="platdev-gdb-remotedebug"></a>4.13. Debugging With the GNU Project Debugger (GDB) Remotely</h2></div></div></div><p>
3129 GDB allows you to examine running programs, which in turn help you to understand and fix problems.
3130 It also allows you to perform post-mortem style analysis of program crashes.
3131 GDB is available as a package within the Yocto Project and by default is
3132 installed in sdk images.
3133 See the "<a class="link" href="#ref-images" target="_top">Images</a>" chapter
3134 in the Yocto Project Reference Manual for a description of these images.
3135 You can find information on GDB at <a class="ulink" href="http://sourceware.org/gdb/" target="_top">http://sourceware.org/gdb/</a>.
3136 </p><div class="tip" title="Tip" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Tip</h3>
3137 For best results, install <code class="filename">-dbg</code> packages for the applications
3138 you are going to debug.
3139 Doing so makes available extra debug symbols that give you more meaningful output.
3140 </div><p>
3141 Sometimes, due to memory or disk space constraints, it is not possible
3142 to use GDB directly on the remote target to debug applications.
3143 These constraints arise because GDB needs to load the debugging information and the
3144 binaries of the process being debugged.
3145 Additionally, GDB needs to perform many computations to locate information such as function
3146 names, variable names and values, stack traces and so forth - even before starting the
3147 debugging process.
3148 These extra computations place more load on the target system and can alter the
3149 characteristics of the program being debugged.
3150 </p><p>
3151 To help get past the previously mentioned constraints, you can use Gdbserver.
3152 Gdbserver runs on the remote target and does not load any debugging information
3153 from the debugged process.
3154 Instead, a GDB instance processes the debugging information that is run on a
3155 remote computer - the host GDB.
3156 The host GDB then sends control commands to Gdbserver to make it stop or start the debugged
3157 program, as well as read or write memory regions of that debugged program.
3158 All the debugging information loaded and processed as well
3159 as all the heavy debugging is done by the host GDB.
3160 Offloading these processes gives the Gdbserver running on the target a chance to remain
3161 small and fast.
3162 </p><p>
3163 Because the host GDB is responsible for loading the debugging information and
3164 for doing the necessary processing to make actual debugging happen, the
3165 user has to make sure the host can access the unstripped binaries complete
3166 with their debugging information and also be sure the target is compiled with no optimizations.
3167 The host GDB must also have local access to all the libraries used by the
3168 debugged program.
3169 Because Gdbserver does not need any local debugging information, the binaries on
3170 the remote target can remain stripped.
3171 However, the binaries must also be compiled without optimization
3172 so they match the host's binaries.
3173 </p><p>
3174 To remain consistent with GDB documentation and terminology, the binary being debugged
3175 on the remote target machine is referred to as the "inferior" binary.
3176 For documentation on GDB see the
3177 <a class="ulink" href="http://sourceware.org/gdb/documentation/" target="_top">GDB site</a>.
3178 </p><div class="section" title="4.13.1. Launching Gdbserver on the Target"><div class="titlepage"><div><div><h3 class="title"><a id="platdev-gdb-remotedebug-launch-gdbserver"></a>4.13.1. Launching Gdbserver on the Target</h3></div></div></div><p>
3179 First, make sure Gdbserver is installed on the target.
3180 If it is not, install the package <code class="filename">gdbserver</code>, which needs the
3181 <code class="filename">libthread-db1</code> package.
3182 </p><p>
3183 As an example, to launch Gdbserver on the target and make it ready to "debug" a
3184 program located at <code class="filename">/path/to/inferior</code>, connect
3185 to the target and launch:
3186 </p><pre class="literallayout">
3187 $ gdbserver localhost:2345 /path/to/inferior
3188 </pre><p>
3189 Gdbserver should now be listening on port 2345 for debugging
3190 commands coming from a remote GDB process that is running on the host computer.
3191 Communication between Gdbserver and the host GDB are done using TCP.
3192 To use other communication protocols, please refer to the
3193 <a class="ulink" href="http://www.gnu.org/software/gdb/" target="_top">Gdbserver documentation</a>.
3194 </p></div><div class="section" title="4.13.2. Launching GDB on the Host Computer"><div class="titlepage"><div><div><h3 class="title"><a id="platdev-gdb-remotedebug-launch-gdb"></a>4.13.2. Launching GDB on the Host Computer</h3></div></div></div><p>
3195 Running GDB on the host computer takes a number of stages.
3196 This section describes those stages.
3197 </p><div class="section" title="4.13.2.1. Building the Cross-GDB Package"><div class="titlepage"><div><div><h4 class="title"><a id="platdev-gdb-remotedebug-launch-gdb-buildcross"></a>4.13.2.1. Building the Cross-GDB Package</h4></div></div></div><p>
3198 A suitable GDB cross-binary is required that runs on your host computer but
3199 also knows about the the ABI of the remote target.
3200 You can get this binary from the meta-toolchain.
3201 Here is an example:
3202 </p><pre class="literallayout">
3203 /usr/local/poky/eabi-glibc/arm/bin/arm-poky-linux-gnueabi-gdb
3204 </pre><p>
3205 where <code class="filename">arm</code> is the target architecture and
3206 <code class="filename">linux-gnueabi</code> the target ABI.
3207 </p><p>
3208 Alternatively, you can use BitBake to build the <code class="filename">gdb-cross</code> binary.
3209 Here is an example:
3210 </p><pre class="literallayout">
3211 $ bitbake gdb-cross
3212 </pre><p>
3213 Once the binary is built, you can find it here:
3214 </p><pre class="literallayout">
3215 tmp/sysroots/&lt;host-arch&gt;/usr/bin/&lt;target-abi&gt;-gdb
3216 </pre><p>
3217 </p></div><div class="section" title="4.13.2.2. Making the Inferior Binaries Available"><div class="titlepage"><div><div><h4 class="title"><a id="platdev-gdb-remotedebug-launch-gdb-inferiorbins"></a>4.13.2.2. Making the Inferior Binaries Available</h4></div></div></div><p>
3218 The inferior binary (complete with all debugging symbols) as well as any
3219 libraries (and their debugging symbols) on which the inferior binary depends
3220 need to be available.
3221 There are a number of ways you can make these available.
3222 </p><p>
3223 Perhaps the easiest way is to have an 'sdk' image that corresponds to the plain
3224 image installed on the device.
3225 In the case of <code class="filename">core-image-sato</code>,
3226 <code class="filename">core-image-sato-sdk</code> would contain suitable symbols.
3227 Because the sdk images already have the debugging symbols installed, it is just a
3228 question of expanding the archive to some location and then informing GDB.
3229 </p><p>
3230 Alternatively, the OpenEmbedded build system can build a custom directory of files
3231 for a specific
3232 debugging purpose by reusing its <code class="filename">tmp/rootfs</code> directory.
3233 This directory contains the contents of the last built image.
3234 This process assumes two things:
3235 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The image running on the target was the last image to
3236 be built.</p></li><li class="listitem"><p>The package (<code class="filename">foo</code> in the following
3237 example) that contains the inferior binary to be debugged has been built
3238 without optimization and has debugging information available.</p></li></ul></div><p>
3239 </p><p>
3240 The following steps show how to build the custom directory of files:
3241 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Install the package (<code class="filename">foo</code> in this case) to
3242 <code class="filename">tmp/rootfs</code>:
3243 </p><pre class="literallayout">
3244 $ tmp/sysroots/i686-linux/usr/bin/opkg-cl -f \
3245 tmp/work/&lt;target-abi&gt;/core-image-sato-1.0-r0/temp/opkg.conf -o \
3246 tmp/rootfs/ update
3247 </pre></li><li class="listitem"><p>Install the debugging information:
3248 </p><pre class="literallayout">
3249 $ tmp/sysroots/i686-linux/usr/bin/opkg-cl -f \
3250 tmp/work/&lt;target-abi&gt;/core-image-sato-1.0-r0/temp/opkg.conf \
3251 -o tmp/rootfs install foo
3252
3253 $ tmp/sysroots/i686-linux/usr/bin/opkg-cl -f \
3254 tmp/work/&lt;target-abi&gt;/core-image-sato-1.0-r0/temp/opkg.conf \
3255 -o tmp/rootfs install foo-dbg
3256 </pre></li></ol></div><p>
3257 </p></div><div class="section" title="4.13.2.3. Launch the Host GDB"><div class="titlepage"><div><div><h4 class="title"><a id="platdev-gdb-remotedebug-launch-gdb-launchhost"></a>4.13.2.3. Launch the Host GDB</h4></div></div></div><p>
3258 To launch the host GDB, you run the <code class="filename">cross-gdb</code> binary and provide
3259 the inferior binary as part of the command line.
3260 For example, the following command form continues with the example used in
3261 the previous section.
3262 This command form loads the <code class="filename">foo</code> binary
3263 as well as the debugging information:
3264 </p><pre class="literallayout">
3265 $ &lt;target-abi&gt;-gdb rootfs/usr/bin/foo
3266 </pre><p>
3267 Once the GDB prompt appears, you must instruct GDB to load all the libraries
3268 of the inferior binary from <code class="filename">tmp/rootfs</code> as follows:
3269 </p><pre class="literallayout">
3270 $ set solib-absolute-prefix /path/to/tmp/rootfs
3271 </pre><p>
3272 The pathname <code class="filename">/path/to/tmp/rootfs</code> must either be
3273 the absolute path to <code class="filename">tmp/rootfs</code> or the location at which
3274 binaries with debugging information reside.
3275 </p><p>
3276 At this point you can have GDB connect to the Gdbserver that is running
3277 on the remote target by using the following command form:
3278 </p><pre class="literallayout">
3279 $ target remote remote-target-ip-address:2345
3280 </pre><p>
3281 The <code class="filename">remote-target-ip-address</code> is the IP address of the
3282 remote target where the Gdbserver is running.
3283 Port 2345 is the port on which the GDBSERVER is running.
3284 </p></div><div class="section" title="4.13.2.4. Using the Debugger"><div class="titlepage"><div><div><h4 class="title"><a id="platdev-gdb-remotedebug-launch-gdb-using"></a>4.13.2.4. Using the Debugger</h4></div></div></div><p>
3285 You can now proceed with debugging as normal - as if you were debugging
3286 on the local machine.
3287 For example, to instruct GDB to break in the "main" function and then
3288 continue with execution of the inferior binary use the following commands
3289 from within GDB:
3290 </p><pre class="literallayout">
3291 (gdb) break main
3292 (gdb) continue
3293 </pre><p>
3294 </p><p>
3295 For more information about using GDB, see the project's online documentation at
3296 <a class="ulink" href="http://sourceware.org/gdb/download/onlinedocs/" target="_top">http://sourceware.org/gdb/download/onlinedocs/</a>.
3297 </p></div></div></div><div class="section" title="4.14. Profiling with OProfile"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="platdev-oprofile"></a>4.14. Profiling with OProfile</h2></div></div></div><p>
3298 <a class="ulink" href="http://oprofile.sourceforge.net/" target="_top">OProfile</a> is a
3299 statistical profiler well suited for finding performance
3300 bottlenecks in both userspace software and in the kernel.
3301 This profiler provides answers to questions like "Which functions does my application spend
3302 the most time in when doing X?"
3303 Because the OpenEmbedded build system is well integrated with OProfile, it makes profiling
3304 applications on target hardware straightforward.
3305 </p><p>
3306 To use OProfile, you need an image that has OProfile installed.
3307 The easiest way to do this is with <code class="filename">tools-profile</code> in the
3308 <code class="filename"><a class="link" href="#var-IMAGE_FEATURES" target="_top">IMAGE_FEATURES</a></code> variable.
3309 You also need debugging symbols to be available on the system where the analysis
3310 takes place.
3311 You can gain access to the symbols by using <code class="filename">dbg-pkgs</code> in the
3312 <code class="filename">IMAGE_FEATURES</code> variable or by
3313 installing the appropriate <code class="filename">-dbg</code> packages.
3314 </p><p>
3315 For successful call graph analysis, the binaries must preserve the frame
3316 pointer register and should also be compiled with the
3317 <code class="filename">-fno-omit-framepointer</code> flag.
3318 You can achieve this by setting the
3319 <code class="filename"><a class="link" href="#var-SELECTED_OPTIMIZATION" target="_top">SELECTED_OPTIMIZATION</a></code>
3320 variable to
3321 <code class="filename">-fexpensive-optimizations -fno-omit-framepointer -frename-registers -O2</code>.
3322 You can also achieve it by setting the
3323 <code class="filename"><a class="link" href="#var-DEBUG_BUILD" target="_top">DEBUG_BUILD</a></code>
3324 variable to "1" in the <code class="filename">local.conf</code> configuration file.
3325 If you use the <code class="filename">DEBUG_BUILD</code> variable you will also add extra debug information
3326 that can make the debug packages large.
3327 </p><div class="section" title="4.14.1. Profiling on the Target"><div class="titlepage"><div><div><h3 class="title"><a id="platdev-oprofile-target"></a>4.14.1. Profiling on the Target</h3></div></div></div><p>
3328 Using OProfile you can perform all the profiling work on the target device.
3329 A simple OProfile session might look like the following:
3330 </p><p>
3331 </p><pre class="literallayout">
3332 # opcontrol --reset
3333 # opcontrol --start --separate=lib --no-vmlinux -c 5
3334 .
3335 .
3336 [do whatever is being profiled]
3337 .
3338 .
3339 # opcontrol --stop
3340 $ opreport -cl
3341 </pre><p>
3342 </p><p>
3343 In this example, the <code class="filename">reset</code> command clears any previously profiled data.
3344 The next command starts OProfile.
3345 The options used when starting the profiler separate dynamic library data
3346 within applications, disable kernel profiling, and enable callgraphing up to
3347 five levels deep.
3348 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
3349 To profile the kernel, you would specify the
3350 <code class="filename">--vmlinux=/path/to/vmlinux</code> option.
3351 The <code class="filename">vmlinux</code> file is usually in the source directory in the
3352 <code class="filename">/boot/</code> directory and must match the running kernel.
3353 </div><p>
3354 </p><p>
3355 After you perform your profiling tasks, the next command stops the profiler.
3356 After that, you can view results with the <code class="filename">opreport</code> command with options
3357 to see the separate library symbols and callgraph information.
3358 </p><p>
3359 Callgraphing logs information about time spent in functions and about a function's
3360 calling function (parent) and called functions (children).
3361 The higher the callgraphing depth, the more accurate the results.
3362 However, higher depths also increase the logging overhead.
3363 Consequently, you should take care when setting the callgraphing depth.
3364 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
3365 On ARM, binaries need to have the frame pointer enabled for callgraphing to work.
3366 To accomplish this use the <code class="filename">-fno-omit-framepointer</code> option
3367 with <code class="filename">gcc</code>.
3368 </div><p>
3369 </p><p>
3370 For more information on using OProfile, see the OProfile
3371 online documentation at
3372 <a class="ulink" href="http://oprofile.sourceforge.net/docs/" target="_top">http://oprofile.sourceforge.net/docs/</a>.
3373 </p></div><div class="section" title="4.14.2. Using OProfileUI"><div class="titlepage"><div><div><h3 class="title"><a id="platdev-oprofile-oprofileui"></a>4.14.2. Using OProfileUI</h3></div></div></div><p>
3374 A graphical user interface for OProfile is also available.
3375 You can download and build this interface from the Yocto Project at
3376 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/oprofileui/" target="_top">http://git.yoctoproject.org/cgit.cgi/oprofileui/</a>.
3377 If the "tools-profile" image feature is selected, all necessary binaries
3378 are installed onto the target device for OProfileUI interaction.
3379 </p><p>
3380 Even though the source directory usually includes all needed patches on the target device, you
3381 might find you need other OProfile patches for recent OProfileUI features.
3382 If so, see the <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/oprofileui/tree/README" target="_top">
3383 OProfileUI README</a> for the most recent information.
3384 </p><div class="section" title="4.14.2.1. Online Mode"><div class="titlepage"><div><div><h4 class="title"><a id="platdev-oprofile-oprofileui-online"></a>4.14.2.1. Online Mode</h4></div></div></div><p>
3385 Using OProfile in online mode assumes a working network connection with the target
3386 hardware.
3387 With this connection, you just need to run "oprofile-server" on the device.
3388 By default, OProfile listens on port 4224.
3389 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
3390 You can change the port using the <code class="filename">--port</code> command-line
3391 option.
3392 </div><p>
3393 </p><p>
3394 The client program is called <code class="filename">oprofile-viewer</code> and its UI is relatively
3395 straightforward.
3396 You access key functionality through the buttons on the toolbar, which
3397 are duplicated in the menus.
3398 Here are the buttons:
3399 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Connect:</em></span> Connects to the remote host.
3400 You can also supply the IP address or hostname.</p></li><li class="listitem"><p><span class="emphasis"><em>Disconnect:</em></span> Disconnects from the target.
3401 </p></li><li class="listitem"><p><span class="emphasis"><em>Start:</em></span> Starts profiling on the device.
3402 </p></li><li class="listitem"><p><span class="emphasis"><em>Stop:</em></span> Stops profiling on the device and
3403 downloads the data to the local host.
3404 Stopping the profiler generates the profile and displays it in the viewer.
3405 </p></li><li class="listitem"><p><span class="emphasis"><em>Download:</em></span> Downloads the data from the
3406 target and generates the profile, which appears in the viewer.</p></li><li class="listitem"><p><span class="emphasis"><em>Reset:</em></span> Resets the sample data on the device.
3407 Resetting the data removes sample information collected from previous
3408 sampling runs.
3409 Be sure you reset the data if you do not want to include old sample information.
3410 </p></li><li class="listitem"><p><span class="emphasis"><em>Save:</em></span> Saves the data downloaded from the
3411 target to another directory for later examination.</p></li><li class="listitem"><p><span class="emphasis"><em>Open:</em></span> Loads previously saved data.
3412 </p></li></ul></div><p>
3413 </p><p>
3414 The client downloads the complete 'profile archive' from
3415 the target to the host for processing.
3416 This archive is a directory that contains the sample data, the object files,
3417 and the debug information for the object files.
3418 The archive is then converted using the <code class="filename">oparchconv</code> script, which is
3419 included in this distribution.
3420 The script uses <code class="filename">opimport</code> to convert the archive from
3421 the target to something that can be processed on the host.
3422 </p><p>
3423 Downloaded archives reside in the build directory in
3424 <code class="filename">/tmp</code> and are cleared up when they are no longer in use.
3425 </p><p>
3426 If you wish to perform kernel profiling, you need to be sure
3427 a <code class="filename">vmlinux</code> file that matches the running kernel is available.
3428 In the source directory, that file is usually located in
3429 <code class="filename">/boot/vmlinux-KERNELVERSION</code>, where
3430 <code class="filename">KERNEL-version</code> is the version of the kernel.
3431 The OpenEmbedded build system generates separate <code class="filename">vmlinux</code>
3432 packages for each kernel it builds.
3433 Thus, it should just be a question of making sure a matching package is
3434 installed (e.g. <code class="filename">opkg install kernel-vmlinux</code>.
3435 The files are automatically installed into development and profiling images
3436 alongside OProfile.
3437 A configuration option exists within the OProfileUI settings page that you can use to
3438 enter the location of the <code class="filename">vmlinux</code> file.
3439 </p><p>
3440 Waiting for debug symbols to transfer from the device can be slow, and it
3441 is not always necessary to actually have them on the device for OProfile use.
3442 All that is needed is a copy of the filesystem with the debug symbols present
3443 on the viewer system.
3444 The "<a class="link" href="#platdev-gdb-remotedebug-launch-gdb" title="4.13.2. Launching GDB on the Host Computer">Launching GDB on the Host Computer</a>"
3445 section covers how to create such a directory with
3446 the source directory and how to use the OProfileUI Settings dialog to specify the location.
3447 If you specify the directory, it will be used when the file checksums
3448 match those on the system you are profiling.
3449 </p></div><div class="section" title="4.14.2.2. Offline Mode"><div class="titlepage"><div><div><h4 class="title"><a id="platdev-oprofile-oprofileui-offline"></a>4.14.2.2. Offline Mode</h4></div></div></div><p>
3450 If network access to the target is unavailable, you can generate
3451 an archive for processing in <code class="filename">oprofile-viewer</code> as follows:
3452 </p><pre class="literallayout">
3453 # opcontrol --reset
3454 # opcontrol --start --separate=lib --no-vmlinux -c 5
3455 .
3456 .
3457 [do whatever is being profiled]
3458 .
3459 .
3460 # opcontrol --stop
3461 # oparchive -o my_archive
3462 </pre><p>
3463 </p><p>
3464 In the above example, <code class="filename">my_archive</code> is the name of the
3465 archive directory where you would like the profile archive to be kept.
3466 After the directory is created, you can copy it to another host and load it
3467 using <code class="filename">oprofile-viewer</code> open functionality.
3468 If necessary, the archive is converted.
3469 </p></div></div></div></div>
3470
3471 <div class="chapter" title="Chapter 5. Common Development Models"><div class="titlepage"><div><div><h2 class="title"><a id="dev-manual-model"></a>Chapter 5. Common Development Models</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#system-development-model">5.1. System Development Workflow</a></span></dt><dd><dl><dt><span class="section"><a href="#developing-a-board-support-package-bsp">5.1.1. Developing a Board Support Package (BSP)</a></span></dt><dt><span class="section"><a href="#modifying-the-kernel">5.1.2. Modifying the Kernel</a></span></dt></dl></dd><dt><span class="section"><a href="#application-development-workflow">5.2. Application Development Workflow</a></span></dt><dd><dl><dt><span class="section"><a href="#workflow-using-the-adt-and-eclipse">5.2.1. Workflow Using the ADT and <span class="trademark">Eclipse</span>™</a></span></dt><dt><span class="section"><a href="#adt-eclipse">5.2.2. Working Within Eclipse</a></span></dt><dt><span class="section"><a href="#workflow-using-stand-alone-cross-development-toolchains">5.2.3. Workflow Using Stand-alone Cross-development Toolchains</a></span></dt></dl></dd><dt><span class="section"><a href="#modifying-temporary-source-code">5.3. Modifying Temporary Source Code</a></span></dt><dd><dl><dt><span class="section"><a href="#finding-the-temporary-source-code">5.3.1. Finding the Temporary Source Code</a></span></dt><dt><span class="section"><a href="#using-a-quilt-workflow">5.3.2. Using a Quilt Workflow</a></span></dt><dt><span class="section"><a href="#using-a-git-workflow">5.3.3. Using a Git Workflow</a></span></dt></dl></dd><dt><span class="section"><a href="#image-development-using-hob">5.4. Image Development Using Hob</a></span></dt><dt><span class="section"><a href="#platdev-appdev-devshell">5.5. Using a Development Shell</a></span></dt></dl></div><p>
3472 Many development models exist for which you can use the Yocto Project.
3473 This chapter overviews the following methods:
3474 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>System Development:</em></span>
3475 System Development covers Board Support Package (BSP) development and kernel
3476 modification or configuration.
3477 If you want to examine specific examples of the system development models,
3478 see the "<a class="link" href="#dev-manual-bsp-appendix" title="Appendix A. BSP Development Example">BSP Development Example</a>"
3479 appendix and the
3480 "<a class="link" href="#dev-manual-kernel-appendix" title="Appendix B. Kernel Modification Example">Kernel Modification Example</a>" appendix.
3481 </p></li><li class="listitem"><p><span class="emphasis"><em>User Application Development:</em></span>
3482 User Application Development covers development of applications that you intend
3483 to run on some target hardware.
3484 For a user-space application development example that uses the
3485 <span class="trademark">Eclipse</span>™ IDE,
3486 see the
3487 Yocto Project Application Developer's Guide.
3488 </p></li><li class="listitem"><p><span class="emphasis"><em>Temporary Source Code Modification:</em></span>
3489 Direct modification of temporary source code is a convenient development model
3490 to quickly iterate and develop towards a solution.
3491 Once the solution has been implemented, you should of course take steps to
3492 get the changes upstream and applied in the affected recipes.</p></li><li class="listitem"><p><span class="emphasis"><em>Image Development using Hob:</em></span>
3493 You can use the <a class="ulink" href="http://www.yoctoproject.org/projects/hob" target="_top">Hob</a> to build
3494 custom operating system images within the build environment.
3495 Hob provides an efficient interface to the OpenEmbedded build system.</p></li><li class="listitem"><p><span class="emphasis"><em>Using a Development Shell:</em></span>
3496 You can use a <code class="filename">devshell</code> to efficiently debug commands or simply
3497 edit packages.
3498 Working inside a development shell is a quick way to set up the OpenEmbedded build
3499 environment to work on parts of a project.</p></li></ul></div><p>
3500</p><div class="section" title="5.1. System Development Workflow"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="system-development-model"></a>5.1. System Development Workflow</h2></div></div></div><p>
3501 System development involves modification or creation of an image that you want to run on
3502 a specific hardware target.
3503 Usually, when you want to create an image that runs on embedded hardware, the image does
3504 not require the same number of features that a full-fledged Linux distribution provides.
3505 Thus, you can create a much smaller image that is designed to use only the hardware
3506 features for your particular hardware.
3507 </p><p>
3508 To help you understand how system development works in the Yocto Project, this section
3509 covers two types of image development: BSP creation and kernel modification or
3510 configuration.
3511 </p><div class="section" title="5.1.1. Developing a Board Support Package (BSP)"><div class="titlepage"><div><div><h3 class="title"><a id="developing-a-board-support-package-bsp"></a>5.1.1. Developing a Board Support Package (BSP)</h3></div></div></div><p>
3512 A BSP is a packageof recipes that, when applied, during a build results in
3513 an image that you can run on a particular board.
3514 Thus, the package, when compiled into the new image, supports the operation of the board.
3515 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
3516 For a brief list of terms used when describing the development process in the Yocto Project,
3517 see the "<a class="link" href="#yocto-project-terms" title="3.4. Yocto Project Terms">Yocto Project Terms</a>" section.
3518 </div><p>
3519 The remainder of this section presents the basic steps used to create a BSP
3520 based on an existing BSP that ships with the Yocto Project.
3521 You can reference the "<a class="link" href="#dev-manual-bsp-appendix" title="Appendix A. BSP Development Example">BSP Development Example</a>"
3522 appendix for a detailed example that uses the Crown Bay BSP as a base BSP from which to start.
3523 </p><p>
3524 The following illustration and list summarize the BSP creation general workflow.
3525 </p><p>
3526 </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 630px"><td align="center"><img src="figures/bsp-dev-flow.png" align="middle" width="540" /></td></tr></table><p>
3527 </p><p>
3528 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Set up your host development system to support
3529 development using the Yocto Project</em></span>: See the
3530 "<a class="link" href="#the-linux-distro" target="_top">The Linux Distributions</a>"
3531 and the
3532 "<a class="link" href="#packages" target="_top">The Packages</a>" sections both
3533 in the Yocto Project Quick Start for requirements.</p></li><li class="listitem"><p><span class="emphasis"><em>Establish a local copy of the project files on your
3534 system</em></span>: You need this <a class="link" href="#source-directory">source
3535 directory</a> available on your host system.
3536 Having these files on your system gives you access to the build
3537 process and to the tools you need.
3538 For information on how to set up the source directory, see the
3539 "<a class="link" href="#getting-setup" title="2.2. Getting Set Up">Getting Setup</a>" section.</p></li><li class="listitem"><p><span class="emphasis"><em>Establish a local copy of the base BSP files</em></span>: Having
3540 the BSP files on your system gives you access to the build
3541 process and to the tools you need for creating a BSP.
3542 For information on how to get these files, see the
3543 "<a class="link" href="#getting-setup" title="2.2. Getting Set Up">Getting Setup</a>" section.</p></li><li class="listitem"><p><span class="emphasis"><em>Choose a BSP that is supported by the Yocto Project
3544 as your base BSP</em></span>:
3545 The Yocto Project ships with several BSPs that support various hardware.
3546 It is best to base your new BSP on an existing BSP rather than create all the
3547 recipes and configuration files from scratch.
3548 While it is possible to create everything from scratch, basing your new BSP
3549 on something that is close is much easier.
3550 Or, at a minimum, leveraging off an existing BSP
3551 gives you some structure with which to start.</p><p>At this point you need to understand your target hardware well enough to determine which
3552 existing BSP it most closely matches.
3553 Things to consider are your hardware’s on-board features, such as CPU type and graphics support.
3554 You should look at the README files for supported BSPs to get an idea of which one
3555 you could use.
3556 A generic <span class="trademark">Intel</span>®
3557 <span class="trademark">Atom</span>™-based BSP to consider is the
3558 Crown Bay that does not support the <span class="trademark">Intel</span>®
3559 Embedded Media Graphics Driver (EMGD).
3560 The remainder of this example uses that base BSP.</p><p>To see the supported BSPs, go to the
3561 <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">Download</a> page on the Yocto Project
3562 website and click on “BSP Downloads.”</p></li><li class="listitem"><p><span class="emphasis"><em>Create your own BSP layer</em></span>: Layers are ideal for
3563 isolating and storing work for a given piece of hardware.
3564 A layer is really just a location or area in which you place the recipes for your BSP.
3565 In fact, a BSP is, in itself, a special type of layer.
3566 </p><p>
3567 Another example that illustrates a layer is an application.
3568 Suppose you are creating an application that has library or other dependencies in
3569 order for it to compile and run.
3570 The layer, in this case, would be where all the recipes that define those dependencies
3571 are kept.
3572 The key point for a layer is that it is an isolated area that contains
3573 all the relevant information for the project that the OpenEmbedded build
3574 system knows about.
3575 For more information on layers, see the
3576 "<a class="link" href="#understanding-and-creating-layers" title="4.1. Understanding and Creating Layers">Understanding and Creating Layers</a>"
3577 section.
3578 For more information on BSP layers, see the
3579 "<a class="link" href="#bsp-layers" target="_top">BSP Layers</a>" section in the
3580 Yocto Project Board Support Package (BSP) Developer's Guide.</p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Four BSPs exist that are part of the
3581 Yocto Project release: <code class="filename">atom-pc</code>, <code class="filename">beagleboard</code>,
3582 <code class="filename">mpc8315e</code>, and <code class="filename">routerstationpro</code>.
3583 The recipes and configurations for these four BSPs are located and dispersed
3584 within the <a class="link" href="#source-directory">source directory</a>.
3585 On the other hand, BSP layers for Crown Bay, Emenlow, Jasper Forest,
3586 N450, Cedar Trail, Fish River, Fish River Island II, Romley, sys940x, tlk,
3587 and Sugar Bay exist in their own separate layers within the larger
3588 <code class="filename">meta-intel</code> layer.</div><p>When you set up a layer for a new BSP, you should follow a standard layout.
3589 This layout is described in the section
3590 "<a class="link" href="#bsp-filelayout" target="_top">Example Filesystem Layout</a>"
3591 section of the Board Support Package (BSP) Development Guide.
3592 In the standard layout, you will notice a suggested structure for recipes and
3593 configuration information.
3594 You can see the standard layout for the Crown Bay BSP in this example by examining the
3595 directory structure of the <code class="filename">meta-crownbay</code> layer inside the
3596 source directory.</p></li><li class="listitem"><p><span class="emphasis"><em>Make configuration changes to your new BSP
3597 layer</em></span>: The standard BSP layer structure organizes the files you need
3598 to edit in <code class="filename">conf</code> and several <code class="filename">recipes-*</code>
3599 directories within the BSP layer.
3600 Configuration changes identify where your new layer is on the local system
3601 and identify which kernel you are going to use.
3602 </p></li><li class="listitem"><p><span class="emphasis"><em>Make recipe changes to your new BSP layer</em></span>: Recipe
3603 changes include altering recipes (<code class="filename">.bb</code> files), removing
3604 recipes you don't use, and adding new recipes that you need to support your hardware.
3605 </p></li><li class="listitem"><p><span class="emphasis"><em>Prepare for the build</em></span>: Once you have made all the
3606 changes to your BSP layer, there remains a few things
3607 you need to do for the OpenEmbedded build system in order for it to create your image.
3608 You need to get the build environment ready by sourcing an environment setup script
3609 and you need to be sure two key configuration files are configured appropriately.</p><p>The entire process for building an image is overviewed in the section
3610 "<a class="link" href="#building-image" target="_top">Building an Image</a>" section
3611 of the Yocto Project Quick Start.
3612 You might want to reference this information.</p></li><li class="listitem"><p><span class="emphasis"><em>Build the image</em></span>: The OpenEmbedded build system
3613 uses the BitBake tool to build images based on the type of image you want to create.
3614 You can find more information on BitBake
3615 <a class="ulink" href="http://docs.openembedded.org/bitbake/html/" target="_top">here</a>.</p><p>The build process supports several types of images to satisfy different needs.
3616 See the
3617 "<a class="link" href="#ref-images" target="_top">Images</a>" chapter
3618 in the Yocto Project Reference Manual for information on
3619 supported images.</p></li></ol></div><p>
3620 </p><p>
3621 You can view a video presentation on "Building Custom Embedded Images with Yocto"
3622 at <a class="ulink" href="http://free-electrons.com/blog/elc-2011-videos" target="_top">Free Electrons</a>.
3623 You can also find supplemental information in
3624 <a class="ulink" href="http://www.yoctoproject.org/docs/1.3/bsp-guide/bsp-guide.html" target="_top">
3625 The Board Support Package (BSP) Development Guide</a>.
3626 Finally, there is wiki page write up of the example also located
3627 <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Transcript:_creating_one_generic_Atom_BSP_from_another" target="_top">
3628 here</a> that you might find helpful.
3629 </p></div><div class="section" title="5.1.2. Modifying the Kernel"><div class="titlepage"><div><div><h3 class="title"><a id="modifying-the-kernel"></a>5.1.2. <a id="kernel-spot"></a>Modifying the Kernel</h3></div></div></div><p>
3630 Kernel modification involves changing the Yocto Project kernel, which could involve changing
3631 configuration options as well as adding new kernel recipes.
3632 Configuration changes can be added in the form of configuration fragments, while recipe
3633 modification comes through the kernel's <code class="filename">recipes-kernel</code> area
3634 in a kernel layer you create.
3635 </p><p>
3636 The remainder of this section presents a high-level overview of the Yocto Project
3637 kernel architecture and the steps to modify the kernel.
3638 For a complete discussion of the kernel, see the
3639 Yocto Project Kernel Architecture and Use Manual.
3640 You can reference the appendix
3641 "<a class="link" href="#dev-manual-kernel-appendix" title="Appendix B. Kernel Modification Example">Kernel Modification Example</a>"
3642 for a detailed example that changes the configuration of a kernel.
3643 </p><div class="section" title="5.1.2.1. Kernel Overview"><div class="titlepage"><div><div><h4 class="title"><a id="kernel-overview"></a>5.1.2.1. Kernel Overview</h4></div></div></div><p>
3644 Traditionally, when one thinks of a patched kernel, they think of a base kernel
3645 source tree and a fixed structure that contains kernel patches.
3646 The Yocto Project, however, employs mechanisms, that in a sense, result in a kernel source
3647 generator.
3648 By the end of this section, this analogy will become clearer.
3649 </p><p>
3650 You can find a web interface to the Yocto Project kernel source repositories at
3651 <a class="ulink" href="http://git.yoctoproject.org" target="_top">http://git.yoctoproject.org</a>.
3652 If you look at the interface, you will see to the left a grouping of
3653 Git repositories titled "Yocto Linux Kernel."
3654 Within this group, you will find several kernels supported by
3655 the Yocto Project:
3656 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em><code class="filename">linux-yocto-2.6.34</code></em></span> - The
3657 stable Yocto Project kernel that is based on the Linux 2.6.34 released kernel.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">linux-yocto-2.6.37</code></em></span> - The
3658 stable Yocto Project kernel that is based on the Linux 2.6.37 released kernel.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">linux-yocto-3.0</code></em></span> - The stable
3659 Yocto Project kernel that is based on the Linux 3.0 released kernel.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">linux-yocto-3.0-1.1.x</code></em></span> - The
3660 stable Yocto Project kernel to use with the Yocto Project Release 1.1.x. This kernel
3661 is based on the Linux 3.0 released kernel.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">linux-yocto-3.2</code></em></span> - The
3662 stable Yocto Project kernel to use with the Yocto Project Release 1.2. This kernel
3663 is based on the Linux 3.2 released kernel.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">linux-yocto-dev</code></em></span> - A development
3664 kernel based on the latest upstream release candidate available.</p></li></ul></div><p>
3665 </p><p>
3666 The kernels are maintained using the Git revision control system
3667 that structures them using the familiar "tree", "branch", and "leaf" scheme.
3668 Branches represent diversions from general code to more specific code, while leaves
3669 represent the end-points for a complete and unique kernel whose source files
3670 when gathered from the root of the tree to the leaf accumulate to create the files
3671 necessary for a specific piece of hardware and its features.
3672 The following figure displays this concept:
3673 </p><p>
3674 </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 540px"><td align="center"><img src="figures/kernel-overview-1.png" align="middle" /></td></tr></table><p>
3675 </p><p>
3676
3677 </p><p>
3678 Within the figure, the "Kernel.org Branch Point" represents the point in the tree
3679 where a supported base kernel is modified from the Linux kernel.
3680 For example, this could be the branch point for the <code class="filename">linux-yocto-3.0</code>
3681 kernel.
3682 Thus, everything further to the right in the structure is based on the
3683 <code class="filename">linux-yocto-3.0</code> kernel.
3684 Branch points to right in the figure represent where the
3685 <code class="filename">linux-yocto-3.0</code> kernel is modified for specific hardware
3686 or types of kernels, such as real-time kernels.
3687 Each leaf thus represents the end-point for a kernel designed to run on a specific
3688 targeted device.
3689 </p><p>
3690
3691 </p><p>
3692 The overall result is a Git-maintained repository from which all the supported
3693 kernel types can be derived for all the supported devices.
3694 A big advantage to this scheme is the sharing of common features by keeping them in
3695 "larger" branches within the tree.
3696 This practice eliminates redundant storage of similar features shared among kernels.
3697 </p><p>
3698
3699 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
3700 Keep in mind the figure does not take into account all the supported Yocto
3701 Project kernel types, but rather shows a single generic kernel just for conceptual purposes.
3702 Also keep in mind that this structure represents the Yocto Project source repositories
3703 that are either pulled from during the build or established on the host development system
3704 prior to the build by either cloning a particular kernel's Git repository or by
3705 downloading and unpacking a tarball.
3706 </div><p>
3707
3708 </p><p>
3709 Storage of all the available kernel source code is one thing, while representing the
3710 code on your host development system is another.
3711 Conceptually, you can think of the kernel source repositories as all the
3712 source files necessary for all the supported kernels.
3713 As a developer, you are just interested in the source files for the kernel on
3714 on which you are working.
3715 And, furthermore, you need them available on your host system.
3716 </p><p>
3717
3718 </p><p>
3719 You make kernel source code available on your host development system by using
3720 Git to create a bare clone of the Yocto Project kernel Git repository
3721 in which you are interested.
3722 Then, you use Git again to clone a copy of that bare clone.
3723 This copy represents the directory structure on your host system that is particular
3724 to the kernel you want.
3725 These are the files you actually modify to change the kernel.
3726 See the <a class="link" href="#local-kernel-files">Yocto Project Kernel</a> item earlier
3727 in this manual for an example of how to set up the kernel source directory
3728 structure on your host system.
3729 </p><p>
3730
3731 </p><p>
3732 This next figure illustrates how the kernel source files might be arranged on
3733 your host system.
3734 </p><p>
3735
3736 </p><p>
3737 </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 360px"><td align="center"><img src="figures/kernel-overview-3-denzil.png" align="middle" /></td></tr></table><p>
3738 </p><p>
3739
3740 </p><p>
3741 In the previous figure, the file structure on the left represents the bare clone
3742 set up to track the Yocto Project kernel Git repository.
3743 The structure on the right represents the copy of the bare clone.
3744 When you make modifcations to the kernel source code, this is the area in which
3745 you work.
3746 Once you make corrections, you must use Git to push the committed changes to the
3747 bare clone.
3748 The example in <a class="xref" href="#modifying-the-kernel-source-code" title="B.1. Modifying the Kernel Source Code">Section B.1, “Modifying the Kernel Source Code”</a> provides a detailed example.
3749 </p><p>
3750
3751 </p><p>
3752 What happens during the build?
3753 When you build the kernel on your development system all files needed for the build
3754 are taken from the source repositories pointed to by the
3755 <code class="filename">SRC_URI</code> variable and gathered in a temporary work area
3756 where they are subsequently used to create the unique kernel.
3757 Thus, in a sense, the process constructs a local source tree specific to your
3758 kernel to generate the new kernel image - a source generator if you will.
3759 </p><p>
3760 The following figure shows the temporary file structure
3761 created on your host system when the build occurs.
3762 This build directory contains all the source files used during the build.
3763 </p><p>
3764 </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 450px"><td align="center"><img src="figures/kernel-overview-2.png" align="middle" /></td></tr></table><p>
3765 </p><p>
3766 Again, for a complete discussion of the Yocto Project kernel's architecture and its
3767 branching strategy, see the
3768 Yocto Project Kernel Architecture and Use Manual.
3769 You can also reference the
3770 "<a class="link" href="#modifying-the-kernel-source-code" title="B.1. Modifying the Kernel Source Code">Modifying the Kernel Source Code</a>"
3771 section for a detailed example that modifies the kernel.
3772 </p></div><div class="section" title="5.1.2.2. Kernel Modification Workflow"><div class="titlepage"><div><div><h4 class="title"><a id="kernel-modification-workflow"></a>5.1.2.2. Kernel Modification Workflow</h4></div></div></div><p>
3773 This illustration and the following list summarizes the kernel modification general workflow.
3774 </p><p>
3775 </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 675px"><td align="center"><img src="figures/kernel-dev-flow.png" align="middle" width="540" /></td></tr></table><p>
3776 </p><p>
3777 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Set up your host development system to support
3778 development using the Yocto Project</em></span>: See
3779 "<a class="link" href="#the-linux-distro" target="_top">The Linux Distributions</a>" and
3780 "<a class="link" href="#packages" target="_top">The Packages</a>" sections both
3781 in the Yocto Project Quick Start for requirements.</p></li><li class="listitem"><p><span class="emphasis"><em>Establish a local copy of project files on your
3782 system</em></span>: Having the <a class="link" href="#source-directory">source
3783 directory</a> on your system gives you access to the build process and tools
3784 you need.
3785 For information on how to get these files, see the bulleted item
3786 "<a class="link" href="#local-yp-release">Yocto Project Release</a>" earlier in this manual.
3787 </p></li><li class="listitem"><p><span class="emphasis"><em>Set up a local copy of the <code class="filename">poky-extras</code> Git
3788 repository</em></span>: This local repository is the area for your configuration
3789 fragments, new kernel recipes, and the kernel <code class="filename">.bbappend</code>
3790 file used during the build.
3791 It is good practice to set this repository up inside your local
3792 source directory.
3793 For information on how to get these files, see the bulleted item
3794 "<a class="link" href="#poky-extras-repo">The <code class="filename">poky-extras</code> Git Repository</a>"
3795 earlier in this manual.
3796 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>While it is certainly possible to modify the kernel without involving
3797 a local Git repository, the suggested workflow for kernel modification
3798 using the Yocto Project does use a Git repository.</div></li><li class="listitem"><p><span class="emphasis"><em>Establish a local copy of the Yocto Project kernel files on your
3799 system</em></span>: In order to make modifications to the kernel you need two things:
3800 a bare clone of the Yocto Project kernel you are modifying and
3801 a copy of that bare clone.
3802 The bare clone is required by the build process and is the area to which you
3803 push your kernel source changes (pulling does not work with bare clones).
3804 The copy of the bare clone is a local Git repository that contains all the kernel's
3805 source files.
3806 You make your changes to the files in this copy of the bare clone.
3807 For information on how to set these two items up, see the bulleted item
3808 "<a class="link" href="#local-kernel-files">Yocto Project Kernel</a>"
3809 earlier in this manual.</p></li><li class="listitem"><p><span class="emphasis"><em>Make changes to the kernel source code if
3810 applicable</em></span>: Modifying the kernel does not always mean directly
3811 changing source files.
3812 However, if you have to do this, you make the changes in the local
3813 Git repository you set up to hold the source files (i.e. the copy of the
3814 bare clone).
3815 Once the changes are made, you need to use Git commands to commit the changes
3816 and then push them to the bare clone.</p></li><li class="listitem"><p><span class="emphasis"><em>Make kernel configuration changes
3817 if applicable</em></span>:
3818 If your situation calls for changing the kernel's configuration, you can
3819 use <code class="filename">menuconfig</code>
3820 to enable and disable kernel configurations.
3821 Using <code class="filename">menuconfig</code> allows you to interactively develop and test the
3822 configuration changes you are making to the kernel.
3823 When saved, changes using <code class="filename">menuconfig</code> update the kernel's
3824 <code class="filename">.config</code>.
3825 Try to resist the temptation of directly editing the <code class="filename">.config</code>
3826 file found in the
3827 <a class="link" href="#build-directory">build directory</a> at
3828 <code class="filename">tmp/sysroots/&lt;machine-name&gt;/kernel</code>.
3829 Doing so, can produce unexpected results when the OpenEmbedded build system
3830 regenerates the configuration file.</p><p>Once you are satisfied with the configuration changes made using
3831 <code class="filename">menuconfig</code>, you can directly examine the
3832 <code class="filename">.config</code> file against a saved original and gather those
3833 changes into a config fragment to be referenced from within the kernel's
3834 <code class="filename">.bbappend</code> file.</p></li><li class="listitem"><p><span class="emphasis"><em>Add or extend kernel recipes if applicable</em></span>:
3835 The standard
3836 layer structure organizes recipe files inside the
3837 <code class="filename">meta-kernel-dev</code> layer that is within the local
3838 <code class="filename">poky-extras</code> Git repository.
3839 If you need to add new kernel recipes, you add them within this layer.
3840 Also within this area, you will find the <code class="filename">.bbappend</code>
3841 file that appends information to the kernel's recipe file used during the
3842 build.
3843 </p></li><li class="listitem"><p><span class="emphasis"><em>Prepare for the build</em></span>: Once you have made all the
3844 changes to your kernel (configurations, source code changes, recipe additions,
3845 or recipe changes), there remains a few things
3846 you need to do in order for the build system to create your image.
3847 If you have not done so, you need to get the build environment ready by sourcing
3848 the environment setup script described earlier.
3849 You also need to be sure two key configuration files
3850 (<code class="filename">local.conf</code> and <code class="filename">bblayers.conf</code>)
3851 are configured appropriately.</p><p>The entire process for building an image is overviewed in the
3852 "<a class="link" href="#building-image" target="_top">Building an Image</a>"
3853 section of the Yocto Project Quick Start.
3854 You might want to reference this information.
3855 Also, you should look at the detailed examples found in the appendices at
3856 at the end of this manual.</p></li><li class="listitem"><p><span class="emphasis"><em>Build the image</em></span>: The OpenEmbedded
3857 build system uses the BitBake
3858 tool to build images based on the type of image you want to create.
3859 You can find more information on BitBake
3860 <a class="ulink" href="http://docs.openembedded.org/bitbake/html/" target="_top">here</a>.</p><p>The build process supports several types of images to satisfy different needs.
3861 See the "<a class="link" href="#ref-images" target="_top">Images</a>" chapter in
3862 the Yocto Project Reference Manual for information on supported images.</p></li><li class="listitem"><p><span class="emphasis"><em>Make your configuration changes available
3863 in the kernel layer</em></span>: Up to this point, all the configuration changes to the
3864 kernel have been done and tested iteratively.
3865 Once they are tested and ready to go, you can move them into the kernel layer,
3866 which allows you to distribute the layer.</p></li><li class="listitem"><p><span class="emphasis"><em>If applicable, share your in-tree changes</em></span>:
3867 If the changes you made
3868 are suited for all Yocto Project kernel users, you might want to send them on
3869 for inclusion into the upstream kernel's Git repository.
3870 If the changes are accepted, the Yocto Project Maintainer pulls them into
3871 the master branch of the kernel tree.
3872 Doing so makes them available to everyone using the kernel.</p></li></ol></div><p>
3873 </p></div></div></div><div class="section" title="5.2. Application Development Workflow"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="application-development-workflow"></a>5.2. Application Development Workflow</h2></div></div></div><p>
3874 Application development involves creating an application that you want
3875 to run on your target hardware, which is running a kernel image created using the
3876 OpenEmbedded build system.
3877 The Yocto Project provides an Application Development Toolkit (ADT) and
3878 stand-alone cross-development toolchains that
3879 facilitate quick development and integration of your application into its run-time environment.
3880 Using the ADT and toolchains, you can compile and link your application.
3881 You can then deploy your application to the actual hardware or to the QEMU emulator for testing.
3882 If you are familiar with the popular Eclipse IDE, you can use an Eclipse Yocto Plug-in to
3883 allow you to develop, deploy, and test your application all from within Eclipse.
3884 </p><p>
3885 While we strongly suggest using the ADT to develop your application, this option might not
3886 be best for you.
3887 If this is the case, you can still use pieces of the Yocto Project for your development process.
3888 However, because the process can vary greatly, this manual does not provide detail on the process.
3889 </p><div class="section" title="5.2.1. Workflow Using the ADT and Eclipse™"><div class="titlepage"><div><div><h3 class="title"><a id="workflow-using-the-adt-and-eclipse"></a>5.2.1. Workflow Using the ADT and <span class="trademark">Eclipse</span>™</h3></div></div></div><p>
3890 To help you understand how application development works using the ADT, this section
3891 provides an overview of the general development process and a detailed example of the process
3892 as it is used from within the Eclipse IDE.
3893 </p><p>
3894 The following illustration and list summarize the application development general workflow.
3895 </p><p>
3896 </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="630"><tr style="height: 720px"><td align="center"><img src="figures/app-dev-flow.png" align="middle" /></td></tr></table><p>
3897 </p><p>
3898 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Prepare the Host System for the Yocto Project</em></span>:
3899 See
3900 "<a class="link" href="#the-linux-distro" target="_top">The Linux Distributions</a>" and
3901 "<a class="link" href="#packages" target="_top">The Packages</a>" sections both
3902 in the Yocto Project Quick Start for requirements.</p></li><li class="listitem"><p><span class="emphasis"><em>Secure the Yocto Project Kernel Target Image</em></span>:
3903 You must have a target kernel image that has been built using the OpenEmbeded
3904 build system.</p><p>Depending on whether the Yocto Project has a pre-built image that matches your target
3905 architecture and where you are going to run the image while you develop your application
3906 (QEMU or real hardware), the area from which you get the image differs.
3907 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Download the image from
3908 <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines" target="_top">
3909 <code class="filename">machines</code></a> if your target architecture is supported
3910 and you are going to develop and test your application on actual hardware.
3911 </p></li><li class="listitem"><p>Download the image from the
3912 <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/qemu" target="_top">
3913 <code class="filename">machines/qemu</code></a> if your target architecture is supported
3914 and you are going to develop and test your application using the QEMU
3915 emulator.</p></li><li class="listitem"><p>Build your image if you cannot find a pre-built image that matches
3916 your target architecture.
3917 If your target architecture is similar to a supported architecture, you can
3918 modify the kernel image before you build it.
3919 See the
3920 "<a class="link" href="#kernel-modification-workflow" title="5.1.2.2. Kernel Modification Workflow">Kernel Modification Workflow</a>"
3921 section earlier in this manual for information on how to create a modified
3922 Yocto Project kernel.</p></li></ul></div><p>For information on pre-built kernel image naming schemes for images
3923 that can run on the QEMU emulator, see the
3924 "<a class="link" href="#downloading-the-pre-built-linux-kernel" target="_top">Downloading the Pre-Built Linux Kernel</a>"
3925 section in the Yocto Project Quick Start.</p></li><li class="listitem"><p><span class="emphasis"><em>Install the ADT</em></span>:
3926 The ADT provides a target-specific cross-development toolchain, the root filesystem,
3927 the QEMU emulator, and other tools that can help you develop your application.
3928 While it is possible to get these pieces separately, the ADT Installer provides an
3929 easy method.
3930 You can get these pieces by running an ADT installer script, which is configurable.
3931 For information on how to install the ADT, see the
3932 "<a class="link" href="#using-the-adt-installer" target="_top">Using the ADT Installer</a>"
3933 section
3934 in the Yocto Project Application Developer's Guide.</p></li><li class="listitem"><p><span class="emphasis"><em>If Applicable, Secure the Target Root Filesystem</em></span>:
3935 If you choose not to install the ADT using the ADT Installer,
3936 you need to find and download the
3937 appropriate root filesystems.
3938 You can find these tarballs in the same areas used for the kernel images.
3939 Depending on the type of image you are running, the root filesystem you need differs.
3940 For example, if you are developing an application that runs on an image that
3941 supports Sato, you need to get root filesystem that supports Sato.
3942 </p></li><li class="listitem"><p><span class="emphasis"><em>Create and Build your Application</em></span>:
3943 At this point, you need to have source files for your application.
3944 Once you have the files, you can use the Eclipse IDE to import them and build the
3945 project.
3946 If you are not using Eclipse, you need to use the cross-development tools you have
3947 installed to create the image.</p></li><li class="listitem"><p><span class="emphasis"><em>Deploy the Image with the Application</em></span>:
3948 If you are using the Eclipse IDE, you can deploy your image to the hardware or to
3949 QEMU through the project's preferences.
3950 If you are not using the Eclipse IDE, then you need to deploy the application using
3951 other methods to the hardware.
3952 Or, if you are using QEMU, you need to use that tool and load your image in for testing.
3953 </p></li><li class="listitem"><p><span class="emphasis"><em>Test and Debug the Application</em></span>:
3954 Once your application is deployed, you need to test it.
3955 Within the Eclipse IDE, you can use the debubbing environment along with the
3956 set of user-space tools installed along with the ADT to debug your application.
3957 Of course, the same user-space tools are available separately if you choose
3958 not to use the Eclipse IDE.</p></li></ol></div><p>
3959 </p></div><div class="section" title="5.2.2. Working Within Eclipse"><div class="titlepage"><div><div><h3 class="title"><a id="adt-eclipse"></a>5.2.2. Working Within Eclipse</h3></div></div></div><p>
3960 The Eclipse IDE is a popular development environment and it fully supports
3961 development using the Yocto Project.
3962 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>This release of the Yocto Project supports both the Juno and Indigo versions
3963 of the Eclipse IDE.
3964 Thus, the following information provides setup information for both versions.
3965 </div><p>
3966 </p><p>
3967 When you install and configure the Eclipse Yocto Project Plug-in into
3968 the Eclipse IDE, you maximize your Yocto Project experience.
3969 Installing and configuring the Plug-in results in an environment that
3970 has extensions specifically designed to let you more easily develop software.
3971 These extensions allow for cross-compilation, deployment, and execution of
3972 your output into a QEMU emulation session.
3973 You can also perform cross-debugging and profiling.
3974 The environment also supports a suite of tools that allows you to perform
3975 remote profiling, tracing, collection of power data, collection of
3976 latency data, and collection of performance data.
3977 </p><p>
3978 This section describes how to install and configure the Eclipse IDE
3979 Yocto Plug-in and how to use it to develop your application.
3980 </p><div class="section" title="5.2.2.1. Setting Up the Eclipse IDE"><div class="titlepage"><div><div><h4 class="title"><a id="setting-up-the-eclipse-ide"></a>5.2.2.1. Setting Up the Eclipse IDE</h4></div></div></div><p>
3981 To develop within the Eclipse IDE, you need to do the following:
3982 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Install the optimal version of the Eclipse IDE.</p></li><li class="listitem"><p>Configure the Eclipse IDE.</p></li><li class="listitem"><p>Install the Eclipse Yocto Plug-in.</p></li><li class="listitem"><p>Configure the Eclipse Yocto Plug-in.</p></li></ol></div><p>
3983 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
3984 Do not install Eclipse from your distribution's package repository.
3985 Be sure to install Eclipse from the official Eclipse download site as directed
3986 in the next section.
3987 </div><p>
3988 </p><div class="section" title="5.2.2.1.1. Installing the Eclipse IDE"><div class="titlepage"><div><div><h5 class="title"><a id="installing-eclipse-ide"></a>5.2.2.1.1. Installing the Eclipse IDE</h5></div></div></div><p>
3989 It is recommended that you have the Juno 4.2 version of the
3990 Eclipse IDE installed on your development system.
3991 However, if you currently have the Indigo 3.7.2 version installed and you do
3992 not want to upgrade the IDE, you can configure Indigo to work with the
3993 Yocto Project.
3994 See the
3995 "<a class="link" href="#configuring-the-eclipse-ide-indigo" title="5.2.2.1.3. Configuring the Eclipse IDE (Indigo)">Configuring the Eclipse IDE (Indigo)</a>"
3996 section.
3997 </p><p>
3998 If you don’t have the Juno 4.2 Eclipse IDE installed, you can find the tarball at
3999 <a class="ulink" href="http://www.eclipse.org/downloads" target="_top">http://www.eclipse.org/downloads</a>.
4000 From that site, choose the Eclipse Classic version particular to your development
4001 host.
4002 This version contains the Eclipse Platform, the Java Development
4003 Tools (JDT), and the Plug-in Development Environment.
4004 </p><p>
4005 Once you have downloaded the tarball, extract it into a clean
4006 directory.
4007 For example, the following commands unpack and install the Eclipse IDE
4008 tarball found in the <code class="filename">Downloads</code> area
4009 into a clean directory using the default name <code class="filename">eclipse</code>:
4010 </p><pre class="literallayout">
4011 $ cd ~
4012 $ tar -xzvf ~/Downloads/eclipse-SDK-4.2-linux-gtk-x86_64.tar.gz
4013 </pre><p>
4014 </p><p>
4015 If you have the Indigo 3.7.2 Eclipse IDE already installed and you want to use that
4016 version, one issue exists that you need to be aware of regarding the Java
4017 Virtual machine’s garbage collection (GC) process.
4018 The GC process does not clean up the permanent generation
4019 space (PermGen).
4020 This space stores metadata descriptions of classes.
4021 The default value is set too small and it could trigger an
4022 out-of-memory error such as the following:
4023 </p><pre class="literallayout">
4024 Java.lang.OutOfMemoryError: PermGen space
4025 </pre><p>
4026 </p><p>
4027 This error causes the application to hang.
4028 </p><p>
4029 To fix this issue, you can use the <code class="filename">--vmargs</code>
4030 option when you start the Indigo 3.7.2 Eclipse IDE
4031 to increase the size of the permanent generation space:
4032 </p><pre class="literallayout">
4033 eclipse --vmargs --XX:PermSize=256M
4034 </pre><p>
4035 </p></div><div class="section" title="5.2.2.1.2. Configuring the Eclipse IDE (Juno)"><div class="titlepage"><div><div><h5 class="title"><a id="configuring-the-eclipse-ide-juno"></a>5.2.2.1.2. Configuring the Eclipse IDE (Juno)</h5></div></div></div><p>
4036 This section presents the steps needed to configure the Juno 4.2 Eclipse IDE.
4037 If you are using Indigo 3.7.2, see the
4038 "<a class="link" href="#configuring-the-eclipse-ide-indigo" title="5.2.2.1.3. Configuring the Eclipse IDE (Indigo)">Configuring the Eclipse IDE (Indigo)</a>".
4039 </p><p>
4040 Before installing and configuring the Eclipse Yocto Plug-in, you need to configure
4041 the Juno 4.2 Eclipse IDE.
4042 Follow these general steps:
4043 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Start the Eclipse IDE.</p></li><li class="listitem"><p>Make sure you are in your Workbench and select
4044 "Install New Software" from the "Help" pull-down menu.
4045 </p></li><li class="listitem"><p>Select <code class="filename">Juno - http://download.eclipse.org/releases/juno</code>
4046 from the "Work with:" pull-down menu.</p></li><li class="listitem"><p>Expand the box next to "Linux Tools" and select the
4047 "LTTng - Linux Tracing Toolkit" boxes.</p></li><li class="listitem"><p>Expand the box next to "Mobile and Device Development" and select the
4048 following boxes:
4049 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename">C/C++ Remote Launch</code></p></li><li class="listitem"><p><code class="filename">Remote System Explorer End-user Runtime</code></p></li><li class="listitem"><p><code class="filename">Remote System Explorer User Actions</code></p></li><li class="listitem"><p><code class="filename">Target Management Terminal</code></p></li><li class="listitem"><p><code class="filename">TCF Remote System Explorer add-in</code></p></li><li class="listitem"><p><code class="filename">TCF Target Explorer</code></p></li></ul></div></li><li class="listitem"><p>Expand the box next to <code class="filename">Programming Languages</code>
4050 and select the <code class="filename">Autotools Support for CDT</code>
4051 and <code class="filename">C/C++ Development Tools</code> boxes.</p></li><li class="listitem"><p>Complete the installation and restart the Eclipse IDE.</p></li></ol></div><p>
4052 </p></div><div class="section" title="5.2.2.1.3. Configuring the Eclipse IDE (Indigo)"><div class="titlepage"><div><div><h5 class="title"><a id="configuring-the-eclipse-ide-indigo"></a>5.2.2.1.3. Configuring the Eclipse IDE (Indigo)</h5></div></div></div><p>
4053 This section presents the steps needed to configure the Indigo 3.7.2 Eclipse IDE.
4054 If you are using Juno 4.2, see the
4055 "<a class="link" href="#configuring-the-eclipse-ide-juno" title="5.2.2.1.2. Configuring the Eclipse IDE (Juno)">Configuring the Eclipse IDE (Juno)</a>".
4056 </p><p>
4057 Before installing and configuring the Eclipse Yocto Plug-in, you need to configure
4058 the Indigo 3.7.2 Eclipse IDE.
4059 Follow these general steps:
4060 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Start the Eclipse IDE.</p></li><li class="listitem"><p>Make sure you are in your Workbench and select
4061 "Install New Software" from the "Help" pull-down menu.
4062 </p></li><li class="listitem"><p>Select <code class="filename">indigo - http://download.eclipse.org/releases/indigo</code>
4063 from the "Work with:" pull-down menu.</p></li><li class="listitem"><p>Expand the box next to <code class="filename">Programming Languages</code>
4064 and select the <code class="filename">Autotools Support for CDT (incubation)</code>
4065 and <code class="filename">C/C++ Development Tools</code> boxes.</p></li><li class="listitem"><p>Expand the box next to "Linux Tools" and select the
4066 "LTTng - Linux Tracing Toolkit(incubation)" boxes.</p></li><li class="listitem"><p>Complete the installation and restart the Eclipse IDE.</p></li><li class="listitem"><p>After the Eclipse IDE restarts and from the Workbench, select
4067 "Install New Software" from the "Help" pull-down menu.</p></li><li class="listitem"><p>Click the
4068 "Available Software Sites" link.</p></li><li class="listitem"><p>Check the box next to
4069 <code class="filename">http://download.eclipse.org/tm/updates/3.3</code>
4070 and click "OK".</p></li><li class="listitem"><p>Select <code class="filename">http://download.eclipse.org/tm/updates/3.3</code>
4071 from the "Work with:" pull-down menu.</p></li><li class="listitem"><p>Check the box next to <code class="filename">TM and RSE Main Features</code>.
4072 </p></li><li class="listitem"><p>Expand the box next to <code class="filename">TM and RSE Optional Add-ons</code>
4073 and select every item except <code class="filename">RSE Unit Tests</code> and
4074 <code class="filename">RSE WinCE Services (incubation)</code>.</p></li><li class="listitem"><p>Complete the installation and restart the Eclipse IDE.</p></li><li class="listitem"><p>If necessary, select
4075 "Install New Software" from the "Help" pull-down menu so you can click the
4076 "Available Software Sites" link again.</p></li><li class="listitem"><p>After clicking "Available Software Sites", check the box next to
4077 <code class="filename">http://download.eclipse.org/tools/cdt/releases/indigo</code>
4078 and click "OK".</p></li><li class="listitem"><p>Select <code class="filename">http://download.eclipse.orgtools/cdt/releases/indigo</code>
4079 from the "Work with:" pull-down menu.</p></li><li class="listitem"><p>Check the box next to <code class="filename">CDT Main Features</code>.
4080 </p></li><li class="listitem"><p>Expand the box next to <code class="filename">CDT Optional Features</code>
4081 and select <code class="filename">C/C++ Remote Launch</code> and
4082 <code class="filename">Target Communication Framework (incubation)</code>.</p></li><li class="listitem"><p>Complete the installation and restart the Eclipse IDE.</p></li></ol></div><p>
4083 </p></div><div class="section" title="5.2.2.1.4. Installing or Accessing the Eclipse Yocto Plug-in"><div class="titlepage"><div><div><h5 class="title"><a id="installing-the-eclipse-yocto-plug-in"></a>5.2.2.1.4. Installing or Accessing the Eclipse Yocto Plug-in</h5></div></div></div><p>
4084 You can install the Eclipse Yocto Plug-in into the Eclipse IDE
4085 one of two ways: use the Yocto Project's Eclipse Update site to install the pre-built plug-in,
4086 or build and install the plug-in from the latest source code.
4087 If you don't want to permanently install the plug-in but just want to try it out
4088 within the Eclipse environment, you can import the plug-in project from the
4089 Yocto Project source repositories.
4090 </p><div class="section" title="5.2.2.1.4.1. Installing the Pre-built Plug-in from the Yocto Project Eclipse Update Site"><div class="titlepage"><div><div><h6 class="title"><a id="new-software"></a>5.2.2.1.4.1. Installing the Pre-built Plug-in from the Yocto Project Eclipse Update Site</h6></div></div></div><p>
4091 To install the Eclipse Yocto Plug-in from the update site,
4092 follow these steps:
4093 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Start up the Eclipse IDE.</p></li><li class="listitem"><p>In Eclipse, select "Install New Software" from the "Help" menu.</p></li><li class="listitem"><p>Click "Add..." in the "Work with:" area.</p></li><li class="listitem"><p>Enter
4094 <code class="filename">http://downloads.yoctoproject.org/releases/eclipse-plugin/1.3</code>
4095 in the URL field and provide a meaningful name in the "Name" field.</p></li><li class="listitem"><p>Click "OK" to have the entry added to the "Work with:"
4096 drop-down list.</p></li><li class="listitem"><p>Select the entry for the plug-in from the "Work with:" drop-down
4097 list.</p></li><li class="listitem"><p>Check the box next to <code class="filename">Development tools and SDKs for Yocto Linux</code>.
4098 </p></li><li class="listitem"><p>Complete the remaining software installation steps and
4099 then restart the Eclipse IDE to finish the installation of the plug-in.
4100 </p></li></ol></div><p>
4101 </p></div><div class="section" title="5.2.2.1.4.2. Installing the Plug-in Using the Latest Source Code"><div class="titlepage"><div><div><h6 class="title"><a id="zip-file-method"></a>5.2.2.1.4.2. Installing the Plug-in Using the Latest Source Code</h6></div></div></div><p>
4102 To install the Eclipse Yocto Plug-in from the latest source code, follow these steps:
4103 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Open a shell and create a Git repository with:
4104 </p><pre class="literallayout">
4105 $ git clone git://git.yoctoproject.org/eclipse-poky yocto-eclipse
4106 </pre><p>
4107 For this example, the repository is named
4108 <code class="filename">~/yocto-eclipse</code>.</p></li><li class="listitem"><p>Locate the <code class="filename">build.sh</code> script in the
4109 Git repository you created in the previous step.
4110 The script is located in the <code class="filename">scripts</code>.</p></li><li class="listitem"><p>Be sure to set and export the <code class="filename">ECLIPSE_HOME</code> environment
4111 variable to the top-level directory in which you installed the Indigo
4112 version of Eclipse.
4113 For example, if your Eclipse directory is <code class="filename">$HOME/eclipse</code>,
4114 use the following:
4115 </p><pre class="literallayout">
4116 $ export ECLIPSE_HOME=$HOME/eclipse
4117 </pre></li><li class="listitem"><p>Run the <code class="filename">build.sh</code> script and provide the
4118 name of the Git branch along with the Yocto Project release you are
4119 using.
4120 Here is an example that uses the <code class="filename">master</code> Git repository
4121 and the <code class="filename">1.1M4</code> release:
4122 </p><pre class="literallayout">
4123 $ scripts/build.sh master 1.1M4
4124 </pre><p>
4125 After running the script, the file
4126 <code class="filename">org.yocto.sdk-&lt;release&gt;-&lt;date&gt;-archive.zip</code>
4127 is in the current directory.</p></li><li class="listitem"><p>If necessary, start the Eclipse IDE and be sure you are in the
4128 Workbench.</p></li><li class="listitem"><p>Select "Install New Software" from the "Help" pull-down menu.
4129 </p></li><li class="listitem"><p>Click "Add".</p></li><li class="listitem"><p>Provide anything you want in the "Name" field.</p></li><li class="listitem"><p>Click "Archive" and browse to the ZIP file you built
4130 in step four.
4131 This ZIP file should not be "unzipped", and must be the
4132 <code class="filename">*archive.zip</code> file created by running the
4133 <code class="filename">build.sh</code> script.</p></li><li class="listitem"><p>Check the box next to the new entry in the installation window and complete
4134 the installation.</p></li><li class="listitem"><p>Restart the Eclipse IDE if necessary.</p></li></ol></div><p>
4135 </p><p>
4136 At this point you should be able to configure the Eclipse Yocto Plug-in as described in the
4137 "<a class="link" href="#configuring-the-eclipse-yocto-plug-in" title="5.2.2.1.5. Configuring the Eclipse Yocto Plug-in">Configuring the Eclipse Yocto Plug-in</a>"
4138 section.</p></div><div class="section" title="5.2.2.1.4.3. Importing the Plug-in Project into the Eclipse Environment"><div class="titlepage"><div><div><h6 class="title"><a id="yocto-project-source"></a>5.2.2.1.4.3. Importing the Plug-in Project into the Eclipse Environment</h6></div></div></div><p>
4139 Importing the Eclipse Yocto Plug-in project from the Yocto Project source repositories
4140 is useful when you want to try out the latest plug-in from the tip of plug-in's
4141 development tree.
4142 It is important to understand when you import the plug-in you are not installing
4143 it into the Eclipse application.
4144 Rather, you are importing the project and just using it.
4145 To import the plug-in project, follow these steps:
4146 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Open a shell and create a Git repository with:
4147 </p><pre class="literallayout">
4148 $ git clone git://git.yoctoproject.org/eclipse-poky yocto-eclipse
4149 </pre><p>
4150 For this example, the repository is named
4151 <code class="filename">~/yocto-eclipse</code>.</p></li><li class="listitem"><p>In Eclipse, select "Import" from the "File" menu.</p></li><li class="listitem"><p>Expand the "General" box and select "existing projects into workspace"
4152 and then click "Next".</p></li><li class="listitem"><p>Select the root directory and browse to
4153 <code class="filename">~/yocto-eclipse/plugins</code>.</p></li><li class="listitem"><p>Three plug-ins exist: "org.yocto.bc.ui", "org.yocto.sdk.ide", and
4154 "org.yocto.sdk.remotetools".
4155 Select and import all of them.</p></li></ol></div><p>
4156 </p><p>
4157 The left navigation pane in the Eclipse application shows the default projects.
4158 Right-click on one of these projects and run it as an Eclipse application.
4159 This brings up a second instance of Eclipse IDE that has the Yocto Plug-in.
4160 </p></div></div><div class="section" title="5.2.2.1.5. Configuring the Eclipse Yocto Plug-in"><div class="titlepage"><div><div><h5 class="title"><a id="configuring-the-eclipse-yocto-plug-in"></a>5.2.2.1.5. Configuring the Eclipse Yocto Plug-in</h5></div></div></div><p>
4161 Configuring the Eclipse Yocto Plug-in involves setting the Cross
4162 Compiler options and the Target options.
4163 The configurations you choose become the default settings for all projects.
4164 You do have opportunities to change them later when
4165 you configure the project (see the following section).
4166 </p><p>
4167 To start, you need to do the following from within the Eclipse IDE:
4168 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Choose <code class="filename">Windows -&gt; Preferences</code> to display
4169 the <code class="filename">Preferences</code> Dialog</p></li><li class="listitem"><p>Click <code class="filename">Yocto Project ADT</code></p></li></ul></div><p>
4170 </p><div class="section" title="5.2.2.1.5.1. Configuring the Cross-Compiler Options"><div class="titlepage"><div><div><h6 class="title"><a id="configuring-the-cross-compiler-options"></a>5.2.2.1.5.1. Configuring the Cross-Compiler Options</h6></div></div></div><p>
4171 To configure the Cross Compiler Options, you must select the type of toolchain,
4172 point to the toolchain, specify the sysroot location, and select the target architecture.
4173 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Selecting the Toolchain Type:</em></span>
4174 Choose between <code class="filename">Standalone pre-built toolchain</code>
4175 and <code class="filename">Build system derived toolchain</code> for Cross
4176 Compiler Options.
4177 </p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p><span class="emphasis"><em>
4178 <code class="filename">Standalone Pre-built Toolchain:</code></em></span>
4179 Select this mode when you are using a stand-alone cross-toolchain.
4180 For example, suppose you are an application developer and do not
4181 need to build a target image.
4182 Instead, you just want to use an architecture-specific toolchain on an
4183 existing kernel and target root filesystem.
4184 </p></li><li class="listitem"><p><span class="emphasis"><em>
4185 <code class="filename">Build System Derived Toolchain:</code></em></span>
4186 Select this mode if the cross-toolchain has been installed and built
4187 as part of the build directory.
4188 When you select <code class="filename">Build system derived toolchain</code>,
4189 you are using the toolchain bundled
4190 inside the build directory.
4191 </p></li></ul></div><p>
4192 </p></li><li class="listitem"><p><span class="emphasis"><em>Point to the Toolchain:</em></span>
4193 If you are using a stand-alone pre-built toolchain, you should be pointing to the
4194 <code class="filename">/opt/poky/1.3</code> directory.
4195 This is the location for toolchains installed by the ADT Installer or by hand.
4196 Sections "<a class="link" href="#configuring-and-running-the-adt-installer-script" target="_top">Configuring
4197 and Running the ADT Installer Script</a>" and
4198 "<a class="link" href="#using-an-existing-toolchain-tarball" target="_top">Using a Cross-Toolchain Tarball</a>"
4199 in the Yocto Project Application Developer's Guide
4200 describe two ways to install a stand-alone cross-toolchain in the
4201 <code class="filename">/opt/poky</code> directory.
4202 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>It is possible to install a stand-alone cross-toolchain in a directory
4203 other than <code class="filename">/opt/poky</code>.
4204 However, doing so is discouraged.</div><p>If you are using a system-derived toolchain, the path you provide
4205 for the <code class="filename">Toolchain Root Location</code>
4206 field is the build directory.
4207 See the "<a class="link" href="#using-the-toolchain-from-within-the-build-tree" target="_top">Using
4208 BitBake and the build directory</a>" section in the Yocto Project Application
4209 Developer's Guide for information on how to install the toolchain into the build
4210directory.</p></li><li class="listitem"><p><span class="emphasis"><em>Specify the Sysroot Location:</em></span>
4211 This location is where the root filesystem for the
4212 target hardware is created on the development system by the ADT Installer.
4213 The QEMU user-space tools, the
4214 NFS boot process, and the cross-toolchain all use the sysroot location.
4215 </p></li><li class="listitem"><p><span class="emphasis"><em>Select the Target Architecture:</em></span>
4216 The target architecture is the type of hardware you are
4217 going to use or emulate.
4218 Use the pull-down <code class="filename">Target Architecture</code> menu to make
4219 your selection.
4220 The pull-down menu should have the supported architectures.
4221 If the architecture you need is not listed in the menu, you
4222 will need to build the image.
4223 See the "<a class="link" href="#building-image" target="_top">Building an Image</a>" section
4224 of the Yocto Project Quick Start for more information.</p></li></ul></div><p>
4225 </p></div><div class="section" title="5.2.2.1.5.2. Configuring the Target Options"><div class="titlepage"><div><div><h6 class="title"><a id="configuring-the-target-options"></a>5.2.2.1.5.2. Configuring the Target Options</h6></div></div></div><p>
4226 You can choose to emulate hardware using the QEMU emulator, or you
4227 can choose to run your image on actual hardware.
4228 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em><code class="filename">QEMU:</code></em></span> Select this option if
4229 you will be using the QEMU emulator.
4230 If you are using the emulator, you also need to locate the kernel
4231 and specify any custom options.</p><p>If you selected <code class="filename">Build system derived toolchain</code>,
4232 the target kernel you built will be located in the
4233 build directory in <code class="filename">tmp/deploy/images</code> directory.
4234 If you selected <code class="filename">Standalone pre-built toolchain</code>, the
4235 pre-built image you downloaded is located
4236 in the directory you specified when you downloaded the image.</p><p>Most custom options are for advanced QEMU users to further
4237 customize their QEMU instance.
4238 These options are specified between paired angled brackets.
4239 Some options must be specified outside the brackets.
4240 In particular, the options <code class="filename">serial</code>,
4241 <code class="filename">nographic</code>, and <code class="filename">kvm</code> must all
4242 be outside the brackets.
4243 Use the <code class="filename">man qemu</code> command to get help on all the options
4244 and their use.
4245 The following is an example:
4246 </p><pre class="literallayout">
4247 serial ‘&lt;-m 256 -full-screen&gt;’
4248 </pre><p>
4249 Regardless of the mode, Sysroot is already defined as part of the
4250 Cross Compiler Options configuration in the
4251 <code class="filename">Sysroot Location:</code> field.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">External HW:</code></em></span> Select this option
4252 if you will be using actual hardware.</p></li></ul></div><p>
4253 </p><p>
4254 Click the <code class="filename">OK</code> button to save your plug-in configurations.
4255 </p></div></div></div><div class="section" title="5.2.2.2. Creating the Project"><div class="titlepage"><div><div><h4 class="title"><a id="creating-the-project"></a>5.2.2.2. Creating the Project</h4></div></div></div><p>
4256 You can create two types of projects: Autotools-based, or Makefile-based.
4257 This section describes how to create Autotools-based projects from within
4258 the Eclipse IDE.
4259 For information on creating Makefile-based projects in a terminal window, see the section
4260 "<a class="link" href="#using-the-command-line" target="_top">Using the Command Line</a>"
4261 in the Yocto Project Application Developer's Guide.
4262 </p><p>
4263 To create a project based on a Yocto template and then display the source code,
4264 follow these steps:
4265 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Select <code class="filename">File -&gt; New -&gt; Project</code>.</p></li><li class="listitem"><p>Double click <code class="filename">CC++</code>.</p></li><li class="listitem"><p>Double click <code class="filename">C Project</code> to create the project.</p></li><li class="listitem"><p>Expand <code class="filename">Yocto Project ADT Project</code>.</p></li><li class="listitem"><p>Select <code class="filename">Hello World ANSI C Autotools Project</code>.
4266 This is an Autotools-based project based on a Yocto template.</p></li><li class="listitem"><p>Put a name in the <code class="filename">Project name:</code> field.
4267 Do not use hyphens as part of the name.</p></li><li class="listitem"><p>Click <code class="filename">Next</code>.</p></li><li class="listitem"><p>Add information in the <code class="filename">Author</code> and
4268 <code class="filename">Copyright notice</code> fields.</p></li><li class="listitem"><p>Be sure the <code class="filename">License</code> field is correct.</p></li><li class="listitem"><p>Click <code class="filename">Finish</code>.</p></li><li class="listitem"><p>If the "open perspective" prompt appears, click "Yes" so that you
4269 in the C/C++ perspective.</p></li><li class="listitem"><p>The left-hand navigation pane shows your project.
4270 You can display your source by double clicking the project's source file.
4271 </p></li></ol></div><p>
4272 </p></div><div class="section" title="5.2.2.3. Configuring the Cross-Toolchains"><div class="titlepage"><div><div><h4 class="title"><a id="configuring-the-cross-toolchains"></a>5.2.2.3. Configuring the Cross-Toolchains</h4></div></div></div><p>
4273 The earlier section, "<a class="link" href="#configuring-the-eclipse-yocto-plug-in" title="5.2.2.1.5. Configuring the Eclipse Yocto Plug-in">Configuring
4274 the Eclipse Yocto Plug-in</a>", sets up the default project
4275 configurations.
4276 You can override these settings for a given project by following these steps:
4277 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Select <code class="filename">Project -&gt; Change Yocto Project Settings</code>:
4278 This selection brings up the <code class="filename">Yocot Project Settings</code> Dialog
4279 and allows you to make changes specific to an individual project.
4280 </p><p>By default, the Cross Compiler Options and Target Options for a project
4281 are inherited from settings you provide using the <code class="filename">Preferences</code>
4282 Dialog as described earlier
4283 in the "<a class="link" href="#configuring-the-eclipse-yocto-plug-in" title="5.2.2.1.5. Configuring the Eclipse Yocto Plug-in">Configuring the Eclipse
4284 Yocto Plug-in</a>" section.
4285 The <code class="filename">Yocto Project Settings</code>
4286 Dialog allows you to override those default settings
4287 for a given project.</p></li><li class="listitem"><p>Make your configurations for the project and click "OK".</p></li><li class="listitem"><p>Select <code class="filename">Project -&gt; Reconfigure Project</code>:
4288 This selection reconfigures the project by running
4289 <code class="filename">autogen.sh</code> in the workspace for your project.
4290 The script also runs <code class="filename">libtoolize</code>, <code class="filename">aclocal</code>,
4291 <code class="filename">autoconf</code>, <code class="filename">autoheader</code>,
4292 <code class="filename">automake --a</code>, and
4293 <code class="filename">./configure</code>.
4294 Click on the <code class="filename">Console</code> tab beneath your source code to
4295 see the results of reconfiguring your project.</p></li></ol></div><p>
4296 </p></div><div class="section" title="5.2.2.4. Building the Project"><div class="titlepage"><div><div><h4 class="title"><a id="building-the-project"></a>5.2.2.4. Building the Project</h4></div></div></div><p>
4297 To build the project, select <code class="filename">Project -&gt; Build Project</code>.
4298 The console should update and you can note the cross-compiler you are using.
4299 </p></div><div class="section" title="5.2.2.5. Starting QEMU in User Space NFS Mode"><div class="titlepage"><div><div><h4 class="title"><a id="starting-qemu-in-user-space-nfs-mode"></a>5.2.2.5. Starting QEMU in User Space NFS Mode</h4></div></div></div><p>
4300 To start the QEMU emulator from within Eclipse, follow these steps:
4301 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Expose the <code class="filename">Run -&gt; External Tools</code> menu.
4302 Your image should appear as a selectable menu item.
4303 </p></li><li class="listitem"><p>Select your image from the menu to launch the
4304 emulator in a new window.</p></li><li class="listitem"><p>If needed, enter your host root password in the shell window at the prompt.
4305 This sets up a <code class="filename">Tap 0</code> connection needed for running in user-space
4306 NFS mode.</p></li><li class="listitem"><p>Wait for QEMU to launch.</p></li><li class="listitem"><p>Once QEMU launches, you can begin operating within that
4307 environment.
4308 For example, you could determine the IP Address
4309 for the user-space NFS by using the <code class="filename">ifconfig</code> command.
4310 </p></li></ol></div><p>
4311 </p></div><div class="section" title="5.2.2.6. Deploying and Debugging the Application"><div class="titlepage"><div><div><h4 class="title"><a id="deploying-and-debugging-the-application"></a>5.2.2.6. Deploying and Debugging the Application</h4></div></div></div><p>
4312 Once the QEMU emulator is running the image, using the Eclipse IDE
4313 you can deploy your application and use the emulator to perform debugging.
4314 Follow these steps to deploy the application.
4315 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Select <code class="filename">Run -&gt; Debug Configurations...</code></p></li><li class="listitem"><p>In the left area, expand <code class="filename">C/C++Remote Application</code>.</p></li><li class="listitem"><p>Locate your project and select it to bring up a new
4316 tabbed view in the <code class="filename">Debug Configurations</code> Dialog.</p></li><li class="listitem"><p>Enter the absolute path into which you want to deploy
4317 the application.
4318 Use the <code class="filename">Remote Absolute File Path for C/C++Application:</code> field.
4319 For example, enter <code class="filename">/usr/bin/&lt;programname&gt;</code>.</p></li><li class="listitem"><p>Click on the <code class="filename">Debugger</code> tab to see the cross-tool debugger
4320 you are using.</p></li><li class="listitem"><p>Click on the <code class="filename">Main</code> tab.</p></li><li class="listitem"><p>Create a new connection to the QEMU instance
4321 by clicking on <code class="filename">new</code>.</p></li><li class="listitem"><p>Select <code class="filename">TCF</code>, which means Target Communication
4322 Framework.</p></li><li class="listitem"><p>Click <code class="filename">Next</code>.</p></li><li class="listitem"><p>Clear out the <code class="filename">host name</code> field and enter the IP Address
4323 determined earlier.</p></li><li class="listitem"><p>Click <code class="filename">Finish</code> to close the
4324 <code class="filename">New Connections</code> Dialog.</p></li><li class="listitem"><p>Use the drop-down menu now in the <code class="filename">Connection</code> field and pick
4325 the IP Address you entered.</p></li><li class="listitem"><p>Click <code class="filename">Debug</code> to bring up a login screen
4326 and login.</p></li><li class="listitem"><p>Accept the debug perspective.</p></li></ol></div><p>
4327 </p></div><div class="section" title="5.2.2.7. Running User-Space Tools"><div class="titlepage"><div><div><h4 class="title"><a id="running-user-space-tools"></a>5.2.2.7. Running User-Space Tools</h4></div></div></div><p>
4328 As mentioned earlier in the manual, several tools exist that enhance
4329 your development experience.
4330 These tools are aids in developing and debugging applications and images.
4331 You can run these user-space tools from within the Eclipse IDE through the
4332 <code class="filename">YoctoTools</code> menu.
4333 </p><p>
4334 Once you pick a tool, you need to configure it for the remote target.
4335 Every tool needs to have the connection configured.
4336 You must select an existing TCF-based RSE connection to the remote target.
4337 If one does not exist, click <code class="filename">New</code> to create one.
4338 </p><p>
4339 Here are some specifics about the remote tools:
4340 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em><code class="filename">OProfile</code>:</em></span> Selecting this tool causes
4341 the <code class="filename">oprofile-server</code> on the remote target to launch on
4342 the local host machine.
4343 The <code class="filename">oprofile-viewer</code> must be installed on the local host machine and the
4344 <code class="filename">oprofile-server</code> must be installed on the remote target,
4345 respectively, in order to use.
4346 You must compile and install the <code class="filename">oprofile-viewer</code> from the source code
4347 on your local host machine.
4348 Furthermore, in order to convert the target's sample format data into a form that the
4349 host can use, you must have <code class="filename">oprofile</code> version 0.9.4 or
4350 greater installed on the host.</p><p>You can locate both the viewer and server from
4351 <a class="ulink" href="http://git.yoctoproject.org/cgit/cgit.cgi/oprofileui/" target="_top">http://git.yoctoproject.org/cgit/cgit.cgi/oprofileui/</a>.
4352 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>The <code class="filename">oprofile-server</code> is installed by default on
4353 the <code class="filename">core-image-sato-sdk</code> image.</div></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">Lttng-ust</code>:</em></span> Selecting this tool runs
4354 <code class="filename">usttrace</code> on the remote target, transfers the output data back
4355 to the local host machine, and uses the <code class="filename">lttng</code> Eclipse plug-in to
4356 graphically display the output.
4357 For information on how to use <code class="filename">lttng</code> to trace an application, see
4358 <a class="ulink" href="http://lttng.org/files/ust/manual/ust.html" target="_top">http://lttng.org/files/ust/manual/ust.html</a>.</p><p>For <code class="filename">Application</code>, you must supply the absolute path name of the
4359 application to be traced by user mode <code class="filename">lttng</code>.
4360 For example, typing <code class="filename">/path/to/foo</code> triggers
4361 <code class="filename">usttrace /path/to/foo</code> on the remote target to trace the
4362 program <code class="filename">/path/to/foo</code>.</p><p><code class="filename">Argument</code> is passed to <code class="filename">usttrace</code>
4363 running on the remote target.</p><p>Before you use the <code class="filename">lttng-ust</code> tool, you need to setup
4364 the <code class="filename">lttng</code> Eclipse plug-in and create a <code class="filename">lttng</code>
4365 project.
4366 Do the following:
4367 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Follow these
4368 <a class="ulink" href="http://wiki.eclipse.org/Linux_Tools_Project/LTTng#Downloading_and_installing_the_LTTng_parser_library" target="_top">instructions</a>
4369 to download and install the <code class="filename">lttng</code> parser library.
4370 </p></li><li class="listitem"><p>Select <code class="filename">Window -&gt; Open Perspective -&gt; Other</code>
4371 and then select <code class="filename">LTTng</code>.</p></li><li class="listitem"><p>Click <code class="filename">OK</code> to change the Eclipse perspective
4372 into the <code class="filename">LTTng</code> perspective.</p></li><li class="listitem"><p>Create a new <code class="filename">LTTng</code> project by selecting
4373 <code class="filename">File -&gt; New -&gt; Project</code>.</p></li><li class="listitem"><p>Choose <code class="filename">LTTng -&gt; LTTng Project</code>.</p></li><li class="listitem"><p>Click <code class="filename">YoctoTools -&gt; lttng-ust</code> to start user mode
4374 <code class="filename">lttng</code> on the remote target.</p></li></ol></div><p>After the output data has been transferred from the remote target back to the local
4375 host machine, new traces will be imported into the selected <code class="filename">LTTng</code> project.
4376 Then you can go to the <code class="filename">LTTng</code> project, right click the imported
4377 trace, and set the trace type as the <code class="filename">LTTng</code> kernel trace.
4378 Finally, right click the imported trace and select <code class="filename">Open</code>
4379 to display the data graphically.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">PowerTOP</code>:</em></span> Selecting this tool runs
4380 <code class="filename">powertop</code> on the remote target machine and displays the results in a
4381 new view called <code class="filename">powertop</code>.</p><p><code class="filename">Time to gather data(sec):</code> is the time passed in seconds before data
4382 is gathered from the remote target for analysis.</p><p><code class="filename">show pids in wakeups list:</code> corresponds to the
4383 <code class="filename">-p</code> argument
4384 passed to <code class="filename">powertop</code>.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">LatencyTOP and Perf</code>:</em></span>
4385 <code class="filename">latencytop</code> identifies system latency, while
4386 <code class="filename">perf</code> monitors the system's
4387 performance counter registers.
4388 Selecting either of these tools causes an RSE terminal view to appear
4389 from which you can run the tools.
4390 Both tools refresh the entire screen to display results while they run.</p></li></ul></div><p>
4391 </p></div><div class="section" title="5.2.2.8. Customizing an Image Using a BitBake Commander Project and Hob"><div class="titlepage"><div><div><h4 class="title"><a id="customizing-an-image-using-a-bitbake-commander-project-and-hob"></a>5.2.2.8. Customizing an Image Using a BitBake Commander Project and Hob</h4></div></div></div><p>
4392 Within Eclipse, you can create a Yocto BitBake Commander project,
4393 edit the metadata, and then use the
4394 <a class="ulink" href="http://www.yoctoproject.org/projects/hob" target="_top">Hob</a> to build a customized
4395 image all within one IDE.
4396 </p><div class="section" title="5.2.2.8.1. Creating the Yocto BitBake Commander Project"><div class="titlepage"><div><div><h5 class="title"><a id="creating-the-yocto-bitbake-commander-project"></a>5.2.2.8.1. Creating the Yocto BitBake Commander Project</h5></div></div></div><p>
4397 To create a Yocto BitBake Commander project, follow these steps:
4398 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Select <code class="filename">Window -&gt; Open Perspective -&gt; Other</code>
4399 and then choose <code class="filename">Bitbake Commander</code>.</p></li><li class="listitem"><p>Click <code class="filename">OK</code> to change the Eclipse perspective into the
4400 Bitbake Commander perspective.</p></li><li class="listitem"><p>Select <code class="filename">File -&gt; New -&gt; Project</code> to create a new Yocto
4401 Bitbake Commander project.</p></li><li class="listitem"><p>Choose <code class="filename">Yocto Project Bitbake Commander -&gt; New Yocto Project</code>
4402 and click <code class="filename">Next</code>.</p></li><li class="listitem"><p>Enter the Project Name and choose the Project Location.
4403 The Yocto project's metadata files will be put under the directory
4404 <code class="filename">&lt;project_location&gt;/&lt;project_name&gt;</code>.
4405 If that directory does not exist, you need to check
4406 the "Clone from Yocto Git Repository" box, which would execute a
4407 <code class="filename">git clone</code> command to get the project's metadata files.
4408 </p></li><li class="listitem"><p>Select <code class="filename">Finish</code> to create the project.</p></li></ol></div><p>
4409 </p></div><div class="section" title="5.2.2.8.2. Editing the Metadata Files"><div class="titlepage"><div><div><h5 class="title"><a id="editing-the-metadata-files"></a>5.2.2.8.2. Editing the Metadata Files</h5></div></div></div><p>
4410 After you create the Yocto Bitbake Commander project, you can modify the metadata files
4411 by opening them in the project.
4412 When editing recipe files (<code class="filename">.bb</code> files), you can view BitBake
4413 variable values and information by hovering the mouse pointer over the variable name and
4414 waiting a few seconds.
4415 </p><p>
4416 To edit the metadata, follow these steps:
4417 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Select your Yocto Bitbake Commander project.</p></li><li class="listitem"><p>Select <code class="filename">File -&gt; New -&gt; Yocto BitBake Commander -&gt; BitBake Recipe</code>
4418 to open a new recipe wizard.</p></li><li class="listitem"><p>Point to your source by filling in the "SRC_URL" field.
4419 For example, you can add a recipe to your
4420 <a class="link" href="#source-directory" target="_top">source directory</a>
4421 by defining "SRC_URL" as follows:
4422 </p><pre class="literallayout">
4423 ftp://ftp.gnu.org/gnu/m4/m4-1.4.9.tar.gz
4424 </pre></li><li class="listitem"><p>Click "Populate" to calculate the archive md5, sha256,
4425 license checksum values and to auto-generate the recipe filename.</p></li><li class="listitem"><p>Fill in the "Description" field.</p></li><li class="listitem"><p>Be sure values for all required fields exist.</p></li><li class="listitem"><p>Click <code class="filename">Finish</code>.</p></li></ol></div><p>
4426 </p></div><div class="section" title="5.2.2.8.3. Building and Customizing the Image"><div class="titlepage"><div><div><h5 class="title"><a id="buiding-and-customizing-the-image"></a>5.2.2.8.3. Building and Customizing the Image</h5></div></div></div><p>
4427 To build and customize the image in Eclipse, follow these steps:
4428 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Select your Yocto Bitbake Commander project.</p></li><li class="listitem"><p>Select <code class="filename">Project -&gt; Launch HOB</code>.</p></li><li class="listitem"><p>Enter the build directory where you want to put your final images.</p></li><li class="listitem"><p>Click <code class="filename">OK</code> to launch Hob.</p></li><li class="listitem"><p>Use Hob to customize and build your own images.
4429 For information on Hob, see the
4430 <a class="ulink" href="http://www.yoctoproject.org/projects/hob" target="_top">Hob Project Page</a> on the
4431 Yocto Project website.</p></li></ol></div><p>
4432 </p></div></div></div><div class="section" title="5.2.3. Workflow Using Stand-alone Cross-development Toolchains"><div class="titlepage"><div><div><h3 class="title"><a id="workflow-using-stand-alone-cross-development-toolchains"></a>5.2.3. Workflow Using Stand-alone Cross-development Toolchains</h3></div></div></div><p>
4433 If you want to develop an application without prior installation of the ADT, you
4434 still can employ the cross-development toolchain, the QEMU emulator, and a number of supported
4435 target image files.
4436 You just need to follow these general steps:
4437 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Install the cross-development toolchain for your target hardware:</em></span>
4438 For information on how to install the toolchain, see the
4439 "<a class="link" href="#using-an-existing-toolchain-tarball" target="_top">Using a Cross-Toolchain Tarball</a>"
4440 section
4441 in the Yocto Project Application Developer's Guide.</p></li><li class="listitem"><p><span class="emphasis"><em>Download the Target Image:</em></span> The Yocto Project supports
4442 several target architectures and has many pre-built kernel images and root filesystem
4443 images.</p><p>If you are going to develop your application on hardware, go to the
4444 <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines" target="_top"><code class="filename">machines</code></a>
4445 download area and choose a target machine area
4446 from which to download the kernel image and root filesystem.
4447 This download area could have several files in it that support development using
4448 actual hardware.
4449 For example, the area might contain <code class="filename">.hddimg</code> files that combine the
4450 kernel image with the filesystem, boot loaders, etc.
4451 Be sure to get the files you need for your particular development process.</p><p>If you are going to develop your application and then run and test it using the QEMU
4452 emulator, go to the
4453 <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/qemu" target="_top"><code class="filename">machines/qemu</code></a>
4454 download area.
4455 From this area, go down into the directory for your target architecture
4456 (e.g. <code class="filename">qemux86_64</code> for an
4457 <span class="trademark">Intel</span>®-based 64-bit architecture).
4458 Download kernel, root filesystem, and any other files you need for your process.
4459 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>In order to use the root filesystem in QEMU, you need to extract it.
4460 See the
4461 "<a class="link" href="#extracting-the-root-filesystem" target="_top">Extracting the Root Filesystem</a>"
4462 section for information on how to extract the root filesystem.</div></li><li class="listitem"><p><span class="emphasis"><em>Develop and Test your Application:</em></span> At this point,
4463 you have the tools to develop your application.
4464 If you need to separately install and use the QEMU emulator, you can go to
4465 <a class="ulink" href="http://www.qemu.org" target="_top">QEMU Home Page</a> to download and learn about the
4466 emulator.</p></li></ol></div><p>
4467 </p></div></div><div class="section" title="5.3. Modifying Temporary Source Code"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="modifying-temporary-source-code"></a>5.3. Modifying Temporary Source Code</h2></div></div></div><p>
4468 You might
4469 find it helpful during development to modify the temporary source code used by recipes
4470 to build packages.
4471 For example, suppose you are developing a patch and you need to experiment a bit
4472 to figure out your solution.
4473 After you have initially built the package, you can iteratively tweak the
4474 source code, which is located in the
4475 <a class="link" href="#build-directory">build directory</a>, and then
4476 you can force a re-compile and quickly test your altered code.
4477 Once you settle on a solution, you can then preserve your changes in the form of
4478 patches.
4479 You can accomplish these steps all within either a
4480 <a class="ulink" href="http://savannah.nongnu.org/projects/quilt" target="_top">Quilt</a> or
4481 <a class="link" href="#git" title="3.6. Git">Git</a> workflow.
4482 </p><div class="section" title="5.3.1. Finding the Temporary Source Code"><div class="titlepage"><div><div><h3 class="title"><a id="finding-the-temporary-source-code"></a>5.3.1. Finding the Temporary Source Code</h3></div></div></div><p>
4483 During a build, the unpacked temporary source code used by recipes
4484 to build packages is available in the build directory as
4485 defined by the
4486 <code class="filename"><a class="link" href="#var-S" target="_top">S</a></code> variable.
4487 Below is the default value for the <code class="filename">S</code> variable as defined in the
4488 <code class="filename">meta/conf/bitbake.conf</code> configuration file in the
4489 <a class="link" href="#source-directory">source directory</a>:
4490 </p><pre class="literallayout">
4491 S = ${WORKDIR}/${BP}
4492 </pre><p>
4493 You should be aware that many recipes override the <code class="filename">S</code> variable.
4494 For example, recipes that fetch their source from Git usually set
4495 <code class="filename">S</code> to <code class="filename">${WORKDIR}/git</code>.
4496 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><code class="filename">BP</code> represents the "Base Package", which is the base package
4497 name and the package version:
4498 <pre class="literallayout">
4499 BP = ${BPN}-${PV}
4500 </pre></div><p>
4501 </p><p>
4502 The path to the work directory for the recipe
4503 (<a class="link" href="#var-WORKDIR" target="_top"><code class="filename">WORKDIR</code></a>) depends
4504 on the package name and the architecture of the target device.
4505 For example, here is the work directory for packages whose targets are not device-dependent:
4506 </p><pre class="literallayout">
4507 ${TMPDIR}/work/${PACKAGE_ARCH}-poky-${TARGET_OS}/${PN}-${PV}-${PR}
4508 </pre><p>
4509 Let's look at an example without variables.
4510 Assuming a top-level source directory named <code class="filename">poky</code>
4511 and a default build directory of <code class="filename">poky/build</code>,
4512 the following is the work directory for the <code class="filename">acl</code> package:
4513 </p><pre class="literallayout">
4514 ~/poky/build/tmp/work/i586-poky-linux/acl-2.2.51-r3
4515 </pre><p>
4516 </p><p>
4517 If your package is dependent on the target device, the work directory varies slightly:
4518 </p><pre class="literallayout">
4519 ${TMPDIR}/work/${MACHINE}-poky-${TARGET_OS}/${PN}-${PV}-${PR}
4520 </pre><p>
4521 Again, assuming top-level source directory named <code class="filename">poky</code>
4522 and a default build directory of <code class="filename">poky/build</code>, the
4523 following is the work directory for the <code class="filename">acl</code> package that is being
4524 built for a MIPS-based device:
4525 </p><pre class="literallayout">
4526 ~/poky/build/tmp/work/mips-poky-linux/acl-2.2.51-r2
4527 </pre><p>
4528 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
4529 To better understand how the OpenEmbedded build system resolves directories during the
4530 build process, see the glossary entries for the
4531 <a class="link" href="#var-WORKDIR" target="_top"><code class="filename">WORKDIR</code></a>,
4532 <a class="link" href="#var-TMPDIR" target="_top"><code class="filename">TMPDIR</code></a>,
4533 <a class="link" href="#var-TOPDIR" target="_top"><code class="filename">TOPDIR</code></a>,
4534 <a class="link" href="#var-PACKAGE_ARCH" target="_top"><code class="filename">PACKAGE_ARCH</code></a>,
4535 <a class="link" href="#var-TARGET_OS" target="_top"><code class="filename">TARGET_OS</code></a>,
4536 <a class="link" href="#var-PN" target="_top"><code class="filename">PN</code></a>,
4537 <a class="link" href="#var-PV" target="_top"><code class="filename">PV</code></a>,
4538 and
4539 <a class="link" href="#var-PR" target="_top"><code class="filename">PR</code></a>
4540 variables in the Yocto Project Reference Manual.
4541 </div><p>
4542 Now that you know where to locate the directory that has the temporary source code, you can use a
4543 Quilt or Git workflow to make your edits, test the changes, and preserve the
4544 changes in the form of patches.
4545 </p></div><div class="section" title="5.3.2. Using a Quilt Workflow"><div class="titlepage"><div><div><h3 class="title"><a id="using-a-quilt-workflow"></a>5.3.2. Using a Quilt Workflow</h3></div></div></div><p>
4546 <a class="ulink" href="http://savannah.nongnu.org/projects/quilt" target="_top">Quilt</a>
4547 is a powerful tool that allows you to capture source code changes without having
4548 a clean source tree.
4549 This section outlines the typical workflow you can use to modify temporary source code,
4550 test changes, and then preserve the changes in the form of a patch all using Quilt.
4551 </p><p>
4552 Follow these general steps:
4553 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Find the Source Code:</em></span>
4554 The temporary source code used by the OpenEmbedded build system is kept in the
4555 build directory.
4556 See the
4557 "<a class="link" href="#finding-the-temporary-source-code" title="5.3.1. Finding the Temporary Source Code">Finding the Temporary Source Code</a>"
4558 section to learn how to locate the directory that has the temporary source code for a
4559 particular package.</p></li><li class="listitem"><p><span class="emphasis"><em>Change Your Working Directory:</em></span>
4560 You need to be in the directory that has the temporary source code.
4561 That directory is defined by the
4562 <a class="link" href="#var-S" target="_top">S</a>
4563 variable.</p></li><li class="listitem"><p><span class="emphasis"><em>Create a New Patch:</em></span>
4564 Before modifying source code, you need to create a new patch.
4565 To create a new patch file, use <code class="filename">quilt new</code> as below:
4566 </p><pre class="literallayout">
4567 $ quilt new my_changes.patch
4568 </pre></li><li class="listitem"><p><span class="emphasis"><em>Notify Quilt and Add Files:</em></span>
4569 After creating the patch, you need to notify Quilt about the files you will
4570 be changing.
4571 Add the files you will be modifying into the patch you just created:
4572 </p><pre class="literallayout">
4573 $ quilt add file1.c file2.c file3.c
4574 </pre></li><li class="listitem"><p><span class="emphasis"><em>Edit the Files:</em></span>
4575 Make the changes to the temporary source code.</p></li><li class="listitem"><p><span class="emphasis"><em>Test Your Changes:</em></span>
4576 Once you have modified the source code, the easiest way to test your changes
4577 is by calling the <code class="filename">compile</code> task as shown in the following example:
4578 </p><pre class="literallayout">
4579 $ bitbake -c compile -f &lt;name_of_package&gt;
4580 </pre><p>
4581 The <code class="filename">-f</code> or <code class="filename">--force</code>
4582 option forces re-execution of the specified task.
4583 If you find problems with your code, you can just keep editing and
4584 re-testing iteratively until things work as expected.
4585 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>All the modifications you make to the temporary source code
4586 disappear once you <code class="filename">-c clean</code> or
4587 <code class="filename">-c cleanall</code> with BitBake for the package.
4588 Modifications will also disappear if you use the <code class="filename">rm_work</code>
4589 feature as described in the
4590 "<a class="link" href="#building-image" target="_top">Building an Image</a>"
4591 section of the Yocto Project Quick Start.
4592 </div></li><li class="listitem"><p><span class="emphasis"><em>Generate the Patch:</em></span>
4593 Once your changes work as expected, you need to use Quilt to generate the final patch that
4594 contains all your modifications.
4595 </p><pre class="literallayout">
4596 $ quilt refresh
4597 </pre><p>
4598 At this point the <code class="filename">my_changes.patch</code> file has all your edits made
4599 to the <code class="filename">file1.c</code>, <code class="filename">file2.c</code>, and
4600 <code class="filename">file3.c</code> files.</p><p>You can find the resulting patch file in the <code class="filename">patches/</code>
4601 subdirectory of the source (<code class="filename">S</code>) directory.</p></li><li class="listitem"><p><span class="emphasis"><em>Copy the Patch File:</em></span>
4602 For simplicity, copy the patch file into a directory named <code class="filename">files</code>,
4603 which you can create in the same directory as the recipe.
4604 Placing the patch here guarantees that the OpenEmbedded build system will find
4605 the patch.
4606 Next, add the patch into the
4607 <code class="filename"><a class="link" href="#var-SRC_URI" target="_top">SRC_URI</a></code>
4608 of the recipe.
4609 Here is an example:
4610 </p><pre class="literallayout">
4611 SRC_URI += "file://my_changes.patch"
4612 </pre></li><li class="listitem"><p><span class="emphasis"><em>Increment the Package Revision Number:</em></span>
4613 Finally, don't forget to 'bump' the
4614 <code class="filename"><a class="link" href="#var-PR" target="_top">PR</a></code>
4615 value in the same recipe since the resulting packages have changed.</p></li></ol></div><p>
4616 </p></div><div class="section" title="5.3.3. Using a Git Workflow"><div class="titlepage"><div><div><h3 class="title"><a id="using-a-git-workflow"></a>5.3.3. Using a Git Workflow</h3></div></div></div><p>
4617 Git is an even more powerful tool that allows you to capture source code changes without having
4618 a clean source tree.
4619 This section outlines the typical workflow you can use to modify temporary source code,
4620 test changes, and then preserve the changes in the form of a patch all using Git.
4621 For general information on Git as it is used in the Yocto Project, see the
4622 "<a class="link" href="#git" title="3.6. Git">Git</a>" section.
4623 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
4624 This workflow uses Git only for its ability to manage local changes to the source code
4625 and produce patches independent of any version control system used with the Yocto Project.
4626 </div><p>
4627 Follow these general steps:
4628 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Find the Source Code:</em></span>
4629 The temporary source code used by the OpenEmbedded build system is kept in the
4630 build directory.
4631 See the
4632 "<a class="link" href="#finding-the-temporary-source-code" title="5.3.1. Finding the Temporary Source Code">Finding the Temporary Source Code</a>"
4633 section to learn how to locate the directory that has the temporary source code for a
4634 particular package.</p></li><li class="listitem"><p><span class="emphasis"><em>Change Your Working Directory:</em></span>
4635 You need to be in the directory that has the temporary source code.
4636 That directory is defined by the
4637 <a class="link" href="#var-S" target="_top">S</a>
4638 variable.</p></li><li class="listitem"><p><span class="emphasis"><em>Initialize a Git Repository:</em></span>
4639 Use the <code class="filename">git init</code> command to initialize a new local repository
4640 that is based on the work directory:
4641 </p><pre class="literallayout">
4642 $ git init
4643 </pre></li><li class="listitem"><p><span class="emphasis"><em>Stage all the files:</em></span>
4644 Use the <code class="filename">git add *</code> command to stage all the files in the source
4645 code directory so that they can be committed:
4646 </p><pre class="literallayout">
4647 $ git add *
4648 </pre></li><li class="listitem"><p><span class="emphasis"><em>Commit the Source Files:</em></span>
4649 Use the <code class="filename">git commit</code> command to initially commit all the files in
4650 the work directory:
4651 </p><pre class="literallayout">
4652 $ git commit
4653 </pre><p>
4654 At this point, your Git repository is aware of all the source code files.
4655 Any edits you now make to files will be tracked by Git.</p></li><li class="listitem"><p><span class="emphasis"><em>Edit the Files:</em></span>
4656 Make the changes to the temporary source code.</p></li><li class="listitem"><p><span class="emphasis"><em>Test Your Changes:</em></span>
4657 Once you have modified the source code, the easiest way to test your changes
4658 is by calling the <code class="filename">compile</code> task as shown in the following example:
4659 </p><pre class="literallayout">
4660 $ bitbake -c compile -f &lt;name_of_package&gt;
4661 </pre><p>
4662 The <code class="filename">-f</code> or <code class="filename">--force</code>
4663 option forces re-execution of the specified task.
4664 If you find problems with your code, you can just keep editing and
4665 re-testing iteratively until things work as expected.
4666 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>All the modifications you make to the temporary source code
4667 disappear once you <code class="filename">-c clean</code> or
4668 <code class="filename">-c cleanall</code> with BitBake for the package.
4669 Modifications will also disappear if you use the <code class="filename">rm_work</code>
4670 feature as described in the
4671 "<a class="link" href="#building-image" target="_top">Building an Image</a>"
4672 section of the Yocto Project Quick Start.
4673 </div></li><li class="listitem"><p><span class="emphasis"><em>See the List of Files You Changed:</em></span>
4674 Use the <code class="filename">git status</code> command to see what files you have actually edited.
4675 The ability to have Git track the files you have changed is an advantage that this
4676 workflow has over the Quilt workflow.
4677 Here is the Git command to list your changed files:
4678 </p><pre class="literallayout">
4679 $ git status
4680 </pre></li><li class="listitem"><p><span class="emphasis"><em>Stage the Modified Files:</em></span>
4681 Use the <code class="filename">git add</code> command to stage the changed files so they
4682 can be committed as follows:
4683 </p><pre class="literallayout">
4684 $ git add file1.c file2.c file3.c
4685 </pre></li><li class="listitem"><p><span class="emphasis"><em>Commit the Staged Files and View Your Changes:</em></span>
4686 Use the <code class="filename">git commit</code> command to commit the changes to the
4687 local repository.
4688 Once you have committed the files, you can use the <code class="filename">git log</code>
4689 command to see your changes:
4690 </p><pre class="literallayout">
4691 $ git commit
4692 $ git log
4693 </pre></li><li class="listitem"><p><span class="emphasis"><em>Generate the Patch:</em></span>
4694 Once the changes are committed, use the <code class="filename">git format-patch</code>
4695 command to generate a patch file:
4696 </p><pre class="literallayout">
4697 $ git format-patch HEAD~1
4698 </pre><p>
4699 The <code class="filename">HEAD~1</code> part of the command causes Git to generate the
4700 patch file for the most recent commit.</p><p>At this point, the patch file has all your edits made
4701 to the <code class="filename">file1.c</code>, <code class="filename">file2.c</code>, and
4702 <code class="filename">file3.c</code> files.
4703 You can find the resulting patch file in the current directory.
4704 The patch file ends with <code class="filename">.patch</code>.</p></li><li class="listitem"><p><span class="emphasis"><em>Copy the Patch File:</em></span>
4705 For simplicity, copy the patch file into a directory named <code class="filename">files</code>,
4706 which you can create in the same directory as the recipe.
4707 Placing the patch here guarantees that the OpenEmbedded build system will find
4708 the patch.
4709 Next, add the patch into the
4710 <code class="filename"><a class="link" href="#var-SRC_URI" target="_top">SRC_URI</a></code>
4711 of the recipe.
4712 Here is an example:
4713 </p><pre class="literallayout">
4714 SRC_URI += "file://my_changes.patch"
4715 </pre></li><li class="listitem"><p><span class="emphasis"><em>Increment the Package Revision Number:</em></span>
4716 Finally, don't forget to 'bump' the
4717 <code class="filename"><a class="link" href="#var-PR" target="_top">PR</a></code>
4718 value in the same recipe since the resulting packages have changed.</p></li></ol></div><p>
4719 </p></div></div><div class="section" title="5.4. Image Development Using Hob"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="image-development-using-hob"></a>5.4. Image Development Using Hob</h2></div></div></div><p>
4720 The <a class="ulink" href="http://www.yoctoproject.org/projects/hob" target="_top">Hob</a> is a graphical user interface for the
4721 OpenEmbedded build system, which is based on BitBake.
4722 You can use the Hob to build custom operating system images within the Yocto Project build environment.
4723 Hob simply provides a friendly interface over the build system used during system development.
4724 In other words, building images with the Hob lets you take care of common build tasks more easily.
4725 </p><p>
4726 For a better understanding of Hob, see the project page at
4727 <a class="ulink" href="http://www.yoctoproject.org/projects/hob" target="_top">http://www.yoctoproject.org/projects/hob</a> on the Yocto Project website.
4728 The page has a short introductory training video on Hob.
4729 The following lists some features of Hob:
4730 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>You can setup and run Hob using these commands:
4731 </p><pre class="literallayout">
4732 $ source oe-init-build-env
4733 $ hob
4734 </pre></li><li class="listitem"><p>You can set the
4735 <a class="link" href="#var-MACHINE" target="_top"><code class="filename">MACHINE</code></a>
4736 for which you are building the image.</p></li><li class="listitem"><p>You can modify various policy settings such as the package format used to build with,
4737 the parrallelism BitBake uses, whether or not to build an external toolchain, and which host
4738 to build against.</p></li><li class="listitem"><p>You can manage
4739 <a class="link" href="#understanding-and-creating-layers" title="4.1. Understanding and Creating Layers">layers</a>.</p></li><li class="listitem"><p>You can select a base image and then add extra packages for your custom build.
4740 </p></li><li class="listitem"><p>You can launch and monitor the build from within Hob.</p></li></ul></div><p>
4741 </p></div><div class="section" title="5.5. Using a Development Shell"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="platdev-appdev-devshell"></a>5.5. Using a Development Shell</h2></div></div></div><p>
4742 When debugging certain commands or even when just editing packages,
4743 <code class="filename">devshell</code> can be a useful tool.
4744 When you invoke <code class="filename">devshell</code>, source files are
4745 extracted into your working directory and patches are applied.
4746 Then, a new terminal is opened and you are placed in the working directory.
4747 In the new terminal, all the OpenEmbedded build-related environment variables are
4748 still defined so you can use commands such as <code class="filename">configure</code> and
4749 <code class="filename">make</code>.
4750 The commands execute just as if the OpenEmbedded build system were executing them.
4751 Consequently, working this way can be helpful when debugging a build or preparing
4752 software to be used with the OpenEmbedded build system.
4753 </p><p>
4754 Following is an example that uses <code class="filename">devshell</code> on a target named
4755 <code class="filename">matchbox-desktop</code>:
4756 </p><pre class="literallayout">
4757 $ bitbake matchbox-desktop -c devshell
4758 </pre><p>
4759 </p><p>
4760 This command opens a terminal with a shell prompt within the OpenEmbedded build environment.
4761 The default shell is xterm.
4762 The following occurs:
4763 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The <code class="filename">PATH</code> variable includes the
4764 cross-toolchain.</p></li><li class="listitem"><p>The <code class="filename">pkgconfig</code> variables find the correct
4765 <code class="filename">.pc</code> files.</p></li><li class="listitem"><p>The <code class="filename">configure</code> command finds the
4766 Yocto Project site files as well as any other necessary files.</p></li></ul></div><p>
4767 Within this environment, you can run <code class="filename">configure</code>
4768 or <code class="filename">compile</code> commands as if they were being run by
4769 the OpenEmbedded build system itself.
4770 As noted earlier, the working directory also automatically changes to the
4771 source directory (<a class="link" href="#var-S" target="_top"><code class="filename">S</code></a>).
4772 </p><p>
4773 When you are finished, you just exit the shell or close the terminal window.
4774 </p><p>
4775 Because an external shell is launched rather than opening directly into the
4776 original terminal window, it allows easier interaction with BitBake's multiple
4777 threads as well as accomodates a future client/server split.
4778 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
4779 It is worth remembering that when using <code class="filename">devshell</code>
4780 you need to use the full compiler name such as <code class="filename">arm-poky-linux-gnueabi-gcc</code>
4781 instead of just using <code class="filename">gcc</code>.
4782 The same applies to other applications such as <code class="filename">binutils</code>,
4783 <code class="filename">libtool</code> and so forth.
4784 BitBake sets up environment variables such as <code class="filename">CC</code>
4785 to assist applications, such as <code class="filename">make</code> to find the correct tools.
4786 </p><p>
4787 It is also worth noting that <code class="filename">devshell</code> still works over
4788 X11 forwarding and similar situations
4789 </p></div></div></div>
4790
4791 <div class="appendix" title="Appendix A. BSP Development Example"><div class="titlepage"><div><div><h2 class="title"><a id="dev-manual-bsp-appendix"></a>Appendix A. BSP Development Example</h2></div></div></div><p>
4792 This appendix provides a complete BSP development example.
4793 The example assumes the following:
4794 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>No previous preparation or use of the Yocto Project.</p></li><li class="listitem"><p>Use of the Crown Bay Board Support Package (BSP) as a "base" BSP from
4795 which to work.
4796 The example begins with the Crown Bay BSP as the starting point
4797 but ends by building a new 'atom-pc' BSP, which was based on the Crown Bay BSP.
4798 </p></li><li class="listitem"><p>Shell commands assume <code class="filename">bash</code></p></li><li class="listitem"><p>Example was developed on an Intel-based Core i7 platform running
4799 Ubuntu 10.04 LTS released in April of 2010.</p></li></ul></div><p>
4800</p><div class="section" title="A.1. Getting Local Source Files and BSP Files"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="getting-local-yocto-project-files-and-bsp-files"></a>A.1. Getting Local Source Files and BSP Files</h2></div></div></div><p>
4801 You need to have the <a class="link" href="#source-directory">source directory</a>
4802 available on your host system.
4803 You can set up this directory through tarball extraction or by cloning the
4804 <code class="filename">poky</code> Git repository.
4805 The following paragraphs describe both methods.
4806 For additional information, see the bulleted item
4807 "<a class="link" href="#local-yp-release">Yocto Project Release</a>".
4808 </p><p>
4809 As mentioned, one way to set up the source directory is to use Git to clone the
4810 <code class="filename">poky</code> repository.
4811 These commands create a local copy of the Git repository.
4812 By default, the top-level directory of the repository is named <code class="filename">poky</code>:
4813 </p><pre class="literallayout">
4814 $ git clone git://git.yoctoproject.org/poky
4815 $ cd poky
4816 </pre><p>
4817 Alternatively, you can start with the downloaded Poky "1.2+snapshot" tarball.
4818 These commands unpack the tarball into a source directory structure.
4819 By default, the top-level directory of the source directory is named
4820 <code class="filename">poky-1.2+snapshot-8.0</code>:
4821 </p><pre class="literallayout">
4822 $ tar xfj poky-1.2+snapshot-8.0.tar.bz2
4823 $ cd poky-1.2+snapshot-8.0
4824 </pre><p>
4825 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>If you're using the tarball method, you can ignore all the following steps that
4826 ask you to carry out Git operations.
4827 You already have the results of those operations
4828 in the form of the 1.2+snapshot release tarballs.
4829 Consequently, there is nothing left to do other than extract those tarballs into the
4830 proper locations.</p><p>Once you expand the released tarball, you have a snapshot of the Git repository
4831 that represents a specific release.
4832 Fundamentally, this is different than having a local copy of the Poky Git repository.
4833 Given the tarball method, changes you make are building on top of a release.
4834 With the Git repository method you have the ability to track development
4835 and keep changes in revision control.
4836 See the
4837 "<a class="link" href="#repositories-tags-and-branches" title="3.6.1. Repositories, Tags, and Branches">Repositories, Tags, and Branches</a>" section
4838 for more discussion around these differences.</p></div><p>
4839 </p><p>
4840 With the local <code class="filename">poky</code> Git repository set up,
4841 you have all the development branches available to you from which you can work.
4842 Next, you need to be sure that your local repository reflects the exact
4843 release in which you are interested.
4844 From inside the repository you can see the development branches that represent
4845 areas of development that have diverged from the main (master) branch
4846 at some point, such as a branch to track a maintenance release's development.
4847 You can also see the tag names used to mark snapshots of stable releases or
4848 points in the repository.
4849 Use the following commands to list out the branches and the tags in the repository,
4850 respectively.
4851 </p><pre class="literallayout">
4852 $ git branch -a
4853 $ git tag -l
4854 </pre><p>
4855 For this example, we are going to use the Yocto Project 1.3 Release, which is code
4856 named "1.2+snapshot".
4857 To make sure we have a local area (branch in Git terms) on our machine that
4858 reflects the 1.3 release, we can use the following commands:
4859 </p><pre class="literallayout">
4860 $ cd ~/poky
4861 $ git fetch --tags
4862 $ git checkout 1.2+snapshot-8.0 -b 1.2+snapshot
4863 Switched to a new branch '1.2+snapshot'
4864 </pre><p>
4865 The <code class="filename">git fetch --tags</code> is somewhat redundant since you just set
4866 up the repository and should have all the tags.
4867 The <code class="filename">fetch</code> command makes sure all the tags are available in your
4868 local repository.
4869 The Git <code class="filename">checkout</code> command with the <code class="filename">-b</code> option
4870 creates a local branch for you named <code class="filename">1.2+snapshot</code>.
4871 Your local branch begins in the same state as the Yocto Project 1.3 released tarball
4872 marked with the <code class="filename">1.2+snapshot-8.0</code> tag in the source repositories.
4873 </p></div><div class="section" title="A.2. Choosing a Base BSP"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="choosing-a-base-bsp-app"></a>A.2. Choosing a Base BSP</h2></div></div></div><p>
4874 For this example, the base BSP is the <span class="trademark">Intel</span>®
4875 <span class="trademark">Atom</span>™ Processor E660 with Intel Platform
4876 Controller Hub EG20T Development Kit, which is otherwise referred to as "Crown Bay."
4877 The BSP layer is <code class="filename">meta-crownbay</code>.
4878 The base BSP is simply the BSP
4879 we will be using as a starting point, so don't worry if you don't actually have Crown Bay
4880 hardware.
4881 The remainder of the example transforms the base BSP into a BSP that should be
4882 able to boot on generic atom-pc (netbook) hardware.
4883 </p><p>
4884 For information on how to choose a base BSP, see
4885 "<a class="link" href="#developing-a-board-support-package-bsp" title="5.1.1. Developing a Board Support Package (BSP)">Developing a Board Support Package (BSP)</a>".
4886 </p></div><div class="section" title="A.3. Getting Your Base BSP"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="getting-your-base-bsp-app"></a>A.3. Getting Your Base BSP</h2></div></div></div><p>
4887 You need to have the base BSP layer on your development system.
4888 Similar to the local <a class="link" href="#source-directory">source directory</a>,
4889 you can get the BSP
4890 layer in a couple of different ways:
4891 download the BSP tarball and extract it, or set up a local Git repository that
4892 has the BSP layers.
4893 You should use the same method that you used to set up the source directory earlier.
4894 See "<a class="link" href="#getting-setup" title="2.2. Getting Set Up">Getting Setup</a>" for information on how to get
4895 the BSP files.
4896 </p><p>
4897 This example assumes the BSP layer will be located within a directory named
4898 <code class="filename">meta-intel</code> contained within the <code class="filename">poky</code>
4899 parent directory.
4900 The following steps will automatically create the
4901 <code class="filename">meta-intel</code> directory and the contained
4902 <code class="filename">meta-crownbay</code> starting point in both the Git and the tarball cases.
4903 </p><p>
4904 If you're using the Git method, you could do the following to create
4905 the starting layout after you have made sure you are in the <code class="filename">poky</code>
4906 directory created in the previous steps:
4907 </p><pre class="literallayout">
4908 $ git clone git://git.yoctoproject.org/meta-intel.git
4909 $ cd meta-intel
4910 </pre><p>
4911 Alternatively, you can start with the downloaded Crown Bay tarball.
4912 You can download the 1.2+snapshot version of the BSP tarball from the
4913 <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">Download</a> page of the
4914 Yocto Project website.
4915 Here is the specific link for the tarball needed for this example:
4916 <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/crownbay-noemgd/crownbay-noemgd-1.2+snapshot-8.0.tar.bz2" target="_top">http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines/crownbay-noemgd/crownbay-noemgd-1.2+snapshot-8.0.tar.bz2</a>.
4917 Again, be sure that you are already in the <code class="filename">poky</code> directory
4918 as described previously before installing the tarball:
4919 </p><pre class="literallayout">
4920 $ tar xfj crownbay-noemgd-1.2+snapshot-8.0.tar.bz2
4921 $ cd meta-intel
4922 </pre><p>
4923 </p><p>
4924 The <code class="filename">meta-intel</code> directory contains all the metadata
4925 that supports BSP creation.
4926 If you're using the Git method, the following
4927 step will switch to the 1.2+snapshot metadata.
4928 If you're using the tarball method, you already have the correct metadata and can
4929 skip to the next step.
4930 Because <code class="filename">meta-intel</code> is its own Git repository, you will want
4931 to be sure you are in the appropriate branch for your work.
4932 For this example we are going to use the <code class="filename">1.2+snapshot</code> branch.
4933 </p><pre class="literallayout">
4934 $ git checkout -b 1.2+snapshot origin/1.2+snapshot
4935 Branch 1.2+snapshot set up to track remote branch 1.2+snapshot from origin.
4936 Switched to a new branch '1.2+snapshot'
4937 </pre><p>
4938 </p></div><div class="section" title="A.4. Making a Copy of the Base BSP to Create Your New BSP Layer"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="making-a-copy-of-the-base bsp-to-create-your-new-bsp-layer-app"></a>A.4. Making a Copy of the Base BSP to Create Your New BSP Layer</h2></div></div></div><p>
4939 Now that you have set up the source directory and included the base BSP files, you need to
4940 create a new layer for your BSP.
4941 To create your BSP layer, you simply copy the <code class="filename">meta-crownbay</code>
4942 layer to a new layer.
4943 </p><p>
4944 For this example, the new layer will be named <code class="filename">meta-mymachine</code>.
4945 The name should follow the BSP layer naming convention, which is
4946 <code class="filename">meta-&lt;name&gt;</code>.
4947 The following assumes your working directory is <code class="filename">meta-intel</code>
4948 inside your source directory.
4949 To start your new layer, just copy the new layer alongside the existing
4950 BSP layers in the <code class="filename">meta-intel</code> directory:
4951 </p><pre class="literallayout">
4952 $ cp -a meta-crownbay/ meta-mymachine
4953 </pre><p>
4954 </p></div><div class="section" title="A.5. Making Changes to Your BSP"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="making-changes-to-your-bsp-app"></a>A.5. Making Changes to Your BSP</h2></div></div></div><p>
4955 Right now you have two identical BSP layers with different names:
4956 <code class="filename">meta-crownbay</code> and <code class="filename">meta-mymachine</code>.
4957 You need to change your configurations so that they work for your new BSP and
4958 your particular hardware.
4959 The following sections look at each of these areas of the BSP.
4960 </p><div class="section" title="A.5.1. Changing the BSP Configuration"><div class="titlepage"><div><div><h3 class="title"><a id="changing-the-bsp-configuration"></a>A.5.1. Changing the BSP Configuration</h3></div></div></div><p>
4961 We will look first at the configurations, which are all done in the layer’s
4962 <code class="filename">conf</code> directory.
4963 </p><p>
4964 First, since in this example the new BSP will not support EMGD, we will get rid of the
4965 <code class="filename">crownbay.conf</code> file and then rename the
4966 <code class="filename">crownbay-noemgd.conf</code> file to <code class="filename">mymachine.conf</code>.
4967 Much of what we do in the configuration directory is designed to help the OpenEmbedded
4968 build system work with the new layer and to be able to find and use the right software.
4969 The following two commands result in a single machine configuration file named
4970 <code class="filename">mymachine.conf</code>.
4971 </p><pre class="literallayout">
4972 $ rm meta-mymachine/conf/machine/crownbay.conf
4973 $ mv meta-mymachine/conf/machine/crownbay-noemgd.conf \
4974 meta-mymachine/conf/machine/mymachine.conf
4975 </pre><p>
4976 </p><p>
4977 Next, we need to make changes to the <code class="filename">mymachine.conf</code> itself.
4978 The only changes we want to make for this example are to the comment lines.
4979 Changing comments, of course, is never strictly necessary, but it's alway good form to make
4980 them reflect reality as much as possible.
4981
4982 Here, simply substitute the Crown Bay name with an appropriate name for the BSP
4983 (<code class="filename">mymachine</code> in this case) and change the description to
4984 something that describes your hardware.
4985 </p><p>
4986 Note that inside the <code class="filename">mymachine.conf</code> is the
4987 <code class="filename">PREFERRED_VERSION_linux-yocto</code> statement.
4988 This statement identifies the kernel that the BSP is going to use.
4989 In this case, the BSP is using <code class="filename">linux-yocto</code>, which is the
4990 current Yocto Project kernel based on the Linux 3.2 release.
4991 </p><p>
4992 The next configuration file in the new BSP layer we need to edit is
4993 <code class="filename">meta-mymachine/conf/layer.conf</code>.
4994 This file identifies build information needed for the new layer.
4995 You can see the
4996 "<a class="link" href="#bsp-filelayout-layer" target="_top">Layer Configuration File</a>" section
4997 in The Board Support Packages (BSP) Development Guide for more information on this configuration file.
4998 Basically, we are changing the existing statements to work with our BSP.
4999 </p><p>
5000 The file contains these statements that reference the Crown Bay BSP:
5001 </p><pre class="literallayout">
5002 BBFILE_COLLECTIONS += "crownbay"
5003 BBFILE_PATTERN_crownbay := "^${LAYERDIR}/"
5004 BBFILE_PRIORITY_crownbay = "6"
5005
5006 LAYERDEPENDS_crownbay = "intel"
5007 </pre><p>
5008 </p><p>
5009 Simply substitute the machine string name <code class="filename">crownbay</code>
5010 with the new machine name <code class="filename">mymachine</code> to get the following:
5011 </p><pre class="literallayout">
5012 BBFILE_COLLECTIONS += "mymachine"
5013 BBFILE_PATTERN_mymachine := "^${LAYERDIR}/"
5014 BBFILE_PRIORITY_mymachine = "6"
5015
5016 LAYERDEPENDS_mymachine = "intel"
5017 </pre><p>
5018 </p></div><div class="section" title="A.5.2. Changing the Recipes in Your BSP"><div class="titlepage"><div><div><h3 class="title"><a id="changing-the-recipes-in-your-bsp"></a>A.5.2. Changing the Recipes in Your BSP</h3></div></div></div><p>
5019 Now we will take a look at the recipes in your new layer.
5020 The standard BSP structure has areas for BSP, graphics, core, and kernel recipes.
5021 When you create a BSP, you use these areas for appropriate recipes and append files.
5022 Recipes take the form of <code class="filename">.bb</code> files, while append files take
5023 the form of <code class="filename">.bbappend</code> files.
5024 If you want to leverage the existing recipes the OpenEmbedded build system uses
5025 but change those recipes, you can use <code class="filename">.bbappend</code> files.
5026 All new recipes and append files for your layer must go in the layer’s
5027 <code class="filename">recipes-bsp</code>, <code class="filename">recipes-kernel</code>,
5028 <code class="filename">recipes-core</code>, and
5029 <code class="filename">recipes-graphics</code> directories.
5030 </p><div class="section" title="A.5.2.1. Changing  recipes-bsp"><div class="titlepage"><div><div><h4 class="title"><a id="changing-recipes-bsp"></a>A.5.2.1. Changing  <code class="filename">recipes-bsp</code></h4></div></div></div><p>
5031 First, let's look at <code class="filename">recipes-bsp</code>.
5032 For this example we are not adding any new BSP recipes.
5033 And, we only need to remove the formfactor we do not want and change the name of
5034 the remaining one that doesn't support EMGD.
5035 These commands take care of the <code class="filename">recipes-bsp</code> recipes:
5036 </p><pre class="literallayout">
5037 $ rm -rf meta-mymachine/recipes-bsp/formfactor/formfactor/crownbay
5038 $ mv meta-mymachine/recipes-bsp/formfactor/formfactor/crownbay-noemgd/ \
5039 meta-mymachine/recipes-bsp/formfactor/formfactor/mymachine
5040 </pre><p>
5041 </p></div><div class="section" title="A.5.2.2. Changing  recipes-graphics"><div class="titlepage"><div><div><h4 class="title"><a id="changing-recipes-graphics"></a>A.5.2.2. Changing  <code class="filename">recipes-graphics</code></h4></div></div></div><p>
5042 Now let's look at <code class="filename">recipes-graphics</code>.
5043 For this example we want to remove anything that supports EMGD and
5044 be sure to rename remaining directories appropriately.
5045 The following commands clean up the <code class="filename">recipes-graphics</code> directory:
5046 </p><pre class="literallayout">
5047 $ rm -rf meta-mymachine/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay
5048 $ mv meta-mymachine/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd \
5049 meta-mymachine/recipes-graphics/xorg-xserver/xserver-xf86-config/mymachine
5050 </pre><p>
5051 </p><p>
5052 At this point the <code class="filename">recipes-graphics</code> directory just has files that
5053 support Video Electronics Standards Association (VESA) graphics modes and not EMGD.
5054 </p></div><div class="section" title="A.5.2.3. Changing  recipes-core"><div class="titlepage"><div><div><h4 class="title"><a id="changing-recipes-core"></a>A.5.2.3. Changing  <code class="filename">recipes-core</code></h4></div></div></div><p>
5055 Now let's look at changes in <code class="filename">recipes-core</code>.
5056 The file <code class="filename">task-core-tools.bbappend</code> in
5057 <code class="filename">recipes-core/tasks</code> appends the similarly named recipe
5058 located in the <a class="link" href="#source-directory">source directory</a> at
5059 <code class="filename">meta/recipes-core/tasks</code>.
5060 The append file in our layer right now is Crown Bay-specific and supports
5061 EMGD and non-EMGD.
5062 Here are the contents of the file:
5063 </p><pre class="literallayout">
5064 RRECOMMENDS_task-core-tools-profile_append_crownbay = " systemtap"
5065 RRECOMMENDS_task-core-tools-profile_append_crownbay-noemgd = " systemtap"
5066 </pre><p>
5067 </p><p>
5068 The <code class="filename">RRECOMMENDS</code> statements list packages that
5069 extend usability.
5070 The first <code class="filename">RRECOMMENDS</code> statement can be removed, while the
5071 second one can be changed to reflect <code class="filename">meta-mymachine</code>:
5072 </p><pre class="literallayout">
5073 RRECOMMENDS_task-core-tools-profile_append_mymachine = " systemtap"
5074 </pre><p>
5075 </p></div><div class="section" title="A.5.2.4. Changing  recipes-kernel"><div class="titlepage"><div><div><h4 class="title"><a id="changing-recipes-kernel"></a>A.5.2.4. Changing  <code class="filename">recipes-kernel</code></h4></div></div></div><p>
5076 Finally, let's look at <code class="filename">recipes-kernel</code> changes.
5077 Recall that the BSP uses the <code class="filename">linux-yocto</code> kernel as determined
5078 earlier in the <code class="filename">mymachine.conf</code>.
5079 The recipe for that kernel is not located in the
5080 BSP layer but rather in the source directory at
5081 <code class="filename">meta/recipes-kernel/linux</code> and is
5082 named <code class="filename">linux-yocto_3.2.bb</code>.
5083 The <code class="filename">SRCREV_machine</code> and <code class="filename">SRCREV_meta</code>
5084 statements point to the exact commits used by the Yocto Project development team
5085 in their source repositories that identify the right kernel for our hardware.
5086 In other words, the <code class="filename">SRCREV</code> values are simply Git commit
5087 IDs that identify which commit on each
5088 of the kernel branches (machine and meta) will be checked out and used to build
5089 the kernel.
5090 </p><p>
5091 However, in the <code class="filename">meta-mymachine</code> layer in
5092 <code class="filename">recipes-kernel/linux</code> resides a <code class="filename">.bbappend</code>
5093 file named <code class="filename">linux-yocto_3.2.bbappend</code> that
5094 appends information to the recipe of the same name in <code class="filename">meta/recipes-kernel/linux</code>.
5095 Thus, the <code class="filename">SRCREV</code> statements in the append file override
5096 the more general statements found in <code class="filename">meta</code>.
5097 </p><p>
5098 The <code class="filename">SRCREV</code> statements in the append file currently identify
5099 the kernel that supports the Crown Bay BSP with and without EMGD support.
5100 Here are the statements:
5101 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>The commit ID strings used in this manual might not match the actual commit
5102 ID strings found in the <code class="filename">linux-yocto_3.2.bbappend</code> file.
5103 For the example, this difference does not matter.</div><p>
5104 </p><pre class="literallayout">
5105 SRCREV_machine_pn-linux-yocto_crownbay ?= \
5106 "211fc7f4d10ec2b82b424286aabbaff9254b7cbd"
5107 SRCREV_meta_pn-linux-yocto_crownbay ?= \
5108 "514847185c78c07f52e02750fbe0a03ca3a31d8f"
5109
5110 SRCREV_machine_pn-linux-yocto_crownbay-noemgd ?= \
5111 "211fc7f4d10ec2b82b424286aabbaff9254b7cbd"
5112 SRCREV_meta_pn-linux-yocto_crownbay-noemgd ?= \
5113 "514847185c78c07f52e02750fbe0a03ca3a31d8f"
5114 </pre><p>
5115 </p><p>
5116 You will notice that there are two pairs of <code class="filename">SRCREV</code> statements.
5117 The top pair identifies the kernel that supports
5118 EMGD, which we don’t care about in this example.
5119 The bottom pair identifies the kernel that we will use:
5120 <code class="filename">linux-yocto</code>.
5121 At this point though, the unique commit strings all are still associated with
5122 Crown Bay and not <code class="filename">meta-mymachine</code>.
5123 </p><p>
5124 To fix this situation in <code class="filename">linux-yocto_3.2.bbappend</code>,
5125 we delete the two <code class="filename">SRCREV</code> statements that support
5126 EMGD (the top pair).
5127 We also change the remaining pair to specify <code class="filename">mymachine</code>
5128 and insert the commit identifiers to identify the kernel in which we
5129 are interested, which will be based on the <code class="filename">atom-pc-standard</code>
5130 kernel.
5131 In this case, because we're working with the 1.2+snapshot branch of everything, we
5132 need to use the <code class="filename">SRCREV</code> values for the atom-pc branch
5133 that are associated with the 1.2+snapshot release.
5134 To find those values, we need to find the <code class="filename">SRCREV</code>
5135 values that 1.2+snapshot uses for the atom-pc branch, which we find in the
5136 <code class="filename">poky/meta-yocto/recipes-kernel/linux/linux-yocto_3.2.bbappend</code>
5137 file.
5138 </p><p>
5139 The machine <code class="filename">SRCREV</code> we want is in the
5140 <code class="filename">SRCREV_machine_atom-pc</code> variable.
5141 The meta <code class="filename">SRCREV</code> isn't specified in this file, so it must be
5142 specified in the base kernel recipe in the
5143 <code class="filename">poky/meta/recipes-kernel/linux/linux-yocto_3.2.bb</code>
5144 file, in the <code class="filename">SRCREV_meta</code> variable found there.
5145 Here are the final <code class="filename">SRCREV</code> statements:
5146 </p><pre class="literallayout">
5147 SRCREV_machine_pn-linux-yocto_mymachine ?= \
5148 "f29531a41df15d74be5ad47d958e4117ca9e489e"
5149 SRCREV_meta_pn-linux-yocto_mymachine ?= \
5150 "b14a08f5c7b469a5077c10942f4e1aec171faa9d"
5151 </pre><p>
5152 </p><p>
5153 In this example, we're using the <code class="filename">SRCREV</code> values we
5154 found already captured in the 1.2+snapshot release because we're creating a BSP based on
5155 1.2+snapshot.
5156 If, instead, we had based our BSP on the master branches, we would want to use
5157 the most recent <code class="filename">SRCREV</code> values taken directly from the kernel repo.
5158 We will not be doing that for this example.
5159 However, if you do base a future BSP on master and
5160 if you are familiar with Git repositories, you probably won’t have trouble locating the
5161 exact commit strings in the Yocto Project source repositories you need to change
5162 the <code class="filename">SRCREV</code> statements.
5163 You can find all the <code class="filename">machine</code> and <code class="filename">meta</code>
5164 branch points (commits) for the <code class="filename">linux-yocto-3.2</code> kernel at
5165 <a class="ulink" href="http://git.yoctoproject.org/cgit/cgit.cgi/linux-yocto-3.2" target="_top">http://git.yoctoproject.org/cgit/cgit.cgi/linux-yocto-3.2</a>.
5166 </p><p>
5167 If you need a little more assistance after going to the link then do the following:
5168 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Expand the list of branches by clicking <code class="filename">[…]</code></p></li><li class="listitem"><p>Click on the <code class="filename">standard/default/common-pc/atom-pc</code>
5169 branch</p></li><li class="listitem"><p>Click on the commit column header to view the top commit</p></li><li class="listitem"><p>Copy the commit string for use in the
5170 <code class="filename">linux-yocto_3.2.bbappend</code> file</p></li></ol></div><p>
5171 </p><p>
5172 For the <code class="filename">SRCREV</code> statement that points to the <code class="filename">meta</code>
5173 branch use the same procedure except expand the <code class="filename">meta</code>
5174 branch in step 2 above.
5175 </p><p>
5176 Also in the <code class="filename">linux-yocto_3.2.bbappend</code> file are
5177 <a class="link" href="#var-COMPATIBLE_MACHINE" target="_top"><code class="filename">COMPATIBLE_MACHINE</code></a>,
5178 <a class="link" href="#var-KMACHINE" target="_top"><code class="filename">KMACHINE</code></a>,
5179 and
5180 <a class="link" href="#var-KBRANCH" target="_top"><code class="filename">KBRANCH</code></a> statements.
5181 Two sets of these exist: one set supports EMGD and one set does not.
5182 Because we are not interested in supporting EMGD those three can be deleted.
5183 The remaining three must be changed so that <code class="filename">mymachine</code> replaces
5184 <code class="filename">crownbay-noemgd</code> and <code class="filename">crownbay</code>.
5185 Because we are using the <code class="filename">atom-pc</code> branch for this new BSP, we can also find
5186 the exact branch we need for the <code class="filename">KMACHINE</code>
5187 and <code class="filename">KBRANCH</code> variables in our new BSP from the value
5188 we find in the
5189 <code class="filename">poky/meta-yocto/recipes-kernel/linux/linux-yocto_3.2.bbappend</code>
5190 file we looked at in a previous step.
5191 In this case, the values we want are in the <code class="filename">KMACHINE_atom-pc</code> variable
5192 and the <code class="filename">KBRANCH_atom-pc</code> variables in that file.
5193 Here is the final <code class="filename">linux-yocto_3.2.bbappend</code> file after all
5194 the edits:
5195 </p><pre class="literallayout">
5196 FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
5197
5198 COMPATIBLE_MACHINE_mymachine = "mymachine"
5199 KMACHINE_mymachine = "atom-pc"
5200 KBRANCH_mymachine = "standard/default/common-pc/atom-pc"
5201
5202 SRCREV_machine_pn-linux-yocto_mymachine ?= \
5203 "f29531a41df15d74be5ad47d958e4117ca9e489e"
5204 SRCREV_meta_pn-linux-yocto_mymachine ?= \
5205 "b14a08f5c7b469a5077c10942f4e1aec171faa9d"
5206 </pre><p>
5207 </p></div></div><div class="section" title="A.5.3. BSP Recipe Change Summary"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-recipe-change-summary"></a>A.5.3. BSP Recipe Change Summary</h3></div></div></div><p>
5208 In summary, the edits to the layer’s recipe files result in removal of any files and
5209 statements that do not support your targeted hardware in addition to the inclusion
5210 of any new recipes you might need.
5211 In this example, it was simply a matter of ridding the new layer
5212 <code class="filename">meta-mymachine</code> of any code that supported the EMGD features
5213 and making sure we were identifying the kernel that supports our example, which
5214 is the <code class="filename">atom-pc-standard</code> kernel.
5215 We did not introduce any new recipes to the layer.
5216 </p><p>
5217 Finally, it is also important to update the layer’s <code class="filename">README</code>
5218 file so that the information in it reflects your BSP.
5219 </p></div></div><div class="section" title="A.6. Preparing for the Build"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="preparing-for-the-build-app"></a>A.6. Preparing for the Build</h2></div></div></div><p>
5220 To get ready to build your image that uses the new layer you need to do the following:
5221 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Get the environment ready for the build by sourcing the environment
5222 script.
5223 The environment script is in the top-level of the source directory.
5224 The script has the string
5225 <code class="filename">init-build-env</code> in the file’s name.
5226 For this example, the following command gets the build environment ready:
5227 </p><pre class="literallayout">
5228 $ source oe-init-build-env yocto-build
5229 </pre><p>
5230 When you source the script, a build directory is created in the current
5231 working directory.
5232 In our example we were in the <code class="filename">poky</code> directory.
5233 Thus, entering the previous command created the <code class="filename">yocto-build</code> directory.
5234 If you do not provide a name for the build directory it defaults to
5235 <code class="filename">build</code>.
5236 The <code class="filename">yocto-build</code> directory contains a
5237 <code class="filename">conf</code> directory that has
5238 two configuration files you will need to check: <code class="filename">bblayers.conf</code>
5239 and <code class="filename">local.conf</code>.</p></li><li class="listitem"><p>Check and edit the resulting <code class="filename">local.conf</code> file.
5240 This file minimally identifies the machine for which to build the image by
5241 configuring the <code class="filename">MACHINE</code> variable.
5242 For this example you must set the variable to mymachine as follows:
5243 </p><pre class="literallayout">
5244 MACHINE ??= “mymachine”
5245 </pre><p>
5246 You should also be sure any other variables in which you are interested are set.
5247 Some variables to consider are <code class="filename">BB_NUMBER_THREADS</code>
5248 and <code class="filename">PARALLEL_MAKE</code>, both of which can greatly reduce your build time
5249 if your development system supports multiple cores.
5250 For development systems that support multiple cores, a good rule of thumb is to set
5251 both the <code class="filename">BB_NUMBER_THREADS</code> and <code class="filename">PARALLEL_MAKE</code>
5252 variables to twice the number of cores your system supports.</p></li><li class="listitem"><p>Update the <code class="filename">bblayers.conf</code> file so that it includes
5253 both the path to your new BSP layer and the path to the
5254 <code class="filename">meta-intel</code> layer.
5255 In this example, you need to include both these paths as part of the
5256 <code class="filename">BBLAYERS</code> variable:
5257 </p><pre class="literallayout">
5258 $HOME/poky/meta-intel
5259 $HOME/poky/meta-intel/meta-mymachine
5260 </pre></li></ol></div><p>
5261 </p><p>
5262 The
5263 <a class="link" href="#ref-variables-glos" target="_top">Variables Glossary</a> chapter in the
5264 Yocto Project Reference Manual has more information on configuration variables.
5265 </p></div><div class="section" title="A.7. Building and Booting the Image"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="building-the-image-app"></a>A.7. Building and Booting the Image</h2></div></div></div><p>
5266 To build the image for our <code class="filename">meta-mymachine</code> BSP enter the following command
5267 from the same shell from which you ran the setup script.
5268 You should run the <code class="filename">bitbake</code> command without any intervening shell commands.
5269 For example, moving your working directory around could cause problems.
5270 Here is the command for this example:
5271 </p><pre class="literallayout">
5272 $ bitbake -k core-image-sato
5273 </pre><p>
5274 </p><p>
5275 This command specifies an image that has Sato support and that can be run from a USB device or
5276 from a CD without having to first install anything.
5277 The build process takes significant time and includes thousands of tasks, which are reported
5278 at the console.
5279 If the build results in any type of error you should check for misspellings in the
5280 files you changed or problems with your host development environment such as missing packages.
5281 </p><p>
5282 Finally, once you have an image, you can try booting it from a device
5283 (e.g. a USB device).
5284 To prepare a bootable USB device, insert a USB flash drive into your build system and
5285 copy the <code class="filename">.hddimg</code> file, located in the
5286 <code class="filename">poky/build/tmp/deploy/images</code>
5287 directory after a successful build to the flash drive.
5288 Assuming the USB flash drive takes device <code class="filename">/dev/sdf</code>,
5289 use <code class="filename">dd</code> to copy the live image to it.
5290 For example:
5291 </p><pre class="literallayout">
5292 # dd if=core-image-sato-mymachine-20111101223904.hddimg of=/dev/sdf
5293 # sync
5294 # eject /dev/sdf
5295 </pre><p>
5296 You should now have a bootable USB flash device.
5297 </p><p>
5298 Insert the device
5299 into a bootable USB socket on the target, and power it on.
5300 The system should boot to the Sato graphical desktop.
5301 <sup>[<a id="id1497755" href="#ftn.id1497755" class="footnote">2</a>]</sup>
5302 </p><p>
5303 For reference, the sato image produced by the previous steps for 1.2+snapshot
5304 should look like the following in terms of size.
5305 If your sato image is much different from this,
5306 you probably made a mistake in one of the above steps:
5307 </p><pre class="literallayout">
5308 260538368 2012-04-27 01:44 core-image-sato-mymachine-20120427025051.hddimg
5309 </pre><p>
5310 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>The previous instructions are also present in the README that was copied
5311 from meta-crownbay, which should also be updated to reflect the specifics of your
5312 new BSP.
5313 That file and the <code class="filename">README.hardware</code> file in the top-level
5314 <code class="filename">poky</code> directory
5315 also provides some suggestions for things to try if booting fails and produces
5316 strange error messages.</div><p>
5317 </p></div><div class="footnotes"><br /><hr width="100" align="left" /><div class="footnote"><p><sup>[<a id="ftn.id1497755" href="#id1497755" class="para">2</a>] </sup>Because
5318 this new image is not in any way tailored to the system you're
5319 booting it on, which is assumed to be some sort of atom-pc (netbook) system for this
5320 example, it might not be completely functional though it should at least boot to a text
5321 prompt.
5322 Specifically, it might fail to boot into graphics without some tweaking.
5323 If this ends up being the case, a possible next step would be to replace the
5324 <code class="filename">mymachine.conf</code>
5325 contents with the contents of <code class="filename">atom-pc.conf</code> and replace
5326 <code class="filename">xorg.conf</code> with <code class="filename">atom-pc xorg.conf</code>
5327 in <code class="filename">meta-yocto</code> and see if it fares any better.
5328 In any case, following the previous steps will give you a buildable image that
5329 will probably boot on most systems.
5330 Getting things working like you want
5331 them to for your hardware will normally require some amount of experimentation with
5332 configuration settings.</p></div></div></div>
5333
5334 <div class="appendix" title="Appendix B. Kernel Modification Example"><div class="titlepage"><div><div><h2 class="title"><a id="dev-manual-kernel-appendix"></a>Appendix B. Kernel Modification Example</h2></div></div></div><p>
5335 Kernel modification involves changing or adding configurations to an existing kernel,
5336 changing or adding recipes to the kernel that are needed to support specific hardware features,
5337 or even altering the source code itself.
5338 This appendix presents simple examples that modify the kernel source code,
5339 change the kernel configuration, and add a kernel source recipe.
5340 </p><div class="section" title="B.1. Modifying the Kernel Source Code"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="modifying-the-kernel-source-code"></a>B.1. Modifying the Kernel Source Code</h2></div></div></div><p>
5341 This example adds some simple QEMU emulator console output at boot time by
5342 adding <code class="filename">printk</code> statements to the kernel's
5343 <code class="filename">calibrate.c</code> source code file.
5344 Booting the modified image causes the added messages to appear on the emulator's
5345 console.
5346 </p><div class="section" title="B.1.1. Understanding the Files You Need"><div class="titlepage"><div><div><h3 class="title"><a id="understanding-the-files-you-need"></a>B.1.1. Understanding the Files You Need</h3></div></div></div><p>
5347 Before you modify the kernel, you need to know what Git repositories and file
5348 structures you need.
5349 Briefly, you need the following:
5350 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>A local
5351 <a class="link" href="#source-directory">source directory</a> for the
5352 poky Git repository</p></li><li class="listitem"><p>Local copies of the
5353 <a class="link" href="#poky-extras-repo"><code class="filename">poky-extras</code></a>
5354 Git repository placed within the source directory.</p></li><li class="listitem"><p>A bare clone of the
5355 <a class="link" href="#local-kernel-files">Yocto Project Kernel</a> upstream Git
5356 repository to which you want to push your modifications.
5357 </p></li><li class="listitem"><p>A copy of that bare clone in which you make your source
5358 modifications</p></li></ul></div><p>
5359 </p><p>
5360 The following figure summarizes these four areas.
5361 Within each rectangular that represents a data structure, a
5362 host development directory pathname appears at the
5363 lower left-hand corner of the box.
5364 These pathnames are the locations used in this example.
5365 The figure also provides key statements and commands used during the kernel
5366 modification process:
5367 </p><p>
5368 </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="630"><tr style="height: 450px"><td align="center"><img src="figures/kernel-example-repos-denzil.png" align="middle" /></td></tr></table><p>
5369 </p><p>
5370 Here is a brief description of the four areas:
5371 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Local Source Directory:</em></span>
5372 This area contains all the metadata that supports building images
5373 using the OpenEmbedded build system.
5374 In this example, the source directory also
5375 contains the build directory, which contains the configuration directory
5376 that lets you control the build.
5377 Also in this example, the source directory contains local copies of the
5378 <code class="filename">poky-extras</code> Git repository.</p><p>See the bulleted item
5379 "<a class="link" href="#local-yp-release">Yocto Project Release</a>"
5380 for information on how to get these files on your local system.</p></li><li class="listitem"><p><span class="emphasis"><em>Local copies of the<code class="filename">poky-extras</code>
5381 Git Repository:</em></span>
5382 This area contains the <code class="filename">meta-kernel-dev</code> layer,
5383 which is where you make changes that append the kernel build recipes.
5384 You edit <code class="filename">.bbappend</code> files to locate your
5385 local kernel source files and to identify the kernel being built.
5386 This Git repository is a gathering place for extensions to the Yocto Project
5387 (or really any) kernel recipes that faciliate the creation and development
5388 of kernel features, BSPs or configurations.</p><p>See the bulleted item
5389 "<a class="link" href="#poky-extras-repo">The
5390 <code class="filename">poky-extras</code> Git Repository</a>"
5391 for information on how to get these files.</p></li><li class="listitem"><p><span class="emphasis"><em>Bare Clone of the Yocto Project kernel:</em></span>
5392 This bare Git repository tracks the upstream Git repository of the Linux
5393 Yocto kernel source code you are changing.
5394 When you modify the kernel you must work through a bare clone.
5395 All source code changes you make to the kernel must be committed and
5396 pushed to the bare clone using Git commands.
5397 As mentioned, the <code class="filename">.bbappend</code> file in the
5398 <code class="filename">poky-extras</code> repository points to the bare clone
5399 so that the build process can locate the locally changed source files.</p><p>See the bulleted item
5400 "<a class="link" href="#local-kernel-files">Yocto Project Kernel</a>"
5401 for information on how to set up the bare clone.
5402 </p></li><li class="listitem"><p><span class="emphasis"><em>Copy of the Yocto Project Kernel Bare Clone:</em></span>
5403 This Git repository contains the actual source files that you modify.
5404 Any changes you make to files in this location need to ultimately be pushed
5405 to the bare clone using the <code class="filename">git push</code> command.</p><p>See the bulleted item
5406 "<a class="link" href="#local-kernel-files">Yocto Project Kernel</a>"
5407 for information on how to set up the bare clone.
5408 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Typically, Git workflows follow a scheme where changes made to a local area
5409 are pulled into a Git repository.
5410 However, because the <code class="filename">git pull</code> command does not work
5411 with bare clones, this workflow pushes changes to the
5412 repository even though you could use other more complicated methods to
5413 get changes into the bare clone.</div><p>
5414 </p></li></ul></div><p>
5415 </p></div><div class="section" title="B.1.2. Setting Up the Local Source Directory"><div class="titlepage"><div><div><h3 class="title"><a id="setting-up-the-local-yocto-project-files-git-repository"></a>B.1.2. Setting Up the Local Source Directory</h3></div></div></div><p>
5416 You can set up the source directory through tarball extraction or by
5417 cloning the <code class="filename">poky</code> Git repository.
5418 This example uses <code class="filename">poky</code> as the root directory of the
5419 local source directory.
5420 See the bulleted item
5421 "<a class="link" href="#local-yp-release">Yocto Project Release</a>"
5422 for information on how to get these files.
5423 </p><p>
5424 Once you have source directory set up,
5425 you have many development branches from which you can work.
5426 From inside the local repository you can see the branch names and the tag names used
5427 in the upstream Git repository by using either of the following commands:
5428 </p><pre class="literallayout">
5429 $ cd poky
5430 $ git branch -a
5431 $ git tag -l
5432 </pre><p>
5433 This example uses the Yocto Project 1.3 Release code named "1.2+snapshot",
5434 which maps to the <code class="filename">1.2+snapshot</code> branch in the repository.
5435 The following commands create and checkout the local <code class="filename">1.2+snapshot</code>
5436 branch:
5437 </p><pre class="literallayout">
5438 $ git checkout -b 1.2+snapshot origin/1.2+snapshot
5439 Branch 1.2+snapshot set up to track remote branch 1.2+snapshot from origin.
5440 Switched to a new branch '1.2+snapshot'
5441 </pre><p>
5442 </p></div><div class="section" title="B.1.3. Setting Up the Local poky-extras Git Repository"><div class="titlepage"><div><div><h3 class="title"><a id="setting-up-the-poky-extras-git-repository"></a>B.1.3. Setting Up the Local poky-extras Git Repository</h3></div></div></div><p>
5443 This example creates a local copy of the <code class="filename">poky-extras</code> Git
5444 repository inside the <code class="filename">poky</code> source directory.
5445 See the bulleted item "<a class="link" href="#poky-extras-repo">The
5446 <code class="filename">poky-extras</code> Git Repository</a>"
5447 for information on how to set up a local copy of the
5448 <code class="filename">poky-extras</code> repository.
5449 </p><p>
5450 Because this example uses the Yocto Project 1.3 Release code
5451 named "1.2+snapshot", which maps to the <code class="filename">1.2+snapshot</code>
5452 branch in the repository, you need to be sure you are using that
5453 branch for <code class="filename">poky-extra</code>.
5454 The following commands create and checkout the local
5455 branch you are using for the <code class="filename">1.2+snapshot</code>
5456 branch:
5457 </p><pre class="literallayout">
5458 $ git checkout -b 1.2+snapshot origin/1.2+snapshot
5459 Branch 1.2+snapshot set up to track remote branch 1.2+snapshot from origin.
5460 Switched to a new branch '1.2+snapshot'
5461 </pre><p>
5462 </p></div><div class="section" title="B.1.4. Setting Up the Bare Clone and its Copy"><div class="titlepage"><div><div><h3 class="title"><a id="setting-up-the-bare-clone-and-its-copy"></a>B.1.4. Setting Up the Bare Clone and its Copy</h3></div></div></div><p>
5463 This example modifies the <code class="filename">linux-yocto-3.2</code> kernel.
5464 Thus, you need to create a bare clone of that kernel and then make a copy of the
5465 bare clone.
5466 See the bulleted item
5467 "<a class="link" href="#local-kernel-files">Yocto Project Kernel</a>"
5468 for information on how to do that.
5469 </p><p>
5470 The bare clone exists for the kernel build tools and simply as the receiving end
5471 of <code class="filename">git push</code>
5472 commands after you make edits and commits inside the copy of the clone.
5473 The copy (<code class="filename">my-linux-yocto-3.2-work</code> in this example) has to have
5474 a local branch created and checked out for your work.
5475 This example uses <code class="filename">common-pc-base</code> as the local branch.
5476 The following commands create and checkout the branch:
5477 </p><pre class="literallayout">
5478 $ cd ~/my-linux-yocto-3.2-work
5479 $ git checkout -b common-pc-base origin/standard/default/common-pc/base
5480 Checking out files: 100% (532/532), done.
5481 Branch common-pc-base set up to track remote branch
5482 standard/default/common-pc/base from origin.
5483 Switched to a new branch 'common-pc-base'
5484 </pre><p>
5485 </p></div><div class="section" title="B.1.5. Building and Booting the Default QEMU Kernel Image"><div class="titlepage"><div><div><h3 class="title"><a id="building-and-booting-the-default-qemu-kernel-image"></a>B.1.5. Building and Booting the Default QEMU Kernel Image</h3></div></div></div><p>
5486 Before we make changes to the kernel source files, this example first builds the
5487 default image and then boots it inside the QEMU emulator.
5488 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
5489 Because a full build can take hours, you should check two variables in the
5490 <code class="filename">build</code> directory that is created after you source the
5491 <code class="filename">oe-init-build-env</code> script.
5492 You can find these variables
5493 <code class="filename">BB_NUMBER_THREADS</code> and <code class="filename">PARALLEL_MAKE</code>
5494 in the <code class="filename">build/conf</code> directory in the
5495 <code class="filename">local.conf</code> configuration file.
5496 By default, these variables are commented out.
5497 If your host development system supports multi-core and multi-thread capabilities,
5498 you can uncomment these statements and set the variables to significantly shorten
5499 the full build time.
5500 As a guideline, set both <code class="filename">BB_NUMBER_THREADS</code> and
5501 <code class="filename">PARALLEL_MAKE</code> to twice the number
5502 of cores your machine supports.
5503 </div><p>
5504 The following two commands <code class="filename">source</code> the build environment setup script
5505 and build the default <code class="filename">qemux86</code> image.
5506 If necessary, the script creates the build directory:
5507 </p><pre class="literallayout">
5508 $ cd ~/poky
5509 $ source oe-init-build-env
5510
5511 ### Shell environment set up for builds. ###
5512
5513 You can now run 'bitbake &lt;target&gt;'
5514
5515 Common targets are:
5516 core-image-minimal
5517 core-image-sato
5518 meta-toolchain
5519 meta-toolchain-sdk
5520 adt-installer
5521 meta-ide-support
5522
5523 You can also run generated qemu images with a command like 'runqemu qemux86'
5524 </pre><p>
5525 </p><p>
5526 The following <code class="filename">bitbake</code> command starts the build:
5527 </p><pre class="literallayout">
5528 $ bitbake -k core-image-minimal
5529 </pre><p>
5530 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Be sure to check the settings in the <code class="filename">local.conf</code>
5531 before starting the build.</div><p>
5532 </p><p>
5533 After the build completes, you can start the QEMU emulator using the resulting image
5534 <code class="filename">qemux86</code> as follows:
5535 </p><pre class="literallayout">
5536 $ runqemu qemux86
5537 </pre><p>
5538 </p><p>
5539 As the image boots in the emulator, console message and status output appears
5540 across the terminal window.
5541 Because the output scrolls by quickly, it is difficult to read.
5542 To examine the output, you log into the system using the
5543 login <code class="filename">root</code> with no password.
5544 Once you are logged in, issue the following command to scroll through the
5545 console output:
5546 </p><pre class="literallayout">
5547 # dmesg | less
5548 </pre><p>
5549 </p><p>
5550 Take note of the output as you will want to look for your inserted print command output
5551 later in the example.
5552 </p></div><div class="section" title="B.1.6. Changing the Source Code and Pushing it to the Bare Clone"><div class="titlepage"><div><div><h3 class="title"><a id="changing-the-source-code-and-pushing-it-to-the-bare-clone"></a>B.1.6. Changing the Source Code and Pushing it to the Bare Clone</h3></div></div></div><p>
5553 The file you change in this example is named <code class="filename">calibrate.c</code>
5554 and is located in the <code class="filename">my-linux-yocto-3.2-work</code> Git repository
5555 (the copy of the bare clone) in <code class="filename">init</code>.
5556 This example simply inserts several <code class="filename">printk</code> statements
5557 at the beginning of the <code class="filename">calibrate_delay</code> function.
5558 </p><p>
5559 Here is the unaltered code at the start of this function:
5560 </p><pre class="literallayout">
5561 void __cpuinit calibrate_delay(void)
5562 {
5563 unsigned long lpj;
5564 static bool printed;
5565 int this_cpu = smp_processor_id();
5566
5567 if (per_cpu(cpu_loops_per_jiffy, this_cpu)) {
5568 .
5569 .
5570 .
5571 </pre><p>
5572 </p><p>
5573 Here is the altered code showing five new <code class="filename">printk</code> statements
5574 near the top of the function:
5575 </p><pre class="literallayout">
5576 void __cpuinit calibrate_delay(void)
5577 {
5578 unsigned long lpj;
5579 static bool printed;
5580 int this_cpu = smp_processor_id();
5581
5582 printk("*************************************\n");
5583 printk("* *\n");
5584 printk("* HELLO YOCTO KERNEL *\n");
5585 printk("* *\n");
5586 printk("*************************************\n");
5587
5588 if (per_cpu(cpu_loops_per_jiffy, this_cpu)) {
5589 .
5590 .
5591 .
5592 </pre><p>
5593 </p><p>
5594 After making and saving your changes, you need to stage them for the push.
5595 The following Git commands are one method of staging and committing your changes:
5596 </p><pre class="literallayout">
5597 $ git add calibrate.c
5598 $ git commit --signoff
5599 </pre><p>
5600 </p><p>
5601 Once the source code has been modified, you need to use Git to push the changes to
5602 the bare clone.
5603 If you do not push the changes, then the OpenEmbedded build system will not pick
5604 up the changed source files.
5605 </p><p>
5606 The following command pushes the changes to the bare clone:
5607 </p><pre class="literallayout">
5608 $ git push origin common-pc-base:standard/default/common-pc/base
5609 </pre><p>
5610 </p></div><div class="section" title="B.1.7. Changing Build Parameters for Your Build"><div class="titlepage"><div><div><h3 class="title"><a id="changing-build-parameters-for-your-build"></a>B.1.7. Changing Build Parameters for Your Build</h3></div></div></div><p>
5611 At this point, the source has been changed and pushed.
5612 The example now defines some variables used by the OpenEmbedded build system
5613 to locate your kernel source.
5614 You essentially need to identify where to find the kernel recipe and the changed source code.
5615 You also need to be sure some basic configurations are in place that identify the
5616 type of machine you are building and to help speed up the build should your host support
5617 multiple-core and thread capabilities.
5618 </p><p>
5619 Do the following to make sure the build parameters are set up for the example.
5620 Once you set up these build parameters, they do not have to change unless you
5621 change the target architecture of the machine you are building or you move
5622 the bare clone, copy of the clone, or the <code class="filename">poky-extras</code> repository:
5623 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Build for the Correct Target Architecture:</em></span> The
5624 <code class="filename">local.conf</code> file in the build directory defines the build's
5625 target architecture.
5626 By default, <code class="filename">MACHINE</code> is set to
5627 <code class="filename">qemux86</code>, which specifies a 32-bit
5628 <span class="trademark">Intel</span>® Architecture
5629 target machine suitable for the QEMU emulator.
5630 In this example, <code class="filename">MACHINE</code> is correctly configured.
5631 </p></li><li class="listitem"><p><span class="emphasis"><em>Optimize Build Time:</em></span> Also in the
5632 <code class="filename">local.conf</code> file are two variables that can speed your
5633 build time if your host supports multi-core and multi-thread capabilities:
5634 <code class="filename">BB_NUMBER_THREADS</code> and <code class="filename">PARALLEL_MAKE</code>.
5635 If the host system has multiple cores then you can optimize build time
5636 by setting both these variables to twice the number of
5637 cores.</p></li><li class="listitem"><p><span class="emphasis"><em>Identify Your <code class="filename">meta-kernel-dev</code>
5638 Layer:</em></span> The <code class="filename">BBLAYERS</code> variable in the
5639 <code class="filename">bblayers.conf</code> file found in the
5640 <code class="filename">poky/build/conf</code> directory needs to have the path to your local
5641 <code class="filename">meta-kernel-dev</code> layer.
5642 By default, the <code class="filename">BBLAYERS</code> variable contains paths to
5643 <code class="filename">meta</code> and <code class="filename">meta-yocto</code> in the
5644 <code class="filename">poky</code> Git repository.
5645 Add the path to your <code class="filename">meta-kernel-dev</code> location.
5646 Be sure to substitute your user information in the statement.
5647 Here is an example:
5648 </p><pre class="literallayout">
5649 BBLAYERS = " \
5650 /home/scottrif/poky/meta \
5651 /home/scottrif/poky/meta-yocto \
5652 /home/scottrif/poky/poky-extras/meta-kernel-dev \
5653 "
5654 </pre></li><li class="listitem"><p><span class="emphasis"><em>Identify Your Source Files:</em></span> In the
5655 <code class="filename">linux-yocto_3.2.bbappend</code> file located in the
5656 <code class="filename">poky-extras/meta-kernel-dev/recipes-kernel/linux</code>
5657 directory, you need to identify the location of the
5658 local source code, which in this example is the bare clone named
5659 <code class="filename">linux-yocto-3.2.git</code>.
5660 To do this, set the <code class="filename">KSRC_linux_yocto</code> variable to point to your
5661 local <code class="filename">linux-yocto-3.2.git</code> Git repository by adding the
5662 following statement.
5663 Be sure to substitute your user information in the statement:
5664 </p><pre class="literallayout">
5665 KSRC_linux_yocto_3_2 ?= "/home/scottrif/linux-yocto-3.2.git"
5666 </pre></li></ul></div><p>
5667 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Before attempting to build the modified kernel, there is one more set of changes you
5668 need to make in the <code class="filename">meta-kernel-dev</code> layer.
5669 Because all the kernel <code class="filename">.bbappend</code> files are parsed during the
5670 build process regardless of whether you are using them or not, you should either
5671 comment out the <code class="filename">COMPATIBLE_MACHINE</code> statements in all
5672 unused <code class="filename">.bbappend</code> files, or simply remove (or rename) all the files
5673 except the one your are using for the build
5674 (i.e. <code class="filename">linux-yocto_3.2.bbappend</code> in this example).</p><p>If you do not make one of these two adjustments, your machine will be compatible
5675 with all the kernel recipes in the <code class="filename">meta-kernel-dev</code> layer.
5676 When your machine is comapatible with all the kernel recipes, the build attempts
5677 to build all kernels in the layer.
5678 You could end up with build errors blocking your work.</p></div></div><div class="section" title="B.1.8. Building and Booting the Modified QEMU Kernel Image"><div class="titlepage"><div><div><h3 class="title"><a id="building-and-booting-the-modified-qemu-kernel-image"></a>B.1.8. Building and Booting the Modified QEMU Kernel Image</h3></div></div></div><p>
5679 Next, you need to build the modified image.
5680 Do the following:
5681 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Your environment should be set up since you previously sourced
5682 the <code class="filename">oe-init-build-env</code> script.
5683 If it isn't, source the script again from <code class="filename">poky</code>.
5684 </p><pre class="literallayout">
5685 $ cd ~/poky
5686 $ source oe-init-build-env
5687 </pre><p>
5688 </p></li><li class="listitem"><p>Be sure old images are cleaned out by running the
5689 <code class="filename">cleanall</code> BitBake task as follows from your build directory:
5690 </p><pre class="literallayout">
5691 $ bitbake -c cleanall linux-yocto
5692 </pre><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Never remove any files by hand from the <code class="filename">tmp/deploy</code>
5693 directory insided the build directory.
5694 Always use the BitBake <code class="filename">cleanall</code> task to clear
5695 out previous builds.</div></li><li class="listitem"><p>Next, build the kernel image using this command:
5696 </p><pre class="literallayout">
5697 $ bitbake -k core-image-minimal
5698 </pre></li><li class="listitem"><p>Finally, boot the modified image in the QEMU emulator
5699 using this command:
5700 </p><pre class="literallayout">
5701 $ runqemu qemux86
5702 </pre></li></ol></div><p>
5703 </p><p>
5704 Log into the machine using <code class="filename">root</code> with no password and then
5705 use the following shell command to scroll through the console's boot output.
5706 </p><pre class="literallayout">
5707 # dmesg | less
5708 </pre><p>
5709 </p><p>
5710 You should see the results of your <code class="filename">printk</code> statements
5711 as part of the output.
5712 </p></div></div><div class="section" title="B.2. Changing the Kernel Configuration"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="changing-the-kernel-configuration"></a>B.2. Changing the Kernel Configuration</h2></div></div></div><p>
5713 This example changes the default behavior, which is "on", of the Symmetric
5714 Multi-processing Support (<code class="filename">CONFIG_SMP</code>) to "off".
5715 It is a simple example that demonstrates how to reconfigure the kernel.
5716 </p><div class="section" title="B.2.1. Getting Set Up to Run this Example"><div class="titlepage"><div><div><h3 class="title"><a id="getting-set-up-to-run-this-example"></a>B.2.1. Getting Set Up to Run this Example</h3></div></div></div><p>
5717 If you took the time to work through the example that modifies the kernel source code
5718 in "<a class="link" href="#modifying-the-kernel-source-code" title="B.1. Modifying the Kernel Source Code">Modifying the Kernel Source
5719 Code</a>" you should already have the source directory set up on your
5720 host machine.
5721 If this is the case, go to the next section, which is titled
5722 "<a class="link" href="#examining-the-default-config-smp-behavior" title="B.2.2. Examining the Default  CONFIG_SMP Behavior">Examining the Default
5723 <code class="filename">CONFIG_SMP</code> Behavior</a>", and continue with the
5724 example.
5725 </p><p>
5726 If you don't have the source directory established on your system,
5727 you can get them through tarball extraction or by
5728 cloning the <code class="filename">poky</code> Git repository.
5729 This example uses <code class="filename">poky</code> as the root directory of the
5730 <a class="link" href="#source-directory">source directory</a>.
5731 See the bulleted item
5732 "<a class="link" href="#local-yp-release">Yocto Project Release</a>"
5733 for information on how to get these files.
5734 </p><p>
5735 Once you have the local copy of the repository set up,
5736 you have many development branches from which you can work.
5737 From inside the repository you can see the branch names and the tag names used
5738 in the upstream Git repository using either of the following commands:
5739 </p><pre class="literallayout">
5740 $ cd poky
5741 $ git branch -a
5742 $ git tag -l
5743 </pre><p>
5744 This example uses the Yocto Project 1.3 Release code named "1.2+snapshot",
5745 which maps to the <code class="filename">1.2+snapshot</code> branch in the repository.
5746 The following commands create and checkout the local <code class="filename">1.2+snapshot</code>
5747 branch:
5748 </p><pre class="literallayout">
5749 $ git checkout -b 1.2+snapshot origin/1.2+snapshot
5750 Branch 1.2+snapshot set up to track remote branch 1.2+snapshot from origin.
5751 Switched to a new branch '1.2+snapshot'
5752 </pre><p>
5753 </p><p>
5754 Next, you need to build the default <code class="filename">qemux86</code> image that you
5755 can boot using QEMU.
5756 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
5757 Because a full build can take hours, you should check two variables in the
5758 <code class="filename">build</code> directory that is created after you source the
5759 <code class="filename">oe-init-build-env</code> script.
5760 You can find these variables
5761 <code class="filename">BB_NUMBER_THREADS</code> and <code class="filename">PARALLEL_MAKE</code>
5762 in the <code class="filename">build/conf</code> directory in the
5763 <code class="filename">local.conf</code> configuration file.
5764 By default, these variables are commented out.
5765 If your host development system supports multi-core and multi-thread capabilities,
5766 you can uncomment these statements and set the variables to significantly shorten
5767 the full build time.
5768 As a guideline, set both the <code class="filename">BB_NUMBER_THREADS</code> and the
5769 <code class="filename">PARALLEL_MAKE</code> variables to twice the number
5770 of cores your machine supports.
5771 </div><p>
5772 The following two commands <code class="filename">source</code> the build environment setup script
5773 and build the default <code class="filename">qemux86</code> image.
5774 If necessary, the script creates the build directory:
5775 </p><pre class="literallayout">
5776 $ cd ~/poky
5777 $ source oe-init-build-env
5778
5779 ### Shell environment set up for builds. ###
5780
5781 You can now run 'bitbake &lt;target&gt;'
5782
5783 Common targets are:
5784 core-image-minimal
5785 core-image-sato
5786 meta-toolchain
5787 meta-toolchain-sdk
5788 adt-installer
5789 meta-ide-support
5790
5791 You can also run generated qemu images with a command like 'runqemu qemux86'
5792 </pre><p>
5793 </p><p>
5794 The following <code class="filename">bitbake</code> command starts the build:
5795 </p><pre class="literallayout">
5796 $ bitbake -k core-image-minimal
5797 </pre><p>
5798 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Be sure to check the settings in the <code class="filename">local.conf</code>
5799 before starting the build.</div><p>
5800 </p></div><div class="section" title="B.2.2. Examining the Default  CONFIG_SMP Behavior"><div class="titlepage"><div><div><h3 class="title"><a id="examining-the-default-config-smp-behavior"></a>B.2.2. Examining the Default  <code class="filename">CONFIG_SMP</code> Behavior</h3></div></div></div><p>
5801 By default, <code class="filename">CONFIG_SMP</code> supports multiple processor machines.
5802 To see this default setting from within the QEMU emulator, boot your image using
5803 the emulator as follows:
5804 </p><pre class="literallayout">
5805 $ runqemu qemux86 qemuparams="-smp 4"
5806 </pre><p>
5807 </p><p>
5808 Login to the machine using <code class="filename">root</code> with no password.
5809 After logging in, enter the following command to see how many processors are
5810 being supported in the emulator.
5811 The emulator reports support for the number of processors you specified using
5812 the <code class="filename">-smp</code> option, four in this case:
5813 </p><pre class="literallayout">
5814 # cat /proc/cpuinfo | grep processor
5815 processor : 0
5816 processor : 1
5817 processor : 2
5818 processor : 3
5819 #
5820 </pre><p>
5821 To check the setting for <code class="filename">CONFIG_SMP</code>, you can use the
5822 following command:
5823 </p><pre class="literallayout">
5824 zcat /proc/config.gz | grep CONFIG_SMP
5825 </pre><p>
5826 The console returns the following showing that multi-processor machine support
5827 is set:
5828 </p><pre class="literallayout">
5829 CONFIG_SMP=y
5830 </pre><p>
5831 Logout of the emulator using the <code class="filename">exit</code> command and
5832 then close it down.
5833 </p></div><div class="section" title="B.2.3. Changing the  CONFIG_SMP Configuration Using  menuconfig"><div class="titlepage"><div><div><h3 class="title"><a id="changing-the-config-smp-configuration-using-menuconfig"></a>B.2.3. Changing the  <code class="filename">CONFIG_SMP</code> Configuration Using  <code class="filename">menuconfig</code></h3></div></div></div><p>
5834 The <code class="filename">menuconfig</code> tool provides an interactive method with which
5835 to set kernel configurations.
5836 You need to run <code class="filename">menuconfig</code> inside the Yocto BitBake environment.
5837 Thus, the environment must be set up using the <code class="filename">oe-init-build-env</code>
5838 script found in the build directory.
5839 If you have not sourced this script do so with the following commands:
5840 </p><pre class="literallayout">
5841 $ cd ~/poky
5842 $ source oe-init-build-env
5843 </pre><p>
5844 </p><p>
5845 After setting up the environment to run <code class="filename">menuconfig</code>, you are ready
5846 to use the tool to interactively change the kernel configuration.
5847 In this example, we are basing our changes on the <code class="filename">linux-yocto-3.2</code>
5848 kernel.
5849 The OpenEmbedded build system recognizes this kernel as
5850 <code class="filename">linux-yocto</code>.
5851 Thus, the following commands from the shell in which you previously sourced the
5852 environment initialization script cleans the shared state cache and the
5853 <a class="link" href="#var-WORKDIR" target="_top"><code class="filename">WORKDIR</code></a>
5854 directory and then builds and launches <code class="filename">menuconfig</code>:
5855 </p><pre class="literallayout">
5856 $ bitbake linux-yocto -c menuconfig
5857 </pre><p>
5858 </p><p>
5859 Once <code class="filename">menuconfig</code> launches, navigate through the user interface
5860 to find the <code class="filename">CONFIG_SMP</code> configuration setting.
5861 You can find it at <code class="filename">Processor Type and Features</code>.
5862 The configuration selection is
5863 <code class="filename">Symmetric Multi-processing Support</code>.
5864 After using the arrow keys to highlight this selection, press "n" to turn it off.
5865 Then, exit out and save your selections.
5866 </p><p>
5867 Once you save the selection, the <code class="filename">.config</code> configuration file
5868 is updated.
5869 This is the file that the build system uses to configure the Yocto Project kernel
5870 when it is built.
5871 You can find and examine this file in the build directory.
5872 This example uses the following:
5873 </p><pre class="literallayout">
5874 ~/poky/build/tmp/work/qemux86-poky-linux/linux-yocto-3.2.11+git1+84f...
5875 ...656ed30-r1/linux-qemux86-standard-build
5876 </pre><p>
5877 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
5878 The previous example directory is artificially split and many of the characters
5879 in the actual filename are omitted in order to make it more readable.
5880 Also, depending on the kernel you are using, the exact pathname might differ
5881 slightly.
5882 </div><p>
5883 </p><p>
5884 Within the <code class="filename">.config</code> file, you can see the following setting:
5885 </p><pre class="literallayout">
5886 # CONFIG_SMP is not set
5887 </pre><p>
5888 </p><p>
5889 A good method to isolate changed configurations is to use a combination of the
5890 <code class="filename">menuconfig</code> tool and simple shell commands.
5891 Before changing configurations with <code class="filename">menuconfig</code>, copy the
5892 existing <code class="filename">.config</code> and rename it to something else,
5893 use <code class="filename">menuconfig</code> to make
5894 as many changes an you want and save them, then compare the renamed configuration
5895 file against the newly created file.
5896 You can use the resulting differences as your base to create configuration fragments
5897 to permanently save in your kernel layer.
5898 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
5899 Be sure to make a copy of the <code class="filename">.config</code> and don't just
5900 rename it.
5901 The build system needs an existing <code class="filename">.config</code>
5902 from which to work.
5903 </div><p>
5904 </p></div><div class="section" title="B.2.4. Recompiling the Kernel and Testing the New Configuration"><div class="titlepage"><div><div><h3 class="title"><a id="recompiling-the-kernel-and-testing-the-new-configuration"></a>B.2.4. Recompiling the Kernel and Testing the New Configuration</h3></div></div></div><p>
5905 At this point, you are ready to recompile your kernel image with
5906 the new setting in effect using the BitBake command below:
5907 </p><pre class="literallayout">
5908 $ bitbake linux-yocto
5909 </pre><p>
5910 </p><p>
5911 Now run the QEMU emulator and pass it the same multi-processor option as before:
5912 </p><pre class="literallayout">
5913 $ runqemu qemux86 qemuparams="-smp 4"
5914 </pre><p>
5915 </p><p>
5916 Login to the machine using <code class="filename">root</code> with no password
5917 and test for the number of processors the kernel supports:
5918 </p><pre class="literallayout">
5919 # cat /proc/cpuinfo | grep processor
5920 processor : 0
5921 #
5922 </pre><p>
5923 </p><p>
5924 From the output, you can see that the kernel no longer supports multi-processor systems.
5925 The output indicates support for a single processor. You can verify the
5926 <code class="filename">CONFIG_SMP</code> setting by using this command:
5927 </p><pre class="literallayout">
5928 zcat /proc/config.gz | grep CONFIG_SMP
5929 </pre><p>
5930 The console returns the following output:
5931 </p><pre class="literallayout">
5932 # CONFIG_SMP is not set
5933 </pre><p>
5934 You have successfully reconfigured the kernel.
5935 </p></div></div><div class="section" title="B.3. Adding Kernel Recipes"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="adding-kernel-recipes"></a>B.3. Adding Kernel Recipes</h2></div></div></div><p>
5936 A future release of this manual will present an example that adds kernel recipes, which provide
5937 new functionality to the kernel.
5938 </p><p>
5939 </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="180"><tr style="height: 270px"><td align="center"><img src="figures/wip.png" align="middle" width="180" /></td></tr></table><p>
5940 </p></div></div>
5941
5942</div>
5943
5944<table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="100%"><tr><td align="left"><img src="figures/adt-title.png" align="left" width="100%" /></td></tr></table>
5945
5946 <div xml:lang="en" class="book" lang="en"><div class="titlepage"><div><div><h1 class="title"><a id="adt-manual"></a></h1></div><div><div class="authorgroup">
5947 <div class="author"><h3 class="author"><span class="firstname">Jessica</span> <span class="surname">Zhang</span></h3><div class="affiliation">
5948 <span class="orgname">Intel Corporation<br /></span>
5949 </div><code class="email">&lt;<a class="email" href="mailto:jessica.zhang@intel.com">jessica.zhang@intel.com</a>&gt;</code></div>
5950 </div></div><div><p class="copyright">Copyright © 2010-2012 Linux Foundation</p></div><div><div class="legalnotice" title="Legal Notice"><a id="id1499739"></a>
5951 <p>
5952 Permission is granted to copy, distribute and/or modify this document under
5953 the terms of the <a class="ulink" href="http://creativecommons.org/licenses/by-sa/2.0/uk/" target="_top">Creative Commons Attribution-Share Alike 2.0 UK: England &amp; Wales</a> as published by Creative Commons.
5954 </p>
5955 <div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
5956 Due to production processes, there could be differences between the Yocto Project
5957 documentation bundled in the release tarball and the
5958 Yocto Project Application Developer's Guide on
5959 the <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project</a> website.
5960 For the latest version of this manual, see the manual on the website.
5961 </div>
5962
5963 </div></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr>
5964 <tr><td align="left">Revision 1.0</td><td align="left">6 April 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0 Release.</td></tr>
5965 <tr><td align="left">Revision 1.0.1</td><td align="left">23 May 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0.1 Release.</td></tr>
5966 <tr><td align="left">Revision 1.1</td><td align="left">6 October 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.1 Release.</td></tr>
5967 <tr><td align="left">Revision 1.2</td><td align="left">April 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.2 Release.</td></tr>
5968 <tr><td align="left">Revision 1.3</td><td align="left">Sometime in 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.3 Release.</td></tr>
5969 </table></div></div></div><hr /></div>
5970
5971
5972 <div class="chapter" title="Chapter 1. Introduction"><div class="titlepage"><div><div><h2 class="title"><a id="adt-intro"></a>Chapter 1. Introduction</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#adt-intro-section">1.1. The Application Development Toolkit (ADT)</a></span></dt><dd><dl><dt><span class="section"><a href="#the-cross-toolchain">1.1.1. The Cross-Toolchain</a></span></dt><dt><span class="section"><a href="#sysroot">1.1.2. Sysroot</a></span></dt><dt><span class="section"><a href="#eclipse-overview">1.1.3. Eclipse Yocto Plug-in</a></span></dt><dt><span class="section"><a href="#the-qemu-emulator">1.1.4. The QEMU Emulator</a></span></dt><dt><span class="section"><a href="#user-space-tools">1.1.5. User-Space Tools</a></span></dt></dl></dd></dl></div><p>
5973 Welcome to the Yocto Project Application Developer's Guide.
5974 This manual provides information that lets you begin developing applications
5975 using the Yocto Project.
5976</p><p>
5977 The Yocto Project provides an application development environment based on
5978 an Application Development Toolkit (ADT) and the availability of stand-alone
5979 cross-development toolchains and other tools.
5980 This manual describes the ADT and how you can configure and install it,
5981 how to access and use the cross-development toolchains, how to
5982 customize the development packages installation,
5983 how to use command line development for both Autotools-based and Makefile-based projects,
5984 and an introduction to the Eclipse Yocto Plug-in.
5985</p><div class="section" title="1.1. The Application Development Toolkit (ADT)"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="adt-intro-section"></a>1.1. The Application Development Toolkit (ADT)</h2></div></div></div><p>
5986 Part of the Yocto Project development solution is an Application Development
5987 Toolkit (ADT).
5988 The ADT provides you with a custom-built, cross-development
5989 platform suited for developing a user-targeted product application.
5990 </p><p>
5991 Fundamentally, the ADT consists of the following:
5992 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>An architecture-specific cross-toolchain and matching
5993 sysroot both built by the OpenEmbedded build system, which uses Poky.
5994 The toolchain and sysroot are based on a metadata configuration and extensions,
5995 which allows you to cross-develop on the host machine for the target hardware.
5996 </p></li><li class="listitem"><p>The Eclipse IDE Yocto Plug-in.</p></li><li class="listitem"><p>The Quick EMUlator (QEMU), which lets you simulate target hardware.
5997 </p></li><li class="listitem"><p>Various user-space tools that greatly enhance your application
5998 development experience.</p></li></ul></div><p>
5999 </p><div class="section" title="1.1.1. The Cross-Toolchain"><div class="titlepage"><div><div><h3 class="title"><a id="the-cross-toolchain"></a>1.1.1. The Cross-Toolchain</h3></div></div></div><p>
6000 The cross-toolchain consists of a cross-compiler, cross-linker, and cross-debugger
6001 that are used to develop user-space applications for targeted hardware.
6002 This toolchain is created either by running the ADT Installer script or
6003 through a build directory that is based on your metadata
6004 configuration or extension for your targeted device.
6005 The cross-toolchain works with a matching target sysroot.
6006 </p></div><div class="section" title="1.1.2. Sysroot"><div class="titlepage"><div><div><h3 class="title"><a id="sysroot"></a>1.1.2. Sysroot</h3></div></div></div><p>
6007 The matching target sysroot contains needed headers and libraries for generating
6008 binaries that run on the target architecture.
6009 The sysroot is based on the target root filesystem image that is built by
6010 the OpenEmbedded build system Poky and uses the same metadata configuration
6011 used to build the cross-toolchain.
6012 </p></div><div class="section" title="1.1.3. Eclipse Yocto Plug-in"><div class="titlepage"><div><div><h3 class="title"><a id="eclipse-overview"></a>1.1.3. Eclipse Yocto Plug-in</h3></div></div></div><p>
6013 The Eclipse IDE is a popular development environment and it fully supports
6014 development using the Yocto Project.
6015 When you install and configure the Eclipse Yocto Project Plug-in into
6016 the Eclipse IDE, you maximize your Yocto Project experience.
6017 Installing and configuring the Plug-in results in an environment that
6018 has extensions specifically designed to let you more easily develop software.
6019 These extensions allow for cross-compilation, deployment, and execution of
6020 your output into a QEMU emulation session.
6021 You can also perform cross-debugging and profiling.
6022 The environment also supports a suite of tools that allows you to perform
6023 remote profiling, tracing, collection of power data, collection of
6024 latency data, and collection of performance data.
6025 </p><p>
6026 For information about the application development workflow that uses the Eclipse
6027 IDE and for a detailed example of how to install and configure the Eclipse
6028 Yocto Project Plug-in, see the
6029 "<a class="link" href="#adt-eclipse" target="_top">Working Within Eclipse</a>" section
6030 of the Yocto Project Development Manual.
6031 </p></div><div class="section" title="1.1.4. The QEMU Emulator"><div class="titlepage"><div><div><h3 class="title"><a id="the-qemu-emulator"></a>1.1.4. The QEMU Emulator</h3></div></div></div><p>
6032 The QEMU emulator allows you to simulate your hardware while running your
6033 application or image.
6034 QEMU is made available a number of ways:
6035 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>If you use the ADT Installer script to install ADT, you can
6036 specify whether or not to install QEMU.</p></li><li class="listitem"><p>If you have downloaded a Yocto Project release and unpacked
6037 it to create a source directory and you have sourced
6038 the environment setup script, QEMU is installed and automatically
6039 available.</p></li><li class="listitem"><p>If you have installed the cross-toolchain
6040 tarball and you have sourcing the toolchain's setup environment script, QEMU
6041 is also installed and automatically available.</p></li></ul></div><p>
6042 </p></div><div class="section" title="1.1.5. User-Space Tools"><div class="titlepage"><div><div><h3 class="title"><a id="user-space-tools"></a>1.1.5. User-Space Tools</h3></div></div></div><p>
6043 User-space tools are included as part of the distribution.
6044 You will find these tools helpful during development.
6045 The tools include LatencyTOP, PowerTOP, OProfile, Perf, SystemTap, and Lttng-ust.
6046 These tools are common development tools for the Linux platform.
6047 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>LatencyTOP:</em></span> LatencyTOP focuses on latency
6048 that causes skips in audio,
6049 stutters in your desktop experience, or situations that overload your server
6050 even when you have plenty of CPU power left.
6051 You can find out more about LatencyTOP at
6052 <a class="ulink" href="http://www.latencytop.org/" target="_top">http://www.latencytop.org/</a>.</p></li><li class="listitem"><p><span class="emphasis"><em>PowerTOP:</em></span> Helps you determine what
6053 software is using the most power.
6054 You can find out more about PowerTOP at
6055 <a class="ulink" href="http://www.linuxpowertop.org/" target="_top">http://www.linuxpowertop.org/</a>.</p></li><li class="listitem"><p><span class="emphasis"><em>OProfile:</em></span> A system-wide profiler for Linux
6056 systems that is capable of profiling all running code at low overhead.
6057 You can find out more about OProfile at
6058 <a class="ulink" href="http://oprofile.sourceforge.net/about/" target="_top">http://oprofile.sourceforge.net/about/</a>.</p></li><li class="listitem"><p><span class="emphasis"><em>Perf:</em></span> Performance counters for Linux used
6059 to keep track of certain types of hardware and software events.
6060 For more information on these types of counters see
6061 <a class="ulink" href="https://perf.wiki.kernel.org/" target="_top">https://perf.wiki.kernel.org/</a> and click
6062 on “Perf tools.”</p></li><li class="listitem"><p><span class="emphasis"><em>SystemTap:</em></span> A free software infrastructure
6063 that simplifies information gathering about a running Linux system.
6064 This information helps you diagnose performance or functional problems.
6065 SystemTap is not available as a user-space tool through the Eclipse IDE Yocto Plug-in.
6066 See <a class="ulink" href="http://sourceware.org/systemtap" target="_top">http://sourceware.org/systemtap</a> for more information
6067 on SystemTap.</p></li><li class="listitem"><p><span class="emphasis"><em>Lttng-ust:</em></span> A User-space Tracer designed to
6068 provide detailed information on user-space activity.
6069 See <a class="ulink" href="http://lttng.org/ust" target="_top">http://lttng.org/ust</a> for more information on Lttng-ust.
6070 </p></li></ul></div><p>
6071 </p></div></div></div>
6072
6073 <div class="chapter" title="Chapter 2. Preparing for Application Development"><div class="titlepage"><div><div><h2 class="title"><a id="adt-prepare"></a>Chapter 2. Preparing for Application Development</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#installing-the-adt">2.1. Installing the ADT and Toolchains</a></span></dt><dd><dl><dt><span class="section"><a href="#using-the-adt-installer">2.1.1. Using the ADT Installer</a></span></dt><dt><span class="section"><a href="#using-an-existing-toolchain-tarball">2.1.2. Using a Cross-Toolchain Tarball</a></span></dt><dt><span class="section"><a href="#using-the-toolchain-from-within-the-build-tree">2.1.3. Using BitBake and the Build Directory</a></span></dt></dl></dd><dt><span class="section"><a href="#setting-up-the-cross-development-environment">2.2. Setting Up the Cross-Development Environment</a></span></dt><dt><span class="section"><a href="#securing-kernel-and-filesystem-images">2.3. Securing Kernel and Filesystem Images</a></span></dt><dd><dl><dt><span class="section"><a href="#getting-the-images">2.3.1. Getting the Images</a></span></dt><dt><span class="section"><a href="#extracting-the-root-filesystem">2.3.2. Extracting the Root Filesystem</a></span></dt></dl></dd></dl></div><p>
6074 In order to develop applications, you need set up your host development system.
6075 Several ways exist that allow you to install cross-development tools, QEMU, the
6076 Eclipse Yocto Plug-in, and other tools.
6077 This chapter describes how to prepare for application development.
6078</p><div class="section" title="2.1. Installing the ADT and Toolchains"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="installing-the-adt"></a>2.1. Installing the ADT and Toolchains</h2></div></div></div><p>
6079 The following list describes installation methods that set up varying degrees of tool
6080 availabiltiy on your system.
6081 Regardless of the installation method you choose,
6082 you must <code class="filename">source</code> the cross-toolchain
6083 environment setup script before you use a toolchain.
6084 See the "<a class="link" href="#setting-up-the-cross-development-environment" title="2.2. Setting Up the Cross-Development Environment">Setting Up the
6085 Cross-Development Environment</a>" section for more information.
6086 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>Avoid mixing installation methods when installing toolchains for different architectures.
6087 For example, avoid using the ADT Installer to install some toolchains and then hand-installing
6088 cross-development toolchains from downloaded tarballs to install toolchains
6089 for different architectures.
6090 Mixing installation methods can result in situations where the ADT Installer becomes
6091 unreliable and might not install the toolchain.</p><p>If you must mix installation methods, you might avoid problems by deleting
6092 <code class="filename">/var/lib/opkg</code>, thus purging the <code class="filename">opkg</code> package
6093 metadata</p></div><p>
6094 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Use the ADT Installer Script:</em></span>
6095 This method is the recommended way to install the ADT because it
6096 automates much of the process for you.
6097 For example, you can configure the installation to install the QEMU emulator
6098 and the user-space NFS, specify which root filesystem profiles to download,
6099 and define the target sysroot location.</p></li><li class="listitem"><p><span class="emphasis"><em>Use an Existing Toolchain Tarball:</em></span>
6100 Using this method, you select and download an architecture-specific
6101 toolchain tarball and then hand-install the toolchain.
6102 If you use this method, you just get the cross-toolchain and QEMU - you do not
6103 get any of the other mentioned benefits had you run the ADT Installer script.</p></li><li class="listitem"><p><span class="emphasis"><em>Use the Toolchain from within the Build Directory:</em></span>
6104 If you already have a
6105 <a class="link" href="#build-directory" target="_top">build directory</a>,
6106 you can build the cross-toolchain within the directory.
6107 However, like the previous method mentioned, you only get the cross-toolchain and QEMU - you
6108 do not get any of the other benefits without taking separate steps.</p></li></ul></div><p>
6109 </p><div class="section" title="2.1.1. Using the ADT Installer"><div class="titlepage"><div><div><h3 class="title"><a id="using-the-adt-installer"></a>2.1.1. Using the ADT Installer</h3></div></div></div><p>
6110 To run the ADT Installer, you need to first get the ADT Installer tarball and then run the ADT
6111 Installer Script.
6112 </p><div class="section" title="2.1.1.1. Getting the ADT Installer Tarball"><div class="titlepage"><div><div><h4 class="title"><a id="getting-the-adt-installer-tarball"></a>2.1.1.1. Getting the ADT Installer Tarball</h4></div></div></div><p>
6113 The ADT Installer is contained in the ADT Installer tarball.
6114 You can download the tarball into any directory from the
6115 <a class="ulink" href="http://downloads.yoctoproject.org/releases" target="_top">Index of Releases</a>, specifically
6116 at
6117 <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/adt_installer" target="_top">http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/adt_installer</a>.
6118 Or, you can use BitBake to generate the tarball inside the existing
6119 <a class="link" href="#build-directory" target="_top">build directory</a>.
6120 </p><p>
6121 If you use BitBake to generate the ADT Installer tarball, you must
6122 <code class="filename">source</code> the environment setup script
6123 (<code class="filename">oe-init-build-env</code>) located
6124 in the source directory before running the <code class="filename">bitbake</code>
6125 command that creates the tarball.
6126 </p><p>
6127 The following example commands download the Poky tarball, set up the
6128 <a class="link" href="#source-directory" target="_top">source directory</a>,
6129 set up the environment while also creating the default build directory,
6130 and run the <code class="filename">bitbake</code> command that results in the tarball
6131 <code class="filename">~/yocto-project/build/tmp/deploy/sdk/adt_installer.tar.bz2</code>:
6132 </p><pre class="literallayout">
6133 $ cd ~
6134 $ mkdir yocto-project
6135 $ cd yocto-project
6136 $ wget http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/poky-1.2+snapshot-8.0.tar.bz2
6137 $ tar xjf poky-1.2+snapshot-8.0.tar.bz2
6138 $ source poky-1.2+snapshot-8.0/oe-init-build-env
6139 $ bitbake adt-installer
6140 </pre><p>
6141 </p></div><div class="section" title="2.1.1.2. Configuring and Running the ADT Installer Script"><div class="titlepage"><div><div><h4 class="title"><a id="configuring-and-running-the-adt-installer-script"></a>2.1.1.2. Configuring and Running the ADT Installer Script</h4></div></div></div><p>
6142 Before running the ADT Installer script, you need to unpack the tarball.
6143 You can unpack the tarball in any directory you wish.
6144 For example, this command copies the ADT Installer tarball from where
6145 it was built into the home directory and then unpacks the tarball into
6146 a top-level directory named <code class="filename">adt-installer</code>:
6147 </p><pre class="literallayout">
6148 $ cd ~
6149 $ cp ~/poky/build/tmp/deploy/sdk/adt_installer.tar.bz2 $HOME
6150 $ tar -xjf adt_installer.tar.bz2
6151 </pre><p>
6152 Unpacking it creates the directory <code class="filename">adt-installer</code>,
6153 which contains the ADT Installer script (<code class="filename">adt_installer</code>)
6154 and its configuration file (<code class="filename">adt_installer.conf</code>).
6155 </p><p>
6156 Before you run the script, however, you should examine the ADT Installer configuration
6157 file and be sure you are going to get what you want.
6158 Your configurations determine which kernel and filesystem image are downloaded.
6159 </p><p>
6160 The following list describes the configurations you can define for the ADT Installer.
6161 For configuration values and restrictions, see the comments in
6162 the <code class="filename">adt-installer.conf</code> file:
6163
6164 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename">YOCTOADT_REPO</code>: This area
6165 includes the IPKG-based packages and the root filesystem upon which
6166 the installation is based.
6167 If you want to set up your own IPKG repository pointed to by
6168 <code class="filename">YOCTOADT_REPO</code>, you need to be sure that the
6169 directory structure follows the same layout as the reference directory
6170 set up at <a class="ulink" href="http://adtrepo.yoctoproject.org" target="_top">http://adtrepo.yoctoproject.org</a>.
6171 Also, your repository needs to be accessible through HTTP.</p></li><li class="listitem"><p><code class="filename">YOCTOADT_TARGETS</code>: The machine
6172 target architectures for which you want to set up cross-development
6173 environments.</p></li><li class="listitem"><p><code class="filename">YOCTOADT_QEMU</code>: Indicates whether
6174 or not to install the emulator QEMU.</p></li><li class="listitem"><p><code class="filename">YOCTOADT_NFS_UTIL</code>: Indicates whether
6175 or not to install user-mode NFS.
6176 If you plan to use the Eclipse IDE Yocto plug-in against QEMU,
6177 you should install NFS.
6178 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>To boot QEMU images using our userspace NFS server, you need
6179 to be running <code class="filename">portmap</code> or <code class="filename">rpcbind</code>.
6180 If you are running <code class="filename">rpcbind</code>, you will also need to add the
6181 <code class="filename">-i</code> option when <code class="filename">rpcbind</code> starts up.
6182 Please make sure you understand the security implications of doing this.
6183 You might also have to modify your firewall settings to allow
6184 NFS booting to work.</div></li><li class="listitem"><p><code class="filename">YOCTOADT_ROOTFS_&lt;arch&gt;</code>: The root
6185 filesystem images you want to download from the
6186 <code class="filename">YOCTOADT_IPKG_REPO</code> repository.</p></li><li class="listitem"><p><code class="filename">YOCTOADT_TARGET_SYSROOT_IMAGE_&lt;arch&gt;</code>: The
6187 particular root filesystem used to extract and create the target sysroot.
6188 The value of this variable must have been specified with
6189 <code class="filename">YOCTOADT_ROOTFS_&lt;arch&gt;</code>.
6190 For example, if you downloaded both <code class="filename">minimal</code> and
6191 <code class="filename">sato-sdk</code> images by setting
6192 <code class="filename">YOCTOADT_ROOTFS_&lt;arch&gt;</code>
6193 to "minimal sato-sdk", then <code class="filename">YOCTOADT_ROOTFS_&lt;arch&gt;</code>
6194 must be set to either <code class="filename">minimal</code> or
6195 <code class="filename">sato-sdk</code>.</p></li><li class="listitem"><p><code class="filename">YOCTOADT_TARGET_SYSROOT_LOC_&lt;arch&gt;</code>: The
6196 location on the development host where the target sysroot is created.
6197 </p></li></ul></div><p>
6198 </p><p>
6199 After you have configured the <code class="filename">adt_installer.conf</code> file,
6200 run the installer using the following command.
6201 Be sure that you are not trying to use cross-compilation tools.
6202 When you run the installer, the environment must use a
6203 host <code class="filename">gcc</code>:
6204 </p><pre class="literallayout">
6205 $ ./adt_installer
6206 </pre><p>
6207 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
6208 The ADT Installer requires the <code class="filename">libtool</code> package to complete.
6209 If you install the recommended packages as described in
6210 "<a class="link" href="#packages" target="_top">The Packages</a>"
6211 section of the Yocto Project Quick Start, then you will have libtool installed.
6212 </div><p>
6213 Once the installer begins to run, you are asked whether you want to run in
6214 interactive or silent mode.
6215 If you want to closely monitor the installation, choose “I” for interactive
6216 mode rather than “S” for silent mode.
6217 Follow the prompts from the script to complete the installation.
6218 </p><p>
6219 Once the installation completes, the ADT, which includes the cross-toolchain, is installed.
6220 You will notice environment setup files for the cross-toolchain in
6221 <code class="filename">/opt/poky/1.3</code>,
6222 and image tarballs in the <code class="filename">adt-installer</code>
6223 directory according to your installer configurations, and the target sysroot located
6224 according to the <code class="filename">YOCTOADT_TARGET_SYSROOT_LOC_&lt;arch&gt;</code> variable
6225 also in your configuration file.
6226 </p></div></div><div class="section" title="2.1.2. Using a Cross-Toolchain Tarball"><div class="titlepage"><div><div><h3 class="title"><a id="using-an-existing-toolchain-tarball"></a>2.1.2. Using a Cross-Toolchain Tarball</h3></div></div></div><p>
6227 If you want to simply install the cross-toolchain by hand, you can do so by using an existing
6228 cross-toolchain tarball.
6229 If you use this method to install the cross-toolchain and you still need to install the target
6230 sysroot, you will have to install sysroot separately.
6231 </p><p>
6232 Follow these steps:
6233 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Go to
6234 <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/toolchain/" target="_top">http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/toolchain/</a>
6235 and find the folder that matches your host development system
6236 (i.e. <code class="filename">i686</code> for 32-bit machines or
6237 <code class="filename">x86-64</code> for 64-bit machines).</p></li><li class="listitem"><p>Go into that folder and download the toolchain tarball whose name
6238 includes the appropriate target architecture.
6239 For example, if your host development system is an Intel-based 64-bit system and
6240 you are going to use your cross-toolchain for an Intel-based 32-bit target, go into the
6241 <code class="filename">x86_64</code> folder and download the following tarball:
6242 </p><pre class="literallayout">
6243 poky-eglibc-x86_64-i586-toolchain-gmae-1.3.tar.bz2
6244 </pre><p>
6245 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>As an alternative to steps one and two, you can build the toolchain tarball
6246 if you have a <a class="link" href="#build-directory" target="_top">build directory</a>.
6247 If you need GMAE, you should use the <code class="filename">bitbake meta-toolchain-gmae</code>
6248 command.
6249 The resulting tarball will support such development.
6250 However, if you are not concerned with GMAE,
6251 you can generate the tarball using <code class="filename">bitbake meta-toolchain</code>.</p><p>Use the appropriate <code class="filename">bitbake</code> command only after you have
6252 sourced the <code class="filename">oe-build-init-env</code> script located in the source
6253 directory.
6254 When the <code class="filename">bitbake</code> command completes, the tarball will
6255 be in <code class="filename">tmp/deploy/sdk</code> in the build directory.
6256 </p></div></li><li class="listitem"><p>Make sure you are in the root directory with root privileges and then expand
6257 the tarball.
6258 The tarball expands into <code class="filename">/opt/poky/1.3</code>.
6259 Once the tarball is expanded, the cross-toolchain is installed.
6260 You will notice environment setup files for the cross-toolchain in the directory.
6261 </p></li></ol></div><p>
6262 </p></div><div class="section" title="2.1.3. Using BitBake and the Build Directory"><div class="titlepage"><div><div><h3 class="title"><a id="using-the-toolchain-from-within-the-build-tree"></a>2.1.3. Using BitBake and the Build Directory</h3></div></div></div><p>
6263 A final way of making the cross-toolchain available is to use BitBake
6264 to generate the toolchain within an existing
6265 <a class="link" href="#build-directory" target="_top">build directory</a>.
6266 This method does not install the toolchain into the
6267 <code class="filename">/opt</code> directory.
6268 As with the previous method, if you need to install the target sysroot, you must
6269 do that separately as well.
6270 </p><p>
6271 Follow these steps to generate the toolchain into the build directory:
6272 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Source the environment setup script
6273 <code class="filename">oe-init-build-env</code> located in the
6274 <a class="link" href="#source-directory" target="_top">source directory</a>.
6275 </p></li><li class="listitem"><p>At this point, you should be sure that the
6276 <a class="link" href="#var-MACHINE" target="_top"><code class="filename">MACHINE</code></a> variable
6277 in the <code class="filename">local.conf</code> file found in the
6278 <code class="filename">conf</code> directory of the build directory
6279 is set for the target architecture.
6280 Comments within the <code class="filename">local.conf</code> file list the values you
6281 can use for the <code class="filename">MACHINE</code> variable.
6282 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>You can populate the build directory with the cross-toolchains for more
6283 than a single architecture.
6284 You just need to edit the <code class="filename">MACHINE</code> variable in the
6285 <code class="filename">local.conf</code> file and re-run the BitBake
6286 command.</div></li><li class="listitem"><p>Run <code class="filename">bitbake meta-ide-support</code> to complete the
6287 cross-toolchain generation.
6288 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>If you change out of your working directory after you
6289 <code class="filename">source</code> the environment setup script and before you run
6290 the <code class="filename">bitbake</code> command, the command might not work.
6291 Be sure to run the <code class="filename">bitbake</code> command immediately
6292 after checking or editing the <code class="filename">local.conf</code> but without
6293 changing out of your working directory.</div><p>
6294 Once the <code class="filename">bitbake</code> command finishes,
6295 the cross-toolchain is generated and populated within the build directory.
6296 You will notice environment setup files for the cross-toolchain in the
6297 build directory in the <code class="filename">tmp</code> directory.
6298 Setup script filenames contain the strings <code class="filename">environment-setup</code>.
6299 </p></li></ol></div><p>
6300 </p></div></div><div class="section" title="2.2. Setting Up the Cross-Development Environment"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="setting-up-the-cross-development-environment"></a>2.2. Setting Up the Cross-Development Environment</h2></div></div></div><p>
6301 Before you can develop using the cross-toolchain, you need to set up the
6302 cross-development environment by sourcing the toolchain's environment setup script.
6303 If you used the ADT Installer or hand-installed cross-toolchain,
6304 then you can find this script in the <code class="filename">/opt/poky/1.3</code>
6305 directory.
6306 If you installed the toolchain in the
6307 <a class="link" href="#build-directory" target="_top">build directory</a>,
6308 you can find the environment setup
6309 script for the toolchain in the build directory's <code class="filename">tmp</code> directory.
6310 </p><p>
6311 Be sure to run the environment setup script that matches the architecture for
6312 which you are developing.
6313 Environment setup scripts begin with the string “<code class="filename">environment-setup</code>”
6314 and include as part of their name the architecture.
6315 For example, the toolchain environment setup script for a 64-bit IA-based architecture would
6316 be the following:
6317 </p><pre class="literallayout">
6318 /opt/poky/1.3/environment-setup-x86_64-poky-linux
6319 </pre><p>
6320 </p></div><div class="section" title="2.3. Securing Kernel and Filesystem Images"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="securing-kernel-and-filesystem-images"></a>2.3. Securing Kernel and Filesystem Images</h2></div></div></div><p>
6321 You will need to have a kernel and filesystem image to boot using your
6322 hardware or the QEMU emulator.
6323 Furthermore, if you plan on booting your image using NFS or you want to use the root filesystem
6324 as the target sysroot, you need to extract the root filesystem.
6325 </p><div class="section" title="2.3.1. Getting the Images"><div class="titlepage"><div><div><h3 class="title"><a id="getting-the-images"></a>2.3.1. Getting the Images</h3></div></div></div><p>
6326 To get the kernel and filesystem images, you either have to build them or download
6327 pre-built versions.
6328 You can find examples for both these situations in the
6329 "<a class="link" href="#test-run" target="_top">A Quick Test Run</a>" section of
6330 the Yocto Project Quick Start.
6331 </p><p>
6332 The Yocto Project ships basic kernel and filesystem images for several
6333 architectures (<code class="filename">x86</code>, <code class="filename">x86-64</code>,
6334 <code class="filename">mips</code>, <code class="filename">powerpc</code>, and <code class="filename">arm</code>)
6335 that you can use unaltered in the QEMU emulator.
6336 These kernel images reside in the release
6337 area - <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines" target="_top">http://downloads.yoctoproject.org/releases/yocto/yocto-1.3/machines</a>
6338 and are ideal for experimentation using Yocto Project.
6339 For information on the image types you can build using the OpenEmbedded build system,
6340 see the
6341 "<a class="link" href="#ref-images" target="_top">Images</a>" chapter in
6342 the Yocto Project Reference Manual.
6343 </p><p>
6344 If you plan on remotely deploying and debugging your application from within the
6345 Eclipse IDE, you must have an image that contains the Yocto Target Communication
6346 Framework (TCF) agent (<code class="filename">tcf-agent</code>).
6347 By default, the Yocto Project provides only one type pre-built image that contains the
6348 <code class="filename">tcf-agent</code>.
6349 And, those images are SDK (e.g.<code class="filename">core-image-sato-sdk</code>).
6350 </p><p>
6351 If you want to use a different image type that contains the <code class="filename">tcf-agent</code>,
6352 you can do so one of two ways:
6353 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Modify the <code class="filename">conf/local.conf</code> configuration in
6354 the <a class="link" href="#build-directory" target="_top">build directory</a>
6355 and then rebuild the image.
6356 With this method, you need to modify the
6357 <a class="link" href="#var-EXTRA_IMAGE_FEATURES" target="_top"><code class="filename">EXTRA_IMAGE_FEATURES</code></a>
6358 variable to have the value of "tools-debug" before rebuilding the image.
6359 Once the image is rebuilt, the <code class="filename">tcf-agent</code> will be included
6360 in the image and is launched automatically after the boot.</p></li><li class="listitem"><p>Manually build the <code class="filename">tcf-agent</code>.
6361 To build the agent, follow these steps:
6362 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Be sure the ADT is installed as described in the
6363 "<a class="link" href="#installing-the-adt" title="2.1. Installing the ADT and Toolchains">Installing the ADT and Toolchains</a>" section.
6364 </p></li><li class="listitem"><p>Set up the cross-development environment as described in the
6365 "<a class="link" href="#setting-up-the-cross-development-environment" title="2.2. Setting Up the Cross-Development Environment">Setting
6366 Up the Cross-Development Environment</a>" section.</p></li><li class="listitem"><p>Get the <code class="filename">tcf-agent</code> source code using
6367 the following commands:
6368 </p><pre class="literallayout">
6369 $ git clone http://git.eclipse.org/gitroot/tcf/org.eclipse.tcf.agent.git
6370 $ cd agent
6371 </pre></li><li class="listitem"><p>Modify the <code class="filename">Makefile.inc</code> file
6372 for the cross-compilation environment by setting the
6373 <code class="filename">OPSYS</code> and
6374 <a class="link" href="#var-MACHINE" target="_top"><code class="filename">MACHINE</code></a>
6375 variables according to your target.</p></li><li class="listitem"><p>Use the cross-development tools to build the
6376 <code class="filename">tcf-agent</code>.
6377 Before you "Make" the file, be sure your cross-tools are set up first.
6378 See the "<a class="link" href="#makefile-based-projects" title="4.2. Makefile-Based Projects">Makefile-Based Projects</a>"
6379 section for information on how to make sure the cross-tools are set up
6380 correctly.</p><p>If the build is successful, the <code class="filename">tcf-agent</code> output will
6381 be <code class="filename">obj/$(OPSYS)/$(MACHINE)/Debug/agent</code>.</p></li><li class="listitem"><p>Deploy the agent into the image's root filesystem.</p></li></ol></div><p>
6382 </p></li></ul></div><p>
6383 </p></div><div class="section" title="2.3.2. Extracting the Root Filesystem"><div class="titlepage"><div><div><h3 class="title"><a id="extracting-the-root-filesystem"></a>2.3.2. Extracting the Root Filesystem</h3></div></div></div><p>
6384 You must extract the root filesystem if you want to boot the image using NFS
6385 or you want to use the root filesystem as the target sysroot.
6386 For example, the Eclipse IDE environment with the Eclipse Yocto Plug-in installed allows you
6387 to use QEMU to boot under NFS.
6388 Another example is if you want to develop your target application using the
6389 root filesystem as the target sysroot.
6390 </p><p>
6391 To extract the root filesystem, first <code class="filename">source</code>
6392 the cross-development environment setup script and then
6393 use the <code class="filename">runqemu-extract-sdk</code> command on the
6394 filesystem image.
6395 For example, the following commands set up the environment and then extract
6396 the root filesystem from a previously built filesystem image tarball named
6397 <code class="filename">core-image-sato-sdk-qemux86-2011091411831.rootfs.tar.bz2</code>.
6398 The example extracts the root filesystem into the <code class="filename">$HOME/qemux86-sato</code>
6399 directory:
6400 </p><pre class="literallayout">
6401 $ source $HOME/poky/build/tmp/environment-setup-i586-poky-linux
6402 $ runqemu-extract-sdk \
6403 tmp/deploy/images/core-image-sato-sdk-qemux86-2011091411831.rootfs.tar.bz2 \
6404 $HOME/qemux86-sato
6405 </pre><p>
6406 In this case, you could now point to the target sysroot at
6407 <code class="filename">$HOME/qemux86-sato</code>.
6408 </p></div></div></div>
6409
6410 <div class="chapter" title="Chapter 3. Optionally Customizing the Development Packages Installation"><div class="titlepage"><div><div><h2 class="title"><a id="adt-package"></a>Chapter 3. Optionally Customizing the Development Packages Installation</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#package-management-systems">3.1. Package Management Systems</a></span></dt><dt><span class="section"><a href="#configuring-the-pms">3.2. Configuring the PMS</a></span></dt></dl></div><p>
6411 Because the Yocto Project is suited for embedded Linux development, it is
6412 likely that you will need to customize your development packages installation.
6413 For example, if you are developing a minimal image, then you might not need
6414 certain packages (e.g. graphics support packages).
6415 Thus, you would like to be able to remove those packages from your target sysroot.
6416 </p><div class="section" title="3.1. Package Management Systems"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="package-management-systems"></a>3.1. Package Management Systems</h2></div></div></div><p>
6417 The OpenEmbedded build system supports the generation of sysroot files using
6418 three different Package Management Systems (PMS):
6419 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>OPKG:</em></span> A less well known PMS whose use
6420 originated in the OpenEmbedded and OpenWrt embedded Linux projects.
6421 This PMS works with files packaged in an <code class="filename">.ipk</code> format.
6422 See <a class="ulink" href="http://en.wikipedia.org/wiki/Opkg" target="_top">http://en.wikipedia.org/wiki/Opkg</a> for more
6423 information about OPKG.</p></li><li class="listitem"><p><span class="emphasis"><em>RPM:</em></span> A more widely known PMS intended for GNU/Linux
6424 distributions.
6425 This PMS works with files packaged in an <code class="filename">.rms</code> format.
6426 The build system currently installs through this PMS by default.
6427 See <a class="ulink" href="http://en.wikipedia.org/wiki/RPM_Package_Manager" target="_top">http://en.wikipedia.org/wiki/RPM_Package_Manager</a>
6428 for more information about RPM.</p></li><li class="listitem"><p><span class="emphasis"><em>Debian:</em></span> The PMS for Debian-based systems
6429 is built on many PMS tools.
6430 The lower-level PMS tool <code class="filename">dpkg</code> forms the base of the Debian PMS.
6431 For information on dpkg see
6432 <a class="ulink" href="http://en.wikipedia.org/wiki/Dpkg" target="_top">http://en.wikipedia.org/wiki/Dpkg</a>.</p></li></ul></div><p>
6433 </p></div><div class="section" title="3.2. Configuring the PMS"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="configuring-the-pms"></a>3.2. Configuring the PMS</h2></div></div></div><p>
6434 Whichever PMS you are using, you need to be sure that the
6435 <a class="link" href="#var-PACKAGE_CLASSES" target="_top"><code class="filename">PACKAGE_CLASSES</code></a>
6436 variable in the <code class="filename">conf/local.conf</code>
6437 file is set to reflect that system.
6438 The first value you choose for the variable specifies the package file format for the root
6439 filesystem at sysroot.
6440 Additional values specify additional formats for convenience or testing.
6441 See the configuration file for details.
6442 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
6443 For build performance information related to the PMS, see
6444 <a class="link" href="#ref-classes-package" target="_top">Packaging - <code class="filename">package*.bbclass</code></a>
6445 in the Yocto Project Reference Manual.
6446 </div><p>
6447 As an example, consider a scenario where you are using OPKG and you want to add
6448 the <code class="filename">libglade</code> package to the target sysroot.
6449 </p><p>
6450 First, you should generate the <code class="filename">ipk</code> file for the
6451 <code class="filename">libglade</code> package and add it
6452 into a working <code class="filename">opkg</code> repository.
6453 Use these commands:
6454 </p><pre class="literallayout">
6455 $ bitbake libglade
6456 $ bitbake package-index
6457 </pre><p>
6458 </p><p>
6459 Next, source the environment setup script found in the
6460 <a class="link" href="#source-directory" target="_top">source directory</a>.
6461 Follow that by setting up the installation destination to point to your
6462 sysroot as <code class="filename">&lt;sysroot_dir&gt;</code>.
6463 Finally, have an OPKG configuration file <code class="filename">&lt;conf_file&gt;</code>
6464 that corresponds to the <code class="filename">opkg</code> repository you have just created.
6465 The following command forms should now work:
6466 </p><pre class="literallayout">
6467 $ opkg-cl –f &lt;conf_file&gt; -o &lt;sysroot_dir&gt; update
6468 $ opkg-cl –f &lt;cconf_file&gt; -o &lt;sysroot_dir&gt; \
6469 --force-overwrite install libglade
6470 $ opkg-cl –f &lt;cconf_file&gt; -o &lt;sysroot_dir&gt; \
6471 --force-overwrite install libglade-dbg
6472 $ opkg-cl –f &lt;conf_file&gt; -o &lt;sysroot_dir&gt; \
6473 --force-overwrite install libglade-dev
6474 </pre><p>
6475 </p></div></div>
6476
6477 <div class="chapter" title="Chapter 4. Using the Command Line"><div class="titlepage"><div><div><h2 class="title"><a id="using-the-command-line"></a>Chapter 4. Using the Command Line</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#autotools-based-projects">4.1. Autotools-Based Projects</a></span></dt><dt><span class="section"><a href="#makefile-based-projects">4.2. Makefile-Based Projects</a></span></dt></dl></div><p>
6478 Recall that earlier the manual discussed how to use an existing toolchain
6479 tarball that had been installed into <code class="filename">/opt/poky</code>,
6480 which is outside of the build directory
6481 (see the section "<a class="link" href="#using-an-existing-toolchain-tarball" title="2.1.2. Using a Cross-Toolchain Tarball">Using an Existing
6482 Toolchain Tarball)</a>".
6483 And, that sourcing your architecture-specific environment setup script
6484 initializes a suitable cross-toolchain development environment.
6485 During the setup, locations for the compiler, QEMU scripts, QEMU binary,
6486 a special version of <code class="filename">pkgconfig</code> and other useful
6487 utilities are added to the <code class="filename">PATH</code> variable.
6488 Variables to assist <code class="filename">pkgconfig</code> and <code class="filename">autotools</code>
6489 are also defined so that,
6490 for example, <code class="filename">configure.sh</code> can find pre-generated
6491 test results for tests that need target hardware on which to run.
6492 These conditions allow you to easily use the toolchain outside of the
6493 OpenEmbedded build environment on both autotools-based projects and
6494 Makefile-based projects.
6495 </p><div class="section" title="4.1. Autotools-Based Projects"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="autotools-based-projects"></a>4.1. Autotools-Based Projects</h2></div></div></div><p>
6496 For an Autotools-based project, you can use the cross-toolchain by just
6497 passing the appropriate host option to <code class="filename">configure.sh</code>.
6498 The host option you use is derived from the name of the environment setup
6499 script in <code class="filename">/opt/poky</code> resulting from unpacking the
6500 cross-toolchain tarball.
6501 For example, the host option for an ARM-based target that uses the GNU EABI
6502 is <code class="filename">armv5te-poky-linux-gnueabi</code>.
6503 Note that the name of the script is
6504 <code class="filename">environment-setup-armv5te-poky-linux-gnueabi</code>.
6505 Thus, the following command works:
6506 </p><pre class="literallayout">
6507 $ configure --host=armv5te-poky-linux-gnueabi \
6508 --with-libtool-sysroot=&lt;sysroot-dir&gt;
6509 </pre><p>
6510 </p><p>
6511 This single command updates your project and rebuilds it using the appropriate
6512 cross-toolchain tools.
6513 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
6514 If <code class="filename">configure</code> script results in problems recognizing the
6515 <code class="filename">--with-libtool-sysroot=&lt;sysroot-dir&gt;</code> option,
6516 regenerate the script to enable the support by doing the following and then
6517 re-running the script:
6518 <pre class="literallayout">
6519 $ libtoolize --automake
6520 $ aclocal -I ${OECORE_NATIVE_SYSROOT}/usr/share/aclocal \
6521 [-I &lt;dir_containing_your_project-specific_m4_macros&gt;]
6522 $ autoconf
6523 $ autoheader
6524 $ automake -a
6525 </pre></div></div><div class="section" title="4.2. Makefile-Based Projects"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="makefile-based-projects"></a>4.2. Makefile-Based Projects</h2></div></div></div><p>
6526 For a Makefile-based project, you use the cross-toolchain by making sure
6527 the tools are used.
6528 You can do this as follows:
6529 </p><pre class="literallayout">
6530 CC=arm-poky-linux-gnueabi-gcc
6531 LD=arm-poky-linux-gnueabi-ld
6532 CFLAGS=”${CFLAGS} --sysroot=&lt;sysroot-dir&gt;”
6533 CXXFLAGS=”${CXXFLAGS} --sysroot=&lt;sysroot-dir&gt;”
6534 </pre><p>
6535 </p></div></div>
6536
6537
6538
6539</div>
6540
6541<table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="100%"><tr><td align="left"><img src="figures/bsp-title.png" align="left" width="100%" /></td></tr></table>
6542
6543 <div xml:lang="en" class="book" lang="en"><div class="titlepage"><div><div><h1 class="title"><a id="bsp-guide"></a></h1></div><div><div class="authorgroup">
6544 <div class="author"><h3 class="author"><span class="firstname">Tom</span> <span class="surname">Zanussi</span></h3><div class="affiliation">
6545 <span class="orgname">Intel Corporation<br /></span>
6546 </div><code class="email">&lt;<a class="email" href="mailto:tom.zanussi@intel.com">tom.zanussi@intel.com</a>&gt;</code></div>
6547 <div class="author"><h3 class="author"><span class="firstname">Richard</span> <span class="surname">Purdie</span></h3><div class="affiliation">
6548 <span class="orgname">Linux Foundation<br /></span>
6549 </div><code class="email">&lt;<a class="email" href="mailto:richard.purdie@linuxfoundation.org">richard.purdie@linuxfoundation.org</a>&gt;</code></div>
6550 </div></div><div><p class="copyright">Copyright © 2010-2012 Linux Foundation</p></div><div><div class="legalnotice" title="Legal Notice"><a id="id1501714"></a>
6551 <p>
6552 Permission is granted to copy, distribute and/or modify this document under
6553 the terms of the <a class="ulink" href="http://creativecommons.org/licenses/by-nc-sa/2.0/uk/" target="_top">Creative Commons Attribution-Non-Commercial-Share Alike 2.0 UK: England &amp; Wales</a> as published by Creative Commons.
6554 </p>
6555 <div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
6556 Due to production processes, there could be differences between the Yocto Project
6557 documentation bundled in the release tarball and the
6558 Yocto Project Board Support Package (BSP) Developer's Guide on
6559 the <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project</a> website.
6560 For the latest version of this manual, see the manual on the website.
6561 </div>
6562 </div></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr>
6563 <tr><td align="left">Revision 0.9</td><td align="left">24 November 2010</td></tr><tr><td align="left" colspan="2">The initial document draft released with the Yocto Project 0.9 Release.</td></tr>
6564 <tr><td align="left">Revision 1.0</td><td align="left">6 April 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0 Release.</td></tr>
6565 <tr><td align="left">Revision 1.0.1</td><td align="left">23 May 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0.1 Release.</td></tr>
6566 <tr><td align="left">Revision 1.1</td><td align="left">6 October 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.1 Release.</td></tr>
6567 <tr><td align="left">Revision 1.2</td><td align="left">April 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.2 Release.</td></tr>
6568 <tr><td align="left">Revision 1.3</td><td align="left">Sometime in 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.3 Release.</td></tr>
6569 </table></div></div></div><hr /></div>
6570
6571
6572 <div class="chapter" title="Chapter 1. Board Support Packages (BSP) - Developer's Guide"><div class="titlepage"><div><div><h2 class="title"><a id="bsp"></a>Chapter 1. Board Support Packages (BSP) - Developer's Guide</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#bsp-layers">1.1. BSP Layers</a></span></dt><dt><span class="section"><a href="#bsp-filelayout">1.2. Example Filesystem Layout</a></span></dt><dd><dl><dt><span class="section"><a href="#bsp-filelayout-license">1.2.1. License Files</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-readme">1.2.2. README File</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-readme-sources">1.2.3. README.sources File</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-binary">1.2.4. Pre-built User Binaries</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-layer">1.2.5. Layer Configuration File</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-machine">1.2.6. Hardware Configuration Options</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-misc-recipes">1.2.7. Miscellaneous Recipe Files</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-core-recipes">1.2.8. Core Recipe Files</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-recipes-graphics">1.2.9. Display Support Files</a></span></dt><dt><span class="section"><a href="#bsp-filelayout-kernel">1.2.10. Linux Kernel Configuration</a></span></dt></dl></dd><dt><span class="section"><a href="#requirements-and-recommendations-for-released-bsps">1.3. Requirements and Recommendations for Released BSPs</a></span></dt><dd><dl><dt><span class="section"><a href="#released-bsp-requirements">1.3.1. Released BSP Requirements</a></span></dt><dt><span class="section"><a href="#released-bsp-recommendations">1.3.2. Released BSP Recommendations</a></span></dt></dl></dd><dt><span class="section"><a href="#customizing-a-recipe-for-a-bsp">1.4. Customizing a Recipe for a BSP</a></span></dt><dt><span class="section"><a href="#bsp-licensing-considerations">1.5. BSP Licensing Considerations</a></span></dt><dt><span class="section"><a href="#using-the-yocto-projects-bsp-tools">1.6. Using the Yocto Project's BSP Tools</a></span></dt><dd><dl><dt><span class="section"><a href="#common-features">1.6.1. Common Features</a></span></dt><dt><span class="section"><a href="#creating-a-new-bsp-layer-using-the-yocto-bsp-script">1.6.2. Creating a new BSP Layer Using the yocto-bsp Script</a></span></dt><dt><span class="section"><a href="#managing-kernel-patches-and-config-items-with-yocto-kernel">1.6.3. Managing Kernel Patches and Config Items with yocto-kernel</a></span></dt></dl></dd></dl></div><p>
6573 A Board Support Package (BSP) is a collection of information that
6574 defines how to support a particular hardware device, set of devices, or
6575 hardware platform.
6576 The BSP includes information about the hardware features
6577 present on the device and kernel configuration information along with any
6578 additional hardware drivers required.
6579 The BSP also lists any additional software
6580 components required in addition to a generic Linux software stack for both
6581 essential and optional platform features.
6582 </p><p>
6583 This chapter (or document if you are reading the BSP Developer's Guide)
6584 talks about BSP Layers, defines a structure for components
6585 so that BSPs follow a commonly understood layout, discusses how to customize
6586 a recipe for a BSP, addresses BSP licensing, and provides information that
6587 shows you how to create and manage a
6588 <a class="link" href="#bsp-layers" title="1.1. BSP Layers">BSP Layer</a> using two Yocto Project
6589 <a class="link" href="#using-the-yocto-projects-bsp-tools" title="1.6. Using the Yocto Project's BSP Tools">BSP Tools</a>.
6590 </p><div class="section" title="1.1. BSP Layers"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="bsp-layers"></a>1.1. BSP Layers</h2></div></div></div><p>
6591 The BSP consists of a file structure inside a base directory.
6592 Collectively, you can think of the base directory and the file structure
6593 as a BSP Layer.
6594 BSP Layers use the following naming convention:
6595 </p><pre class="literallayout">
6596 meta-&lt;bsp_name&gt;
6597 </pre><p>
6598 "bsp_name" is a placeholder for the machine or platform name.
6599 </p><p>
6600 The layer's base directory (<code class="filename">meta-&lt;bsp_name&gt;</code>) is the root
6601 of the BSP Layer.
6602 This root is what you add to the
6603 <a class="link" href="#var-BBLAYERS" target="_top"><code class="filename">BBLAYERS</code></a>
6604 variable in the <code class="filename">conf/bblayers.conf</code> file found in the
6605 <a class="link" href="#build-directory" target="_top">build directory</a>.
6606 Adding the root allows the OpenEmbedded build system to recognize the BSP
6607 definition and from it build an image.
6608 Here is an example:
6609 </p><pre class="literallayout">
6610 BBLAYERS = " \
6611 /usr/local/src/yocto/meta \
6612 /usr/local/src/yocto/meta-yocto \
6613 /usr/local/src/yocto/meta-&lt;bsp_name&gt; \
6614 "
6615 </pre><p>
6616 </p><p>
6617 Some BSPs require additional layers on
6618 top of the BSP's root layer in order to be functional.
6619 For these cases, you also need to add those layers to the
6620 <code class="filename">BBLAYERS</code> variable in order to build the BSP.
6621 You must also specify in the "Dependencies" section of the BSP's
6622 <code class="filename">README</code> file any requirements for additional
6623 layers and, preferably, any
6624 build instructions that might be contained elsewhere
6625 in the <code class="filename">README</code> file.
6626 </p><p>
6627 Some layers function as a layer to hold other BSP layers.
6628 An example of this type of layer is the <code class="filename">meta-intel</code> layer.
6629 The <code class="filename">meta-intel</code> layer contains over 10 individual BSP layers.
6630 </p><p>
6631 For more detailed information on layers, see the
6632 "<a class="link" href="#understanding-and-creating-layers" target="_top">Understanding and Creating Layers</a>"
6633 section of the Yocto Project Development Manual.
6634 You can also see the detailed examples in the appendices of the
6635 Yocto Project Development Manual.
6636 </p></div><div class="section" title="1.2. Example Filesystem Layout"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="bsp-filelayout"></a>1.2. Example Filesystem Layout</h2></div></div></div><p>
6637 Providing a common form allows end-users to understand and become familiar
6638 with the layout.
6639 A common format also encourages standardization of software support of hardware.
6640 </p><p>
6641 The proposed form does have elements that are specific to the
6642 OpenEmbedded build system.
6643 It is intended that this information can be
6644 used by other build systems besides the OpenEmbedded build system
6645 and that it will be simple
6646 to extract information and convert it to other formats if required.
6647 The OpenEmbedded build system, through its standard layers mechanism, can directly
6648 accept the format described as a layer.
6649 The BSP captures all
6650 the hardware-specific details in one place in a standard format, which is
6651 useful for any person wishing to use the hardware platform regardless of
6652 the build system they are using.
6653 </p><p>
6654 The BSP specification does not include a build system or other tools -
6655 it is concerned with the hardware-specific components only.
6656 At the end-distribution point, you can ship the BSP combined with a build system
6657 and other tools.
6658 However, it is important to maintain the distinction that these
6659 are separate components that happen to be combined in certain end products.
6660 </p><p>
6661 Before looking at the common form for the file structure inside a BSP Layer,
6662 you should be aware that some requirements do exist in order for a BSP to
6663 be considered compliant with the Yocto Project.
6664 For that list of requirements, see the
6665 "<a class="link" href="#released-bsp-requirements" title="1.3.1. Released BSP Requirements">Released BSP Requirements</a>"
6666 section.
6667 </p><p>
6668 Below is the common form for the file structure inside a BSP Layer.
6669 While you can use this basic form for the standard, realize that the actual structures
6670 for specific BSPs could differ.
6671
6672 </p><pre class="literallayout">
6673 meta-&lt;bsp_name&gt;/
6674 meta-&lt;bsp_name&gt;/&lt;bsp_license_file&gt;
6675 meta-&lt;bsp_name&gt;/README
6676 meta-&lt;bsp_name&gt;/README.sources
6677 meta-&lt;bsp_name&gt;/binary/&lt;bootable_images&gt;
6678 meta-&lt;bsp_name&gt;/conf/layer.conf
6679 meta-&lt;bsp_name&gt;/conf/machine/*.conf
6680 meta-&lt;bsp_name&gt;/recipes-bsp/*
6681 meta-&lt;bsp_name&gt;/recipes-core/*
6682 meta-&lt;bsp_name&gt;/recipes-graphics/*
6683 meta-&lt;bsp_name&gt;/recipes-kernel/linux/linux-yocto_&lt;kernel_rev&gt;.bbappend
6684 </pre><p>
6685 </p><p>
6686 Below is an example of the Crown Bay BSP:
6687
6688 </p><pre class="literallayout">
6689 meta-crownbay/COPYING.MIT
6690 meta-crownbay/README
6691 meta-crownbay/README.sources
6692 meta-crownbay/binary/
6693 meta-crownbay/conf/
6694 meta-crownbay/conf/layer.conf
6695 meta-crownbay/conf/machine/
6696 meta-crownbay/conf/machine/crownbay.conf
6697 meta-crownbay/conf/machine/crownbay-noemgd.conf
6698 meta-crownbay/recipes-bsp/
6699 meta-crownbay/recipes-bsp/formfactor/
6700 meta-crownbay/recipes-bsp/formfactor/formfactor_0.0.bbappend
6701 meta-crownbay/recipes-bsp/formfactor/formfactor/
6702 meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/
6703 meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/machconfig
6704 meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay-noemgd/
6705 meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay-noemgd/machconfig
6706 meta-crownbay/recipes-core/
6707 meta-crownbay/recipes-core/tasks/
6708 meta-crownbay/recipes-core/tasks/task-core-tools-profile.bbappend
6709 meta-crownbay/recipes-graphics/
6710 meta-crownbay/recipes-graphics/xorg-xserver/
6711 meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config_0.1.bbappend
6712 meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/
6713 meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/
6714 meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/xorg.conf
6715 meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd/
6716 meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd/xorg.conf
6717 meta-crownbay/recipes-kernel/
6718 meta-crownbay/recipes-kernel/linux/
6719 meta-crownbay/recipes-kernel/linux/linux-yocto-rt_3.0.bbappend
6720 meta-crownbay/recipes-kernel/linux/linux-yocto_2.6.37.bbappend
6721 meta-crownbay/recipes-kernel/linux/linux-yocto_3.0.bbappend
6722 </pre><p>
6723 </p><p>
6724 The following sections describe each part of the proposed BSP format.
6725 </p><div class="section" title="1.2.1. License Files"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-license"></a>1.2.1. License Files</h3></div></div></div><p>
6726 You can find these files in the BSP Layer at:
6727 </p><pre class="literallayout">
6728 meta-&lt;bsp_name&gt;/&lt;bsp_license_file&gt;
6729 </pre><p>
6730 </p><p>
6731 These optional files satisfy licensing requirements for the BSP.
6732 The type or types of files here can vary depending on the licensing requirements.
6733 For example, in the Crown Bay BSP all licensing requirements are handled with the
6734 <code class="filename">COPYING.MIT</code> file.
6735 </p><p>
6736 Licensing files can be MIT, BSD, GPLv*, and so forth.
6737 These files are recommended for the BSP but are optional and totally up to the BSP developer.
6738 </p></div><div class="section" title="1.2.2. README File"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-readme"></a>1.2.2. README File</h3></div></div></div><p>
6739 You can find this file in the BSP Layer at:
6740 </p><pre class="literallayout">
6741 meta-&lt;bsp_name&gt;/README
6742 </pre><p>
6743 </p><p>
6744 This file provides information on how to boot the live images that are optionally
6745 included in the <code class="filename">binary/</code> directory.
6746 The <code class="filename">README</code> file also provides special information needed for
6747 building the image.
6748 </p><p>
6749 At a minimum, the <code class="filename">README</code> file must
6750 contain a list of dependencies, such as the names of
6751 any other layers on which the BSP depends and the name of
6752 the BSP maintainer with his or her contact information.
6753 </p></div><div class="section" title="1.2.3. README.sources File"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-readme-sources"></a>1.2.3. README.sources File</h3></div></div></div><p>
6754 You can find this file in the BSP Layer at:
6755 </p><pre class="literallayout">
6756 meta-&lt;bsp_name&gt;/README.sources
6757 </pre><p>
6758 </p><p>
6759 This file provides information on where to locate the BSP source files.
6760 For example, information provides where to find the sources that comprise
6761 the images shipped with the BSP.
6762 Information is also included to help you find the metadata used to generate the images
6763 that ship with the BSP.
6764 </p></div><div class="section" title="1.2.4. Pre-built User Binaries"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-binary"></a>1.2.4. Pre-built User Binaries</h3></div></div></div><p>
6765 You can find these files in the BSP Layer at:
6766 </p><pre class="literallayout">
6767 meta-&lt;bsp_name&gt;/binary/&lt;bootable_images&gt;
6768 </pre><p>
6769 </p><p>
6770 This optional area contains useful pre-built kernels and user-space filesystem
6771 images appropriate to the target system.
6772 This directory typically contains graphical (e.g. sato) and minimal live images
6773 when the BSP tarball has been created and made available in the
6774 <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project</a> website.
6775 You can use these kernels and images to get a system running and quickly get started
6776 on development tasks.
6777 </p><p>
6778 The exact types of binaries present are highly hardware-dependent.
6779 However, a README file should be present in the BSP Layer that explains how to use
6780 the kernels and images with the target hardware.
6781 If pre-built binaries are present, source code to meet licensing requirements must also
6782 exist in some form.
6783 </p></div><div class="section" title="1.2.5. Layer Configuration File"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-layer"></a>1.2.5. Layer Configuration File</h3></div></div></div><p>
6784 You can find this file in the BSP Layer at:
6785 </p><pre class="literallayout">
6786 meta-&lt;bsp_name&gt;/conf/layer.conf
6787 </pre><p>
6788 </p><p>
6789 The <code class="filename">conf/layer.conf</code> file identifies the file structure as a
6790 layer, identifies the
6791 contents of the layer, and contains information about how the build
6792 system should use it.
6793 Generally, a standard boilerplate file such as the following works.
6794 In the following example, you would replace "<code class="filename">bsp</code>" and
6795 "<code class="filename">_bsp</code>" with the actual name
6796 of the BSP (i.e. <code class="filename">&lt;bsp_name&gt;</code> from the example template).
6797 </p><p>
6798 </p><pre class="literallayout">
6799 # We have a conf and classes directory, add to BBPATH
6800 BBPATH := "${BBPATH}:${LAYERDIR}"
6801
6802 # We have a recipes directory, add to BBFILES
6803 BBFILES := "${BBFILES} ${LAYERDIR}/recipes-*/*.bb \
6804 ${LAYERDIR}/recipes-*/*.bbappend"
6805
6806 BBFILE_COLLECTIONS += "bsp"
6807 BBFILE_PATTERN_bsp := "^${LAYERDIR}/"
6808 BBFILE_PRIORITY_bsp = "6"
6809 </pre><p>
6810 </p><p>
6811 To illustrate the string substitutions, here are the last three statements from the Crown
6812 Bay <code class="filename">conf/layer.conf</code> file:
6813 </p><pre class="literallayout">
6814 BBFILE_COLLECTIONS += "crownbay"
6815 BBFILE_PATTERN_crownbay := "^${LAYERDIR}/"
6816 BBFILE_PRIORITY_crownbay = "6"
6817 </pre><p>
6818 </p><p>
6819 This file simply makes BitBake aware of the recipes and configuration directories.
6820 The file must exist so that the OpenEmbedded build system can recognize the BSP.
6821 </p></div><div class="section" title="1.2.6. Hardware Configuration Options"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-machine"></a>1.2.6. Hardware Configuration Options</h3></div></div></div><p>
6822 You can find these files in the BSP Layer at:
6823 </p><pre class="literallayout">
6824 meta-&lt;bsp_name&gt;/conf/machine/*.conf
6825 </pre><p>
6826 </p><p>
6827 The machine files bind together all the information contained elsewhere
6828 in the BSP into a format that the build system can understand.
6829 If the BSP supports multiple machines, multiple machine configuration files
6830 can be present.
6831 These filenames correspond to the values to which users have set the
6832 <a class="link" href="#var-MACHINE" target="_top"><code class="filename">MACHINE</code></a> variable.
6833 </p><p>
6834 These files define things such as the kernel package to use
6835 (<a class="link" href="#var-PREFERRED_PROVIDER" target="_top"><code class="filename">PREFERRED_PROVIDER</code></a>
6836 of virtual/kernel), the hardware drivers to
6837 include in different types of images, any special software components
6838 that are needed, any bootloader information, and also any special image
6839 format requirements.
6840 </p><p>
6841 Each BSP Layer requires at least one machine file.
6842 However, you can supply more than one file.
6843 For example, in the Crown Bay BSP shown earlier in this section, the
6844 <code class="filename">conf/machine</code> directory contains two configuration files:
6845 <code class="filename">crownbay.conf</code> and <code class="filename">crownbay-noemgd.conf</code>.
6846 The <code class="filename">crownbay.conf</code> file is used for the Crown Bay BSP
6847 that supports the <span class="trademark">Intel</span>® Embedded
6848 Media and Graphics Driver (<span class="trademark">Intel</span>®
6849 EMGD), while the <code class="filename">crownbay-noemgd.conf</code> file is used for the
6850 Crown Bay BSP that does not support the <span class="trademark">Intel</span>®
6851 EMGD.
6852 </p><p>
6853 This <code class="filename">crownbay.conf</code> file could also include
6854 a hardware "tuning" file that is commonly used to
6855 define the package architecture and specify
6856 optimization flags, which are carefully chosen to give best
6857 performance on a given processor.
6858 </p><p>
6859 Tuning files are found in the <code class="filename">meta/conf/machine/include</code>
6860 directory within the
6861 <a class="link" href="#source-directory" target="_top">source directory</a>.
6862 Tuning files can also reside in the BSP Layer itself.
6863 For example, the <code class="filename">ia32-base.inc</code> file resides in the
6864 <code class="filename">meta-intel</code> BSP Layer in <code class="filename">conf/machine/include</code>.
6865 </p><p>
6866 To use an include file, you simply include them in the machine configuration file.
6867 For example, the Crown Bay BSP <code class="filename">crownbay.conf</code> has the
6868 following statements:
6869 </p><pre class="literallayout">
6870 include conf/machine/include/tune-atom.inc
6871 include conf/machine/include/ia32-base.inc
6872 </pre><p>
6873 </p></div><div class="section" title="1.2.7. Miscellaneous Recipe Files"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-misc-recipes"></a>1.2.7. Miscellaneous Recipe Files</h3></div></div></div><p>
6874 You can find these files in the BSP Layer at:
6875 </p><pre class="literallayout">
6876 meta-&lt;bsp_name&gt;/recipes-bsp/*
6877 </pre><p>
6878 </p><p>
6879 This optional directory contains miscellaneous recipe files for the BSP.
6880 Most notably would be the formfactor files.
6881 For example, in the Crown Bay BSP there is the
6882 <code class="filename">formfactor_0.0.bbappend</code> file, which is an append file used
6883 to augment the recipe that starts the build.
6884 Furthermore, there are machine-specific settings used during the build that are
6885 defined by the <code class="filename">machconfig</code> files.
6886 In the Crown Bay example, two <code class="filename">machconfig</code> files exist:
6887 one that supports the
6888 <span class="trademark">Intel</span>® Embedded
6889 Media and Graphics Driver (<span class="trademark">Intel</span>®
6890 EMGD) and one that does not:
6891 </p><pre class="literallayout">
6892 meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/machconfig
6893 meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay-noemgd/machconfig
6894 meta-crownbay/recipes-bsp/formfactor/formfactor_0.0.bbappend
6895 </pre><p>
6896 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
6897 If a BSP does not have a formfactor entry, defaults are established according to
6898 the formfactor configuration file that is installed by the main
6899 formfactor recipe
6900 <code class="filename">meta/recipes-bsp/formfactor/formfactor_0.0.bb</code>,
6901 which is found in the
6902 <a class="link" href="#source-directory" target="_top">source directory</a>.
6903 </p></div></div><div class="section" title="1.2.8. Core Recipe Files"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-core-recipes"></a>1.2.8. Core Recipe Files</h3></div></div></div><p>
6904 You can find these files in the BSP Layer at:
6905 </p><pre class="literallayout">
6906 meta-&lt;bsp_name&gt;/recipes-core/*
6907 </pre><p>
6908 </p><p>
6909 This directory contains recipe files that are almost always necessary to build a
6910 useful, working Linux image.
6911 Thus, the term "core" is used to group these recipes.
6912 For example, in the Crown Bay BSP there is the
6913 <code class="filename">task-core-tools-profile.bbappend</code> file, which is an append file used
6914 to recommend that the
6915 <a class="ulink" href="http://sourceware.org/systemtap/wiki" target="_top">SystemTap</a>
6916 package be included as a package when the image is built.
6917 </p></div><div class="section" title="1.2.9. Display Support Files"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-recipes-graphics"></a>1.2.9. Display Support Files</h3></div></div></div><p>
6918 You can find these files in the BSP Layer at:
6919 </p><pre class="literallayout">
6920 meta-&lt;bsp_name&gt;/recipes-graphics/*
6921 </pre><p>
6922 </p><p>
6923 This optional directory contains recipes for the BSP if it has
6924 special requirements for graphics support.
6925 All files that are needed for the BSP to support a display are kept here.
6926 For example, the Crown Bay BSP contains two versions of the
6927 <code class="filename">xorg.conf</code> file.
6928 The version in <code class="filename">crownbay</code> builds a BSP that supports the
6929 <span class="trademark">Intel</span>® Embedded Media Graphics Driver (EMGD),
6930 while the version in <code class="filename">crownbay-noemgd</code> builds
6931 a BSP that supports Video Electronics Standards Association (VESA) graphics only:
6932 </p><pre class="literallayout">
6933 meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config_0.1.bbappend
6934 meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/xorg.conf
6935 meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd/xorg.conf
6936 </pre><p>
6937 </p></div><div class="section" title="1.2.10. Linux Kernel Configuration"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-filelayout-kernel"></a>1.2.10. Linux Kernel Configuration</h3></div></div></div><p>
6938 You can find these files in the BSP Layer at:
6939 </p><pre class="literallayout">
6940 meta-&lt;bsp_name&gt;/recipes-kernel/linux/linux-yocto_*.bbappend
6941 </pre><p>
6942 </p><p>
6943 These files append your specific changes to the main kernel recipe you are using.
6944 </p><p>
6945 For your BSP, you typically want to use an existing Yocto Project kernel recipe found in the
6946 <a class="link" href="#source-directory" target="_top">source directory</a>
6947 at <code class="filename">meta/recipes-kernel/linux</code>.
6948 You can append your specific changes to the kernel recipe by using a
6949 similarly named append file, which is located in the BSP Layer (e.g.
6950 the <code class="filename">meta-&lt;bsp_name&gt;/recipes-kernel/linux</code> directory).
6951 </p><p>
6952 Suppose you are using the <code class="filename">linux-yocto_3.4.bb</code> recipe to build
6953 the kernel.
6954 In other words, you have selected the kernel in your
6955 <code class="filename">&lt;bsp_name&gt;.conf</code> file by adding the following statements:
6956 </p><pre class="literallayout">
6957 PREFERRED_PROVIDER_virtual/kernel ?= "linux-yocto"
6958 PREFERRED_VERSION_linux-yocto = "3.4%"
6959 </pre><p>
6960 You would use the <code class="filename">linux-yocto_3.4.bbappend</code> file to append
6961 specific BSP settings to the kernel, thus configuring the kernel for your particular BSP.
6962 </p><p>
6963 As an example, look at the existing Crown Bay BSP.
6964 The append file used is:
6965 </p><pre class="literallayout">
6966 meta-crownbay/recipes-kernel/linux/linux-yocto_3.4.bbappend
6967 </pre><p>
6968 The following listing shows the file.
6969 Be aware that the actual commit ID strings in this example listing might be different
6970 than the actual strings in the file from the <code class="filename">meta-intel</code>
6971 Git source repository.
6972 </p><pre class="literallayout">
6973 FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
6974
6975 COMPATIBLE_MACHINE_crownbay = "crownbay"
6976 KMACHINE_crownbay = "crownbay"
6977 KBRANCH_crownbay = "standard/default/crownbay"
6978
6979 COMPATIBLE_MACHINE_crownbay-noemgd = "crownbay-noemgd"
6980 KMACHINE_crownbay-noemgd = "crownbay"
6981 KBRANCH_crownbay-noemgd = "standard/default/crownbay"
6982
6983 SRCREV_machine_pn-linux-yocto_crownbay ?= "48101e609711fcfe8d5e737a37a5a69f4bd57d9a"
6984 SRCREV_meta_pn-linux-yocto_crownbay ?= "5b4c9dc78b5ae607173cc3ddab9bce1b5f78129b"
6985
6986 SRCREV_machine_pn-linux-yocto_crownbay-noemgd ?= "48101e609711fcfe8d5e737a37a5a69f4bd57d9a"
6987 SRCREV_meta_pn-linux-yocto_crownbay-noemgd ?= "5b4c9dc78b5ae607173cc3ddab9bce1b5f78129b"
6988 </pre><p>
6989 This append file contains statements used to support the Crown Bay BSP for both
6990 <span class="trademark">Intel</span>® EMGD and the VESA graphics.
6991 The build process, in this case, recognizes and uses only the statements that
6992 apply to the defined machine name - <code class="filename">crownbay</code> in this case.
6993 So, the applicable statements in the <code class="filename">linux-yocto_3.4.bbappend</code>
6994 file are follows:
6995 </p><pre class="literallayout">
6996 FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
6997
6998 COMPATIBLE_MACHINE_crownbay = "crownbay"
6999 KMACHINE_crownbay = "crownbay"
7000 KBRANCH_crownbay = "standard/default/crownbay"
7001
7002 SRCREV_machine_pn-linux-yocto_crownbay ?= "48101e609711fcfe8d5e737a37a5a69f4bd57d9a"
7003 SRCREV_meta_pn-linux-yocto_crownbay ?= "5b4c9dc78b5ae607173cc3ddab9bce1b5f78129b"
7004 </pre><p>
7005 The append file defines <code class="filename">crownbay</code> as the
7006 <a class="link" href="#var-COMPATIBLE_MACHINE" target="_top"><code class="filename">COMPATIBLE_MACHINE</code></a>
7007 and uses the
7008 <a class="link" href="#var-KMACHINE" target="_top"><code class="filename">KMACHINE</code></a> variable to
7009 ensure the machine name used by the OpenEmbedded build system maps to the
7010 machine name used by the Linux Yocto kernel.
7011 The file also uses the optional
7012 <a class="link" href="#var-KBRANCH" target="_top"><code class="filename">KBRANCH</code></a> variable
7013 to ensure the build process uses the <code class="filename">standard/default/crownbay</code>
7014 kernel branch.
7015 Finally, the append file points to the specific top commits in the
7016 <a class="link" href="#source-directory" target="_top">source directory</a> Git
7017 repository and the <code class="filename">meta</code> Git repository branches to identify the
7018 exact kernel needed to build the Crown Bay BSP.
7019 </p><p>
7020 One thing missing in this particular BSP, which you will typically need when
7021 developing a BSP, is the kernel configuration file (<code class="filename">.config</code>) for your BSP.
7022 When developing a BSP, you probably have a kernel configuration file or a set of kernel
7023 configuration files that, when taken together, define the kernel configuration for your BSP.
7024 You can accomplish this definition by putting the configurations in a file or a set of files
7025 inside a directory located at the same level as your kernel's append file and having the same
7026 name as the kernel's main recipe file.
7027 With all these conditions met, simply reference those files in a
7028 <code class="filename">SRC_URI</code> statement in the append file.
7029 </p><p>
7030 For example, suppose you had a some configuration options in a file called
7031 <code class="filename">network_configs.cfg</code>.
7032 You can place that file inside a directory named <code class="filename">/linux-yocto</code> and then add
7033 a <code class="filename">SRC_URI</code> statement such as the following to the append file.
7034 When the OpenEmbedded build system builds the kernel, the configuration options are
7035 picked up and applied.
7036 </p><pre class="literallayout">
7037 SRC_URI += "file://network_configs.cfg"
7038 </pre><p>
7039 </p><p>
7040 To group related configurations into multiple files, you perform a similar procedure.
7041 Here is an example that groups separate configurations specifically for Ethernet and graphics
7042 into their own files and adds the configurations
7043 by using a <code class="filename">SRC_URI</code> statement like the following in your append file:
7044 </p><pre class="literallayout">
7045 SRC_URI += "file://myconfig.cfg \
7046 file://eth.cfg \
7047 file://gfx.cfg"
7048 </pre><p>
7049 </p><p>
7050 The <code class="filename">FILESEXTRAPATHS</code> variable is in boilerplate form in the
7051 previous example in order to make it easy to do that.
7052 This variable must be in your layer or BitBake will not find the patches or
7053 configurations even if you have them in your <code class="filename">SRC_URI</code>.
7054 The <code class="filename">FILESEXTRAPATHS</code> variable enables the build process to
7055 find those configuration files.
7056 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>
7057 Other methods exist to accomplish grouping and defining configuration options.
7058 For example, if you are working with a local clone of the kernel repository,
7059 you could checkout the kernel's <code class="filename">meta</code> branch, make your changes,
7060 and then push the changes to the local bare clone of the kernel.
7061 The result is that you directly add configuration options to the
7062 <code class="filename">meta</code> branch for your BSP.
7063 The configuration options will likely end up in that location anyway if the BSP gets
7064 added to the Yocto Project.
7065 For an example showing how to change the BSP configuration, see the
7066 "<a class="link" href="#changing-the-bsp-configuration" target="_top">Changing the BSP Configuration</a>"
7067 section in the Yocto Project Development Manual.
7068 For a better understanding of working with a local clone of the kernel repository
7069 and a local bare clone of the kernel, see the
7070 "<a class="link" href="#modifying-the-kernel-source-code" target="_top">Modifying the Kernel
7071 Source Code</a>" section also in the Yocto Project Development Manual.
7072 </p><p>
7073 In general, however, the Yocto Project maintainers take care of moving the
7074 <code class="filename">SRC_URI</code>-specified
7075 configuration options to the kernel's <code class="filename">meta</code> branch.
7076 Not only is it easier for BSP developers to not have to worry about putting those
7077 configurations in the branch, but having the maintainers do it allows them to apply
7078 'global' knowledge about the kinds of common configuration options multiple BSPs in
7079 the tree are typically using.
7080 This allows for promotion of common configurations into common features.
7081 </p></div></div></div><div class="section" title="1.3. Requirements and Recommendations for Released BSPs"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="requirements-and-recommendations-for-released-bsps"></a>1.3. Requirements and Recommendations for Released BSPs</h2></div></div></div><p>
7082 Certain requirements exist for a released BSP to be considered
7083 compliant with the Yocto Project.
7084 Additionally, a single recommendation also exists.
7085 This section describes the requirements and recommendation for
7086 released BSPs.
7087 </p><div class="section" title="1.3.1. Released BSP Requirements"><div class="titlepage"><div><div><h3 class="title"><a id="released-bsp-requirements"></a>1.3.1. Released BSP Requirements</h3></div></div></div><p>
7088 Before looking at BSP requirements, you should consider the following:
7089 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The requirements here assume the BSP layer is a well-formed, "legal"
7090 layer that can be added to the Yocto Project.
7091 For guidelines on creating a layer that meets these base requirements, see the
7092 "<a class="link" href="#bsp-layers" title="1.1. BSP Layers">BSP Layers</a>" and the
7093 "<a class="link" href="#understanding-and-creating-layers" target="_top">Understanding
7094 and Creating Layers"</a> in the Yocto Project Development Manual.</p></li><li class="listitem"><p>The requirements in this section apply regardless of how you
7095 ultimately package a BSP.
7096 You should consult the packaging and distribution guidelines for your
7097 specific release process.
7098 For an example of packaging and distribution requirements, see the
7099 <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Third_Party_BSP_Release_Process" target="_top">Third
7100 Party BSP Release Process</a> wiki page.</p></li><li class="listitem"><p>The requirements for the BSP as it is made available to a developer
7101 are completely independent of the released form of the BSP.
7102 For example, the BSP metadata can be contained within a Git repository
7103 and could have a directory structure completely different from what appears
7104 in the officially released BSP layer.</p></li><li class="listitem"><p>It is not required that specific packages or package
7105 modifications exist in the BSP layer, beyond the requirements for general
7106 compliance with the Yocto Project.
7107 For example, no requirement exists dictating that a specific kernel or
7108 kernel version be used in a given BSP.</p></li></ul></div><p>
7109 </p><p>
7110 Following are the requirements for a released BSP that conforms to the
7111 Yocto Project:
7112 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Layer Name:</em></span>
7113 The BSP must have a layer name that follows the Yocto
7114 Project standards.
7115 For information on BSP layer names, see the
7116 "<a class="link" href="#bsp-layers" title="1.1. BSP Layers">BSP Layers</a>" section.
7117 </p></li><li class="listitem"><p><span class="emphasis"><em>File System Layout:</em></span>
7118 When possible, use the same directory names in your
7119 BSP layer as listed in the <code class="filename">recipes.txt</code> file.
7120 In particular, you should place recipes
7121 (<code class="filename">.bb</code> files) and recipe
7122 modifications (<code class="filename">.bbappend</code> files) into
7123 <code class="filename">recipes-*</code> subdirectories by functional area
7124 as outlined in <code class="filename">recipes.txt</code>.
7125 If you cannot find a category in <code class="filename">recipes.txt</code>
7126 to fit a particular recipe, you can make up your own
7127 <code class="filename">recipe-*</code> subdirectory.
7128 You can find <code class="filename">recipes.txt</code> in the
7129 <code class="filename">meta</code> directory of the
7130 <a class="link" href="#source-directory" target="_top">source directory</a>,
7131 or in the OpenEmbedded Core Layer
7132 (<code class="filename">openembedded-core</code>) found at
7133 <a class="ulink" href="http://git.openembedded.org/openembedded-core/tree/meta" target="_top">http://git.openembedded.org/openembedded-core/tree/meta</a>.
7134 </p><p>Within any particular <code class="filename">recipes-*</code> category, the layout
7135 should match what is found in the OpenEmbedded Core
7136 Git repository (<code class="filename">openembedded-core</code>)
7137 or the source directory (<code class="filename">poky</code>).
7138 In other words, make sure you place related files in appropriately
7139 related <code class="filename">recipes-*</code> subdirectories specific to the
7140 recipe's function, or within a subdirectory containing a set of closely-related
7141 recipes.
7142 The recipes themselves should follow the general guidelines
7143 for recipes used in the Yocto Project found in the
7144 <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Recipe_%26_Patch_Style_Guide" target="_top">Yocto
7145 Recipe and Patch Style Guide</a>.</p></li><li class="listitem"><p><span class="emphasis"><em>License File:</em></span>
7146 You must include a license file in the
7147 <code class="filename">meta-&lt;bsp_name&gt;</code> directory.
7148 This license covers the BSP metadata as a whole.
7149 You must specify which license to use since there is no
7150 default license if one is not specified.
7151 See the
7152 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/meta-intel/tree/meta-fishriver/COPYING.MIT" target="_top"><code class="filename">COPYING.MIT</code></a>
7153 file for the Fish River BSP in the <code class="filename">meta-fishriver</code> BSP layer
7154 as an example.</p></li><li class="listitem"><p><span class="emphasis"><em>README File:</em></span>
7155 You must include a <code class="filename">README</code> file in the
7156 <code class="filename">meta-&lt;bsp_name&gt;</code> directory.
7157 See the
7158 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/meta-intel/tree/meta-fishriver/README" target="_top"><code class="filename">README</code></a>
7159 file for the Fish River BSP in the <code class="filename">meta-fishriver</code> BSP layer
7160 as an example.</p><p>At a minimum, the <code class="filename">README</code> file should
7161 contain the following:
7162 </p><div class="itemizedlist"><ul class="itemizedlist" type="circle"><li class="listitem"><p>A brief description about the hardware the BSP
7163 targets.</p></li><li class="listitem"><p>A list of all the dependencies a
7164 on which a BSP layer depends.
7165 These dependencies are typically a list of required layers needed
7166 to build the BSP.
7167 However, the dependencies should also contain information regarding
7168 any other dependencies the BSP might have.</p></li><li class="listitem"><p>Any required special licensing information.
7169 For example, this information includes information on
7170 special variables needed to satisfy a EULA,
7171 or instructions on information needed to build or distribute
7172 binaries built from the BSP metadata.</p></li><li class="listitem"><p>The name and contact information for the
7173 BSP layer maintainer.
7174 This is the person to whom patches and questions should
7175 be sent.</p></li><li class="listitem"><p>Instructions on how to build the BSP using the BSP
7176 layer.</p></li><li class="listitem"><p>Instructions on how to boot the BSP build from
7177 the BSP layer.</p></li><li class="listitem"><p>Instructions on how to boot the binary images
7178 contained in the <code class="filename">/binary</code> directory,
7179 if present.</p></li><li class="listitem"><p>Information on any known bugs or issues that users
7180 should know about when either building or booting the BSP
7181 binaries.</p></li></ul></div></li><li class="listitem"><p><span class="emphasis"><em>README.sources File:</em></span>
7182 You must include a <code class="filename">README.sources</code> in the
7183 <code class="filename">meta-&lt;bsp_name&gt;</code> directory.
7184 This file specifies exactly where you can find the sources used to
7185 generate the binary images contained in the
7186 <code class="filename">/binary</code> directory, if present.
7187 See the
7188 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/meta-intel/tree/meta-fishriver/README.sources" target="_top"><code class="filename">README.sources</code></a>
7189 file for the Fish River BSP in the <code class="filename">meta-fishriver</code> BSP layer
7190 as an example.</p></li><li class="listitem"><p><span class="emphasis"><em>Layer Configuration File:</em></span>
7191 You must include a <code class="filename">conf/layer.conf</code> in the
7192 <code class="filename">meta-&lt;bsp_name&gt;</code> directory.
7193 This file identifies the <code class="filename">meta-&lt;bsp_name&gt;</code>
7194 BSP layer as a layer to the build system.</p></li><li class="listitem"><p><span class="emphasis"><em>Machine Configuration File:</em></span>
7195 You must include a <code class="filename">conf/machine/&lt;bsp_name&gt;.conf</code>
7196 in the <code class="filename">meta-&lt;bsp_name&gt;</code> directory.
7197 This configuration file defines a machine target that can be built
7198 using the BSP layer.
7199 Multiple machine configuration files define variations of machine
7200 configurations that are supported by the BSP.
7201 If a BSP supports more multiple machine variations, you need to
7202 adequately describe each variation in the BSP
7203 <code class="filename">README</code> file.
7204 Do not use multiple machine configuration files to describe disparate
7205 hardware.
7206 Multiple machine configuration files should describe very similar targets.
7207 If you do have very different targets, you should create a separate
7208 BSP.
7209 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>It is completely possible for a developer to structure the
7210 working repository as a conglomeration of unrelated BSP
7211 files, and to possibly generate specifically targeted 'release' BSPs
7212 from that directory using scripts or some other mechanism.
7213 Such considerations are outside the scope of this document.</div><p>
7214 </p></li></ul></div><p>
7215 </p></div><div class="section" title="1.3.2. Released BSP Recommendations"><div class="titlepage"><div><div><h3 class="title"><a id="released-bsp-recommendations"></a>1.3.2. Released BSP Recommendations</h3></div></div></div><p>
7216 Following are recommendations for a released BSP that conforms to the
7217 Yocto Project:
7218 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Bootable Images:</em></span>
7219 BSP releases
7220 can contain one or more bootable images.
7221 Including bootable images allows users to easily try out the BSP
7222 on their own hardware.</p><p>In some cases, it might not be convenient to include a
7223 bootable image.
7224 In this case, you might want to make two versions of the
7225 BSP available: one that contains binary images, and one
7226 that does not.
7227 The version that does not contain bootable images avoids
7228 unnecessary download times for users not interested in the images.
7229 </p><p>If you need to distribute a BSP and include bootable images or build kernel and
7230 filesystems meant to allow users to boot the BSP for evaluation
7231 purposes, you should put the images and artifacts within a
7232 <code class="filename">binary/</code> subdirectory located in the
7233 <code class="filename">meta-&lt;bsp_name&gt;</code> directory.
7234 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>If you do include a bootable image as part of the BSP and the image
7235 was built by software covered by the GPL or other open source licenses,
7236 it is your responsibility to understand
7237 and meet all licensing requirements, which could include distribution
7238 of source files.</div></li><li class="listitem"><p><span class="emphasis"><em>Use a Yocto Linux Kernel:</em></span>
7239 Kernel recipes in the BSP should be based on a Yocto Linux kernel.
7240 Basing your recipes on these kernels reduces the costs for maintaining
7241 the BSP and increases its scalability.
7242 See the <code class="filename">Yocto Linux Kernel</code> category in the
7243 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top"><code class="filename">Yocto Source Repositories</code></a>
7244 for these kernels.</p></li></ul></div><p>
7245 </p></div></div><div class="section" title="1.4. Customizing a Recipe for a BSP"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="customizing-a-recipe-for-a-bsp"></a>1.4. Customizing a Recipe for a BSP</h2></div></div></div><p>
7246 If you plan on customizing a recipe for a particular BSP, you need to do the
7247 following:
7248 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Include within the BSP layer a <code class="filename">.bbappend</code>
7249 file for the modified recipe.</p></li><li class="listitem"><p>Place the BSP-specific file in the BSP's recipe
7250 <code class="filename">.bbappend</code> file path under a directory named
7251 after the machine.</p></li></ul></div><p>
7252 </p><p>
7253 To better understand this, consider an example that customizes a recipe by adding
7254 a BSP-specific configuration file named <code class="filename">interfaces</code> to the
7255 <code class="filename">netbase_4.47.bb</code> recipe for machine "xyz".
7256 Do the following:
7257 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Edit the <code class="filename">netbase_4.47.bbappend</code> file so that it
7258 contains the following:
7259 </p><pre class="literallayout">
7260 FILESEXTRAPATHS_prepend := "${THISDIR}/files:"
7261 PRINC := "${@int(PRINC) + 2}"
7262 </pre></li><li class="listitem"><p>Create and place the new <code class="filename">interfaces</code>
7263 configuration file in the BSP's layer here:
7264 </p><pre class="literallayout">
7265 meta-xyz/recipes-core/netbase/files/xyz/interfaces
7266 </pre></li></ol></div><p>
7267 </p></div><div class="section" title="1.5. BSP Licensing Considerations"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="bsp-licensing-considerations"></a>1.5. BSP Licensing Considerations</h2></div></div></div><p>
7268 In some cases, a BSP contains separately licensed Intellectual Property (IP)
7269 for a component or components.
7270 For these cases, you are required to accept the terms of a commercial or other
7271 type of license that requires some kind of explicit End User License Agreement (EULA).
7272 Once the license is accepted, the OpenEmbedded build system can then build and
7273 include the corresponding component in the final BSP image.
7274 If the BSP is available as a pre-built image, you can download the image after
7275 agreeing to the license or EULA.
7276 </p><p>
7277 You could find that some separately licensed components that are essential
7278 for normal operation of the system might not have an unencumbered (or free)
7279 substitute.
7280 Without these essential components, the system would be non-functional.
7281 Then again, you might find that other licensed components that are simply
7282 'good-to-have' or purely elective do have an unencumbered, free replacement
7283 component that you can use rather than agreeing to the separately licensed component.
7284 Even for components essential to the system, you might find an unencumbered component
7285 that is not identical but will work as a less-capable version of the
7286 licensed version in the BSP recipe.
7287 </p><p>
7288 For cases where you can substitute a free component and still
7289 maintain the system's functionality, the Yocto Project website's
7290 <a class="ulink" href="http://www.yoctoproject.org/download/all?keys=&amp;download_type=1&amp;download_version=" target="_top">BSP
7291 Download Page</a> makes available de-featured BSPs
7292 that are completely free of any IP encumbrances.
7293 For these cases, you can use the substitution directly and
7294 without any further licensing requirements.
7295 If present, these fully de-featured BSPs are named appropriately
7296 different as compared to the names of the respective
7297 encumbered BSPs.
7298 If available, these substitutions are your
7299 simplest and most preferred options.
7300 Use of these substitutions of course assumes the resulting functionality meets
7301 system requirements.
7302 </p><p>
7303 If however, a non-encumbered version is unavailable or
7304 it provides unsuitable functionality or quality, you can use an encumbered
7305 version.
7306 </p><p>
7307 A couple different methods exist within the OpenEmbedded build system to
7308 satisfy the licensing requirements for an encumbered BSP.
7309 The following list describes them in order of preference:
7310 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Use the <code class="filename">LICENSE_FLAGS</code> variable
7311 to define the recipes that have commercial or other types of
7312 specially-licensed packages:</em></span>
7313 For each of those recipes, you can
7314 specify a matching license string in a
7315 <code class="filename">local.conf</code> variable named
7316 <code class="filename">LICENSE_FLAGS_WHITELIST</code>.
7317 Specifying the matching license string signifies that you agree to the license.
7318 Thus, the build system can build the corresponding recipe and include
7319 the component in the image.
7320 See the
7321 "<a class="link" href="#enabling-commercially-licensed-recipes" target="_top">Enabling
7322 Commercially Licensed Recipes</a>" section in the Yocto Project Reference
7323 Manual for details on how to use these variables.</p><p>If you build as you normally would, without
7324 specifying any recipes in the
7325 <code class="filename">LICENSE_FLAGS_WHITELIST</code>, the build stops and
7326 provides you with the list of recipes that you have
7327 tried to include in the image that need entries in
7328 the <code class="filename">LICENSE_FLAGS_WHITELIST</code>.
7329 Once you enter the appropriate license flags into the whitelist,
7330 restart the build to continue where it left off.
7331 During the build, the prompt will not appear again
7332 since you have satisfied the requirement.</p><p>Once the appropriate license flags are on the white list
7333 in the <code class="filename">LICENSE_FLAGS_WHITELIST</code> variable, you
7334 can build the encumbered image with no change at all
7335 to the normal build process.</p></li><li class="listitem"><p><span class="emphasis"><em>Get a pre-built version of the BSP:</em></span>
7336 You can get this type of BSP by visiting the Yocto Project website's
7337 <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">Download</a>
7338 page and clicking on "BSP Downloads".
7339 You can download BSP tarballs that contain proprietary components
7340 after agreeing to the licensing
7341 requirements of each of the individually encumbered
7342 packages as part of the download process.
7343 Obtaining the BSP this way allows you to access an encumbered
7344 image immediately after agreeing to the
7345 click-through license agreements presented by the
7346 website.
7347 Note that if you want to build the image
7348 yourself using the recipes contained within the BSP
7349 tarball, you will still need to create an
7350 appropriate <code class="filename">LICENSE_FLAGS_WHITELIST</code> to match the
7351 encumbered recipes in the BSP.</p></li></ol></div><p>
7352 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
7353 Pre-compiled images are bundled with
7354 a time-limited kernel that runs for a
7355 predetermined amount of time (10 days) before it forces
7356 the system to reboot.
7357 This limitation is meant to discourage direct redistribution
7358 of the image.
7359 You must eventually rebuild the image if you want to remove this restriction.
7360 </div></div><div class="section" title="1.6. Using the Yocto Project's BSP Tools"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="using-the-yocto-projects-bsp-tools"></a>1.6. Using the Yocto Project's BSP Tools</h2></div></div></div><p>
7361 The Yocto Project includes a couple of tools that enable
7362 you to create a <a class="link" href="#bsp-layers" title="1.1. BSP Layers">BSP layer</a>
7363 from scratch and do basic configuration and maintenance
7364 of the kernel without ever looking at a metadata file.
7365 These tools are <code class="filename">yocto-bsp</code> and <code class="filename">yocto-kernel</code>,
7366 respectively.
7367 </p><p>
7368 The following sections describe the common location and help features as well
7369 as details for the <code class="filename">yocto-bsp</code> and <code class="filename">yocto-kernel</code>
7370 tools.
7371 </p><div class="section" title="1.6.1. Common Features"><div class="titlepage"><div><div><h3 class="title"><a id="common-features"></a>1.6.1. Common Features</h3></div></div></div><p>
7372 Designed to have a command interface somewhat like
7373 <a class="link" href="#git" target="_top">Git</a>, each
7374 tool is structured as a set of sub-commands under a
7375 top-level command.
7376 The top-level command (<code class="filename">yocto-bsp</code>
7377 or <code class="filename">yocto-kernel</code>) itself does
7378 nothing but invoke or provide help on the sub-commands
7379 it supports.
7380 </p><p>
7381 Both tools reside in the <code class="filename">scripts/</code> subdirectory
7382 of the <a class="link" href="#source-directory" target="_top">source directory</a>.
7383 Consequently, to use the scripts, you must <code class="filename">source</code> the
7384 environment just as you would when invoking a build:
7385 </p><pre class="literallayout">
7386 $ source oe-init-build-env [build_dir]
7387 </pre><p>
7388 </p><p>
7389 The most immediately useful function is to get help on both tools.
7390 The built-in help system makes it easy to drill down at
7391 any time and view the syntax required for any specific command.
7392 Simply enter the name of the command, or the command along with
7393 <code class="filename">help</code> to display a list of the available sub-commands.
7394 Here is an example:
7395 </p><pre class="literallayout">
7396 $ yocto-bsp
7397 $ yocto-bsp help
7398
7399 Usage:
7400
7401 Create a customized Yocto BSP layer.
7402
7403 usage: yocto-bsp [--version] [--help] COMMAND [ARGS]
7404
7405 The most commonly used 'yocto-bsp' commands are:
7406 create Create a new Yocto BSP
7407 list List available values for options and BSP properties
7408
7409 See 'yocto-bsp help COMMAND' for more information on a specific command.
7410
7411
7412 Options:
7413 --version show program's version number and exit
7414 -h, --help show this help message and exit
7415 -D, --debug output debug information
7416 </pre><p>
7417 </p><p>
7418 Similarly, entering just the name of a sub-command shows the detailed usage
7419 for that sub-command:
7420 </p><pre class="literallayout">
7421 $ yocto-bsp create
7422
7423 Usage:
7424
7425 Create a new Yocto BSP
7426 usage: yocto-bsp create &lt;bsp-name&gt; &lt;karch&gt; [-o &lt;DIRNAME&gt; | --outdir &lt;DIRNAME&gt;]
7427 [-i &lt;JSON PROPERTY FILE&gt; | --infile &lt;JSON PROPERTY_FILE&gt;]
7428
7429 This command creates a Yocto BSP based on the specified parameters.
7430 The new BSP will be a new BSP layer contained by default within
7431 the top-level directory specified as 'meta-bsp-name'. The -o option
7432 can be used to place the BSP layer in a directory with a different
7433 name and location.
7434
7435 ...
7436 </pre><p>
7437 </p><p>
7438 For any sub-command, you can also use the word 'help' just before the
7439 sub-command to get more extensive documentation:
7440 </p><pre class="literallayout">
7441 $ yocto-bsp help create
7442
7443 NAME
7444 yocto-bsp create - Create a new Yocto BSP
7445
7446 SYNOPSIS
7447 yocto-bsp create &lt;bsp-name&gt; &lt;karch&gt; [-o &lt;DIRNAME&gt; | --outdir &lt;DIRNAME&gt;]
7448 [-i &lt;JSON PROPERTY FILE&gt; | --infile &lt;JSON PROPERTY_FILE&gt;]
7449
7450 DESCRIPTION
7451 This command creates a Yocto BSP based on the specified
7452 parameters. The new BSP will be a new Yocto BSP layer contained
7453 by default within the top-level directory specified as
7454 'meta-bsp-name'. The -o option can be used to place the BSP layer
7455 in a directory with a different name and location.
7456
7457 The value of the 'karch' parameter determines the set of files
7458 that will be generated for the BSP, along with the specific set of
7459 'properties' that will be used to fill out the BSP-specific
7460 portions of the BSP.
7461
7462 ...
7463
7464 NOTE: Once created, you should add your new layer to your
7465 bblayers.conf file in order for it to be subsequently seen and
7466 modified by the yocto-kernel tool.
7467
7468 NOTE for x86- and x86_64-based BSPs: The generated BSP assumes the
7469 presence of the of the meta-intel layer, so you should also have a
7470 meta-intel layer present and added to your bblayers.conf as well.
7471 </pre><p>
7472 </p><p>
7473 Now that you know where these two commands reside and how to access information
7474 on them, you should find it relatively straightforward to discover the commands
7475 necessary to create a BSP and perform basic kernel maintenance on that BSP using
7476 the tools.
7477 The next sections provide a concrete starting point to expand on a few points that
7478 might not be immediately obvious or that could use further explanation.
7479 </p></div><div class="section" title="1.6.2. Creating a new BSP Layer Using the yocto-bsp Script"><div class="titlepage"><div><div><h3 class="title"><a id="creating-a-new-bsp-layer-using-the-yocto-bsp-script"></a>1.6.2. Creating a new BSP Layer Using the yocto-bsp Script</h3></div></div></div><p>
7480 The <code class="filename">yocto-bsp</code> script creates a new
7481 <a class="link" href="#bsp-layers" title="1.1. BSP Layers">BSP layer</a> for any architecture supported
7482 by the Yocto Project, as well as QEMU versions of the same.
7483 The default mode of the script's operation is to prompt you for information needed
7484 to generate the BSP layer.
7485 For the current set of BSPs, the script prompts you for various important
7486 parameters such as:
7487 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>which kernel to use</p></li><li class="listitem"><p>which branch of that kernel to use (or re-use)</p></li><li class="listitem"><p>whether or not to use X, and if so, which drivers to use</p></li><li class="listitem"><p>whether to turn on SMP</p></li><li class="listitem"><p>whether the BSP has a keyboard</p></li><li class="listitem"><p>whether the BSP has a touchscreen</p></li><li class="listitem"><p>any remaining configurable items associated with the BSP</p></li></ul></div><p>
7488 </p><p>
7489 You use the <code class="filename">yocto-bsp create</code> sub-command to create
7490 a new BSP layer.
7491 This command requires you to specify a particular architecture on which to
7492 base the BSP.
7493 Assuming you have sourced the environment, you can use the
7494 <code class="filename">yocto-bsp list karch</code> sub-command to list the
7495 architectures available for BSP creation as follows:
7496 </p><pre class="literallayout">
7497 $ yocto-bsp list karch
7498 Architectures available:
7499 arm
7500 powerpc
7501 i386
7502 mips
7503 x86_64
7504 qemu
7505 </pre><p>
7506 </p><p>
7507 The remainder of this section presents an example that uses
7508 <code class="filename">myarm</code> as the machine name and <code class="filename">qemu</code>
7509 as the machine architecture.
7510 Of the available architectures, <code class="filename">qemu</code> is the only architecture
7511 that causes the script to prompt you further for an actual architecture.
7512 In every other way, this architecture is representative of how creating a BSP for
7513 a 'real' machine would work.
7514 The reason the example uses this architecture is because it is an emulated architecture
7515 and can easily be followed without requiring actual hardware.
7516 </p><p>
7517 As the <code class="filename">yocto-bsp create</code> command runs, default values for
7518 the prompts appear in brackets.
7519 Pressing enter without supplying anything on the command line or pressing enter
7520 and providing an invalid response causes the script to accept the default value.
7521 </p><p>
7522 Following is the complete example:
7523 </p><pre class="literallayout">
7524 $ yocto-bsp create myarm qemu
7525 Which qemu architecture would you like to use? [default: x86]
7526 1) common 32-bit x86
7527 2) common 64-bit x86
7528 3) common 32-bit ARM
7529 4) common 32-bit PowerPC
7530 5) common 32-bit MIPS
7531 3
7532 Would you like to use the default (3.2) kernel? (Y/n)
7533 Do you need a new machine branch for this BSP (the alternative is to re-use an existing branch)? [Y/n]
7534 Getting branches from remote repo git://git.yoctoproject.org/linux-yocto-3.2...
7535 Please choose a machine branch to base this BSP on =&gt; [default: standard/default/common-pc]
7536 1) base
7537 2) standard/base
7538 3) standard/default/arm-versatile-926ejs
7539 4) standard/default/base
7540 5) standard/default/beagleboard
7541 6) standard/default/cedartrailbsp (copy).xml
7542 7) standard/default/common-pc-64/base
7543 8) standard/default/common-pc-64/jasperforest
7544 9) standard/default/common-pc-64/romley
7545 10) standard/default/common-pc-64/sugarbay
7546 11) standard/default/common-pc/atom-pc
7547 12) standard/default/common-pc/base
7548 13) standard/default/crownbay
7549 14) standard/default/emenlow
7550 15) standard/default/fishriver
7551 16) standard/default/fri2
7552 17) standard/default/fsl-mpc8315e-rdb
7553 18) standard/default/mti-malta32-be
7554 19) standard/default/mti-malta32-le
7555 20) standard/default/preempt-rt
7556 21) standard/default/qemu-ppc32
7557 22) standard/default/routerstationpro
7558 23) standard/preempt-rt/base
7559 24) standard/preempt-rt/qemu-ppc32
7560 25) standard/preempt-rt/routerstationpro
7561 26) standard/tiny
7562 3
7563 Do you need SMP support? (Y/n)
7564 Does your BSP have a touchscreen? (y/N)
7565 Does your BSP have a keyboard? (Y/n)
7566 New qemu BSP created in meta-myarm
7567 </pre><p>
7568 Let's take a closer look at the example now:
7569 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>For the <code class="filename">qemu</code> architecture,
7570 the script first prompts you for which emulated architecture to use.
7571 In the example, we use the <code class="filename">arm</code> architecture.
7572 </p></li><li class="listitem"><p>The script then prompts you for the kernel.
7573 The default kernel is 3.2 and is acceptable.
7574 So, the example accepts the default.
7575 If you enter 'n', the script prompts you to further enter the kernel
7576 you do want to use (e.g. 3.0, 3.2_preempt-rt, etc.).</p></li><li class="listitem"><p>Next, the script asks whether you would like to have a new
7577 branch created especially for your BSP in the local
7578 <a class="link" href="#local-kernel-files" target="_top">Linux Yocto Kernel</a>
7579 Git repository .
7580 If not, then the script re-uses an existing branch.</p><p>In this example, the default (or 'yes') is accepted.
7581 Thus, a new branch is created for the BSP rather than using a common, shared
7582 branch.
7583 The new branch is the branch committed to for any patches you might later add.
7584 The reason a new branch is the default is that typically
7585 new BSPs do require BSP-specific patches.
7586 The tool thus assumes that most of time a new branch is required.
7587 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>In the current implementation, creation or re-use of a branch does
7588 not actually matter.
7589 The reason is because the generated BSPs assume that patches and
7590 configurations live in recipe-space, which is something that can be done
7591 with or without a dedicated branch.
7592 Generated BSPs, however, are different.
7593 This difference becomes significant once the tool's 'publish' functionality
7594 is implemented.</div></li><li class="listitem"><p>Regardless of which choice is made in the previous step,
7595 you are now given the opportunity to select a particular machine branch on
7596 which to base your new BSP-specific machine branch on
7597 (or to re-use if you had elected to not create a new branch).
7598 Because this example is generating an <code class="filename">arm</code> BSP, the example
7599 uses <code class="filename">#3</code> at the prompt, which selects the arm-versatile branch.
7600 </p></li><li class="listitem"><p>The remainder of the prompts are routine.
7601 Defaults are accepted for each.</p></li><li class="listitem"><p>By default, the script creates the new BSP Layer in the
7602 <a class="link" href="#build-directory" target="_top">build directory</a>.
7603 </p></li></ol></div><p>
7604 </p><p>
7605 Once the BSP Layer is created, you must add it to your
7606 <code class="filename">bblayers.conf</code> file.
7607 Here is an example:
7608 </p><pre class="literallayout">
7609 BBLAYERS = " \
7610 /usr/local/src/yocto/meta \
7611 /usr/local/src/yocto/meta-yocto \
7612 /usr/local/src/yocto/meta-myarm \
7613 "
7614 </pre><p>
7615 Adding the layer to this file allows the build system to build the BSP and
7616 the <code class="filename">yocto-kernel</code> tool to be able to find the layer and
7617 other metadata it needs on which to operate.
7618 </p></div><div class="section" title="1.6.3. Managing Kernel Patches and Config Items with yocto-kernel"><div class="titlepage"><div><div><h3 class="title"><a id="managing-kernel-patches-and-config-items-with-yocto-kernel"></a>1.6.3. Managing Kernel Patches and Config Items with yocto-kernel</h3></div></div></div><p>
7619 Assuming you have created a <a class="link" href="#bsp-layers" title="1.1. BSP Layers">BSP Layer</a> using
7620 <a class="link" href="#creating-a-new-bsp-layer-using-the-yocto-bsp-script" title="1.6.2. Creating a new BSP Layer Using the yocto-bsp Script">
7621 <code class="filename">yocto-bsp</code></a> and you added it to your
7622 <a class="link" href="#var-BBLAYERS" target="_top"><code class="filename">BBLAYERS</code></a>
7623 variable in the <code class="filename">bblayers.conf</code> file, you can now use
7624 the <code class="filename">yocto-kernel</code> script to add patches and configuration
7625 items to the BSP's kernel.
7626 </p><p>
7627 The <code class="filename">yocto-kernel</code> script allows you to add, remove, and list patches
7628 and kernel config settings to a BSP's kernel
7629 <code class="filename">.bbappend</code> file.
7630 All you need to do is use the appropriate sub-command.
7631 Recall that the easiest way to see exactly what sub-commands are available
7632 is to use the <code class="filename">yocto-kernel</code> built-in help as follows:
7633 </p><pre class="literallayout">
7634 $ yocto-kernel
7635 Usage:
7636
7637 Modify and list Yocto BSP kernel config items and patches.
7638
7639 usage: yocto-kernel [--version] [--help] COMMAND [ARGS]
7640
7641 The most commonly used 'yocto-kernel' commands are:
7642 config list List the modifiable set of bare kernel config options for a BSP
7643 config add Add or modify bare kernel config options for a BSP
7644 config rm Remove bare kernel config options from a BSP
7645 patch list List the patches associated with a BSP
7646 patch add Patch the Yocto kernel for a BSP
7647 patch rm Remove patches from a BSP
7648
7649 See 'yocto-kernel help COMMAND' for more information on a specific command.
7650 </pre><p>
7651 </p><p>
7652 The <code class="filename">yocto-kernel patch add</code> sub-command allows you to add a
7653 patch to a BSP.
7654 The following example adds two patches to the <code class="filename">myarm</code> BSP:
7655 </p><pre class="literallayout">
7656 $ yocto-kernel patch add myarm ~/test.patch
7657 Added patches:
7658 test.patch
7659
7660 $ yocto-kernel patch add myarm ~/yocto-testmod.patch
7661 Added patches:
7662 yocto-testmod.patch
7663 </pre><p>
7664 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Although the previous example adds patches one at a time, it is possible
7665 to add multiple patches at the same time.</div><p>
7666 </p><p>
7667 You can verify patches have been added by using the
7668 <code class="filename">yocto-kernel patch list</code> sub-command.
7669 Here is an example:
7670 </p><pre class="literallayout">
7671 $ yocto-kernel patch list myarm
7672 The current set of machine-specific patches for myarm is:
7673 1) test.patch
7674 2) yocto-testmod.patch
7675 </pre><p>
7676 </p><p>
7677 You can also use the <code class="filename">yocto-kernel</code> script to
7678 remove a patch using the <code class="filename">yocto-kernel patch rm</code> sub-command.
7679 Here is an example:
7680 </p><pre class="literallayout">
7681 $ yocto-kernel patch rm myarm
7682 Specify the patches to remove:
7683 1) test.patch
7684 2) yocto-testmod.patch
7685 1
7686 Removed patches:
7687 test.patch
7688 </pre><p>
7689 </p><p>
7690 Again, using the <code class="filename">yocto-kernel patch list</code> sub-command,
7691 you can verify that the patch was in fact removed:
7692 </p><pre class="literallayout">
7693 $ yocto-kernel patch list myarm
7694 The current set of machine-specific patches for myarm is:
7695 1) yocto-testmod.patch
7696 </pre><p>
7697 </p><p>
7698 In a completely similar way, you can use the <code class="filename">yocto-kernel config add</code>
7699 sub-command to add one or more kernel config item settings to a BSP.
7700 The following commands add a couple of config items to the
7701 <code class="filename">myarm</code> BSP:
7702 </p><pre class="literallayout">
7703 $ yocto-kernel config add myarm CONFIG_MISC_DEVICES=y
7704 Added items:
7705 CONFIG_MISC_DEVICES=y
7706
7707 $ yocto-kernel config add myarm KCONFIG_YOCTO_TESTMOD=y
7708 Added items:
7709 CONFIG_YOCTO_TESTMOD=y
7710 </pre><p>
7711 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>Although the previous example adds config items one at a time, it is possible
7712 to add multiple config items at the same time.</div><p>
7713 </p><p>
7714 You can list the config items now associated with the BSP.
7715 Doing so shows you the config items you added as well as others associated
7716 with the BSP:
7717 </p><pre class="literallayout">
7718 $ yocto-kernel config list myarm
7719 The current set of machine-specific kernel config items for myarm is:
7720 1) CONFIG_MISC_DEVICES=y
7721 2) CONFIG_YOCTO_TESTMOD=y
7722 </pre><p>
7723 </p><p>
7724 Finally, you can remove one or more config items using the
7725 <code class="filename">yocto-kernel config rm</code> sub-command in a manner
7726 completely analogous to <code class="filename">yocto-kernel patch rm</code>.
7727 </p></div></div></div>
7728
7729
7730
7731</div>
7732
7733<table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="100%"><tr><td align="left"><img src="figures/kernel-title.png" align="left" width="100%" /></td></tr></table>
7734
7735 <div xml:lang="en" class="book" lang="en"><div class="titlepage"><div><div><h1 class="title"><a id="kernel-manual"></a></h1></div><div><div class="authorgroup">
7736 <div class="author"><h3 class="author"><span class="firstname">Bruce</span> <span class="surname">Ashfield</span></h3><div class="affiliation">
7737 <span class="orgname">Wind River Corporation<br /></span>
7738 </div><code class="email">&lt;<a class="email" href="mailto:bruce.ashfield@windriver.com">bruce.ashfield@windriver.com</a>&gt;</code></div>
7739 </div></div><div><p class="copyright">Copyright © 2010-2012 Linux Foundation</p></div><div><div class="legalnotice" title="Legal Notice"><a id="id1504523"></a>
7740 <p>
7741 Permission is granted to copy, distribute and/or modify this document under
7742 the terms of the <a class="ulink" href="http://creativecommons.org/licenses/by-sa/2.0/uk/" target="_top">Creative Commons Attribution-Share Alike 2.0 UK: England &amp; Wales</a> as published by Creative Commons.
7743 </p>
7744 <div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
7745 Due to production processes, there could be differences between the Yocto Project
7746 documentation bundled in the release tarball and the
7747 Yocto Project Kernel Architecture and Use Manual on
7748 the <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project</a> website.
7749 For the latest version of this manual, see the manual on the website.
7750 </div>
7751 </div></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr>
7752 <tr><td align="left">Revision 0.9</td><td align="left">24 November 2010</td></tr><tr><td align="left" colspan="2">The initial document draft released with the Yocto Project 0.9 Release.</td></tr>
7753 <tr><td align="left">Revision 1.0</td><td align="left">6 April 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0 Release.</td></tr>
7754 <tr><td align="left">Revision 1.0.1</td><td align="left">23 May 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0.1 Release.</td></tr>
7755 <tr><td align="left">Revision 1.1</td><td align="left">6 October 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.1 Release.</td></tr>
7756 <tr><td align="left">Revision 1.2</td><td align="left">April 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.2 Release.</td></tr>
7757 <tr><td align="left">Revision 1.3</td><td align="left">Sometime in 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.3 Release.</td></tr>
7758 </table></div></div></div><hr /></div>
7759
7760
7761 <div class="chapter" title="Chapter 1. Yocto Project Kernel Architecture and Use Manual"><div class="titlepage"><div><div><h2 class="title"><a id="kernel-doc-intro"></a>Chapter 1. Yocto Project Kernel Architecture and Use Manual</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#kernel-intro-section">1.1. Introduction</a></span></dt></dl></div><div class="section" title="1.1. Introduction"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="kernel-intro-section"></a>1.1. Introduction</h2></div></div></div><p>
7762 The Yocto Project presents kernels as a fully patched, history-clean Git
7763 repositories.
7764 Each repository represents selected features, board support,
7765 and configurations extensively tested by the Yocto Project.
7766 Yocto Project kernels allow the end user to leverage community
7767 best practices to seamlessly manage the development, build and debug cycles.
7768 </p><p>
7769 This manual describes Yocto Project kernels by providing information
7770 on history, organization, benefits, and use.
7771 The manual consists of two sections:
7772 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Concepts:</em></span> Describes concepts behind a kernel.
7773 You will understand how a kernel is organized and why it is organized in
7774 the way it is. You will understand the benefits of a kernel's organization
7775 and the mechanisms used to work with the kernel and how to apply it in your
7776 design process.</p></li><li class="listitem"><p><span class="emphasis"><em>Using a Kernel:</em></span> Describes best practices
7777 and "how-to" information
7778 that lets you put a kernel to practical use.
7779 Some examples are how to examine changes in a branch and how to
7780 save kernel modifications.</p></li></ul></div><p>
7781 </p><p>
7782 For more information on the Linux kernel, see the following links:
7783 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The Linux Foundation's guide for kernel development
7784 process - <a class="ulink" href="http://ldn.linuxfoundation.org/book/1-a-guide-kernel-development-process" target="_top">http://ldn.linuxfoundation.org/book/1-a-guide-kernel-development-process</a></p></li><li class="listitem"><p>A fairly encompassing guide on Linux kernel development -
7785 <a class="ulink" href="http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob_plain;f=Documentation/HOWTO;hb=HEAD" target="_top">http://git.kernel.org/?p=linux/kernel/git/torvalds/linux-2.6.git;a=blob_plain;f=Documentation/HOWTO;hb=HEAD</a></p></li></ul></div><p>
7786 </p><p>
7787 For more discussion on the Yocto Project kernel, you can see these sections
7788 in the Yocto Project Development Manual:
7789 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>
7790 "<a class="link" href="#kernel-overview" target="_top">Kernel Overview</a>"</p></li><li class="listitem"><p>
7791 "<a class="link" href="#kernel-modification-workflow" target="_top">Kernel Modification Workflow</a>"
7792 </p></li><li class="listitem"><p>
7793 "<a class="link" href="#dev-manual-kernel-appendix" target="_top">Kernel Modification Example</a>"</p></li></ul></div><p>
7794 </p><p>
7795 For general information on the Yocto Project, visit the website at
7796 <a class="ulink" href="http://www.yoctoproject.org" target="_top">http://www.yoctoproject.org</a>.
7797 </p></div></div>
7798
7799 <div class="chapter" title="Chapter 2. Yocto Project Kernel Concepts"><div class="titlepage"><div><div><h2 class="title"><a id="kernel-concepts"></a>Chapter 2. Yocto Project Kernel Concepts</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#concepts-org">2.1. Introduction</a></span></dt><dt><span class="section"><a href="#kernel-goals">2.2. Kernel Goals</a></span></dt><dt><span class="section"><a href="#kernel-big-picture">2.3. Yocto Project Kernel Development and Maintenance Overview</a></span></dt><dt><span class="section"><a href="#kernel-architecture">2.4. Kernel Architecture</a></span></dt><dd><dl><dt><span class="section"><a href="#architecture-overview">2.4.1. Overview</a></span></dt><dt><span class="section"><a href="#branching-and-workflow">2.4.2. Branching Strategy and Workflow</a></span></dt><dt><span class="section"><a href="#source-code-manager-git">2.4.3. Source Code Manager - Git</a></span></dt></dl></dd><dt><span class="section"><a href="#kernel-configuration">2.5. Kernel Configuration</a></span></dt><dt><span class="section"><a href="#kernel-tools">2.6. Kernel Tools</a></span></dt></dl></div><div class="section" title="2.1. Introduction"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="concepts-org"></a>2.1. Introduction</h2></div></div></div><p>
7800 This chapter provides conceptual information about the kernel:
7801 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Kernel Goals</p></li><li class="listitem"><p>Kernel Development and Maintenance Overview</p></li><li class="listitem"><p>Kernel Architecture</p></li><li class="listitem"><p>Kernel Tools</p></li></ul></div><p>
7802 </p></div><div class="section" title="2.2. Kernel Goals"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="kernel-goals"></a>2.2. Kernel Goals</h2></div></div></div><p>
7803 The complexity of embedded kernel design has increased dramatically.
7804 Whether it is managing multiple implementations of a particular feature or tuning and
7805 optimizing board specific features, both flexibility and maintainability are key concerns.
7806 The Linux kernels available through the Yocto Project are presented with the embedded
7807 developer's needs in mind and have evolved to assist in these key concerns.
7808 For example, prior methods such as applying hundreds of patches to an extracted
7809 tarball have been replaced with proven techniques that allow easy inspection,
7810 bisection and analysis of changes.
7811 Application of these techniques also creates a platform for performing integration and
7812 collaboration with the thousands of upstream development projects.
7813 </p><p>
7814 With all these considerations in mind, the Yocto Project's kernel and development team
7815 strives to attain these goals:
7816 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Allow the end user to leverage community best practices to seamlessly
7817 manage the development, build and debug cycles.</p></li><li class="listitem"><p>Create a platform for performing integration and collaboration with the
7818 thousands of upstream development projects that exist.</p></li><li class="listitem"><p>Provide mechanisms that support many different work flows, front-ends and
7819 management techniques.</p></li><li class="listitem"><p>Deliver the most up-to-date kernel possible while still ensuring that
7820 the baseline kernel is the most stable official release.</p></li><li class="listitem"><p>Include major technological features as part of the Yocto Project's
7821 upward revision strategy.</p></li><li class="listitem"><p>Present a kernel Git repository that, similar to the upstream
7822 <code class="filename">kernel.org</code> tree,
7823 has a clear and continuous history.</p></li><li class="listitem"><p>Deliver a key set of supported kernel types, where each type is tailored
7824 to meet a specific use (e.g. networking, consumer, devices, and so forth).</p></li><li class="listitem"><p>Employ a Git branching strategy that, from a developer's point of view,
7825 results in a linear path from the baseline <code class="filename">kernel.org</code>,
7826 through a select group of features and
7827 ends with their BSP-specific commits.</p></li></ul></div><p>
7828 </p></div><div class="section" title="2.3. Yocto Project Kernel Development and Maintenance Overview"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="kernel-big-picture"></a>2.3. Yocto Project Kernel Development and Maintenance Overview</h2></div></div></div><p>
7829 Kernels available through the Yocto Project, like other kernels, are based off the Linux
7830 kernel releases from <a class="ulink" href="http://www.kernel.org" target="_top">http://www.kernel.org</a>.
7831 At the beginning of a major development cycle, the Yocto Project team
7832 chooses its kernel based on factors such as release timing, the anticipated release
7833 timing of final upstream <code class="filename">kernel.org</code> versions, and Yocto Project
7834 feature requirements.
7835 Typically, the kernel chosen is in the
7836 final stages of development by the community.
7837 In other words, the kernel is in the release
7838 candidate or "rc" phase and not yet a final release.
7839 But, by being in the final stages of external development, the team knows that the
7840 <code class="filename">kernel.org</code> final release will clearly be within the early stages of
7841 the Yocto Project development window.
7842 </p><p>
7843 This balance allows the team to deliver the most up-to-date kernel
7844 as possible, while still ensuring that the team has a stable official release for
7845 the baseline Linux kernel version.
7846 </p><p>
7847 The ultimate source for kernels available through the Yocto Project are released kernels
7848 from <code class="filename">kernel.org</code>.
7849 In addition to a foundational kernel from <code class="filename">kernel.org</code>, the
7850 kernels available contain a mix of important new mainline
7851 developments, non-mainline developments (when there is no alternative),
7852 Board Support Package (BSP) developments,
7853 and custom features.
7854 These additions result in a commercially released Yocto Project Linux kernel that caters
7855 to specific embedded designer needs for targeted hardware.
7856 </p><p>
7857 Once a kernel is officially released, the Yocto Project team goes into
7858 their next development cycle, or upward revision (uprev) cycle, while still
7859 continuing maintenance on the released kernel.
7860 It is important to note that the most sustainable and stable way
7861 to include feature development upstream is through a kernel uprev process.
7862 Back-porting hundreds of individual fixes and minor features from various
7863 kernel versions is not sustainable and can easily compromise quality.
7864 </p><p>
7865 During the uprev cycle, the Yocto Project team uses an ongoing analysis of
7866 kernel development, BSP support, and release timing to select the best
7867 possible <code class="filename">kernel.org</code> version.
7868 The team continually monitors community kernel
7869 development to look for significant features of interest.
7870 The team does consider back-porting large features if they have a significant advantage.
7871 User or community demand can also trigger a back-port or creation of new
7872 functionality in the Yocto Project baseline kernel during the uprev cycle.
7873 </p><p>
7874 Generally speaking, every new kernel both adds features and introduces new bugs.
7875 These consequences are the basic properties of upstream kernel development and are
7876 managed by the Yocto Project team's kernel strategy.
7877 It is the Yocto Project team's policy to not back-port minor features to the released kernel.
7878 They only consider back-porting significant technological jumps - and, that is done
7879 after a complete gap analysis.
7880 The reason for this policy is that back-porting any small to medium sized change
7881 from an evolving kernel can easily create mismatches, incompatibilities and very
7882 subtle errors.
7883 </p><p>
7884 These policies result in both a stable and a cutting
7885 edge kernel that mixes forward ports of existing features and significant and critical
7886 new functionality.
7887 Forward porting functionality in the kernels available through the Yocto Project kernel
7888 can be thought of as a "micro uprev."
7889 The many “micro uprevs” produce a kernel version with a mix of
7890 important new mainline, non-mainline, BSP developments and feature integrations.
7891 This kernel gives insight into new features and allows focused
7892 amounts of testing to be done on the kernel, which prevents
7893 surprises when selecting the next major uprev.
7894 The quality of these cutting edge kernels is evolving and the kernels are used in leading edge
7895 feature and BSP development.
7896 </p></div><div class="section" title="2.4. Kernel Architecture"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="kernel-architecture"></a>2.4. Kernel Architecture</h2></div></div></div><p>
7897 This section describes the architecture of the kernels available through the
7898 Yocto Project and provides information
7899 on the mechanisms used to achieve that architecture.
7900 </p><div class="section" title="2.4.1. Overview"><div class="titlepage"><div><div><h3 class="title"><a id="architecture-overview"></a>2.4.1. Overview</h3></div></div></div><p>
7901 As mentioned earlier, a key goal of the Yocto Project is to present the
7902 developer with
7903 a kernel that has a clear and continuous history that is visible to the user.
7904 The architecture and mechanisms used achieve that goal in a manner similar to the
7905 upstream <code class="filename">kernel.org</code>.
7906 </p><p>
7907 You can think of a Yocto Project kernel as consisting of a baseline Linux kernel with
7908 added features logically structured on top of the baseline.
7909 The features are tagged and organized by way of a branching strategy implemented by the
7910 source code manager (SCM) Git.
7911 For information on Git as applied to the Yocto Project, see the
7912 "<a class="link" href="#git" target="_top">Git</a>" section in the
7913 Yocto Project Development Manual.
7914 </p><p>
7915 The result is that the user has the ability to see the added features and
7916 the commits that make up those features.
7917 In addition to being able to see added features, the user can also view the history of what
7918 made up the baseline kernel.
7919 </p><p>
7920 The following illustration shows the conceptual Yocto Project kernel.
7921 </p><p>
7922 </p><table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="540"><tr style="height: 630px"><td align="center"><img src="figures/kernel-architecture-overview.png" align="middle" /></td></tr></table><p>
7923 </p><p>
7924 In the illustration, the "Kernel.org Branch Point"
7925 marks the specific spot (or release) from
7926 which the Yocto Project kernel is created.
7927 From this point "up" in the tree, features and differences are organized and tagged.
7928 </p><p>
7929 The "Yocto Project Baseline Kernel" contains functionality that is common to every kernel
7930 type and BSP that is organized further up the tree.
7931 Placing these common features in the
7932 tree this way means features don't have to be duplicated along individual branches of the
7933 structure.
7934 </p><p>
7935 From the Yocto Project Baseline Kernel, branch points represent specific functionality
7936 for individual BSPs as well as real-time kernels.
7937 The illustration represents this through three BSP-specific branches and a real-time
7938 kernel branch.
7939 Each branch represents some unique functionality for the BSP or a real-time kernel.
7940 </p><p>
7941 In this example structure, the real-time kernel branch has common features for all
7942 real-time kernels and contains
7943 more branches for individual BSP-specific real-time kernels.
7944 The illustration shows three branches as an example.
7945 Each branch points the way to specific, unique features for a respective real-time
7946 kernel as they apply to a given BSP.
7947 </p><p>
7948 The resulting tree structure presents a clear path of markers (or branches) to the
7949 developer that, for all practical purposes, is the kernel needed for any given set
7950 of requirements.
7951 </p></div><div class="section" title="2.4.2. Branching Strategy and Workflow"><div class="titlepage"><div><div><h3 class="title"><a id="branching-and-workflow"></a>2.4.2. Branching Strategy and Workflow</h3></div></div></div><p>
7952 The Yocto Project team creates kernel branches at points where functionality is
7953 no longer shared and thus, needs to be isolated.
7954 For example, board-specific incompatibilities would require different functionality
7955 and would require a branch to separate the features.
7956 Likewise, for specific kernel features, the same branching strategy is used.
7957 </p><p>
7958 This branching strategy results in a tree that has features organized to be specific
7959 for particular functionality, single kernel types, or a subset of kernel types.
7960 This strategy also results in not having to store the same feature twice
7961 internally in the tree.
7962 Rather, the kernel team stores the unique differences required to apply the
7963 feature onto the kernel type in question.
7964 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
7965 The Yocto Project team strives to place features in the tree such that they can be
7966 shared by all boards and kernel types where possible.
7967 However, during development cycles or when large features are merged,
7968 the team cannot always follow this practice.
7969 In those cases, the team uses isolated branches to merge features.
7970 </div><p>
7971 </p><p>
7972 BSP-specific code additions are handled in a similar manner to kernel-specific additions.
7973 Some BSPs only make sense given certain kernel types.
7974 So, for these types, the team creates branches off the end of that kernel type for all
7975 of the BSPs that are supported on that kernel type.
7976 From the perspective of the tools that create the BSP branch, the BSP is really no
7977 different than a feature.
7978 Consequently, the same branching strategy applies to BSPs as it does to features.
7979 So again, rather than store the BSP twice, the team only stores the unique
7980 differences for the BSP across the supported multiple kernels.
7981 </p><p>
7982 While this strategy can result in a tree with a significant number of branches, it is
7983 important to realize that from the developer's point of view, there is a linear
7984 path that travels from the baseline <code class="filename">kernel.org</code>, through a select
7985 group of features and ends with their BSP-specific commits.
7986 In other words, the divisions of the kernel are transparent and are not relevant
7987 to the developer on a day-to-day basis.
7988 From the developer's perspective, this path is the "master" branch.
7989 The developer does not need to be aware of the existence of any other branches at all.
7990 Of course, there is value in the existence of these branches
7991 in the tree, should a person decide to explore them.
7992 For example, a comparison between two BSPs at either the commit level or at the line-by-line
7993 code <code class="filename">diff</code> level is now a trivial operation.
7994 </p><p>
7995 Working with the kernel as a structured tree follows recognized community best practices.
7996 In particular, the kernel as shipped with the product, should be
7997 considered an "upstream source" and viewed as a series of
7998 historical and documented modifications (commits).
7999 These modifications represent the development and stabilization done
8000 by the Yocto Project kernel development team.
8001 </p><p>
8002 Because commits only change at significant release points in the product life cycle,
8003 developers can work on a branch created
8004 from the last relevant commit in the shipped Yocto Project kernel.
8005 As mentioned previously, the structure is transparent to the developer
8006 because the kernel tree is left in this state after cloning and building the kernel.
8007 </p></div><div class="section" title="2.4.3. Source Code Manager - Git"><div class="titlepage"><div><div><h3 class="title"><a id="source-code-manager-git"></a>2.4.3. Source Code Manager - Git</h3></div></div></div><p>
8008 The Source Code Manager (SCM) is Git.
8009 This SCM is the obvious mechanism for meeting the previously mentioned goals.
8010 Not only is it the SCM for <code class="filename">kernel.org</code> but,
8011 Git continues to grow in popularity and supports many different work flows,
8012 front-ends and management techniques.
8013 </p><p>
8014 You can find documentation on Git at <a class="ulink" href="http://git-scm.com/documentation" target="_top">http://git-scm.com/documentation</a>.
8015 You can also get an introduction to Git as it applies to the Yocto Project in the
8016 "<a class="link" href="#git" target="_top">Git</a>"
8017 section in the Yocto Project Development Manual.
8018 These referenced sections overview Git and describe a minimal set of
8019 commands that allows you to be functional using Git.
8020 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
8021 You can use as much, or as little, of what Git has to offer to accomplish what
8022 you need for your project.
8023 You do not have to be a "Git Master" in order to use it with the Yocto Project.
8024 </div><p>
8025 </p></div></div><div class="section" title="2.5. Kernel Configuration"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="kernel-configuration"></a>2.5. Kernel Configuration</h2></div></div></div><p>
8026 Kernel configuration, along with kernel features, defines how a kernel
8027 image is built for the Yocto Project.
8028 Through configuration settings, you can customize a Yocto Project kernel to be
8029 specific to particular hardware.
8030 For example, you can specify sound support or networking support.
8031 This section describes basic concepts behind Kernel configuration within the
8032 Yocto Project and references you to other areas for specific configuration
8033 applications.
8034 </p><p>
8035 Conceptually, configuration of a Yocto Project kernel occurs similarly to that needed for any
8036 Linux kernel.
8037 The build process for a Yocto Project kernel uses a <code class="filename">.config</code> file, which
8038 is created through the Linux Kernel Coinfiguration (LKC) tool.
8039 You can directly set various configurations in the
8040 <code class="filename">.config</code> file by using the <code class="filename">menuconfig</code>
8041 tool as built by BitBake.
8042 You can also define configurations in the file by using configuration fragments.
8043 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
8044 It is not recommended that you edit the <code class="filename">.config</code> file directly.
8045 </div><p>
8046 Here are some brief descriptions of the ways you can affect the
8047 <code class="filename">.config</code> file:
8048 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>The <code class="filename">menuconfig</code> Tool:</em></span>
8049 One of many front-ends that allows you to define kernel configurations.
8050 Some others are <code class="filename">make config</code>,
8051 <code class="filename">make nconfig</code>, and <code class="filename">make gconfig</code>.
8052 In the Yocto Project environment, you must use BitBake to build the
8053 <code class="filename">menuconfig</code> tool before you can use it to define
8054 configurations:
8055 </p><pre class="literallayout">
8056 $ bitbake linux-yocto -c menuconfig
8057 </pre><p>
8058 After the tool is built, you can interact with it normally.
8059 You can see how <code class="filename">menuconfig</code> is used to change a simple
8060 kernel configuration in the
8061 "<a class="link" href="#changing-the-config-smp-configuration-using-menuconfig" target="_top">Changing the  <code class="filename">CONFIG_SMP</code> Configuration Using  <code class="filename">menuconfig</code></a>"
8062 section of the Yocto Project Development Manual.
8063 For general information on <code class="filename">menuconfig</code>, see
8064 <a class="ulink" href="http://en.wikipedia.org/wiki/Menuconfig" target="_top">http://en.wikipedia.org/wiki/Menuconfig</a>.
8065 </p></li><li class="listitem"><p><span class="emphasis"><em>Configuration Fragments:</em></span> A file with a
8066 list of kernel options just as they would appear syntactically in the
8067 <code class="filename">.config</code> file.
8068 Configuration fragments are typically logical groupings and are assembled
8069 by the OpenEmbedded build system to produce input used by the LKC
8070 that ultimately generates the <code class="filename">.config</code> file.</p><p>The
8071 <code class="filename"><a class="link" href="#var-KERNEL_FEATURES" target="_top">KERNEL_FEATURES</a></code>
8072 variable can be used to list configuration fragments.
8073 For further discussion on applying configuration fragments, see the
8074 "<a class="link" href="#bsp-filelayout-kernel" target="_top">Linux Kernel Configuration</a>"
8075 section in the Yocto Project Board Support Package (BSP) Guide.
8076 </p></li></ul></div><p>
8077 </p></div><div class="section" title="2.6. Kernel Tools"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="kernel-tools"></a>2.6. Kernel Tools</h2></div></div></div><p>
8078 Since most standard workflows involve moving forward with an existing tree by
8079 continuing to add and alter the underlying baseline, the tools that manage
8080 the Yocto Project's kernel construction are largely hidden from the developer to
8081 present a simplified view of the kernel for ease of use.
8082 </p><p>
8083 Fundamentally, the kernel tools that manage and construct the
8084 Yocto Project kernel accomplish the following:
8085 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Group patches into named, reusable features.</p></li><li class="listitem"><p>Allow top-down control of included features.</p></li><li class="listitem"><p>Bind kernel configurations to kernel patches and features.</p></li><li class="listitem"><p>Present a seamless Git repository that blends Yocto Project value
8086 with the <code class="filename">kernel.org</code> history and development.</p></li></ul></div><p>
8087 </p></div></div>
8088
8089 <div class="chapter" title="Chapter 3. Working with the Yocto Project Kernel"><div class="titlepage"><div><div><h2 class="title"><a id="kernel-how-to"></a>Chapter 3. Working with the Yocto Project Kernel</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#actions-org">3.1. Introduction</a></span></dt><dt><span class="section"><a href="#tree-construction">3.2. Tree Construction</a></span></dt><dt><span class="section"><a href="#build-strategy">3.3. Build Strategy</a></span></dt><dt><span class="section"><a href="#workflow-examples">3.4. Workflow Examples</a></span></dt><dd><dl><dt><span class="section"><a href="#change-inspection-kernel-changes-commits">3.4.1. Change Inspection: Changes/Commits</a></span></dt><dt><span class="section"><a href="#development-saving-kernel-modifications">3.4.2. Development: Saving Kernel Modifications</a></span></dt><dt><span class="section"><a href="#scm-working-with-the-yocto-project-kernel-in-another-scm">3.4.3. Working with the Yocto Project Kernel in Another SCM</a></span></dt><dt><span class="section"><a href="#bsp-creating">3.4.4. Creating a BSP Based on an Existing Similar BSP</a></span></dt><dt><span class="section"><a href="#tip-dirty-string">3.4.5. "-dirty" String</a></span></dt></dl></dd></dl></div><div class="section" title="3.1. Introduction"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="actions-org"></a>3.1. Introduction</h2></div></div></div><p>
8090 This chapter describes how to accomplish tasks involving a kernel's tree structure.
8091 The information is designed to help the developer that wants to modify the Yocto
8092 Project kernel and contribute changes upstream to the Yocto Project.
8093 The information covers the following:
8094 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Tree construction</p></li><li class="listitem"><p>Build strategies</p></li><li class="listitem"><p>Workflow examples</p></li></ul></div><p>
8095 </p></div><div class="section" title="3.2. Tree Construction"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="tree-construction"></a>3.2. Tree Construction</h2></div></div></div><p>
8096 This section describes construction of the Yocto Project kernel source repositories
8097 as accomplished by the Yocto Project team to create kernel repositories.
8098 These kernel repositories are found under the heading "Yocto Linux Kernel" at
8099 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a>
8100 and can be shipped as part of a Yocto Project release.
8101 The team creates these repositories by
8102 compiling and executing the set of feature descriptions for every BSP/feature
8103 in the product.
8104 Those feature descriptions list all necessary patches,
8105 configuration, branching, tagging and feature divisions found in a kernel.
8106 Thus, the Yocto Project kernel repository (or tree) is built.
8107 </p><p>
8108 The existence of this tree allows you to access and clone a particular
8109 Yocto Project kernel repository and use it to build images based on their configurations
8110 and features.
8111 </p><p>
8112 You can find the files used to describe all the valid features and BSPs
8113 in the Yocto Project kernel in any clone of the Yocto Project kernel source repository
8114 Git tree.
8115 For example, the following command clones the Yocto Project baseline kernel that
8116 branched off of <code class="filename">linux.org</code> version 3.4:
8117 </p><pre class="literallayout">
8118 $ git clone git://git.yoctoproject.org/linux-yocto-3.4
8119 </pre><p>
8120 For another example of how to set up a local Git repository of the Yocto Project
8121 kernel files, see the
8122 "<a class="link" href="#local-kernel-files" target="_top">Yocto Project Kernel</a>" bulleted
8123 item in the Yocto Project Development Manual.
8124 </p><p>
8125 Once you have cloned the kernel Git repository on your local machine, you can
8126 switch to the <code class="filename">meta</code> branch within the repository.
8127 Here is an example that assumes the local Git repository for the kernel is in
8128 a top-level directory named <code class="filename">linux-yocto-3.4</code>:
8129 </p><pre class="literallayout">
8130 $ cd ~/linux-yocto-3.4
8131 $ git checkout -b meta origin/meta
8132 </pre><p>
8133 Once you have checked out and switched to the <code class="filename">meta</code> branch,
8134 you can see a snapshot of all the kernel configuration and feature descriptions that are
8135 used to build that particular kernel repository.
8136 These descriptions are in the form of <code class="filename">.scc</code> files.
8137 </p><p>
8138 You should realize, however, that browsing your local kernel repository
8139 for feature descriptions and patches is not an effective way to determine what is in a
8140 particular kernel branch.
8141 Instead, you should use Git directly to discover the changes in a branch.
8142 Using Git is an efficient and flexible way to inspect changes to the kernel.
8143 For examples showing how to use Git to inspect kernel commits, see the following sections
8144 in this chapter.
8145 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
8146 Ground up reconstruction of the complete kernel tree is an action only taken by the
8147 Yocto Project team during an active development cycle.
8148 When you create a clone of the kernel Git repository, you are simply making it
8149 efficiently available for building and development.
8150 </div><p>
8151 </p><p>
8152 The following steps describe what happens when the Yocto Project Team constructs
8153 the Yocto Project kernel source Git repository (or tree) found at
8154 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a> given the
8155 introduction of a new top-level kernel feature or BSP.
8156 These are the actions that effectively create the tree
8157 that includes the new feature, patch or BSP:
8158 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>A top-level kernel feature is passed to the kernel build subsystem.
8159 Normally, this feature is a BSP for a particular kernel type.</p></li><li class="listitem"><p>The file that describes the top-level feature is located by searching
8160 these system directories:
8161 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The in-tree kernel-cache directories, which are located
8162 in <code class="filename">meta/cfg/kernel-cache</code></p></li><li class="listitem"><p>Areas pointed to by <code class="filename">SRC_URI</code> statements
8163 found in recipes</p></li></ul></div><p>
8164 For a typical build, the target of the search is a
8165 feature description in an <code class="filename">.scc</code> file
8166 whose name follows this format:
8167 </p><pre class="literallayout">
8168 &lt;bsp_name&gt;-&lt;kernel_type&gt;.scc
8169 </pre><p>
8170 </p></li><li class="listitem"><p>Once located, the feature description is either compiled into a simple script
8171 of actions, or into an existing equivalent script that is already part of the
8172 shipped kernel.</p></li><li class="listitem"><p>Extra features are appended to the top-level feature description.
8173 These features can come from the
8174 <a class="link" href="#var-KERNEL_FEATURES" target="_top"><code class="filename">KERNEL_FEATURES</code></a>
8175 variable in recipes.</p></li><li class="listitem"><p>Each extra feature is located, compiled and appended to the script
8176 as described in step three.</p></li><li class="listitem"><p>The script is executed to produce a series of <code class="filename">meta-*</code>
8177 directories.
8178 These directories are descriptions of all the branches, tags, patches and configurations that
8179 need to be applied to the base Git repository to completely create the
8180 source (build) branch for the new BSP or feature.</p></li><li class="listitem"><p>The base repository is cloned, and the actions
8181 listed in the <code class="filename">meta-*</code> directories are applied to the
8182 tree.</p></li><li class="listitem"><p>The Git repository is left with the desired branch checked out and any
8183 required branching, patching and tagging has been performed.</p></li></ol></div><p>
8184 </p><p>
8185 The kernel tree is now ready for developer consumption to be locally cloned,
8186 configured, and built into a Yocto Project kernel specific to some target hardware.
8187 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3><p>The generated <code class="filename">meta-*</code> directories add to the kernel
8188 as shipped with the Yocto Project release.
8189 Any add-ons and configuration data are applied to the end of an existing branch.
8190 The full repository generation that is found in the
8191 official Yocto Project kernel repositories at
8192 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a>
8193 is the combination of all supported boards and configurations.</p><p>The technique the Yocto Project team uses is flexible and allows for seamless
8194 blending of an immutable history with additional patches specific to a
8195 deployment.
8196 Any additions to the kernel become an integrated part of the branches.</p></div><p>
8197 </p></div><div class="section" title="3.3. Build Strategy"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="build-strategy"></a>3.3. Build Strategy</h2></div></div></div><p>
8198 Once a local Git repository of the Yocto Project kernel exists on a development system,
8199 you can consider the compilation phase of kernel development - building a kernel image.
8200 Some prerequisites exist that are validated by the build process before compilation
8201 starts:
8202 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The <code class="filename">SRC_URI</code> points to the kernel Git
8203 repository.</p></li><li class="listitem"><p>A BSP build branch exists.
8204 This branch has the following form:
8205 </p><pre class="literallayout">
8206 &lt;kernel_type&gt;/&lt;bsp_name&gt;
8207 </pre></li></ul></div><p>
8208 The OpenEmbedded build system makes sure these conditions exist before attempting compilation.
8209 Other means, however, do exist, such as as bootstrapping a BSP, see
8210 the "<a class="link" href="#workflow-examples" title="3.4. Workflow Examples">Workflow Examples</a>".
8211 </p><p>
8212 Before building a kernel, the build process verifies the tree
8213 and configures the kernel by processing all of the
8214 configuration "fragments" specified by feature descriptions in the <code class="filename">.scc</code>
8215 files.
8216 As the features are compiled, associated kernel configuration fragments are noted
8217 and recorded in the <code class="filename">meta-*</code> series of directories in their compilation order.
8218 The fragments are migrated, pre-processed and passed to the Linux Kernel
8219 Configuration subsystem (<code class="filename">lkc</code>) as raw input in the form
8220 of a <code class="filename">.config</code> file.
8221 The <code class="filename">lkc</code> uses its own internal dependency constraints to do the final
8222 processing of that information and generates the final <code class="filename">.config</code> file
8223 that is used during compilation.
8224 </p><p>
8225 Using the board's architecture and other relevant values from the board's template,
8226 kernel compilation is started and a kernel image is produced.
8227 </p><p>
8228 The other thing that you notice once you configure a kernel is that
8229 the build process generates a build tree that is separate from your kernel's local Git
8230 source repository tree.
8231 This build tree has a name that uses the following form, where
8232 <code class="filename">${MACHINE}</code> is the metadata name of the machine (BSP) and "kernel_type" is one
8233 of the Yocto Project supported kernel types (e.g. "standard"):
8234 </p><pre class="literallayout">
8235 linux-${MACHINE}-&lt;kernel_type&gt;-build
8236 </pre><p>
8237 </p><p>
8238 The existing support in the <code class="filename">kernel.org</code> tree achieves this
8239 default functionality.
8240 </p><p>
8241 This behavior means that all the generated files for a particular machine or BSP are now in
8242 the build tree directory.
8243 The files include the final <code class="filename">.config</code> file, all the <code class="filename">.o</code>
8244 files, the <code class="filename">.a</code> files, and so forth.
8245 Since each machine or BSP has its own separate build directory in its own separate branch
8246 of the Git repository, you can easily switch between different builds.
8247 </p></div><div class="section" title="3.4. Workflow Examples"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="workflow-examples"></a>3.4. Workflow Examples</h2></div></div></div><p>
8248 As previously noted, the Yocto Project kernel has built-in Git integration.
8249 However, these utilities are not the only way to work with the kernel repository.
8250 The Yocto Project has not made changes to Git or to other tools that
8251 would invalidate alternate workflows.
8252 Additionally, the way the kernel repository is constructed results in using
8253 only core Git functionality, thus allowing any number of tools or front ends to use the
8254 resulting tree.
8255 </p><p>
8256 This section contains several workflow examples.
8257 Many of the examples use Git commands.
8258 You can find Git documentation at
8259 <a class="ulink" href="http://git-scm.com/documentation" target="_top">http://git-scm.com/documentation</a>.
8260 You can find a simple overview of using Git with the Yocto Project in the
8261 "<a class="link" href="#git" target="_top">Git</a>"
8262 section of the Yocto Project Development Manual.
8263 </p><div class="section" title="3.4.1. Change Inspection: Changes/Commits"><div class="titlepage"><div><div><h3 class="title"><a id="change-inspection-kernel-changes-commits"></a>3.4.1. Change Inspection: Changes/Commits</h3></div></div></div><p>
8264 A common question when working with a kernel is:
8265 "What changes have been applied to this tree?"
8266 </p><p>
8267 In projects that have a collection of directories that
8268 contain patches to the kernel, it is possible to inspect or "grep" the contents
8269 of the directories to get a general feel for the changes.
8270 This sort of patch inspection is not an efficient way to determine what has been
8271 done to the kernel.
8272 The reason it is inefficient is because there are many optional patches that are
8273 selected based on the kernel type and the feature description.
8274 Additionally, patches could exist in directories that are not included in the search.
8275 </p><p>
8276 A more efficient way to determine what has changed in the branch is to use
8277 Git and inspect or search the kernel tree.
8278 This method gives you a full view of not only the source code modifications,
8279 but also provides the reasons for the changes.
8280 </p><div class="section" title="3.4.1.1. What Changed in a Kernel?"><div class="titlepage"><div><div><h4 class="title"><a id="what-changed-in-a-kernel"></a>3.4.1.1. What Changed in a Kernel?</h4></div></div></div><p>
8281 Following are a few examples that show how to use Git commands to examine changes.
8282 Because Git repositories in the Yocto Project do not break existing Git
8283 functionality, and because there exists many permutations of these types of
8284 Git commands, many methods exist by which you can discover changes.
8285 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
8286 In the following examples, unless you provide a commit range,
8287 <code class="filename">kernel.org</code> history is blended with Yocto Project
8288 kernel changes.
8289 You can form ranges by using branch names from the kernel tree as the
8290 upper and lower commit markers with the Git commands.
8291 You can see the branch names through the web interface to the
8292 Yocto Project source repositories at
8293 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi" target="_top">http://git.yoctoproject.org/cgit.cgi</a>.
8294 For example, the branch names for the <code class="filename">linux-yocto-3.4</code>
8295 kernel repository can be seen at
8296 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/linux-yocto-3.4/refs/heads" target="_top">http://git.yoctoproject.org/cgit.cgi/linux-yocto-3.4/refs/heads</a>.
8297 </div><p>
8298 To see a full range of the changes, use the
8299 <code class="filename">git whatchanged</code> command and specify a commit range
8300 for the branch (<code class="filename">&lt;commit&gt;..&lt;commit&gt;</code>).
8301 </p><p>
8302 Here is an example that looks at what has changed in the
8303 <code class="filename">emenlow</code> branch of the
8304 <code class="filename">linux-yocto-3.4</code> kernel.
8305 The lower commit range is the commit associated with the
8306 <code class="filename">standard/base</code> branch, while
8307 the upper commit range is the commit associated with the
8308 <code class="filename">standard/emenlow</code> branch.
8309 </p><pre class="literallayout">
8310 $ git whatchanged origin/standard/base..origin/standard/emenlow
8311 </pre><p>
8312 </p><p>
8313 To see a summary of changes use the <code class="filename">git log</code> command.
8314 Here is an example using the same branches:
8315 </p><pre class="literallayout">
8316 $ git log --oneline origin/standard/base..origin/standard/emenlow
8317 </pre><p>
8318 The <code class="filename">git log</code> output might be more useful than
8319 the <code class="filename">git whatchanged</code> as you get
8320 a short, one-line summary of each change and not the entire commit.
8321 </p><p>
8322 If you want to see code differences associated with all the changes, use
8323 the <code class="filename">git diff</code> command.
8324 Here is an example:
8325 </p><pre class="literallayout">
8326 $ git diff origin/standard/base..origin/standard/emenlow
8327 </pre><p>
8328 </p><p>
8329 You can see the commit log messages and the text differences using the
8330 <code class="filename">git show</code> command:
8331 Here is an example:
8332 </p><pre class="literallayout">
8333 $ git show origin/standard/base..origin/standard/emenlow
8334 </pre><p>
8335 </p><p>
8336 You can create individual patches for each change by using the
8337 <code class="filename">git format-patch</code> command.
8338 Here is an example that that creates patch files for each commit and
8339 places them in your <code class="filename">Documents</code> directory:
8340 </p><pre class="literallayout">
8341 $ git format-patch -o $HOME/Documents origin/standard/base..origin/standard/emenlow
8342 </pre><p>
8343 </p></div><div class="section" title="3.4.1.2. Show a Particular Feature or Branch Change"><div class="titlepage"><div><div><h4 class="title"><a id="show-a-particular-feature-or-branch-change"></a>3.4.1.2. Show a Particular Feature or Branch Change</h4></div></div></div><p>
8344 Developers use tags in the Yocto Project kernel tree to divide changes for significant
8345 features or branches.
8346 Once you know a particular tag, you can use Git commands
8347 to show changes associated with the tag and find the branches that contain
8348 the feature.
8349 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
8350 Because BSP branch, <code class="filename">kernel.org</code>, and feature tags are all
8351 present, there could be many tags.
8352 </div><p>
8353 The <code class="filename">git show &lt;tag&gt;</code> command shows changes that are tagged by
8354 a feature.
8355 Here is an example that shows changes tagged by the <code class="filename">systemtap</code>
8356 feature:
8357 </p><pre class="literallayout">
8358 $ git show systemtap
8359 </pre><p>
8360 You can use the <code class="filename">git branch --contains &lt;tag&gt;</code> command
8361 to show the branches that contain a particular feature.
8362 This command shows the branches that contain the <code class="filename">systemtap</code>
8363 feature:
8364 </p><pre class="literallayout">
8365 $ git branch --contains systemtap
8366 </pre><p>
8367 </p><p>
8368 You can use many other comparisons to isolate BSP and kernel changes.
8369 For example, you can compare against <code class="filename">kernel.org</code> tags
8370 such as the <code class="filename">v3.4</code> tag.
8371 </p></div></div><div class="section" title="3.4.2. Development: Saving Kernel Modifications"><div class="titlepage"><div><div><h3 class="title"><a id="development-saving-kernel-modifications"></a>3.4.2. Development: Saving Kernel Modifications</h3></div></div></div><p>
8372 Another common operation is to build a BSP supplied by the Yocto Project, make some
8373 changes, rebuild, and then test.
8374 Those local changes often need to be exported, shared or otherwise maintained.
8375 </p><p>
8376 Since the Yocto Project kernel source tree is backed by Git, this activity is
8377 much easier as compared to with previous releases.
8378 Because Git tracks file modifications, additions and deletions, it is easy
8379 to modify the code and later realize that you need to save the changes.
8380 It is also easy to determine what has changed.
8381 This method also provides many tools to commit, undo and export those modifications.
8382 </p><p>
8383 This section and its sub-sections, describe general application of Git's
8384 <code class="filename">push</code> and <code class="filename">pull</code> commands, which are used to
8385 get your changes upstream or source your code from an upstream repository.
8386 The Yocto Project provides scripts that help you work in a collaborative development
8387 environment.
8388 For information on these scripts, see the
8389 "<a class="link" href="#pushing-a-change-upstream" target="_top">Using Scripts to Push a Change
8390 Upstream and Request a Pull</a>" and
8391 "<a class="link" href="#submitting-a-patch" target="_top">Using Email to Submit a Patch</a>"
8392 sections in the Yocto Project Development Manual.
8393 </p><p>
8394 There are many ways to save kernel modifications.
8395 The technique employed
8396 depends on the destination for the patches:
8397
8398 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Bulk storage</p></li><li class="listitem"><p>Internal sharing either through patches or by using Git</p></li><li class="listitem"><p>External submissions</p></li><li class="listitem"><p>Exporting for integration into another Source Code
8399 Manager (SCM)</p></li></ul></div><p>
8400 </p><p>
8401 Because of the following list of issues, the destination of the patches also influences
8402 the method for gathering them:
8403
8404 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Bisectability</p></li><li class="listitem"><p>Commit headers</p></li><li class="listitem"><p>Division of subsystems for separate submission or review</p></li></ul></div><p>
8405 </p><div class="section" title="3.4.2.1. Bulk Export"><div class="titlepage"><div><div><h4 class="title"><a id="bulk-export"></a>3.4.2.1. Bulk Export</h4></div></div></div><p>
8406 This section describes how you can "bulk" export changes that have not
8407 been separated or divided.
8408 This situation works well when you are simply storing patches outside of the kernel
8409 source repository, either permanently or temporarily, and you are not committing
8410 incremental changes during development.
8411 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
8412 This technique is not appropriate for full integration of upstream submission
8413 because changes are not properly divided and do not provide an avenue for per-change
8414 commit messages.
8415 Therefore, this example assumes that changes have not been committed incrementally
8416 during development and that you simply must gather and export them.
8417 </div><p>
8418 </p><pre class="literallayout">
8419 # bulk export of ALL modifications without separation or division
8420 # of the changes
8421
8422 $ git add .
8423 $ git commit -s -a -m &lt;msg&gt;
8424 or
8425 $ git commit -s -a # and interact with $EDITOR
8426 </pre><p>
8427 </p><p>
8428 The previous operations capture all the local changes in the project source
8429 tree in a single Git commit.
8430 And, that commit is also stored in the project's source tree.
8431 </p><p>
8432 Once the changes are exported, you can restore them manually using a template
8433 or through integration with the <code class="filename">default_kernel</code>.
8434 </p></div><div class="section" title="3.4.2.2. Incremental/Planned Sharing"><div class="titlepage"><div><div><h4 class="title"><a id="incremental-planned-sharing"></a>3.4.2.2. Incremental/Planned Sharing</h4></div></div></div><p>
8435 This section describes how to save modifications when you are making incremental
8436 commits or practicing planned sharing.
8437 The examples in this section assume that you have incrementally committed
8438 changes to the tree during development and now need to export them.
8439 The sections that follow
8440 describe how you can export your changes internally through either patches or by
8441 using Git commands.
8442 </p><p>
8443 During development, the following commands are of interest.
8444 For full Git documentation, refer to the Git documentation at
8445 <a class="ulink" href="http://github.com" target="_top">http://github.com</a>.
8446
8447 </p><pre class="literallayout">
8448 # edit a file
8449 $ vi &lt;path&gt;/file
8450 # stage the change
8451 $ git add &lt;path&gt;/file
8452 # commit the change
8453 $ git commit -s
8454 # remove a file
8455 $ git rm &lt;path&gt;/file
8456 # commit the change
8457 $ git commit -s
8458
8459 ... etc.
8460 </pre><p>
8461 </p><p>
8462 Distributed development with Git is possible when you use a universally
8463 agreed-upon unique commit identifier (set by the creator of the commit) that maps to a
8464 specific change set with a specific parent.
8465 This identifier is created for you when
8466 you create a commit, and is re-created when you amend, alter or re-apply
8467 a commit.
8468 As an individual in isolation, this is of no interest.
8469 However, if you
8470 intend to share your tree with normal Git <code class="filename">push</code> and
8471 <code class="filename">pull</code> operations for
8472 distributed development, you should consider the ramifications of changing a
8473 commit that you have already shared with others.
8474 </p><p>
8475 Assuming that the changes have not been pushed upstream, or pulled into
8476 another repository, you can update both the commit content and commit messages
8477 associated with development by using the following commands:
8478
8479 </p><pre class="literallayout">
8480 $ Git add &lt;path&gt;/file
8481 $ Git commit --amend
8482 $ Git rebase or Git rebase -i
8483 </pre><p>
8484 </p><p>
8485 Again, assuming that the changes have not been pushed upstream, and that
8486 no pending works-in-progress exist (use <code class="filename">git status</code> to check), then
8487 you can revert (undo) commits by using the following commands:
8488
8489 </p><pre class="literallayout">
8490 # remove the commit, update working tree and remove all
8491 # traces of the change
8492 $ git reset --hard HEAD^
8493 # remove the commit, but leave the files changed and staged for re-commit
8494 $ git reset --soft HEAD^
8495 # remove the commit, leave file change, but not staged for commit
8496 $ git reset --mixed HEAD^
8497 </pre><p>
8498 </p><p>
8499 You can create branches, "cherry-pick" changes, or perform any number of Git
8500 operations until the commits are in good order for pushing upstream
8501 or for pull requests.
8502 After a <code class="filename">push</code> or <code class="filename">pull</code> command,
8503 commits are normally considered
8504 "permanent" and you should not modify them.
8505 If the commits need to be changed, you can incrementally do so with new commits.
8506 These practices follow standard Git workflow and the <code class="filename">kernel.org</code> best
8507 practices, which is recommended.
8508 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
8509 It is recommended to tag or branch before adding changes to a Yocto Project
8510 BSP or before creating a new one.
8511 The reason for this recommendation is because the branch or tag provides a
8512 reference point to facilitate locating and exporting local changes.
8513 </div><p>
8514 </p><div class="section" title="3.4.2.2.1. Exporting Changes Internally by Using Patches"><div class="titlepage"><div><div><h5 class="title"><a id="export-internally-via-patches"></a>3.4.2.2.1. Exporting Changes Internally by Using Patches</h5></div></div></div><p>
8515 This section describes how you can extract committed changes from a working directory
8516 by exporting them as patches.
8517 Once the changes have been extracted, you can use the patches for upstream submission,
8518 place them in a Yocto Project template for automatic kernel patching,
8519 or apply them in many other common uses.
8520 </p><p>
8521 This example shows how to create a directory with sequentially numbered patches.
8522 Once the directory is created, you can apply it to a repository using the
8523 <code class="filename">git am</code> command to reproduce the original commit and all
8524 the related information such as author, date, commit log, and so forth.
8525 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
8526 The new commit identifiers (ID) will be generated upon re-application.
8527 This action reflects that the commit is now applied to an underlying commit
8528 with a different ID.
8529 </div><p>
8530 </p><pre class="literallayout">
8531 # &lt;first-commit&gt; can be a tag if one was created before development
8532 # began. It can also be the parent branch if a branch was created
8533 # before development began.
8534
8535 $ git format-patch -o &lt;dir&gt; &lt;first commit&gt;..&lt;last commit&gt;
8536 </pre><p>
8537 </p><p>
8538 In other words:
8539 </p><pre class="literallayout">
8540 # Identify commits of interest.
8541
8542 # If the tree was tagged before development
8543 $ git format-patch -o &lt;save dir&gt; &lt;tag&gt;
8544
8545 # If no tags are available
8546 $ git format-patch -o &lt;save dir&gt; HEAD^ # last commit
8547 $ git format-patch -o &lt;save dir&gt; HEAD^^ # last 2 commits
8548 $ git whatchanged # identify last commit
8549 $ git format-patch -o &lt;save dir&gt; &lt;commit id&gt;
8550 $ git format-patch -o &lt;save dir&gt; &lt;rev-list&gt;
8551 </pre><p>
8552 </p></div><div class="section" title="3.4.2.2.2. Exporting Changes Internally by Using Git"><div class="titlepage"><div><div><h5 class="title"><a id="export-internally-via-git"></a>3.4.2.2.2. Exporting Changes Internally by Using Git</h5></div></div></div><p>
8553 This section describes how you can export changes from a working directory
8554 by pushing the changes into a master repository or by making a pull request.
8555 Once you have pushed the changes to the master repository, you can then
8556 pull those same changes into a new kernel build at a later time.
8557 </p><p>
8558 Use this command form to push the changes:
8559 </p><pre class="literallayout">
8560 $ git push ssh://&lt;master_server&gt;/&lt;path_to_repo&gt;
8561 &lt;local_branch&gt;:&lt;remote_branch&gt;
8562 </pre><p>
8563 </p><p>
8564 For example, the following command pushes the changes from your local branch
8565 <code class="filename">yocto/standard/common-pc/base</code> to the remote branch with the same name
8566 in the master repository <code class="filename">//git.mycompany.com/pub/git/kernel-3.4</code>.
8567 </p><pre class="literallayout">
8568 $ git push ssh://git.mycompany.com/pub/git/kernel-3.4 \
8569 yocto/standard/common-pc/base:yocto/standard/common-pc/base
8570 </pre><p>
8571 </p><p>
8572 A pull request entails using the <code class="filename">git request-pull</code> command to compose
8573 an email to the
8574 maintainer requesting that a branch be pulled into the master repository, see
8575 <a class="ulink" href="http://github.com/guides/pull-requests" target="_top">http://github.com/guides/pull-requests</a> for an example.
8576 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
8577 Other commands such as <code class="filename">git stash</code> or branching can also be used to save
8578 changes, but are not covered in this document.
8579 </div><p>
8580 </p></div></div><div class="section" title="3.4.2.3. Exporting Changes for External (Upstream) Submission"><div class="titlepage"><div><div><h4 class="title"><a id="export-for-external-upstream-submission"></a>3.4.2.3. Exporting Changes for External (Upstream) Submission</h4></div></div></div><p>
8581 This section describes how to export changes for external upstream submission.
8582 If the patch series is large or the maintainer prefers to pull
8583 changes, you can submit these changes by using a pull request.
8584 However, it is common to send patches as an email series.
8585 This method allows easy review and integration of the changes.
8586 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
8587 Before sending patches for review be sure you understand the
8588 community standards for submitting and documenting changes and follow their best practices.
8589 For example, kernel patches should follow standards such as:
8590 <div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>
8591 <a class="ulink" href="http://linux.yyz.us/patch-format.html" target="_top">http://linux.yyz.us/patch-format.html</a></p></li><li class="listitem"><p>Documentation/SubmittingPatches (in any linux
8592 kernel source tree)</p></li></ul></div></div><p>
8593 </p><p>
8594 The messages used to commit changes are a large part of these standards.
8595 Consequently, be sure that the headers for each commit have the required information.
8596 For information on how to follow the Yocto Project commit message standards, see the
8597 "<a class="link" href="#how-to-submit-a-change" target="_top">How to Submit a
8598 Change</a>" section in the Yocto Project Development Manual.
8599 </p><p>
8600 If the initial commits were not properly documented or do not meet those standards,
8601 you can re-base by using the <code class="filename">git rebase -i</code> command to
8602 manipulate the commits and
8603 get them into the required format.
8604 Other techniques such as branching and cherry-picking commits are also viable options.
8605 </p><p>
8606 Once you complete the commits, you can generate the email that sends the patches
8607 to the maintainer(s) or lists that review and integrate changes.
8608 The command <code class="filename">git send-email</code> is commonly used to ensure
8609 that patches are properly
8610 formatted for easy application and avoid mailer-induced patch damage.
8611 </p><p>
8612 The following is an example of dumping patches for external submission:
8613 </p><pre class="literallayout">
8614 # dump the last 4 commits
8615 $ git format-patch --thread -n -o ~/rr/ HEAD^^^^
8616 $ git send-email --compose --subject '[RFC 0/N] &lt;patch series summary&gt;' \
8617 --to foo@yoctoproject.org --to bar@yoctoproject.org \
8618 --cc list@yoctoproject.org ~/rr
8619 # the editor is invoked for the 0/N patch, and when complete the entire
8620 # series is sent via email for review
8621 </pre><p>
8622 </p></div><div class="section" title="3.4.2.4. Exporting Changes for Import into Another SCM"><div class="titlepage"><div><div><h4 class="title"><a id="export-for-import-into-other-scm"></a>3.4.2.4. Exporting Changes for Import into Another SCM</h4></div></div></div><p>
8623 When you want to export changes for import into another
8624 Source Code Manager (SCM), you can use any of the previously discussed
8625 techniques.
8626 However, if the patches are manually applied to a secondary tree and then
8627 that tree is checked into the SCM, you can lose change information such as
8628 commit logs.
8629 This process is not recommended.
8630 </p><p>
8631 Many SCMs can directly import Git commits, or can translate Git patches so that
8632 information is not lost.
8633 Those facilities are SCM-dependent and you should use them whenever possible.
8634 </p></div></div><div class="section" title="3.4.3. Working with the Yocto Project Kernel in Another SCM"><div class="titlepage"><div><div><h3 class="title"><a id="scm-working-with-the-yocto-project-kernel-in-another-scm"></a>3.4.3. Working with the Yocto Project Kernel in Another SCM</h3></div></div></div><p>
8635 This section describes kernel development in an SCM other than Git,
8636 which is not the same as exporting changes to another SCM described earlier.
8637 For this scenario, you use the OpenEmbedded build system to
8638 develop the kernel in a different SCM.
8639 The following must be true for you to accomplish this:
8640 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The delivered Yocto Project kernel must be exported into the second
8641 SCM.</p></li><li class="listitem"><p>Development must be exported from that secondary SCM into a
8642 format that can be used by the OpenEmbedded build system.</p></li></ul></div><p>
8643 </p><div class="section" title="3.4.3.1. Exporting the Delivered Kernel to the SCM"><div class="titlepage"><div><div><h4 class="title"><a id="exporting-delivered-kernel-to-scm"></a>3.4.3.1. Exporting the Delivered Kernel to the SCM</h4></div></div></div><p>
8644 Depending on the SCM, it might be possible to export the entire Yocto Project
8645 kernel Git repository, branches and all, into a new environment.
8646 This method is preferred because it has the most flexibility and potential to maintain
8647 the meta data associated with each commit.
8648 </p><p>
8649 When a direct import mechanism is not available, it is still possible to
8650 export a branch (or series of branches) and check them into a new repository.
8651 </p><p>
8652 The following commands illustrate some of the steps you could use to
8653 import the <code class="filename">yocto/standard/common-pc/base</code>
8654 kernel into a secondary SCM:
8655 </p><pre class="literallayout">
8656 $ git checkout yocto/standard/common-pc/base
8657 $ cd .. ; echo linux/.git &gt; .cvsignore
8658 $ cvs import -m "initial import" linux MY_COMPANY start
8659 </pre><p>
8660 </p><p>
8661 You could now relocate the CVS repository and use it in a centralized manner.
8662 </p><p>
8663 The following commands illustrate how you can condense and merge two BSPs into a
8664 second SCM:
8665 </p><pre class="literallayout">
8666 $ git checkout yocto/standard/common-pc/base
8667 $ git merge yocto/standard/common-pc-64/base
8668 # resolve any conflicts and commit them
8669 $ cd .. ; echo linux/.git &gt; .cvsignore
8670 $ cvs import -m "initial import" linux MY_COMPANY start
8671 </pre><p>
8672 </p></div><div class="section" title="3.4.3.2. Importing Changes for the Build"><div class="titlepage"><div><div><h4 class="title"><a id="importing-changes-for-build"></a>3.4.3.2. Importing Changes for the Build</h4></div></div></div><p>
8673 Once development has reached a suitable point in the second development
8674 environment, you need to export the changes as patches.
8675 To export them, place the changes in a recipe and
8676 automatically apply them to the kernel during patching.
8677 </p></div></div><div class="section" title="3.4.4. Creating a BSP Based on an Existing Similar BSP"><div class="titlepage"><div><div><h3 class="title"><a id="bsp-creating"></a>3.4.4. Creating a BSP Based on an Existing Similar BSP</h3></div></div></div><p>
8678 This section overviews the process of creating a BSP based on an
8679 existing similar BSP.
8680 The information is introductory in nature and does not provide step-by-step examples.
8681 For detailed information on how to create a BSP given an existing similar BSP, see
8682 the "<a class="link" href="#dev-manual-bsp-appendix" target="_top">BSP Development
8683 Example</a>" appendix in the Yocto Project Development Manual, or see the
8684 <a class="ulink" href="https://wiki.yoctoproject.org/wiki/Transcript:_creating_one_generic_Atom_BSP_from_another" target="_top">Transcript:_creating_one_generic_Atom_BSP_from_another</a>
8685 wiki page.
8686 </p><p>
8687 The basic steps you need to follow are:
8688 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p><span class="emphasis"><em>Make sure you have set up a local source directory:</em></span>
8689 You must create a local <a class="link" href="#source-directory" target="_top">source
8690 directory</a> by either creating a Git repository (recommended) or
8691 extracting a Yocto Project release tarball.</p></li><li class="listitem"><p><span class="emphasis"><em>Choose an existing BSP available with the Yocto Project:</em></span>
8692 Try to map your board features as closely to the features of a BSP that is
8693 already supported and exists in the Yocto Project.
8694 Starting with something as close as possible to your board makes developing
8695 your BSP easier.
8696 You can find all the BSPs that are supported and ship with the Yocto Project
8697 on the Yocto Project's Download page at
8698 <a class="ulink" href="http://www.yoctoproject.org/download" target="_top">http://www.yoctoproject.org/download</a>.</p></li><li class="listitem"><p><span class="emphasis"><em>Be sure you have the Base BSP:</em></span>
8699 You need to either have a local Git repository of the base BSP set up or
8700 have downloaded and extracted the files from a release BSP tarball.
8701 Either method gives you access to the BSP source files.</p></li><li class="listitem"><p><span class="emphasis"><em>Make a copy of the existing BSP, thus isolating your new
8702 BSP work:</em></span>
8703 Copying the existing BSP file structure gives you a new area in which to work.</p></li><li class="listitem"><p><span class="emphasis"><em>Make configuration and recipe changes to your new BSP:</em></span>
8704 Configuration changes involve the files in the BSP's <code class="filename">conf</code>
8705 directory.
8706 Changes include creating a machine-specific configuration file and editing the
8707 <code class="filename">layer.conf</code> file.
8708 The configuration changes identify the kernel you will be using.
8709 Recipe changes include removing, modifying, or adding new recipe files that
8710 instruct the build process on what features to include in the image.</p></li><li class="listitem"><p><span class="emphasis"><em>Prepare for the build:</em></span>
8711 Before you actually initiate the build, you need to set up the build environment
8712 by sourcing the environment initialization script.
8713 After setting up the environment, you need to make some build configuration
8714 changes to the <code class="filename">local.conf</code> and <code class="filename">bblayers.conf</code>
8715 files.</p></li><li class="listitem"><p><span class="emphasis"><em>Build the image:</em></span>
8716 The OpenEmbedded build system uses BitBake to create the image.
8717 You need to decide on the type of image you are going to build (e.g. minimal, base,
8718 core, sato, and so forth) and then start the build using the <code class="filename">bitbake</code>
8719 command.</p></li></ol></div><p>
8720 </p></div><div class="section" title="3.4.5. &quot;-dirty&quot; String"><div class="titlepage"><div><div><h3 class="title"><a id="tip-dirty-string"></a>3.4.5. "-dirty" String</h3></div></div></div><p>
8721 If kernel images are being built with "-dirty" on the end of the version
8722 string, this simply means that modifications in the source
8723 directory have not been committed.
8724 </p><pre class="literallayout">
8725 $ git status
8726 </pre><p>
8727 </p><p>
8728 You can use the above Git command to report modified, removed, or added files.
8729 You should commit those changes to the tree regardless of whether they will be saved,
8730 exported, or used.
8731 Once you commit the changes you need to rebuild the kernel.
8732 </p><p>
8733 To brute force pickup and commit all such pending changes, enter the following:
8734 </p><pre class="literallayout">
8735 $ git add .
8736 $ git commit -s -a -m "getting rid of -dirty"
8737 </pre><p>
8738 </p><p>
8739 Next, rebuild the kernel.
8740 </p></div></div></div>
8741
8742
8743
8744</div>
8745
8746<table border="0" summary="manufactured viewport for HTML img" cellspacing="0" cellpadding="0" width="100%"><tr><td align="left"><img src="figures/poky-title.png" align="left" width="100%" /></td></tr></table>
8747
8748 <div xml:lang="en" class="book" lang="en"><div class="titlepage"><div><div><h1 class="title"><a id="poky-ref-manual"></a></h1></div><div><div class="authorgroup">
8749 <div class="author"><h3 class="author"><span class="firstname">Richard</span> <span class="surname">Purdie</span></h3><div class="affiliation">
8750 <span class="orgname">Linux Foundation<br /></span>
8751 </div><code class="email">&lt;<a class="email" href="mailto:richard.purdie@linuxfoundation.org">richard.purdie@linuxfoundation.org</a>&gt;</code></div>
8752
8753 </div></div><div><p class="copyright">Copyright © 2010-2012 Linux Foundation</p></div><div><div class="legalnotice" title="Legal Notice"><a id="id1506919"></a>
8754 <p>
8755 Permission is granted to copy, distribute and/or modify this document under
8756 the terms of the <a class="ulink" href="http://creativecommons.org/licenses/by-sa/2.0/uk/" target="_top">Creative Commons Attribution-Share Alike 2.0 UK: England &amp; Wales</a> as published by Creative Commons.
8757 </p>
8758 <div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
8759 Due to production processes, there could be differences between the Yocto Project
8760 documentation bundled in the release tarball and the
8761 Yocto Project Reference Manual on
8762 the <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project</a> website.
8763 For the latest version of this manual, see the manual on the website.
8764 </div>
8765 </div></div><div><div class="revhistory"><table border="1" width="100%" summary="Revision history"><tr><th align="left" valign="top" colspan="2"><b>Revision History</b></th></tr>
8766 <tr><td align="left">Revision 4.0+git</td><td align="left">24 November 2010</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 0.9 Release</td></tr>
8767 <tr><td align="left">Revision 1.0</td><td align="left">6 April 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0 Release.</td></tr>
8768 <tr><td align="left">Revision 1.0.1</td><td align="left">23 May 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.0.1 Release.</td></tr>
8769 <tr><td align="left">Revision 1.1</td><td align="left">6 October 2011</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.1 Release.</td></tr>
8770 <tr><td align="left">Revision 1.2</td><td align="left">April 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.2 Release.</td></tr>
8771 <tr><td align="left">Revision 1.3</td><td align="left">Sometime in 2012</td></tr><tr><td align="left" colspan="2">Released with the Yocto Project 1.3 Release.</td></tr>
8772 </table></div></div></div><hr /></div>
8773
8774
8775 <div class="chapter" title="Chapter 1. Introduction"><div class="titlepage"><div><div><h2 class="title"><a id="intro"></a>Chapter 1. Introduction</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#intro-welcome">1.1. Introduction</a></span></dt><dt><span class="section"><a href="#intro-manualoverview">1.2. Documentation Overview</a></span></dt><dt><span class="section"><a href="#intro-requirements">1.3. System Requirements</a></span></dt><dt><span class="section"><a href="#intro-getit">1.4. Obtaining the Yocto Project</a></span></dt><dt><span class="section"><a href="#intro-getit-dev">1.5. Development Checkouts</a></span></dt></dl></div><div class="section" title="1.1. Introduction"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="intro-welcome"></a>1.1. Introduction</h2></div></div></div><p>
8776 This manual provides reference information for the current release of the Yocto Project.
8777 The Yocto Project is an open-source collaboration project focused on embedded Linux
8778 developers.
8779 Amongst other things, the Yocto Project uses the OpenEmbedded build system, which
8780 is based on the Poky project, to construct complete Linux images.
8781 You can find complete introductory and getting started information on the Yocto Project
8782 by reading the
8783 Yocto Project Quick Start.
8784 For task-based information using the Yocto Project, see the
8785 Yocto Project Development Manual.
8786 You can also find lots of information on the Yocto Project on the
8787 <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project website</a>.
8788 </p></div><div class="section" title="1.2. Documentation Overview"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="intro-manualoverview"></a>1.2. Documentation Overview</h2></div></div></div><p>
8789 This reference manual consists of the following:
8790 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>
8791 <a class="link" href="#usingpoky" title="Chapter 2. Using the Yocto Project">Using the Yocto Project</a>:</em></span> This chapter
8792 provides an overview of the components that make up the Yocto Project
8793 followed by information about debugging images created in the Yocto Project.
8794 </p></li><li class="listitem"><p><span class="emphasis"><em>
8795 <a class="link" href="#technical-details" title="Chapter 3. Technical Details">Technical Details</a>:</em></span>
8796 This chapter describes fundamental Yocto Project components as well as an explanation
8797 behind how the Yocto Project uses shared state (sstate) cache to speed build time.
8798 </p></li><li class="listitem"><p><span class="emphasis"><em>
8799 <a class="link" href="#ref-structure" title="Chapter 4. Source Directory Structure">Directory Structure</a>:</em></span>
8800 This chapter describes the
8801 <a class="link" href="#source-directory" target="_top">source directory</a> created
8802 either by unpacking a released Yocto Project tarball on your host development system,
8803 or by cloning the upstream
8804 <a class="link" href="#poky" target="_top">Poky</a> Git repository.
8805 </p></li><li class="listitem"><p><span class="emphasis"><em>
8806 <a class="link" href="#ref-bitbake" title="Chapter 5. BitBake">BitBake</a>:</em></span>
8807 This chapter provides an overview of the BitBake tool and its role within
8808 the Yocto Project.</p></li><li class="listitem"><p><span class="emphasis"><em>
8809 <a class="link" href="#ref-classes" title="Chapter 6. Classes">Classes</a>:</em></span>
8810 This chapter describes the classes used in the Yocto Project.</p></li><li class="listitem"><p><span class="emphasis"><em>
8811 <a class="link" href="#ref-images" title="Chapter 7. Images">Images</a>:</em></span>
8812 This chapter describes the standard images that the Yocto Project supports.
8813 </p></li><li class="listitem"><p><span class="emphasis"><em>
8814 <a class="link" href="#ref-features" title="Chapter 8. Reference: Features">Features</a>:</em></span>
8815 This chapter describes mechanisms for creating distribution, machine, and image
8816 features during the build process using the OpenEmbedded build system.</p></li><li class="listitem"><p><span class="emphasis"><em>
8817 <a class="link" href="#ref-variables-glos" title="Chapter 9. Variables Glossary">Variables Glossary</a>:</em></span>
8818 This chapter presents most variables used by the OpenEmbedded build system, which
8819 using BitBake.
8820 Entries describe the function of the variable and how to apply them.
8821 </p></li><li class="listitem"><p><span class="emphasis"><em>
8822 <a class="link" href="#ref-varlocality" title="Chapter 10. Variable Context">Variable Context</a>:</em></span>
8823 This chapter provides variable locality or context.</p></li><li class="listitem"><p><span class="emphasis"><em>
8824 <a class="link" href="#faq" title="Chapter 11. FAQ">FAQ</a>:</em></span>
8825 This chapter provides answers for commonly asked questions in the Yocto Project
8826 development environment.</p></li><li class="listitem"><p><span class="emphasis"><em>
8827 <a class="link" href="#resources" title="Chapter 12. Contributing to the Yocto Project">Contributing to the Yocto Project</a>:</em></span>
8828 This chapter provides guidance on how you can contribute back to the Yocto
8829 Project.</p></li></ul></div><p>
8830 </p></div><div class="section" title="1.3. System Requirements"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="intro-requirements"></a>1.3. System Requirements</h2></div></div></div><p>
8831 For Yocto Project system requirements, see the
8832 <a class="link" href="#yp-resources" target="_top">
8833 What You Need and How You Get It</a> section in the Yocto Project Quick Start.
8834 </p></div><div class="section" title="1.4. Obtaining the Yocto Project"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="intro-getit"></a>1.4. Obtaining the Yocto Project</h2></div></div></div><p>
8835 The Yocto Project development team makes the Yocto Project available through a number
8836 of methods:
8837 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Releases:</em></span> Stable, tested releases are available through
8838 <a class="ulink" href="http://downloads.yoctoproject.org/releases/yocto/" target="_top">http://downloads.yoctoproject.org/releases/yocto/</a>.</p></li><li class="listitem"><p><span class="emphasis"><em>Nightly Builds:</em></span> These releases are available at
8839 <a class="ulink" href="http://autobuilder.yoctoproject.org/nightly" target="_top">http://autobuilder.yoctoproject.org/nightly</a>.
8840 These builds include Yocto Project releases, meta-toolchain tarballs, and
8841 experimental builds.</p></li><li class="listitem"><p><span class="emphasis"><em>Yocto Project Website:</em></span> You can find releases
8842 of the Yocto Project and supported BSPs at the
8843 <a class="ulink" href="http://www.yoctoproject.org" target="_top">Yocto Project website</a>.
8844 Along with these downloads, you can find lots of other information at this site.
8845 </p></li></ul></div><p>
8846 </p></div><div class="section" title="1.5. Development Checkouts"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="intro-getit-dev"></a>1.5. Development Checkouts</h2></div></div></div><p>
8847 Development using the Yocto Project requires a local
8848 <a class="link" href="#source-directory" target="_top">source directory</a>.
8849 You can set up the source directory by downloading a Yocto Project release tarball and unpacking it,
8850 or by cloning a copy of the upstream
8851 <a class="link" href="#poky" target="_top">Poky</a> Git repository.
8852 For information on both these methods, see the
8853 "<a class="link" href="#getting-setup" target="_top">Getting Setup</a>"
8854 section in the Yocto Project Development Manual.
8855 </p></div></div>
8856
8857 <div class="chapter" title="Chapter 2. Using the Yocto Project"><div class="titlepage"><div><div><h2 class="title"><a id="usingpoky"></a>Chapter 2. Using the Yocto Project</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#usingpoky-build">2.1. Running a Build</a></span></dt><dd><dl><dt><span class="section"><a href="#build-overview">2.1.1. Build Overview</a></span></dt><dt><span class="section"><a href="#building-an-image-using-gpl-components">2.1.2. Building an Image Using GPL Components</a></span></dt></dl></dd><dt><span class="section"><a href="#usingpoky-install">2.2. Installing and Using the Result</a></span></dt><dt><span class="section"><a href="#usingpoky-debugging">2.3. Debugging Build Failures</a></span></dt><dd><dl><dt><span class="section"><a href="#usingpoky-debugging-taskfailures">2.3.1. Task Failures</a></span></dt><dt><span class="section"><a href="#usingpoky-debugging-taskrunning">2.3.2. Running Specific Tasks</a></span></dt><dt><span class="section"><a href="#usingpoky-debugging-dependencies">2.3.3. Dependency Graphs</a></span></dt><dt><span class="section"><a href="#usingpoky-debugging-bitbake">2.3.4. General BitBake Problems</a></span></dt><dt><span class="section"><a href="#usingpoky-debugging-buildfile">2.3.5. Building with No Dependencies</a></span></dt><dt><span class="section"><a href="#usingpoky-debugging-variables">2.3.6. Variables</a></span></dt><dt><span class="section"><a href="#recipe-logging-mechanisms">2.3.7. Recipe Logging Mechanisms</a></span></dt><dt><span class="section"><a href="#usingpoky-debugging-others">2.3.8. Other Tips</a></span></dt></dl></dd></dl></div><p>
8858 This chapter describes common usage for the Yocto Project.
8859 The information is introductory in nature as other manuals in the Yocto Project
8860 documentation set provide more details on how to use the Yocto Project.
8861 </p><div class="section" title="2.1. Running a Build"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-build"></a>2.1. Running a Build</h2></div></div></div><p>
8862 You can find general information on how to build an image using the OpenEmbedded build
8863 system in the
8864 "<a class="link" href="#building-image" target="_top">Building an Image</a>"
8865 section of the Yocto Project Quick Start.
8866 This section provides a summary of the build process and provides information
8867 for less obvious aspects of the build process.
8868 </p><div class="section" title="2.1.1. Build Overview"><div class="titlepage"><div><div><h3 class="title"><a id="build-overview"></a>2.1.1. Build Overview</h3></div></div></div><p>
8869 The first thing you need to do is set up the OpenEmbedded build environment by sourcing
8870 the environment setup script as follows:
8871 </p><pre class="literallayout">
8872 $ source oe-init-build-env [build_dir]
8873 </pre><p>
8874 </p><p>
8875 The <code class="filename">build_dir</code> is optional and specifies the directory the
8876 OpenEmbedded build system uses for the build -
8877 the <a class="link" href="#build-directory" target="_top">build directory</a>.
8878 If you do not specify a build directory it defaults to <code class="filename">build</code>
8879 in your current working directory.
8880 A common practice is to use a different build directory for different targets.
8881 For example, <code class="filename">~/build/x86</code> for a <code class="filename">qemux86</code>
8882 target, and <code class="filename">~/build/arm</code> for a <code class="filename">qemuarm</code> target.
8883 See <a class="link" href="#structure-core-script" title="4.1.9. oe-init-build-env">oe-init-build-env</a>
8884 for more information on this script.
8885 </p><p>
8886 Once the build environment is set up, you can build a target using:
8887 </p><pre class="literallayout">
8888 $ bitbake &lt;target&gt;
8889 </pre><p>
8890 </p><p>
8891 The <code class="filename">target</code> is the name of the recipe you want to build.
8892 Common targets are the images in <code class="filename">meta/recipes-core/images</code>,
8893 <code class="filename">/meta/recipes-sato/images</code>, etc. all found in the
8894 <a class="link" href="#source-directory" target="_top">source directory</a>.
8895 Or, the target can be the name of a recipe for a specific piece of software such as
8896 <span class="application">busybox</span>.
8897 For more details about the images the OpenEmbedded build system supports, see the
8898 "<a class="link" href="#ref-images" title="Chapter 7. Images">Images</a>" chapter.
8899 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
8900 Building an image without GNU Public License Version 3 (GPLv3) components is
8901 only supported for minimal and base images.
8902 See the "<a class="link" href="#ref-images" title="Chapter 7. Images">Images</a>" chapter for more information.
8903 </div></div><div class="section" title="2.1.2. Building an Image Using GPL Components"><div class="titlepage"><div><div><h3 class="title"><a id="building-an-image-using-gpl-components"></a>2.1.2. Building an Image Using GPL Components</h3></div></div></div><p>
8904 When building an image using GPL components, you need to maintain your original
8905 settings and not switch back and forth applying different versions of the GNU
8906 Public License.
8907 If you rebuild using different versions of GPL, dependency errors might occur
8908 due to some components not being rebuilt.
8909 </p></div></div><div class="section" title="2.2. Installing and Using the Result"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-install"></a>2.2. Installing and Using the Result</h2></div></div></div><p>
8910 Once an image has been built, it often needs to be installed.
8911 The images and kernels built by the OpenEmbedded build system are placed in the
8912 <a class="link" href="#build-directory" target="_top">build directory</a> in
8913 <code class="filename">tmp/deploy/images</code>.
8914 For information on how to run pre-built images such as <code class="filename">qemux86</code>
8915 and <code class="filename">qemuarm</code>, see the
8916 "<a class="link" href="#using-pre-built" target="_top">Using Pre-Built Binaries and QEMU</a>"
8917 section in the Yocto Project Quick Start.
8918 For information about how to install these images, see the documentation for your
8919 particular board/machine.
8920 </p></div><div class="section" title="2.3. Debugging Build Failures"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-debugging"></a>2.3. Debugging Build Failures</h2></div></div></div><p>
8921 The exact method for debugging build failures depends on the nature of the
8922 problem and on the system's area from which the bug originates.
8923 Standard debugging practices such as comparison against the last
8924 known working version with examination of the changes and the re-application of steps
8925 to identify the one causing the problem are
8926 valid for the Yocto Project just as they are for any other system.
8927 Even though it is impossible to detail every possible potential failure,
8928 this section provides some general tips to aid in debugging.
8929 </p><div class="section" title="2.3.1. Task Failures"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-debugging-taskfailures"></a>2.3.1. Task Failures</h3></div></div></div><p>The log file for shell tasks is available in
8930 <code class="filename">${WORKDIR}/temp/log.do_taskname.pid</code>.
8931 For example, the <code class="filename">compile</code> task for the QEMU minimal image for the x86
8932 machine (<code class="filename">qemux86</code>) might be
8933 <code class="filename">tmp/work/qemux86-poky-linux/core-image-minimal-1.0-r0/temp/log.do_compile.20830</code>.
8934 To see what BitBake runs to generate that log, look at the corresponding
8935 <code class="filename">run.do_taskname.pid</code> file located in the same directory.
8936 </p><p>
8937 Presently, the output from Python tasks is sent directly to the console.
8938 </p></div><div class="section" title="2.3.2. Running Specific Tasks"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-debugging-taskrunning"></a>2.3.2. Running Specific Tasks</h3></div></div></div><p>
8939 Any given package consists of a set of tasks.
8940 The standard BitBake behavior in most cases is: <code class="filename">fetch</code>,
8941 <code class="filename">unpack</code>,
8942 <code class="filename">patch</code>, <code class="filename">configure</code>,
8943 <code class="filename">compile</code>, <code class="filename">install</code>, <code class="filename">package</code>,
8944 <code class="filename">package_write</code>, and <code class="filename">build</code>.
8945 The default task is <code class="filename">build</code> and any tasks on which it depends
8946 build first.
8947 Some tasks exist, such as <code class="filename">devshell</code>, that are not part of the
8948 default build chain.
8949 If you wish to run a task that is not part of the default build chain, you can use the
8950 <code class="filename">-c</code> option in BitBake as follows:
8951 </p><pre class="literallayout">
8952 $ bitbake matchbox-desktop -c devshell
8953 </pre><p>
8954 </p><p>
8955 If you wish to rerun a task, use the <code class="filename">-f</code> force option.
8956 For example, the following sequence forces recompilation after changing files in the
8957 working directory.
8958 </p><pre class="literallayout">
8959 $ bitbake matchbox-desktop
8960 .
8961 .
8962 [make some changes to the source code in the working directory]
8963 .
8964 .
8965 $ bitbake matchbox-desktop -c compile -f
8966 $ bitbake matchbox-desktop
8967 </pre><p>
8968 </p><p>
8969 This sequence first builds <code class="filename">matchbox-desktop</code> and then recompiles it.
8970 The last command reruns all tasks (basically the packaging tasks) after the compile.
8971 BitBake recognizes that the <code class="filename">compile</code> task was rerun and therefore
8972 understands that the other tasks also need to be run again.
8973 </p><p>
8974 You can view a list of tasks in a given package by running the
8975 <code class="filename">listtasks</code> task as follows:
8976 </p><pre class="literallayout">
8977 $ bitbake matchbox-desktop -c listtasks
8978 </pre><p>
8979 The results are in the file <code class="filename">${WORKDIR}/temp/log.do_listtasks</code>.
8980 </p></div><div class="section" title="2.3.3. Dependency Graphs"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-debugging-dependencies"></a>2.3.3. Dependency Graphs</h3></div></div></div><p>
8981 Sometimes it can be hard to see why BitBake wants to build some other packages before a given
8982 package you have specified.
8983 The <code class="filename">bitbake -g targetname</code> command creates the
8984 <code class="filename">depends.dot</code>, <code class="filename">package-depends.dot</code>,
8985 and <code class="filename">task-depends.dot</code> files in the current directory.
8986 These files show the package and task dependencies and are useful for debugging problems.
8987 You can use the <code class="filename">bitbake -g -u depexp targetname</code> command to
8988 display the results in a more human-readable form.
8989 </p></div><div class="section" title="2.3.4. General BitBake Problems"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-debugging-bitbake"></a>2.3.4. General BitBake Problems</h3></div></div></div><p>
8990 You can see debug output from BitBake by using the <code class="filename">-D</code> option.
8991 The debug output gives more information about what BitBake
8992 is doing and the reason behind it.
8993 Each <code class="filename">-D</code> option you use increases the logging level.
8994 The most common usage is <code class="filename">-DDD</code>.
8995 </p><p>
8996 The output from <code class="filename">bitbake -DDD -v targetname</code> can reveal why
8997 BitBake chose a certain version of a package or why BitBake
8998 picked a certain provider.
8999 This command could also help you in a situation where you think BitBake did something
9000 unexpected.
9001 </p></div><div class="section" title="2.3.5. Building with No Dependencies"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-debugging-buildfile"></a>2.3.5. Building with No Dependencies</h3></div></div></div><p>
9002 If you really want to build a specific <code class="filename">.bb</code> file, you can use
9003 the command form <code class="filename">bitbake -b &lt;somepath/somefile.bb&gt;</code>.
9004 This command form does not check for dependencies so you should use it
9005 only when you know its dependencies already exist.
9006 You can also specify fragments of the filename.
9007 In this case, BitBake checks for a unique match.
9008 </p></div><div class="section" title="2.3.6. Variables"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-debugging-variables"></a>2.3.6. Variables</h3></div></div></div><p>
9009 The <code class="filename">-e</code> option dumps the resulting environment for
9010 either the configuration (no package specified) or for a
9011 specific package when specified; or <code class="filename">-b recipename</code>
9012 to show the environment from parsing a single recipe file only.
9013 </p></div><div class="section" title="2.3.7. Recipe Logging Mechanisms"><div class="titlepage"><div><div><h3 class="title"><a id="recipe-logging-mechanisms"></a>2.3.7. Recipe Logging Mechanisms</h3></div></div></div><p>
9014 Best practices exist while writing recipes that both log build progress and
9015 act on build conditions such as warnings and errors.
9016 Both Python and Bash language bindings exist for the logging mechanism:
9017 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Python:</em></span> For Python functions, BitBake
9018 supports several loglevels: <code class="filename">bb.fatal</code>,
9019 <code class="filename">bb.error</code>, <code class="filename">bb.warn</code>,
9020 <code class="filename">bb.note</code>, <code class="filename">bb.plain</code>,
9021 and <code class="filename">bb.debug</code>.</p></li><li class="listitem"><p><span class="emphasis"><em>Bash:</em></span> For Bash functions, the same set
9022 of loglevels exist and are accessed with a similar syntax:
9023 <code class="filename">bbfatal</code>, <code class="filename">bberror</code>,
9024 <code class="filename">bbwarn</code>, <code class="filename">bbnote</code>,
9025 <code class="filename">bbplain</code>, and <code class="filename">bbdebug</code>.</p></li></ul></div><p>
9026 </p><p>
9027 For guidance on how logging is handled in both Python and Bash recipes, see the
9028 <code class="filename">logging.bbclass</code> file in the
9029 <code class="filename">meta/classes</code> folder of the
9030 <a class="link" href="#source-directory" target="_top">source directory</a>.
9031 </p><div class="section" title="2.3.7.1. Logging With Python"><div class="titlepage"><div><div><h4 class="title"><a id="logging-with-python"></a>2.3.7.1. Logging With Python</h4></div></div></div><p>
9032 When creating recipes using Python and inserting code that handles build logs
9033 keep in mind the goal is to have informative logs while keeping the console as
9034 "silent" as possible.
9035 Also, if you want status messages in the log use the "debug" loglevel.
9036 </p><p>
9037 Following is an example written in Python.
9038 The code handles logging for a function that determines the number of tasks
9039 needed to be run:
9040 </p><pre class="literallayout">
9041 python do_listtasks() {
9042 bb.debug(2, "Starting to figure out the task list")
9043 if noteworthy_condition:
9044 bb.note("There are 47 tasks to run")
9045 bb.debug(2, "Got to point xyz")
9046 if warning_trigger:
9047 bb.warn("Detected warning_trigger, this might be a problem later.")
9048 if recoverable_error:
9049 bb.error("Hit recoverable_error, you really need to fix this!")
9050 if fatal_error:
9051 bb.fatal("fatal_error detected, unable to print the task list")
9052 bb.plain("The tasks present are abc")
9053 bb.debug(2, "Finished figuring out the tasklist")
9054 }
9055 </pre><p>
9056 </p></div><div class="section" title="2.3.7.2. Logging With Bash"><div class="titlepage"><div><div><h4 class="title"><a id="logging-with-bash"></a>2.3.7.2. Logging With Bash</h4></div></div></div><p>
9057 When creating recipes using Bash and inserting code that handles build
9058 logs you have the same goals - informative with minimal console output.
9059 The syntax you use for recipes written in Bash is similar to that of
9060 recipes written in Python described in the previous section.
9061 </p><p>
9062 Following is an example written in Bash.
9063 The code logs the progress of the <code class="filename">do_my_function</code> function.
9064 </p><pre class="literallayout">
9065 do_my_function() {
9066 bbdebug 2 "Running do_my_function"
9067 if [ exceptional_condition ]; then
9068 bbnote "Hit exceptional_condition"
9069 fi
9070 bbdebug 2 "Got to point xyz"
9071 if [ warning_trigger ]; then
9072 bbwarn "Detected warning_trigger, this might cause a problem later."
9073 fi
9074 if [ recoverable_error ]; then
9075 bberror "Hit recoverable_error, correcting"
9076 fi
9077 if [ fatal_error ]; then
9078 bbfatal "fatal_error detected"
9079 fi
9080 bbdebug 2 "Completed do_my_function"
9081 }
9082 </pre><p>
9083 </p></div></div><div class="section" title="2.3.8. Other Tips"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-debugging-others"></a>2.3.8. Other Tips</h3></div></div></div><p>
9084 Here are some other tips that you might find useful:
9085 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>When adding new packages, it is worth watching for
9086 undesirable items making their way into compiler command lines.
9087 For example, you do not want references to local system files like
9088 <code class="filename">/usr/lib/</code> or <code class="filename">/usr/include/</code>.
9089 </p></li><li class="listitem"><p>If you want to remove the psplash boot splashscreen,
9090 add <code class="filename">psplash=false</code> to the kernel command line.
9091 Doing so prevents psplash from loading and thus allows you to see the console.
9092 It is also possible to switch out of the splashscreen by
9093 switching the virtual console (e.g. Fn+Left or Fn+Right on a Zaurus).
9094 </p></li></ul></div><p>
9095 </p></div></div></div>
9096
9097 <div class="chapter" title="Chapter 3. Technical Details"><div class="titlepage"><div><div><h2 class="title"><a id="technical-details"></a>Chapter 3. Technical Details</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#usingpoky-components">3.1. Yocto Project Components</a></span></dt><dd><dl><dt><span class="section"><a href="#usingpoky-components-bitbake">3.1.1. BitBake</a></span></dt><dt><span class="section"><a href="#usingpoky-components-metadata">3.1.2. Metadata (Recipes)</a></span></dt><dt><span class="section"><a href="#usingpoky-components-classes">3.1.3. Classes</a></span></dt><dt><span class="section"><a href="#usingpoky-components-configuration">3.1.4. Configuration</a></span></dt></dl></dd><dt><span class="section"><a href="#shared-state-cache">3.2. Shared State Cache</a></span></dt><dd><dl><dt><span class="section"><a href="#overall-architecture">3.2.1. Overall Architecture</a></span></dt><dt><span class="section"><a href="#checksums">3.2.2. Checksums (Signatures)</a></span></dt><dt><span class="section"><a href="#shared-state">3.2.3. Shared State</a></span></dt><dt><span class="section"><a href="#tips-and-tricks">3.2.4. Tips and Tricks</a></span></dt></dl></dd><dt><span class="section"><a href="#x32">3.3. x32</a></span></dt><dd><dl><dt><span class="section"><a href="#support">3.3.1. Support</a></span></dt><dt><span class="section"><a href="#future-development-and-limitations">3.3.2. Future Development and Limitations</a></span></dt><dt><span class="section"><a href="#using-x32-right-now">3.3.3. Using x32 Right Now</a></span></dt></dl></dd><dt><span class="section"><a href="#licenses">3.4. Licenses</a></span></dt><dd><dl><dt><span class="section"><a href="#usingpoky-configuring-LIC_FILES_CHKSUM">3.4.1. Tracking License Changes</a></span></dt><dt><span class="section"><a href="#enabling-commercially-licensed-recipes">3.4.2. Enabling Commercially Licensed Recipes</a></span></dt></dl></dd></dl></div><p>
9098 This chapter provides technical details for various parts of the Yocto Project.
9099 Currently, topics include Yocto Project components and shared state (sstate) cache.
9100 </p><div class="section" title="3.1. Yocto Project Components"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="usingpoky-components"></a>3.1. Yocto Project Components</h2></div></div></div><p>
9101 The BitBake task executor together with various types of configuration files form the
9102 OpenEmbedded Core.
9103 This section overviews the BitBake task executor and the
9104 configuration files by describing what they are used for and how they interact.
9105 </p><p>
9106 BitBake handles the parsing and execution of the data files.
9107 The data itself is of various types:
9108 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>Recipes:</em></span> Provides details about particular
9109 pieces of software</p></li><li class="listitem"><p><span class="emphasis"><em>Class Data:</em></span> An abstraction of common build
9110 information (e.g. how to build a Linux kernel).</p></li><li class="listitem"><p><span class="emphasis"><em>Configuration Data:</em></span> Defines machine-specific settings,
9111 policy decisions, etc.
9112 Configuration data acts as the glue to bind everything together.</p></li></ul></div><p>
9113 For more information on data, see the
9114 "<a class="link" href="#yocto-project-terms" target="_top">Yocto Project Terms</a>"
9115 section in the Yocto Project Development Manual.
9116 </p><p>
9117 BitBake knows how to combine multiple data sources together and refers to each data source
9118 as a layer.
9119 For information on layers, see the
9120 "<a class="link" href="#understanding-and-creating-layers" target="_top">Understanding and
9121 Creating Layers</a>" section of the Yocto Project Development Manual.
9122 </p><p>
9123 Following are some brief details on these core components.
9124 For more detailed information on these components see the
9125 "<a class="link" href="#ref-structure" title="Chapter 4. Source Directory Structure">Directory Structure</a>" chapter.
9126 </p><div class="section" title="3.1.1. BitBake"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-components-bitbake"></a>3.1.1. BitBake</h3></div></div></div><p>
9127 BitBake is the tool at the heart of the OpenEmbedded build system and is responsible
9128 for parsing the metadata, generating a list of tasks from it,
9129 and then executing those tasks.
9130 To see a list of the options BitBake supports, use the following help command:
9131 </p><pre class="literallayout">
9132 $ bitbake --help
9133 </pre><p>
9134 </p><p>
9135 The most common usage for BitBake is <code class="filename">bitbake &lt;packagename&gt;</code>, where
9136 <code class="filename">packagename</code> is the name of the package you want to build
9137 (referred to as the "target" in this manual).
9138 The target often equates to the first part of a <code class="filename">.bb</code> filename.
9139 So, to run the <code class="filename">matchbox-desktop_1.2.3.bb</code> file, you
9140 might type the following:
9141 </p><pre class="literallayout">
9142 $ bitbake matchbox-desktop
9143 </pre><p>
9144 Several different versions of <code class="filename">matchbox-desktop</code> might exist.
9145 BitBake chooses the one selected by the distribution configuration.
9146 You can get more details about how BitBake chooses between different
9147 target versions and providers in the
9148 "<a class="link" href="#ref-bitbake-providers" title="5.2. Preferences and Providers">Preferences and Providers</a>" section.
9149 </p><p>
9150 BitBake also tries to execute any dependent tasks first.
9151 So for example, before building <code class="filename">matchbox-desktop</code>, BitBake
9152 would build a cross compiler and <code class="filename">eglibc</code> if they had not already
9153 been built.
9154 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>This release of the Yocto Project does not support the <code class="filename">glibc</code>
9155 GNU version of the Unix standard C library. By default, the OpenEmbedded build system
9156 builds with <code class="filename">eglibc</code>.</div><p>
9157 </p><p>
9158 A useful BitBake option to consider is the <code class="filename">-k</code> or
9159 <code class="filename">--continue</code> option.
9160 This option instructs BitBake to try and continue processing the job as much
9161 as possible even after encountering an error.
9162 When an error occurs, the target that
9163 failed and those that depend on it cannot be remade.
9164 However, when you use this option other dependencies can still be processed.
9165 </p></div><div class="section" title="3.1.2. Metadata (Recipes)"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-components-metadata"></a>3.1.2. Metadata (Recipes)</h3></div></div></div><p>
9166 The <code class="filename">.bb</code> files are usually referred to as "recipes."
9167 In general, a recipe contains information about a single piece of software.
9168 The information includes the location from which to download the source patches
9169 (if any are needed), which special configuration options to apply,
9170 how to compile the source files, and how to package the compiled output.
9171 </p><p>
9172 The term "package" can also be used to describe recipes.
9173 However, since the same word is used for the packaged output from the OpenEmbedded
9174 build system (i.e. <code class="filename">.ipk</code> or <code class="filename">.deb</code> files),
9175 this document avoids using the term "package" when referring to recipes.
9176 </p></div><div class="section" title="3.1.3. Classes"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-components-classes"></a>3.1.3. Classes</h3></div></div></div><p>
9177 Class files (<code class="filename">.bbclass</code>) contain information that is useful to share
9178 between metadata files.
9179 An example is the Autotools class, which contains
9180 common settings for any application that Autotools uses.
9181 The "<a class="link" href="#ref-classes" title="Chapter 6. Classes">Reference: Classes</a>" chapter provides details
9182 about common classes and how to use them.
9183 </p></div><div class="section" title="3.1.4. Configuration"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-components-configuration"></a>3.1.4. Configuration</h3></div></div></div><p>
9184 The configuration files (<code class="filename">.conf</code>) define various configuration variables
9185 that govern the OpenEmbedded build process.
9186 These files fall into several areas that define machine configuration options,
9187 distribution configuration options, compiler tuning options, general common configuration
9188 options and user configuration options (<code class="filename">local.conf</code>, which is found
9189 in the <a class="ulink" href="build-directory" target="_top">build directory</a>).
9190 </p></div></div><div class="section" title="3.2. Shared State Cache"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="shared-state-cache"></a>3.2. Shared State Cache</h2></div></div></div><p>
9191 By design, the OpenEmbedded build system builds everything from scratch unless
9192 BitBake can determine that parts don't need to be rebuilt.
9193 Fundamentally, building from scratch is attractive as it means all parts are
9194 built fresh and there is no possibility of stale data causing problems.
9195 When developers hit problems, they typically default back to building from scratch
9196 so they know the state of things from the start.
9197 </p><p>
9198 Building an image from scratch is both an advantage and a disadvantage to the process.
9199 As mentioned in the previous paragraph, building from scratch ensures that
9200 everything is current and starts from a known state.
9201 However, building from scratch also takes much longer as it generally means
9202 rebuilding things that don't necessarily need rebuilt.
9203 </p><p>
9204 The Yocto Project implements shared state code that supports incremental builds.
9205 The implementation of the shared state code answers the following questions that
9206 were fundamental roadblocks within the OpenEmbedded incremental build support system:
9207 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">What pieces of the system have changed and what pieces have not changed?</li><li class="listitem">How are changed pieces of software removed and replaced?</li><li class="listitem">How are pre-built components that don't need to be rebuilt from scratch
9208 used when they are available?</li></ul></div><p>
9209 </p><p>
9210 For the first question, the build system detects changes in the "inputs" to a given task by
9211 creating a checksum (or signature) of the task's inputs.
9212 If the checksum changes, the system assumes the inputs have changed and the task needs to be
9213 rerun.
9214 For the second question, the shared state (sstate) code tracks which tasks add which output
9215 to the build process.
9216 This means the output from a given task can be removed, upgraded or otherwise manipulated.
9217 The third question is partly addressed by the solution for the second question
9218 assuming the build system can fetch the sstate objects from remote locations and
9219 install them if they are deemed to be valid.
9220 </p><p>
9221 The rest of this section goes into detail about the overall incremental build
9222 architecture, the checksums (signatures), shared state, and some tips and tricks.
9223 </p><div class="section" title="3.2.1. Overall Architecture"><div class="titlepage"><div><div><h3 class="title"><a id="overall-architecture"></a>3.2.1. Overall Architecture</h3></div></div></div><p>
9224 When determining what parts of the system need to be built, BitBake
9225 uses a per-task basis and does not use a per-recipe basis.
9226 You might wonder why using a per-task basis is preferred over a per-recipe basis.
9227 To help explain, consider having the IPK packaging backend enabled and then switching to DEB.
9228 In this case, <code class="filename">do_install</code> and <code class="filename">do_package</code>
9229 output are still valid.
9230 However, with a per-recipe approach, the build would not include the
9231 <code class="filename">.deb</code> files.
9232 Consequently, you would have to invalidate the whole build and rerun it.
9233 Rerunning everything is not the best situation.
9234 Also in this case, the core must be "taught" much about specific tasks.
9235 This methodology does not scale well and does not allow users to easily add new tasks
9236 in layers or as external recipes without touching the packaged-staging core.
9237 </p></div><div class="section" title="3.2.2. Checksums (Signatures)"><div class="titlepage"><div><div><h3 class="title"><a id="checksums"></a>3.2.2. Checksums (Signatures)</h3></div></div></div><p>
9238 The shared state code uses a checksum, which is a unique signature of a task's
9239 inputs, to determine if a task needs to be run again.
9240 Because it is a change in a task's inputs that triggers a rerun, the process
9241 needs to detect all the inputs to a given task.
9242 For shell tasks, this turns out to be fairly easy because
9243 the build process generates a "run" shell script for each task and
9244 it is possible to create a checksum that gives you a good idea of when
9245 the task's data changes.
9246 </p><p>
9247 To complicate the problem, there are things that should not be included in
9248 the checksum.
9249 First, there is the actual specific build path of a given task -
9250 the <code class="filename">WORKDIR</code>.
9251 It does not matter if the working directory changes because it should not
9252 affect the output for target packages.
9253 Also, the build process has the objective of making native/cross packages relocatable.
9254 The checksum therefore needs to exclude <code class="filename">WORKDIR</code>.
9255 The simplistic approach for excluding the working directory is to set
9256 <code class="filename">WORKDIR</code> to some fixed value and create the checksum
9257 for the "run" script.
9258 </p><p>
9259 Another problem results from the "run" scripts containing functions that
9260 might or might not get called.
9261 The incremental build solution contains code that figures out dependencies
9262 between shell functions.
9263 This code is used to prune the "run" scripts down to the minimum set,
9264 thereby alleviating this problem and making the "run" scripts much more
9265 readable as a bonus.
9266 </p><p>
9267 So far we have solutions for shell scripts.
9268 What about python tasks?
9269 The same approach applies even though these tasks are more difficult.
9270 The process needs to figure out what variables a python function accesses
9271 and what functions it calls.
9272 Again, the incremental build solution contains code that first figures out
9273 the variable and function dependencies, and then creates a checksum for the data
9274 used as the input to the task.
9275 </p><p>
9276 Like the <code class="filename">WORKDIR</code> case, situations exist where dependencies
9277 should be ignored.
9278 For these cases, you can instruct the build process to ignore a dependency
9279 by using a line like the following:
9280 </p><pre class="literallayout">
9281 PACKAGE_ARCHS[vardepsexclude] = "MACHINE"
9282 </pre><p>
9283 This example ensures that the <code class="filename">PACKAGE_ARCHS</code> variable does not
9284 depend on the value of <code class="filename">MACHINE</code>, even if it does reference it.
9285 </p><p>
9286 Equally, there are cases where we need to add dependencies BitBake is not able to find.
9287 You can accomplish this by using a line like the following:
9288 </p><pre class="literallayout">
9289 PACKAGE_ARCHS[vardeps] = "MACHINE"
9290 </pre><p>
9291 This example explicitly adds the <code class="filename">MACHINE</code> variable as a
9292 dependency for <code class="filename">PACKAGE_ARCHS</code>.
9293 </p><p>
9294 Consider a case with inline python, for example, where BitBake is not
9295 able to figure out dependencies.
9296 When running in debug mode (i.e. using <code class="filename">-DDD</code>), BitBake
9297 produces output when it discovers something for which it cannot figure out
9298 dependencies.
9299 The Yocto Project team has currently not managed to cover those dependencies
9300 in detail and is aware of the need to fix this situation.
9301 </p><p>
9302 Thus far, this section has limited discussion to the direct inputs into a task.
9303 Information based on direct inputs is referred to as the "basehash" in the
9304 code.
9305 However, there is still the question of a task's indirect inputs - the
9306 things that were already built and present in the build directory.
9307 The checksum (or signature) for a particular task needs to add the hashes
9308 of all the tasks on which the particular task depends.
9309 Choosing which dependencies to add is a policy decision.
9310 However, the effect is to generate a master checksum that combines the basehash
9311 and the hashes of the task's dependencies.
9312 </p><p>
9313 At the code level, there are a variety of ways both the basehash and the
9314 dependent task hashes can be influenced.
9315 Within the BitBake configuration file, we can give BitBake some extra information
9316 to help it construct the basehash.
9317 The following statements effectively result in a list of global variable
9318 dependency excludes - variables never included in any checksum:
9319 </p><pre class="literallayout">
9320 BB_HASHBASE_WHITELIST ?= "TMPDIR FILE PATH PWD BB_TASKHASH BBPATH"
9321 BB_HASHBASE_WHITELIST += "DL_DIR SSTATE_DIR THISDIR FILESEXTRAPATHS"
9322 BB_HASHBASE_WHITELIST += "FILE_DIRNAME HOME LOGNAME SHELL TERM USER"
9323 BB_HASHBASE_WHITELIST += "FILESPATH USERNAME STAGING_DIR_HOST STAGING_DIR_TARGET"
9324 </pre><p>
9325 The previous example actually excludes
9326 <a class="link" href="#var-WORKDIR" title="WORKDIR"><code class="filename">WORKDIR</code></a>
9327 since it is actually constructed as a path within
9328 <a class="link" href="#var-TMPDIR" title="TMPDIR"><code class="filename">TMPDIR</code></a>, which is on
9329 the whitelist.
9330 </p><p>
9331 The rules for deciding which hashes of dependent tasks to include through
9332 dependency chains are more complex and are generally accomplished with a
9333 python function.
9334 The code in <code class="filename">meta/lib/oe/sstatesig.py</code> shows two examples
9335 of this and also illustrates how you can insert your own policy into the system
9336 if so desired.
9337 This file defines the two basic signature generators <code class="filename">OE-Core</code>
9338 uses: "OEBasic" and "OEBasicHash".
9339 By default, there is a dummy "noop" signature handler enabled in BitBake.
9340 This means that behavior is unchanged from previous versions.
9341 <code class="filename">OE-Core</code> uses the "OEBasic" signature handler by default
9342 through this setting in the <code class="filename">bitbake.conf</code> file:
9343 </p><pre class="literallayout">
9344 BB_SIGNATURE_HANDLER ?= "OEBasic"
9345 </pre><p>
9346 The "OEBasicHash" <code class="filename">BB_SIGNATURE_HANDLER</code> is the same as the
9347 "OEBasic" version but adds the task hash to the stamp files.
9348 This results in any metadata change that changes the task hash, automatically
9349 causing the task to be run again.
9350 This removes the need to bump <a class="link" href="#var-PR" title="PR"><code class="filename">PR</code></a>
9351 values and changes to metadata automatically ripple across the build.
9352 Currently, this behavior is not the default behavior for <code class="filename">OE-Core</code>
9353 but is the default in <code class="filename">poky</code>.
9354 </p><p>
9355 It is also worth noting that the end result of these signature generators is to
9356 make some dependency and hash information available to the build.
9357 This information includes:
9358 </p><pre class="literallayout">
9359 BB_BASEHASH_task-&lt;taskname&gt; - the base hashes for each task in the recipe
9360 BB_BASEHASH_&lt;filename:taskname&gt; - the base hashes for each dependent task
9361 BBHASHDEPS_&lt;filename:taskname&gt; - The task dependencies for each task
9362 BB_TASKHASH - the hash of the currently running task
9363 </pre><p>
9364 </p></div><div class="section" title="3.2.3. Shared State"><div class="titlepage"><div><div><h3 class="title"><a id="shared-state"></a>3.2.3. Shared State</h3></div></div></div><p>
9365 Checksums and dependencies, as discussed in the previous section, solve half the
9366 problem.
9367 The other part of the problem is being able to use checksum information during the build
9368 and being able to reuse or rebuild specific components.
9369 </p><p>
9370 The shared state class (<code class="filename">sstate.bbclass</code>)
9371 is a relatively generic implementation of how to "capture" a snapshot of a given task.
9372 The idea is that the build process does not care about the source of a task's output.
9373 Output could be freshly built or it could be downloaded and unpacked from
9374 somewhere - the build process doesn't need to worry about its source.
9375 </p><p>
9376 There are two types of output, one is just about creating a directory
9377 in <code class="filename">WORKDIR</code>.
9378 A good example is the output of either <code class="filename">do_install</code> or
9379 <code class="filename">do_package</code>.
9380 The other type of output occurs when a set of data is merged into a shared directory
9381 tree such as the sysroot.
9382 </p><p>
9383 The Yocto Project team has tried to keep the details of the implementation hidden in
9384 <code class="filename">sstate.bbclass</code>.
9385 From a user's perspective, adding shared state wrapping to a task
9386 is as simple as this <code class="filename">do_deploy</code> example taken from
9387 <code class="filename">do_deploy.bbclass</code>:
9388 </p><pre class="literallayout">
9389 DEPLOYDIR = "${WORKDIR}/deploy-${PN}"
9390 SSTATETASKS += "do_deploy"
9391 do_deploy[sstate-name] = "deploy"
9392 do_deploy[sstate-inputdirs] = "${DEPLOYDIR}"
9393 do_deploy[sstate-outputdirs] = "${DEPLOY_DIR_IMAGE}"
9394
9395 python do_deploy_setscene () {
9396 sstate_setscene(d)
9397 }
9398 addtask do_deploy_setscene
9399 </pre><p>
9400 In the example, we add some extra flags to the task, a name field ("deploy"), an
9401 input directory where the task sends data, and the output
9402 directory where the data from the task should eventually be copied.
9403 We also add a <code class="filename">_setscene</code> variant of the task and add the task
9404 name to the <code class="filename">SSTATETASKS</code> list.
9405 </p><p>
9406 If you have a directory whose contents you need to preserve, you can do this with
9407 a line like the following:
9408 </p><pre class="literallayout">
9409 do_package[sstate-plaindirs] = "${PKGD} ${PKGDEST}"
9410 </pre><p>
9411 This method, as well as the following example, also works for multiple directories.
9412 </p><pre class="literallayout">
9413 do_package[sstate-inputdirs] = "${PKGDESTWORK} ${SHLIBSWORKDIR}"
9414 do_package[sstate-outputdirs] = "${PKGDATA_DIR} ${SHLIBSDIR}"
9415 do_package[sstate-lockfile] = "${PACKAGELOCK}"
9416 </pre><p>
9417 These methods also include the ability to take a lockfile when manipulating
9418 shared state directory structures since some cases are sensitive to file
9419 additions or removals.
9420 </p><p>
9421 Behind the scenes, the shared state code works by looking in
9422 <code class="filename">SSTATE_DIR</code> and
9423 <code class="filename">SSTATE_MIRRORS</code> for shared state files.
9424 Here is an example:
9425 </p><pre class="literallayout">
9426 SSTATE_MIRRORS ?= "\
9427 file://.* http://someserver.tld/share/sstate/ \n \
9428 file://.* file:///some/local/dir/sstate/"
9429 </pre><p>
9430 </p><p>
9431 The shared state package validity can be detected just by looking at the
9432 filename since the filename contains the task checksum (or signature) as
9433 described earlier in this section.
9434 If a valid shared state package is found, the build process downloads it
9435 and uses it to accelerate the task.
9436 </p><p>
9437 The build processes uses the <code class="filename">*_setscene</code> tasks
9438 for the task acceleration phase.
9439 BitBake goes through this phase before the main execution code and tries
9440 to accelerate any tasks for which it can find shared state packages.
9441 If a shared state package for a task is available, the shared state
9442 package is used.
9443 This means the task and any tasks on which it is dependent are not
9444 executed.
9445 </p><p>
9446 As a real world example, the aim is when building an IPK-based image,
9447 only the <code class="filename">do_package_write_ipk</code> tasks would have their
9448 shared state packages fetched and extracted.
9449 Since the sysroot is not used, it would never get extracted.
9450 This is another reason why a task-based approach is preferred over a
9451 recipe-based approach, which would have to install the output from every task.
9452 </p></div><div class="section" title="3.2.4. Tips and Tricks"><div class="titlepage"><div><div><h3 class="title"><a id="tips-and-tricks"></a>3.2.4. Tips and Tricks</h3></div></div></div><p>
9453 The code in the build system that supports incremental builds is not
9454 simple code.
9455 This section presents some tips and tricks that help you work around
9456 issues related to shared state code.
9457 </p><div class="section" title="3.2.4.1. Debugging"><div class="titlepage"><div><div><h4 class="title"><a id="debugging"></a>3.2.4.1. Debugging</h4></div></div></div><p>
9458 When things go wrong, debugging needs to be straightforward.
9459 Because of this, the Yocto Project team included strong debugging
9460 tools:
9461 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Whenever a shared state package is written out, so is a
9462 corresponding <code class="filename">.siginfo</code> file.
9463 This practice results in a pickled python database of all
9464 the metadata that went into creating the hash for a given shared state
9465 package.</p></li><li class="listitem"><p>If BitBake is run with the <code class="filename">--dump-signatures</code>
9466 (or <code class="filename">-S</code>) option, BitBake dumps out
9467 <code class="filename">.siginfo</code> files in
9468 the stamp directory for every task it would have executed instead of
9469 building the specified target package.</p></li><li class="listitem"><p>There is a <code class="filename">bitbake-diffsigs</code> command that
9470 can process these <code class="filename">.siginfo</code> files.
9471 If one file is specified, it will dump out the dependency
9472 information in the file.
9473 If two files are specified, it will compare the two files and dump out
9474 the differences between the two.
9475 This allows the question of "What changed between X and Y?" to be
9476 answered easily.</p></li></ul></div><p>
9477 </p></div><div class="section" title="3.2.4.2. Invalidating Shared State"><div class="titlepage"><div><div><h4 class="title"><a id="invalidating-shared-state"></a>3.2.4.2. Invalidating Shared State</h4></div></div></div><p>
9478 The shared state code uses checksums and shared state
9479 cache to avoid unnecessarily rebuilding tasks.
9480 As with all schemes, this one has some drawbacks.
9481 It is possible that you could make implicit changes that are not factored
9482 into the checksum calculation, but do affect a task's output.
9483 A good example is perhaps when a tool changes its output.
9484 Let's say that the output of <code class="filename">rpmdeps</code> needed to change.
9485 The result of the change should be that all the "package", "package_write_rpm",
9486 and "package_deploy-rpm" shared state cache items would become invalid.
9487 But, because this is a change that is external to the code and therefore implicit,
9488 the associated shared state cache items do not become invalidated.
9489 In this case, the build process would use the cached items rather than running the
9490 task again.
9491 Obviously, these types of implicit changes can cause problems.
9492 </p><p>
9493 To avoid these problems during the build, you need to understand the effects of any
9494 change you make.
9495 Note that any changes you make directly to a function automatically are factored into
9496 the checksum calculation and thus, will invalidate the associated area of sstate cache.
9497 You need to be aware of any implicit changes that are not obvious changes to the
9498 code and could affect the output of a given task.
9499 Once you are aware of such a change, you can take steps to invalidate the cache
9500 and force the task to run.
9501 The step to take is as simple as changing a function's comments in the source code.
9502 For example, to invalidate package shared state files, change the comment statements
9503 of <code class="filename">do_package</code> or the comments of one of the functions it calls.
9504 The change is purely cosmetic, but it causes the checksum to be recalculated and
9505 forces the task to be run again.
9506 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
9507 For an example of a commit that makes a cosmetic change to invalidate
9508 a shared state, see this
9509 <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/poky/commit/meta/classes/package.bbclass?id=737f8bbb4f27b4837047cb9b4fbfe01dfde36d54" target="_top">commit</a>.
9510 </div></div></div></div><div class="section" title="3.3. x32"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="x32"></a>3.3. x32</h2></div></div></div><p>
9511 x32 is a new processor-specific Application Binary Interface (psABI) for x86_64.
9512 An ABI defines the calling conventions between functions in a processing environment.
9513 The interface determines what registers are used and what the sizes are for various C data types.
9514 </p><p>
9515 Some processing environments prefer using 32-bit applications even when running
9516 on Intel 64-bit platforms.
9517 Consider the i386 psABI, which is a very old 32-bit ABI for Intel 64-bit platforms.
9518 The i386 psABI does not provide efficient use and access of the Intel 64-bit processor resources,
9519 leaving the system underutilized.
9520 Now consider the x86_64 psABI.
9521 This ABI is newer and uses 64-bits for data sizes and program pointers.
9522 The extra bits increase the footprint size of the programs, libraries,
9523 and also increases the memory and file system size requirements.
9524 Executing under the x32 psABI enables user programs to utilize CPU and system resources
9525 more efficiently while keeping the memory footprint of the applications low.
9526 Extra bits are used for registers but not for addressing mechanisms.
9527 </p><div class="section" title="3.3.1. Support"><div class="titlepage"><div><div><h3 class="title"><a id="support"></a>3.3.1. Support</h3></div></div></div><p>
9528 While the x32 psABI specifications are not fully finalized, this Yocto Project
9529 release supports current development specifications of x32 psABI.
9530 As of this release of the Yocto Project, x32 psABI support exists as follows:
9531 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>You can create packages and images in x32 psABI format on x86_64 architecture targets.
9532 </p></li><li class="listitem"><p>You can use the x32 psABI support through the <code class="filename">meta-x32</code>
9533 layer on top of the OE-core/Yocto layer.</p></li><li class="listitem"><p>The toolchain from the <code class="filename">experimental/meta-x32</code> layer
9534 is used for building x32 psABI program binaries.</p></li><li class="listitem"><p>You can successfully build many recipes with the x32 toolchain.</p></li><li class="listitem"><p>You can create and boot <code class="filename">core-image-minimal</code> and
9535 <code class="filename">core-image-sato</code> images.</p></li></ul></div><p>
9536 </p></div><div class="section" title="3.3.2. Future Development and Limitations"><div class="titlepage"><div><div><h3 class="title"><a id="future-development-and-limitations"></a>3.3.2. Future Development and Limitations</h3></div></div></div><p>
9537 As of this Yocto Project release, the x32 psABI kernel and library interfaces
9538 specifications are not finalized.
9539 </p><p>
9540 Future Plans for the x32 psABI in the Yocto Project include the following:
9541 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Enhance and fix the few remaining recipes so they
9542 work with and support x32 toolchains.</p></li><li class="listitem"><p>Enhance RPM Package Manager (RPM) support for x32 binaries.</p></li><li class="listitem"><p>Support larger images.</p></li><li class="listitem"><p>Integrate x32 recipes, toolchain, and kernel changes from
9543 <code class="filename">experimental/meta-x32</code> into OE-core.</p></li></ul></div><p>
9544 </p></div><div class="section" title="3.3.3. Using x32 Right Now"><div class="titlepage"><div><div><h3 class="title"><a id="using-x32-right-now"></a>3.3.3. Using x32 Right Now</h3></div></div></div><p>
9545 Despite the fact the x32 psABI support is in development state for this release of the
9546 Yocto Project, you can follow these steps to use the x32 spABI:
9547 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Add the <code class="filename">experimental/meta-x32</code> layer to your local
9548 <a class="link" href="#build-directory" target="_top">build directory</a>.
9549 You can find the <code class="filename">experimental/meta-x32</code> source repository at
9550 <a class="ulink" href="http://git.yoctoproject.org" target="_top">http://git.yoctoproject.org</a>.</p></li><li class="listitem"><p>Edit your <code class="filename">conf/bblayers.conf</code> file so that it includes
9551 the <code class="filename">meta-x32</code>.
9552 Here is an example:
9553 </p><pre class="literallayout">
9554 BBLAYERS ?= " \
9555 /home/nitin/prj/poky.git/meta \
9556 /home/nitin/prj/poky.git/meta-yocto \
9557 /home/nitin/prj/meta-x32.git \
9558 "
9559 </pre></li><li class="listitem"><p>Enable the x32 psABI tuning file for <code class="filename">x86_64</code>
9560 machines by editing the <code class="filename">conf/local.conf</code> like this:
9561 </p><pre class="literallayout">
9562 MACHINE = "qemux86-64"
9563 DEFAULTTUNE = "x86-64-x32"
9564 baselib = "${@d.getVar('BASE_LIB_tune-' + (d.getVar('DEFAULTTUNE', True) \
9565 or 'INVALID'), True) or 'lib'}"
9566 #MACHINE = "atom-pc"
9567 #DEFAULTTUNE = "core2-64-x32"
9568 </pre></li><li class="listitem"><p>As usual, use BitBake to build an image that supports the x32 psABI.
9569 Here is an example:
9570 </p><pre class="literallayout">
9571 $ bitake core-image-sato
9572 </pre></li><li class="listitem"><p>As usual, run your image using QEMU:
9573 </p><pre class="literallayout">
9574 $ runqemu qemux86-64 core-image-sato
9575 </pre></li></ul></div><p>
9576 </p></div></div><div class="section" title="3.4. Licenses"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="licenses"></a>3.4. Licenses</h2></div></div></div><p>
9577 This section describes the mechanism by which the OpenEmbedded build system
9578 tracks changes to licensing text.
9579 The section also describes how to enable commercially licensed recipes,
9580 which by default are disabled.
9581 </p><div class="section" title="3.4.1. Tracking License Changes"><div class="titlepage"><div><div><h3 class="title"><a id="usingpoky-configuring-LIC_FILES_CHKSUM"></a>3.4.1. Tracking License Changes</h3></div></div></div><p>
9582 The license of an upstream project might change in the future.
9583 In order to prevent these changes going unnoticed, the
9584 <code class="filename"><a class="link" href="#var-LIC_FILES_CHKSUM" title="LIC_FILES_CHKSUM">LIC_FILES_CHKSUM</a></code>
9585 variable tracks changes to the license text. The checksums are validated at the end of the
9586 configure step, and if the checksums do not match, the build will fail.
9587 </p><div class="section" title="3.4.1.1. Specifying the LIC_FILES_CHKSUM Variable"><div class="titlepage"><div><div><h4 class="title"><a id="usingpoky-specifying-LIC_FILES_CHKSUM"></a>3.4.1.1. Specifying the <code class="filename">LIC_FILES_CHKSUM</code> Variable</h4></div></div></div><p>
9588 The <code class="filename">LIC_FILES_CHKSUM</code>
9589 variable contains checksums of the license text in the source code for the recipe.
9590 Following is an example of how to specify <code class="filename">LIC_FILES_CHKSUM</code>:
9591 </p><pre class="literallayout">
9592 LIC_FILES_CHKSUM = "file://COPYING;md5=xxxx \
9593 file://licfile1.txt;beginline=5;endline=29;md5=yyyy \
9594 file://licfile2.txt;endline=50;md5=zzzz \
9595 ..."
9596 </pre><p>
9597 </p><p>
9598 The build system uses the
9599 <code class="filename"><a class="link" href="#var-S" title="S">S</a></code> variable as the
9600 default directory used when searching files listed in
9601 <code class="filename">LIC_FILES_CHKSUM</code>.
9602 The previous example employs the default directory.
9603 </p><p>
9604 You can also use relative paths as shown in the following example:
9605 </p><pre class="literallayout">
9606 LIC_FILES_CHKSUM = "file://src/ls.c;startline=5;endline=16;\
9607 md5=bb14ed3c4cda583abc85401304b5cd4e"
9608 LIC_FILES_CHKSUM = "file://../license.html;md5=5c94767cedb5d6987c902ac850ded2c6"
9609 </pre><p>
9610 </p><p>
9611 In this example, the first line locates a file in
9612 <code class="filename">${S}/src/ls.c</code>.
9613 The second line refers to a file in
9614 <code class="filename"><a class="link" href="#var-WORKDIR" title="WORKDIR">WORKDIR</a></code>, which is the parent
9615 of <code class="filename"><a class="link" href="#var-S" title="S">S</a></code>.
9616 </p><p>
9617 Note that this variable is mandatory for all recipes, unless the
9618 <code class="filename">LICENSE</code> variable is set to "CLOSED".
9619 </p></div><div class="section" title="3.4.1.2. Explanation of Syntax"><div class="titlepage"><div><div><h4 class="title"><a id="usingpoky-LIC_FILES_CHKSUM-explanation-of-syntax"></a>3.4.1.2. Explanation of Syntax</h4></div></div></div><p>
9620 As mentioned in the previous section, the
9621 <code class="filename">LIC_FILES_CHKSUM</code> variable lists all the
9622 important files that contain the license text for the source code.
9623 It is possible to specify a checksum for an entire file, or a specific section of a
9624 file (specified by beginning and ending line numbers with the "beginline" and "endline"
9625 parameters, respectively).
9626 The latter is useful for source files with a license notice header,
9627 README documents, and so forth.
9628 If you do not use the "beginline" parameter, then it is assumed that the text begins on the
9629 first line of the file.
9630 Similarly, if you do not use the "endline" parameter, it is assumed that the license text
9631 ends with the last line of the file.
9632 </p><p>
9633 The "md5" parameter stores the md5 checksum of the license text.
9634 If the license text changes in any way as compared to this parameter
9635 then a mismatch occurs.
9636 This mismatch triggers a build failure and notifies the developer.
9637 Notification allows the developer to review and address the license text changes.
9638 Also note that if a mismatch occurs during the build, the correct md5
9639 checksum is placed in the build log and can be easily copied to the recipe.
9640 </p><p>
9641 There is no limit to how many files you can specify using the
9642 <code class="filename">LIC_FILES_CHKSUM</code> variable.
9643 Generally, however, every project requires a few specifications for license tracking.
9644 Many projects have a "COPYING" file that stores the license information for all the source
9645 code files.
9646 This practice allows you to just track the "COPYING" file as long as it is kept up to date.
9647 </p><div class="tip" title="Tip" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Tip</h3>
9648 If you specify an empty or invalid "md5" parameter, BitBake returns an md5 mis-match
9649 error and displays the correct "md5" parameter value during the build.
9650 The correct parameter is also captured in the build log.
9651 </div><div class="tip" title="Tip" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Tip</h3>
9652 If the whole file contains only license text, you do not need to use the "beginline" and
9653 "endline" parameters.
9654 </div></div></div><div class="section" title="3.4.2. Enabling Commercially Licensed Recipes"><div class="titlepage"><div><div><h3 class="title"><a id="enabling-commercially-licensed-recipes"></a>3.4.2. Enabling Commercially Licensed Recipes</h3></div></div></div><p>
9655 By default, the OpenEmbedded build system disables
9656 components that have commercial or other special licensing
9657 requirements.
9658 Such requirements are defined on a
9659 recipe-by-recipe basis through the <code class="filename">LICENSE_FLAGS</code> variable
9660 definition in the affected recipe.
9661 For instance, the
9662 <code class="filename">$HOME/poky/meta/recipes-multimedia/gstreamer/gst-plugins-ugly</code>
9663 recipe contains the following statement:
9664 </p><pre class="literallayout">
9665 LICENSE_FLAGS = "commercial"
9666 </pre><p>
9667 Here is a slightly more complicated example that contains both an
9668 explicit package name and version (after variable expansion):
9669 </p><pre class="literallayout">
9670 LICENSE_FLAGS = "license_${PN}_${PV}"
9671 </pre><p>
9672 In order for a component restricted by a <code class="filename">LICENSE_FLAGS</code>
9673 definition to be enabled and included in an image, it
9674 needs to have a matching entry in the global
9675 <code class="filename">LICENSE_FLAGS_WHITELIST</code> variable, which is a variable
9676 typically defined in your <code class="filename">local.conf</code> file.
9677 For example, to enable
9678 the <code class="filename">$HOME/poky/meta/recipes-multimedia/gstreamer/gst-plugins-ugly</code>
9679 package, you could add either the string
9680 "commercial_gst-plugins-ugly" or the more general string
9681 "commercial" to <code class="filename">LICENSE_FLAGS_WHITELIST</code>.
9682 See the
9683 "<a class="link" href="#license-flag-matching" title="3.4.2.1. License Flag Matching">License Flag Matching</a>" section
9684 for a full explanation of how <code class="filename">LICENSE_FLAGS</code> matching works.
9685 Here is the example:
9686 </p><pre class="literallayout">
9687 LICENSE_FLAGS_WHITELIST = "commercial_gst-plugins-ugly"
9688 </pre><p>
9689 Likewise, to additionally enable the package containing
9690 <code class="filename">LICENSE_FLAGS = "license_${PN}_${PV}"</code>, and assuming
9691 that the actual recipe name was <code class="filename">emgd_1.10.bb</code>,
9692 the following string would enable that package as well as
9693 the original <code class="filename">gst-plugins-ugly</code> package:
9694 </p><pre class="literallayout">
9695 LICENSE_FLAGS_WHITELIST = "commercial_gst-plugins-ugly license_emgd_1.10"
9696 </pre><p>
9697 As a convenience, you do not need to specify the complete license string
9698 in the whitelist for every package.
9699 you can use an abbreviated form, which consists
9700 of just the first portion or portions of the license string before
9701 the initial underscore character or characters.
9702 A partial string will match
9703 any license that contains the given string as the first
9704 portion of its license.
9705 For example, the following
9706 whitelist string will also match both of the packages
9707 previously mentioned as well as any other packages that have
9708 licenses starting with "commercial" or "license".
9709 </p><pre class="literallayout">
9710 LICENSE_FLAGS_WHITELIST = "commercial license"
9711 </pre><p>
9712 </p><div class="section" title="3.4.2.1. License Flag Matching"><div class="titlepage"><div><div><h4 class="title"><a id="license-flag-matching"></a>3.4.2.1. License Flag Matching</h4></div></div></div><p>
9713 The definition of 'matching' in reference to a
9714 recipe's <code class="filename">LICENSE_FLAGS</code> setting is simple.
9715 However, some things exist that you should know about in order to
9716 correctly and effectively use it.
9717 </p><p>
9718 Before a flag
9719 defined by a particular recipe is tested against the
9720 contents of the <code class="filename">LICENSE_FLAGS_WHITELIST</code> variable, the
9721 string <code class="filename">_${PN}</code> (with
9722 <a class="link" href="#var-PN" title="PN"><code class="filename">PN</code></a> expanded of course) is
9723 appended to the flag, thus automatically making each
9724 <code class="filename">LICENSE_FLAGS</code> value recipe-specific.
9725 That string is
9726 then matched against the whitelist.
9727 So if you specify <code class="filename">LICENSE_FLAGS = "commercial"</code> in recipe
9728 "foo" for example, the string <code class="filename">"commercial_foo"</code>
9729 would normally be what is specified in the whitelist in order for it to
9730 match.
9731 </p><p>
9732 You can broaden the match by
9733 putting any "_"-separated beginning subset of a
9734 <code class="filename">LICENSE_FLAGS</code> flag in the whitelist, which will also
9735 match.
9736 For example, simply specifying "commercial" in
9737 the whitelist would match any expanded <code class="filename">LICENSE_FLAGS</code>
9738 definition starting with "commercial" such as
9739 "commercial_foo" and "commercial_bar", which are the
9740 strings that would be automatically generated for
9741 hypothetical "foo" and "bar" recipes assuming those
9742 recipes had simply specified the following:
9743 </p><pre class="literallayout">
9744 LICENSE_FLAGS = "commercial"
9745 </pre><p>
9746 </p><p>
9747 Broadening the match allows for a range of specificity for the items
9748 in the whitelist, from more general to perfectly
9749 specific.
9750 So you have the choice of exhaustively
9751 enumerating each license flag in the whitelist to
9752 allow only those specific recipes into the image, or
9753 of using a more general string to pick up anything
9754 matching just the first component or components of the specified
9755 string.
9756 </p><p>
9757 This scheme works even if the flag already
9758 has <code class="filename">_${PN}</code> appended - the extra <code class="filename">_${PN}</code> is
9759 redundant, but does not affect the outcome.
9760 For example, a license flag of "commercial_1.2_foo" would
9761 turn into "commercial_1.2_foo_foo" and would match
9762 both the general "commercial" and the specific
9763 "commercial_1.2_foo", as expected.
9764 The flag would also match
9765 "commercial_1.2_foo_foo" and "commercial_1.2", which
9766 does not make much sense regarding use in the whitelist.
9767 </p><p>
9768 For a versioned string, you could instead specify
9769 "commercial_foo_1.2", which would turn into
9770 "commercial_foo_1.2_foo".
9771 And, as expected, this flag allows
9772 you to pick up this package along with
9773 anything else "commercial" when you specify "commercial"
9774 in the whitelist.
9775 Or, the flag allows you to pick up this package along with anything "commercial_foo"
9776 regardless of version when you use "commercial_foo" in the whitelist.
9777 Finally, you can be completely specific about the package and version and specify
9778 "commercial_foo_1.2" package and version.
9779 </p></div><div class="section" title="3.4.2.2. Other Variables Related to Commercial Licenses"><div class="titlepage"><div><div><h4 class="title"><a id="other-variables-related-to-commercial-licenses"></a>3.4.2.2. Other Variables Related to Commercial Licenses</h4></div></div></div><p>
9780 Other helpful variables related to commercial
9781 license handling exist and are defined in the
9782 <code class="filename">$HOME/poky/meta/conf/distro/include/default-distrovars.inc</code> file:
9783 </p><pre class="literallayout">
9784 COMMERCIAL_AUDIO_PLUGINS ?= ""
9785 COMMERCIAL_VIDEO_PLUGINS ?= ""
9786 COMMERCIAL_QT = ""
9787 </pre><p>
9788 If you want to enable these components, you can do so by making sure you have
9789 the following statements in your <code class="filename">local.conf</code> configuration file:
9790 </p><pre class="literallayout">
9791 COMMERCIAL_AUDIO_PLUGINS = "gst-plugins-ugly-mad \
9792 gst-plugins-ugly-mpegaudioparse"
9793 COMMERCIAL_VIDEO_PLUGINS = "gst-plugins-ugly-mpeg2dec \
9794 gst-plugins-ugly-mpegstream gst-plugins-bad-mpegvideoparse"
9795 COMMERCIAL_QT ?= "qmmp"
9796 LICENSE_FLAGS_WHITELIST = "commercial_gst-plugins-ugly commercial_gst-plugins-bad commercial_qmmp"
9797 </pre><p>
9798 Of course, you could also create a matching whitelist
9799 for those components using the more general "commercial"
9800 in the whitelist, but that would also enable all the
9801 other packages with <code class="filename">LICENSE_FLAGS</code> containing
9802 "commercial", which you may or may not want:
9803 </p><pre class="literallayout">
9804 LICENSE_FLAGS_WHITELIST = "commercial"
9805 </pre><p>
9806 </p><p>
9807 Specifying audio and video plug-ins as part of the
9808 <code class="filename">COMMERCIAL_AUDIO_PLUGINS</code> and
9809 <code class="filename">COMMERCIAL_VIDEO_PLUGINS</code> statements
9810 or commercial qt components as part of
9811 the <code class="filename">COMMERCIAL_QT</code> statement (along
9812 with the enabling <code class="filename">LICENSE_FLAGS_WHITELIST</code>) includes the
9813 plug-ins or components into built images, thus adding
9814 support for media formats or components.
9815 </p></div></div></div></div>
9816
9817 <div class="chapter" title="Chapter 4. Source Directory Structure"><div class="titlepage"><div><div><h2 class="title"><a id="ref-structure"></a>Chapter 4. Source Directory Structure</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#structure-core">4.1. Top level core components</a></span></dt><dd><dl><dt><span class="section"><a href="#structure-core-bitbake">4.1.1. <code class="filename">bitbake/</code></a></span></dt><dt><span class="section"><a href="#structure-core-build">4.1.2. <code class="filename">build/</code></a></span></dt><dt><span class="section"><a href="#handbook">4.1.3. <code class="filename">documentation</code></a></span></dt><dt><span class="section"><a href="#structure-core-meta">4.1.4. <code class="filename">meta/</code></a></span></dt><dt><span class="section"><a href="#structure-core-meta-demoapps">4.1.5. <code class="filename">meta-demoapps/</code></a></span></dt><dt><span class="section"><a href="#structure-core-meta-rt">4.1.6. <code class="filename">meta-rt/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-skeleton">4.1.7. <code class="filename">meta-skeleton/</code></a></span></dt><dt><span class="section"><a href="#structure-core-scripts">4.1.8. <code class="filename">scripts/</code></a></span></dt><dt><span class="section"><a href="#structure-core-script">4.1.9. <code class="filename">oe-init-build-env</code></a></span></dt><dt><span class="section"><a href="#structure-basic-top-level">4.1.10. <code class="filename">LICENSE, README, and README.hardware</code></a></span></dt></dl></dd><dt><span class="section"><a href="#structure-build">4.2. The Build Directory - <code class="filename">build/</code></a></span></dt><dd><dl><dt><span class="section"><a href="#structure-build-pseudodone">4.2.1. <code class="filename">build/pseudodone</code></a></span></dt><dt><span class="section"><a href="#structure-build-conf-local.conf">4.2.2. <code class="filename">build/conf/local.conf</code></a></span></dt><dt><span class="section"><a href="#structure-build-conf-bblayers.conf">4.2.3. <code class="filename">build/conf/bblayers.conf</code></a></span></dt><dt><span class="section"><a href="#structure-build-conf-sanity_info">4.2.4. <code class="filename">build/conf/sanity_info</code></a></span></dt><dt><span class="section"><a href="#structure-build-downloads">4.2.5. <code class="filename">build/downloads/</code></a></span></dt><dt><span class="section"><a href="#structure-build-sstate-cache">4.2.6. <code class="filename">build/sstate-cache/</code></a></span></dt><dt><span class="section"><a href="#structure-build-tmp">4.2.7. <code class="filename">build/tmp/</code></a></span></dt><dt><span class="section"><a href="#structure-build-tmp-buildstats">4.2.8. <code class="filename">build/tmp/buildstats/</code></a></span></dt><dt><span class="section"><a href="#structure-build-tmp-cache">4.2.9. <code class="filename">build/tmp/cache/</code></a></span></dt><dt><span class="section"><a href="#structure-build-tmp-deploy">4.2.10. <code class="filename">build/tmp/deploy/</code></a></span></dt><dt><span class="section"><a href="#structure-build-tmp-deploy-deb">4.2.11. <code class="filename">build/tmp/deploy/deb/</code></a></span></dt><dt><span class="section"><a href="#structure-build-tmp-deploy-rpm">4.2.12. <code class="filename">build/tmp/deploy/rpm/</code></a></span></dt><dt><span class="section"><a href="#structure-build-tmp-deploy-licenses">4.2.13. <code class="filename">build/tmp/deploy/licenses/</code></a></span></dt><dt><span class="section"><a href="#structure-build-tmp-deploy-images">4.2.14. <code class="filename">build/tmp/deploy/images/</code></a></span></dt><dt><span class="section"><a href="#structure-build-tmp-deploy-ipk">4.2.15. <code class="filename">build/tmp/deploy/ipk/</code></a></span></dt><dt><span class="section"><a href="#structure-build-tmp-sysroots">4.2.16. <code class="filename">build/tmp/sysroots/</code></a></span></dt><dt><span class="section"><a href="#structure-build-tmp-stamps">4.2.17. <code class="filename">build/tmp/stamps/</code></a></span></dt><dt><span class="section"><a href="#structure-build-tmp-log">4.2.18. <code class="filename">build/tmp/log/</code></a></span></dt><dt><span class="section"><a href="#structure-build-tmp-pkgdata">4.2.19. <code class="filename">build/tmp/pkgdata/</code></a></span></dt><dt><span class="section"><a href="#structure-build-tmp-work">4.2.20. <code class="filename">build/tmp/work/</code></a></span></dt></dl></dd><dt><span class="section"><a href="#structure-meta">4.3. The Metadata - <code class="filename">meta/</code></a></span></dt><dd><dl><dt><span class="section"><a href="#structure-meta-classes">4.3.1. <code class="filename">meta/classes/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-conf">4.3.2. <code class="filename">meta/conf/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-conf-machine">4.3.3. <code class="filename">meta/conf/machine/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-conf-distro">4.3.4. <code class="filename">meta/conf/distro/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-recipes-bsp">4.3.5. <code class="filename">meta/recipes-bsp/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-recipes-connectivity">4.3.6. <code class="filename">meta/recipes-connectivity/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-recipes-core">4.3.7. <code class="filename">meta/recipes-core/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-recipes-devtools">4.3.8. <code class="filename">meta/recipes-devtools/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-recipes-extended">4.3.9. <code class="filename">meta/recipes-extended/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-recipes-gnome">4.3.10. <code class="filename">meta/recipes-gnome/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-recipes-graphics">4.3.11. <code class="filename">meta/recipes-graphics/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-recipes-kernel">4.3.12. <code class="filename">meta/recipes-kernel/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-recipes-multimedia">4.3.13. <code class="filename">meta/recipes-multimedia/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-recipes-qt">4.3.14. <code class="filename">meta/recipes-qt/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-recipes-rt">4.3.15. <code class="filename">meta/recipes-rt/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-recipes-sato">4.3.16. <code class="filename">meta/recipes-sato/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-recipes-support">4.3.17. <code class="filename">meta/recipes-support/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-site">4.3.18. <code class="filename">meta/site/</code></a></span></dt><dt><span class="section"><a href="#structure-meta-recipes-txt">4.3.19. <code class="filename">meta/recipes.txt</code></a></span></dt></dl></dd></dl></div><p>
9818 The <a class="link" href="#source-directory" target="_top">source directory</a> consists of several components.
9819 Understanding them and knowing where they are located is key to using the Yocto Project well.
9820 This chapter describes the source directory and gives information about the various
9821 files and directories.
9822</p><p>
9823 For information on how to establish a local source directory on your development system, see the
9824 "<a class="link" href="#getting-setup" target="_top">Getting Set Up</a>"
9825 section in the Yocto Project Development Manual.
9826</p><div class="section" title="4.1. Top level core components"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="structure-core"></a>4.1. Top level core components</h2></div></div></div><div class="section" title="4.1.1. bitbake/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-core-bitbake"></a>4.1.1. <code class="filename">bitbake/</code></h3></div></div></div><p>
9827 The <a class="ulink" href="source-directory" target="_top">source directory</a>
9828 includes a copy of BitBake for ease of use.
9829 The copy usually matches the current stable BitBake release from the BitBake project.
9830 BitBake, a metadata interpreter, reads the Yocto Project metadata and runs the tasks
9831 defined by that data.
9832 Failures are usually from the metadata and not from BitBake itself.
9833 Consequently, most users do not need to worry about BitBake.
9834 </p><p>
9835 When you run the <code class="filename">bitbake</code> command, the wrapper script in
9836 <code class="filename">scripts/</code> is executed to run the main BitBake executable,
9837 which resides in the <code class="filename">bitbake/bin/</code> directory.
9838 Sourcing the <a class="link" href="#structure-core-script" title="4.1.9. oe-init-build-env">oe-init-build-env</a>
9839 script places the <code class="filename">scripts</code> and <code class="filename">bitbake/bin</code>
9840 directories (in that order) into the shell's <code class="filename">PATH</code> environment
9841 variable.
9842 </p><p>
9843 For more information on BitBake, see the BitBake on-line manual at
9844 <a class="ulink" href="http://docs.openembedded.org/bitbake/html/" target="_top">http://docs.openembedded.org/bitbake/html/</a>.
9845 </p></div><div class="section" title="4.1.2. build/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-core-build"></a>4.1.2. <code class="filename">build/</code></h3></div></div></div><p>
9846 This directory contains user configuration files and the output
9847 generated by the OpenEmbedded build system in its standard configuration where
9848 the source tree is combined with the output.
9849 The <a class="link" href="#build-directory" target="_top">build directory</a>
9850 is created initially when you <code class="filename">source</code>
9851 the OpenEmbedded build environment setup script <code class="filename">oe-init-build-env</code>.
9852 </p><p>
9853 It is also possible to place output and configuration
9854 files in a directory separate from the
9855 <a class="link" href="#source-directory" target="_top">source directory</a>
9856 by providing a directory name when you <code class="filename">source</code>
9857 the setup script.
9858 For information on separating output from your local source directory files, see <a class="link" href="#structure-core-script" title="4.1.9. oe-init-build-env">oe-init-build-env</a>.
9859 </p></div><div class="section" title="4.1.3. documentation"><div class="titlepage"><div><div><h3 class="title"><a id="handbook"></a>4.1.3. <code class="filename">documentation</code></h3></div></div></div><p>
9860 This directory holds the source for the Yocto Project documentation
9861 as well as templates and tools that allow you to generate PDF and HTML
9862 versions of the manuals.
9863 Each manual is contained in a sub-folder.
9864 For example, the files for this manual reside in
9865 <code class="filename">poky-ref-manual</code>.
9866 </p></div><div class="section" title="4.1.4. meta/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-core-meta"></a>4.1.4. <code class="filename">meta/</code></h3></div></div></div><p>
9867 This directory contains the OpenEmbedded Core metadata.
9868 The directory holds machine definitions, the Yocto Project distribution,
9869 and the packages that make up a given system.
9870 </p></div><div class="section" title="4.1.5. meta-demoapps/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-core-meta-demoapps"></a>4.1.5. <code class="filename">meta-demoapps/</code></h3></div></div></div><p>
9871 This directory contains recipes for applications and demos that are not part of the
9872 OpenEmbedded core.
9873 </p></div><div class="section" title="4.1.6. meta-rt/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-core-meta-rt"></a>4.1.6. <code class="filename">meta-rt/</code></h3></div></div></div><p>
9874 This directory contains recipes for real-time kernels.
9875 </p></div><div class="section" title="4.1.7. meta-skeleton/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-skeleton"></a>4.1.7. <code class="filename">meta-skeleton/</code></h3></div></div></div><p>
9876 This directory contains template recipes for BSP and kernel development.
9877 </p></div><div class="section" title="4.1.8. scripts/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-core-scripts"></a>4.1.8. <code class="filename">scripts/</code></h3></div></div></div><p>
9878 This directory contains various integration scripts that implement
9879 extra functionality in the Yocto Project environment (e.g. QEMU scripts).
9880 The <a class="link" href="#structure-core-script" title="4.1.9. oe-init-build-env">oe-init-build-env</a> script appends this
9881 directory to the shell's <code class="filename">PATH</code> environment variable.
9882 </p><p>
9883 The <code class="filename">scripts</code> directory has useful scripts that assist contributing
9884 back to the Yocto Project, such as <code class="filename">create_pull_request</code> and
9885 <code class="filename">send_pull_request</code>.
9886 </p></div><div class="section" title="4.1.9. oe-init-build-env"><div class="titlepage"><div><div><h3 class="title"><a id="structure-core-script"></a>4.1.9. <code class="filename">oe-init-build-env</code></h3></div></div></div><p>
9887 This script sets up the OpenEmbedded build environment.
9888 Running this script with the <code class="filename">source</code> command in
9889 a shell makes changes to <code class="filename">PATH</code> and sets other core BitBake variables based on the
9890 current working directory.
9891 You need to run this script before running BitBake commands.
9892 The script uses other scripts within the <code class="filename">scripts</code> directory to do
9893 the bulk of the work.
9894 </p><p>
9895 By default, running this script without a build directory argument creates the
9896 <code class="filename">build</code> directory.
9897 If you provide a build directory argument when you <code class="filename">source</code>
9898 the script, you direct OpenEmbedded build system to create a
9899 <a class="link" href="#build-directory" target="_top">build directory</a> of your choice.
9900 For example, the following command creates a build directory named
9901 <code class="filename">mybuilds</code> that is outside of the
9902 <a class="link" href="#source-directory" target="_top">source directory</a>:
9903 </p><pre class="literallayout">
9904 $ source oe-init-build-env ~/mybuilds
9905 </pre><p>
9906 </p></div><div class="section" title="4.1.10. LICENSE, README, and README.hardware"><div class="titlepage"><div><div><h3 class="title"><a id="structure-basic-top-level"></a>4.1.10. <code class="filename">LICENSE, README, and README.hardware</code></h3></div></div></div><p>
9907 These files are standard top-level files.
9908 </p></div></div><div class="section" title="4.2. The Build Directory - build/"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="structure-build"></a>4.2. The Build Directory - <code class="filename">build/</code></h2></div></div></div><div class="section" title="4.2.1. build/pseudodone"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-pseudodone"></a>4.2.1. <code class="filename">build/pseudodone</code></h3></div></div></div><p>
9909 This tag file indicates that the initial pseudo binary was created.
9910 The file is built the first time BitBake is invoked.
9911 </p></div><div class="section" title="4.2.2. build/conf/local.conf"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-conf-local.conf"></a>4.2.2. <code class="filename">build/conf/local.conf</code></h3></div></div></div><p>
9912 This file contains all the local user configuration for your build environment.
9913 If there is no <code class="filename">local.conf</code> present, it is created from
9914 <code class="filename">local.conf.sample</code>.
9915 The <code class="filename">local.conf</code> file contains documentation on the various configuration options.
9916 Any variable set here overrides any variable set elsewhere within the environment unless
9917 that variable is hard-coded within a file (e.g. by using '=' instead of '?=').
9918 Some variables are hard-coded for various reasons but these variables are
9919 relatively rare.
9920 </p><p>
9921 Edit this file to set the <code class="filename"><a class="link" href="#var-MACHINE" title="MACHINE">MACHINE</a></code>
9922 for which you want to build, which package types you
9923 wish to use (<code class="filename">PACKAGE_CLASSES</code>), or where you want to downloaded files
9924 (<code class="filename"><a class="link" href="#var-DL_DIR" title="DL_DIR">DL_DIR</a></code>).
9925 </p></div><div class="section" title="4.2.3. build/conf/bblayers.conf"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-conf-bblayers.conf"></a>4.2.3. <code class="filename">build/conf/bblayers.conf</code></h3></div></div></div><p>
9926 This file defines layers, which is a directory tree, traversed (or walked) by BitBake.
9927 If <code class="filename">bblayers.conf</code>
9928 is not present, it is created from <code class="filename">bblayers.conf.sample</code> when
9929 you <code class="filename">source</code> the environment setup script.
9930 </p></div><div class="section" title="4.2.4. build/conf/sanity_info"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-conf-sanity_info"></a>4.2.4. <code class="filename">build/conf/sanity_info</code></h3></div></div></div><p>
9931 This file is created during the build to indicate the state of the sanity checks.
9932 </p></div><div class="section" title="4.2.5. build/downloads/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-downloads"></a>4.2.5. <code class="filename">build/downloads/</code></h3></div></div></div><p>
9933 This directory is used for the upstream source tarballs.
9934 The directory can be reused by multiple builds or moved to another location.
9935 You can control the location of this directory through the
9936 <code class="filename"><a class="link" href="#var-DL_DIR" title="DL_DIR">DL_DIR</a></code> variable.
9937 </p></div><div class="section" title="4.2.6. build/sstate-cache/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-sstate-cache"></a>4.2.6. <code class="filename">build/sstate-cache/</code></h3></div></div></div><p>
9938 This directory is used for the shared state cache.
9939 The directory can be reused by multiple builds or moved to another location.
9940 You can control the location of this directory through the
9941 <code class="filename"><a class="link" href="#var-SSTATE_DIR" title="SSTATE_DIR">SSTATE_DIR</a></code> variable.
9942 </p></div><div class="section" title="4.2.7. build/tmp/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-tmp"></a>4.2.7. <code class="filename">build/tmp/</code></h3></div></div></div><p>
9943 This directory receives all the OpenEmbedded build system's output.
9944 BitBake creates this directory if it does not exist.
9945 As a last resort, to clean up a build and start it from scratch (other than the downloads),
9946 you can remove everything in the <code class="filename">tmp</code> directory or get rid of the
9947 directory completely.
9948 If you do, you should also completely remove the <code class="filename">build/sstate-cache</code>
9949 directory as well.
9950 </p></div><div class="section" title="4.2.8. build/tmp/buildstats/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-tmp-buildstats"></a>4.2.8. <code class="filename">build/tmp/buildstats/</code></h3></div></div></div><p>
9951 This directory stores the build statistics.
9952 </p></div><div class="section" title="4.2.9. build/tmp/cache/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-tmp-cache"></a>4.2.9. <code class="filename">build/tmp/cache/</code></h3></div></div></div><p>
9953 When BitBake parses the metadata, it creates a cache file of the result that can
9954 be used when subsequently running commands.
9955 These results are stored here on a per-machine basis.
9956 </p></div><div class="section" title="4.2.10. build/tmp/deploy/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-tmp-deploy"></a>4.2.10. <code class="filename">build/tmp/deploy/</code></h3></div></div></div><p>
9957 This directory contains any 'end result' output from the OpenEmbedded build process.
9958 </p></div><div class="section" title="4.2.11. build/tmp/deploy/deb/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-tmp-deploy-deb"></a>4.2.11. <code class="filename">build/tmp/deploy/deb/</code></h3></div></div></div><p>
9959 This directory receives any <code class="filename">.deb</code> packages produced by
9960 the build process.
9961 The packages are sorted into feeds for different architecture types.
9962 </p></div><div class="section" title="4.2.12. build/tmp/deploy/rpm/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-tmp-deploy-rpm"></a>4.2.12. <code class="filename">build/tmp/deploy/rpm/</code></h3></div></div></div><p>
9963 This directory receives any <code class="filename">.rpm</code> packages produced by
9964 the build process.
9965 The packages are sorted into feeds for different architecture types.
9966 </p></div><div class="section" title="4.2.13. build/tmp/deploy/licenses/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-tmp-deploy-licenses"></a>4.2.13. <code class="filename">build/tmp/deploy/licenses/</code></h3></div></div></div><p>
9967 This directory receives package licensing information.
9968 For example, the directory contains sub-directories for <code class="filename">bash</code>,
9969 <code class="filename">busybox</code>, and <code class="filename">eglibc</code> (among others) that in turn
9970 contain appropriate <code class="filename">COPYING</code> license files with other licensing information.
9971 </p></div><div class="section" title="4.2.14. build/tmp/deploy/images/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-tmp-deploy-images"></a>4.2.14. <code class="filename">build/tmp/deploy/images/</code></h3></div></div></div><p>
9972 This directory receives complete filesystem images.
9973 If you want to flash the resulting image from a build onto a device, look here for the image.
9974 </p><p>
9975 Be careful when deleting files in this directory.
9976 You can safely delete old images from this directory (e.g.
9977 <code class="filename">core-image-*</code>, <code class="filename">hob-image-*</code>,
9978 etc.).
9979 However, the kernel (<code class="filename">*zImage*</code>, <code class="filename">*uImage*</code>, etc.),
9980 bootloader and other supplementary files might be deployed here prior to building an
9981 image.
9982 Because these files, however, are not directly produced from the image, if you
9983 delete them they will not be automatically re-created when you build the image again.
9984 </p><p>
9985 If you do accidentally delete files here, you will need to force them to be
9986 re-created.
9987 In order to do that, you will need to know the target that produced them.
9988 For example, these commands rebuild and re-create the kernel files:
9989 </p><pre class="literallayout">
9990 $ bitbake -c clean virtual/kernel
9991 $ bitbake virtual/kernel
9992 </pre><p>
9993 </p></div><div class="section" title="4.2.15. build/tmp/deploy/ipk/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-tmp-deploy-ipk"></a>4.2.15. <code class="filename">build/tmp/deploy/ipk/</code></h3></div></div></div><p>
9994 This directory receives <code class="filename">.ipk</code> packages produced by
9995 the build process.</p></div><div class="section" title="4.2.16. build/tmp/sysroots/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-tmp-sysroots"></a>4.2.16. <code class="filename">build/tmp/sysroots/</code></h3></div></div></div><p>
9996 This directory contains shared header files and libraries as well as other shared
9997 data.
9998 Packages that need to share output with other packages do so within this directory.
9999 The directory is subdivided by architecture so multiple builds can run within
10000 the one build directory.
10001 </p></div><div class="section" title="4.2.17. build/tmp/stamps/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-tmp-stamps"></a>4.2.17. <code class="filename">build/tmp/stamps/</code></h3></div></div></div><p>
10002 This directory holds information that that BitBake uses for accounting purposes
10003 to track what tasks have run and when they have run.
10004 The directory is sub-divided by architecture.
10005 The files in the directory are empty of data.
10006 However, BitBake uses the filenames and timestamps for tracking purposes.
10007 </p></div><div class="section" title="4.2.18. build/tmp/log/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-tmp-log"></a>4.2.18. <code class="filename">build/tmp/log/</code></h3></div></div></div><p>
10008 This directory contains general logs that are not otherwise placed using the
10009 package's <code class="filename"><a class="link" href="#var-WORKDIR" title="WORKDIR">WORKDIR</a></code>.
10010 Examples of logs are the output from the <code class="filename">check_pkg</code> or
10011 <code class="filename">distro_check</code> tasks.
10012 Running a build does not necessarily mean this directory is created.
10013 </p></div><div class="section" title="4.2.19. build/tmp/pkgdata/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-tmp-pkgdata"></a>4.2.19. <code class="filename">build/tmp/pkgdata/</code></h3></div></div></div><p>
10014 This directory contains intermediate packaging data that is used later in the packaging process.
10015 For more information, see the "<a class="link" href="#ref-classes-package" title="6.12. Packaging - package*.bbclass">Packaging - package*.bbclass</a>" section.
10016 </p></div><div class="section" title="4.2.20. build/tmp/work/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-build-tmp-work"></a>4.2.20. <code class="filename">build/tmp/work/</code></h3></div></div></div><p>
10017 This directory contains architecture-specific work sub-directories for packages built by BitBake.
10018 All tasks execute from a work directory.
10019 For example, the source for a particular package is unpacked, patched, configured and compiled all
10020 within its own work directory.
10021 Within the work directory, organization is based on the package group for which the source
10022 is being compiled.
10023 </p><p>
10024 It is worth considering the structure of a typical work directory.
10025 As an example, consider the <code class="filename">linux-yocto-kernel-3.0</code>
10026 on the machine <code class="filename">qemux86</code>
10027 built within the Yocto Project.
10028 For this package, a work directory of
10029 <code class="filename">tmp/work/qemux86-poky-linux/linux-yocto-3.0+git1+&lt;.....&gt;</code>,
10030 referred to as <code class="filename"><a class="link" href="#var-WORKDIR" title="WORKDIR">WORKDIR</a></code>, is created.
10031 Within this directory, the source is unpacked to
10032 <code class="filename">linux-qemux86-standard-build</code> and then patched by Quilt
10033 (see the
10034 "<a class="link" href="#using-a-quilt-workflow" target="_top">Modifying Package
10035 Source Code with Quilt</a>" section in the Yocto Project Development Manual.
10036 Within the <code class="filename">linux-qemux86-standard-build</code> directory,
10037 standard Quilt directories <code class="filename">linux-3.0/patches</code>
10038 and <code class="filename">linux-3.0/.pc</code> are created,
10039 and standard Quilt commands can be used.
10040 </p><p>
10041 There are other directories generated within WORKDIR.
10042 The most important directory is WORKDIR<code class="filename">/temp/</code>, which has log files for each
10043 task (<code class="filename">log.do_*.pid</code>) and contains the scripts BitBake runs for
10044 each task (<code class="filename">run.do_*.pid</code>).
10045 The WORKDIR<code class="filename">/image/</code> directory is where "make
10046 install" places its output that is then split into sub-packages
10047 within WORKDIR<code class="filename">/packages-split/</code>.
10048 </p></div></div><div class="section" title="4.3. The Metadata - meta/"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="structure-meta"></a>4.3. The Metadata - <code class="filename">meta/</code></h2></div></div></div><p>
10049 As mentioned previously, metadata is the core of the Yocto Project.
10050 Metadata has several important subdivisions:
10051 </p><div class="section" title="4.3.1. meta/classes/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-classes"></a>4.3.1. <code class="filename">meta/classes/</code></h3></div></div></div><p>
10052 This directory contains the <code class="filename">*.bbclass</code> files.
10053 Class files are used to abstract common code so it can be reused by multiple
10054 packages.
10055 Every package inherits the <code class="filename">base.bbclass</code> file.
10056 Examples of other important classes are <code class="filename">autotools.bbclass</code>, which
10057 in theory allows any Autotool-enabled package to work with the Yocto Project with minimal effort.
10058 Another example is <code class="filename">kernel.bbclass</code> that contains common code and functions
10059 for working with the Linux kernel.
10060 Functions like image generation or packaging also have their specific class files
10061 such as <code class="filename">image.bbclass</code>, <code class="filename">rootfs_*.bbclass</code> and
10062 <code class="filename">package*.bbclass</code>.
10063 </p></div><div class="section" title="4.3.2. meta/conf/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-conf"></a>4.3.2. <code class="filename">meta/conf/</code></h3></div></div></div><p>
10064 This directory contains the core set of configuration files that start from
10065 <code class="filename">bitbake.conf</code> and from which all other configuration
10066 files are included.
10067 See the include statements at the end of the file and you will note that even
10068 <code class="filename">local.conf</code> is loaded from there.
10069 While <code class="filename">bitbake.conf</code> sets up the defaults, you can often override
10070 these by using the (<code class="filename">local.conf</code>) file, machine file or
10071 the distribution configuration file.
10072 </p></div><div class="section" title="4.3.3. meta/conf/machine/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-conf-machine"></a>4.3.3. <code class="filename">meta/conf/machine/</code></h3></div></div></div><p>
10073 This directory contains all the machine configuration files.
10074 If you set <code class="filename">MACHINE="qemux86"</code>,
10075 the OpenEmbedded build system looks for a <code class="filename">qemux86.conf</code> file in this
10076 directory.
10077 The <code class="filename">include</code> directory contains various data common to multiple machines.
10078 If you want to add support for a new machine to the Yocto Project, look in this directory.
10079 </p></div><div class="section" title="4.3.4. meta/conf/distro/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-conf-distro"></a>4.3.4. <code class="filename">meta/conf/distro/</code></h3></div></div></div><p>
10080 Any distribution-specific configuration is controlled from this directory.
10081 For the Yocto Project, the <code class="filename">defaultsetup.conf</code> is the main file here.
10082 This directory includes the versions and the
10083 <code class="filename">SRCDATE</code> definitions for applications that are configured here.
10084 An example of an alternative configuration might be <code class="filename">poky-bleeding.conf</code>.
10085 Although this file mainly inherits its configuration from Poky.
10086 </p></div><div class="section" title="4.3.5. meta/recipes-bsp/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-recipes-bsp"></a>4.3.5. <code class="filename">meta/recipes-bsp/</code></h3></div></div></div><p>
10087 This directory contains anything linking to specific hardware or hardware
10088 configuration information such as "u-boot" and "grub".
10089 </p></div><div class="section" title="4.3.6. meta/recipes-connectivity/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-recipes-connectivity"></a>4.3.6. <code class="filename">meta/recipes-connectivity/</code></h3></div></div></div><p>
10090 This directory contains libraries and applications related to communication with other devices.
10091 </p></div><div class="section" title="4.3.7. meta/recipes-core/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-recipes-core"></a>4.3.7. <code class="filename">meta/recipes-core/</code></h3></div></div></div><p>
10092 This directory contains what is needed to build a basic working Linux image
10093 including commonly used dependencies.
10094 </p></div><div class="section" title="4.3.8. meta/recipes-devtools/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-recipes-devtools"></a>4.3.8. <code class="filename">meta/recipes-devtools/</code></h3></div></div></div><p>
10095 This directory contains tools that are primarily used by the build system.
10096 The tools, however, can also be used on targets.
10097 </p></div><div class="section" title="4.3.9. meta/recipes-extended/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-recipes-extended"></a>4.3.9. <code class="filename">meta/recipes-extended/</code></h3></div></div></div><p>
10098 This directory contains non-essential applications that add features compared to the
10099 alternatives in core.
10100 You might need this directory for full tool functionality or for Linux Standard Base (LSB)
10101 compliance.
10102 </p></div><div class="section" title="4.3.10. meta/recipes-gnome/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-recipes-gnome"></a>4.3.10. <code class="filename">meta/recipes-gnome/</code></h3></div></div></div><p>
10103 This directory contains all things related to the GTK+ application framework.
10104 </p></div><div class="section" title="4.3.11. meta/recipes-graphics/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-recipes-graphics"></a>4.3.11. <code class="filename">meta/recipes-graphics/</code></h3></div></div></div><p>
10105 This directory contains X and other graphically related system libraries
10106 </p></div><div class="section" title="4.3.12. meta/recipes-kernel/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-recipes-kernel"></a>4.3.12. <code class="filename">meta/recipes-kernel/</code></h3></div></div></div><p>
10107 This directory contains the kernel and generic applications and libraries that
10108 have strong kernel dependencies.
10109 </p></div><div class="section" title="4.3.13. meta/recipes-multimedia/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-recipes-multimedia"></a>4.3.13. <code class="filename">meta/recipes-multimedia/</code></h3></div></div></div><p>
10110 This directory contains codecs and support utilities for audio, images and video.
10111 </p></div><div class="section" title="4.3.14. meta/recipes-qt/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-recipes-qt"></a>4.3.14. <code class="filename">meta/recipes-qt/</code></h3></div></div></div><p>
10112 This directory contains all things related to the Qt application framework.
10113 </p></div><div class="section" title="4.3.15. meta/recipes-rt/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-recipes-rt"></a>4.3.15. <code class="filename">meta/recipes-rt/</code></h3></div></div></div><p>
10114 This directory contains package and image recipes for using and testing
10115 the <code class="filename">PREEMPT_RT</code> kernel.
10116 </p></div><div class="section" title="4.3.16. meta/recipes-sato/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-recipes-sato"></a>4.3.16. <code class="filename">meta/recipes-sato/</code></h3></div></div></div><p>
10117 This directory contains the Sato demo/reference UI/UX and its associated applications
10118 and configuration data.
10119 </p></div><div class="section" title="4.3.17. meta/recipes-support/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-recipes-support"></a>4.3.17. <code class="filename">meta/recipes-support/</code></h3></div></div></div><p>
10120 This directory contains recipes that used by other recipes, but that are not directly
10121 included in images (i.e. dependencies of other recipes).
10122 </p></div><div class="section" title="4.3.18. meta/site/"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-site"></a>4.3.18. <code class="filename">meta/site/</code></h3></div></div></div><p>
10123 This directory contains a list of cached results for various architectures.
10124 Because certain "autoconf" test results cannot be determined when cross-compiling due to
10125 the tests not able to run on a live system, the information in this directory is
10126 passed to "autoconf" for the various architectures.
10127 </p></div><div class="section" title="4.3.19. meta/recipes.txt"><div class="titlepage"><div><div><h3 class="title"><a id="structure-meta-recipes-txt"></a>4.3.19. <code class="filename">meta/recipes.txt</code></h3></div></div></div><p>
10128 This file is a description of the contents of <code class="filename">recipes-*</code>.
10129 </p></div></div></div>
10130
10131 <div class="chapter" title="Chapter 5. BitBake"><div class="titlepage"><div><div><h2 class="title"><a id="ref-bitbake"></a>Chapter 5. BitBake</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#ref-bitbake-parsing">5.1. Parsing</a></span></dt><dt><span class="section"><a href="#ref-bitbake-providers">5.2. Preferences and Providers</a></span></dt><dt><span class="section"><a href="#ref-bitbake-dependencies">5.3. Dependencies</a></span></dt><dt><span class="section"><a href="#ref-bitbake-tasklist">5.4. The Task List</a></span></dt><dt><span class="section"><a href="#ref-bitbake-runtask">5.5. Running a Task</a></span></dt><dt><span class="section"><a href="#ref-bitbake-commandline">5.6. BitBake Command Line</a></span></dt><dt><span class="section"><a href="#ref-bitbake-fetchers">5.7. Fetchers</a></span></dt></dl></div><p>
10132 BitBake is a program written in Python that interprets the metadata used by the OpenEmbedded
10133 build system.
10134 At some point, developers wonder what actually happens when you enter:
10135 </p><pre class="literallayout">
10136 $ bitbake core-image-sato
10137 </pre><p>
10138 </p><p>
10139 This chapter provides an overview of what happens behind the scenes from BitBake's perspective.
10140 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
10141 BitBake strives to be a generic "task" executor that is capable of handling complex dependency relationships.
10142 As such, it has no real knowledge of what the tasks being executed actually do.
10143 BitBake just considers a list of tasks with dependencies and handles metadata
10144 that consists of variables in a certain format that get passed to the tasks.
10145 </div><div class="section" title="5.1. Parsing"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-bitbake-parsing"></a>5.1. Parsing</h2></div></div></div><p>
10146 BitBake parses configuration files, classes, and <code class="filename">.bb</code> files.
10147 </p><p>
10148 The first thing BitBake does is look for the <code class="filename">bitbake.conf</code> file.
10149 This file resides in the
10150 <a class="link" href="#source-directory" target="_top">source directory</a>
10151 within the <code class="filename">meta/conf/</code> directory.
10152 BitBake finds it by examining its
10153 <a class="link" href="#var-BBPATH" title="BBPATH"><code class="filename">BBPATH</code></a> environment
10154 variable and looking for the <code class="filename">meta/conf/</code>
10155 directory.
10156 </p><p>
10157 The <code class="filename">bitbake.conf</code> file lists other configuration
10158 files to include from a <code class="filename">conf/</code>
10159 directory below the directories listed in <code class="filename">BBPATH</code>.
10160 In general, the most important configuration file from a user's perspective
10161 is <code class="filename">local.conf</code>, which contains a user's customized
10162 settings for the OpenEmbedded build environment.
10163 Other notable configuration files are the distribution
10164 configuration file (set by the
10165 <code class="filename"><a class="link" href="#var-DISTRO" title="DISTRO">DISTRO</a></code> variable)
10166 and the machine configuration file
10167 (set by the
10168 <code class="filename"><a class="link" href="#var-MACHINE" title="MACHINE">MACHINE</a></code> variable).
10169 The <code class="filename">DISTRO</code> and <code class="filename">MACHINE</code> BitBake environment
10170 variables are both usually set in
10171 the <code class="filename">local.conf</code> file.
10172 Valid distribution
10173 configuration files are available in the <code class="filename">meta/conf/distro/</code> directory
10174 and valid machine configuration
10175 files in the <code class="filename">meta/conf/machine/</code> directory.
10176 Within the <code class="filename">meta/conf/machine/include/</code>
10177 directory are various <code class="filename">tune-*.inc</code> configuration files that provide common
10178 "tuning" settings specific to and shared between particular architectures and machines.
10179 </p><p>
10180 After the parsing of the configuration files, some standard classes are included.
10181 The <code class="filename">base.bbclass</code> file is always included.
10182 Other classes that are specified in the configuration using the
10183 <code class="filename"><a class="link" href="#var-INHERIT" title="INHERIT">INHERIT</a></code>
10184 variable are also included.
10185 Class files are searched for in a <code class="filename">classes</code> subdirectory
10186 under the paths in <code class="filename">BBPATH</code> in the same way as
10187 configuration files.
10188 </p><p>
10189 After classes are included, the variable
10190 <code class="filename"><a class="link" href="#var-BBFILES" title="BBFILES">BBFILES</a></code>
10191 is set, usually in
10192 <code class="filename">local.conf</code>, and defines the list of places to search for
10193 <code class="filename">.bb</code> files.
10194 By default, the <code class="filename">BBFILES</code> variable specifies the
10195 <code class="filename">meta/recipes-*/</code> directory within Poky.
10196 Adding extra content to <code class="filename">BBFILES</code> is best achieved through the use of
10197 BitBake layers as described in the
10198 "<a class="link" href="#understanding-and-creating-layers" target="_top">Understanding and
10199 Creating Layers</a>" section of the Yocto Project Development Manual.
10200 </p><p>
10201 BitBake parses each <code class="filename">.bb</code> file in <code class="filename">BBFILES</code> and
10202 stores the values of various variables.
10203 In summary, for each <code class="filename">.bb</code>
10204 file the configuration plus the base class of variables are set, followed
10205 by the data in the <code class="filename">.bb</code> file
10206 itself, followed by any inherit commands that
10207 <code class="filename">.bb</code> file might contain.
10208 </p><p>
10209 Because parsing <code class="filename">.bb</code> files is a time
10210 consuming process, a cache is kept to speed up subsequent parsing.
10211 This cache is invalid if the timestamp of the <code class="filename">.bb</code>
10212 file itself changes, or if the timestamps of any of the include,
10213 configuration or class files the <code class="filename">.bb</code>
10214 file depends on changes.
10215 </p></div><div class="section" title="5.2. Preferences and Providers"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-bitbake-providers"></a>5.2. Preferences and Providers</h2></div></div></div><p>
10216 Once all the <code class="filename">.bb</code> files have been
10217 parsed, BitBake starts to build the target (<code class="filename">core-image-sato</code>
10218 in the previous section's example) and looks for providers of that target.
10219 Once a provider is selected, BitBake resolves all the dependencies for
10220 the target.
10221 In the case of <code class="filename">core-image-sato</code>, it would lead to
10222 <code class="filename">task-base.bb</code>,
10223 which in turn leads to packages like <code class="filename">Contacts</code>,
10224 <code class="filename">Dates</code> and <code class="filename">BusyBox</code>.
10225 These packages in turn depend on <code class="filename">eglibc</code> and the toolchain.
10226 </p><p>
10227 Sometimes a target might have multiple providers.
10228 A common example is "virtual/kernel", which is provided by each kernel package.
10229 Each machine often selects the best kernel provider by using a line similar to the
10230 following in the machine configuration file:
10231 </p><pre class="literallayout">
10232 PREFERRED_PROVIDER_virtual/kernel = "linux-yocto"
10233 </pre><p>
10234 The default <code class="filename"><a class="link" href="#var-PREFERRED_PROVIDER" title="PREFERRED_PROVIDER">PREFERRED_PROVIDER</a></code>
10235 is the provider with the same name as the target.
10236 </p><p>
10237 Understanding how providers are chosen is made complicated by the fact
10238 that multiple versions might exist.
10239 BitBake defaults to the highest version of a provider.
10240 Version comparisons are made using the same method as Debian.
10241 You can use the
10242 <code class="filename"><a class="link" href="#var-PREFERRED_VERSION" title="PREFERRED_VERSION">PREFERRED_VERSION</a></code>
10243 variable to specify a particular version (usually in the distro configuration).
10244 You can influence the order by using the
10245 <code class="filename"><a class="link" href="#var-DEFAULT_PREFERENCE" title="DEFAULT_PREFERENCE">DEFAULT_PREFERENCE</a></code>
10246 variable.
10247 By default, files have a preference of "0".
10248 Setting the <code class="filename">DEFAULT_PREFERENCE</code> to "-1" makes the
10249 package unlikely to be used unless it is explicitly referenced.
10250 Setting the <code class="filename">DEFAULT_PREFERENCE</code> to "1" makes it likely the package is used.
10251 <code class="filename">PREFERRED_VERSION</code> overrides any <code class="filename">DEFAULT_PREFERENCE</code> setting.
10252 <code class="filename">DEFAULT_PREFERENCE</code> is often used to mark newer and more experimental package
10253 versions until they have undergone sufficient testing to be considered stable.
10254 </p><p>
10255 In summary, BitBake has created a list of providers, which is prioritized, for each target.
10256 </p></div><div class="section" title="5.3. Dependencies"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-bitbake-dependencies"></a>5.3. Dependencies</h2></div></div></div><p>
10257 Each target BitBake builds consists of multiple tasks such as
10258 <code class="filename">fetch</code>, <code class="filename">unpack</code>,
10259 <code class="filename">patch</code>, <code class="filename">configure</code>,
10260 and <code class="filename">compile</code>.
10261 For best performance on multi-core systems, BitBake considers each task as an independent
10262 entity with its own set of dependencies.
10263 </p><p>
10264 Dependencies are defined through several variables.
10265 You can find information about variables BitBake uses in the
10266 <a class="ulink" href="http://docs.openembedded.org/bitbake/html/" target="_top">BitBake manual</a>.
10267 At a basic level, it is sufficient to know that BitBake uses the
10268 <code class="filename"><a class="link" href="#var-DEPENDS" title="DEPENDS">DEPENDS</a></code> and
10269 <code class="filename"><a class="link" href="#var-RDEPENDS" title="RDEPENDS">RDEPENDS</a></code> variables when
10270 calculating dependencies.
10271 </p></div><div class="section" title="5.4. The Task List"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-bitbake-tasklist"></a>5.4. The Task List</h2></div></div></div><p>
10272 Based on the generated list of providers and the dependency information,
10273 BitBake can now calculate exactly what tasks it needs to run and in what
10274 order it needs to run them.
10275 The build now starts with BitBake forking off threads up to the limit set in the
10276 <code class="filename"><a class="link" href="#var-BB_NUMBER_THREADS" title="BB_NUMBER_THREADS">BB_NUMBER_THREADS</a></code> variable.
10277 BitBake continues to fork threads as long as there are tasks ready to run,
10278 those tasks have all their dependencies met, and the thread threshold has not been
10279 exceeded.
10280 </p><p>
10281 It is worth noting that you can greatly speed up the build time by properly setting
10282 the <code class="filename">BB_NUMBER_THREADS</code> variable.
10283 See the
10284 "<a class="link" href="#building-image" target="_top">Building an Image</a>"
10285 section in the Yocto Project Quick Start for more information.
10286 </p><p>
10287 As each task completes, a timestamp is written to the directory specified by the
10288 <code class="filename"><a class="link" href="#var-STAMP" title="STAMP">STAMP</a></code> variable (usually
10289 <code class="filename">build/tmp/stamps/*/</code>).
10290 On subsequent runs, BitBake looks at the <code class="filename">/build/tmp/stamps</code>
10291 directory and does not rerun
10292 tasks that are already completed unless a timestamp is found to be invalid.
10293 Currently, invalid timestamps are only considered on a per
10294 <code class="filename">.bb</code> file basis.
10295 So, for example, if the configure stamp has a timestamp greater than the
10296 compile timestamp for a given target, then the compile task would rerun.
10297 Running the compile task again, however, has no effect on other providers
10298 that depend on that target.
10299 This behavior could change or become configurable in future versions of BitBake.
10300 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
10301 Some tasks are marked as "nostamp" tasks.
10302 No timestamp file is created when these tasks are run.
10303 Consequently, "nostamp" tasks are always rerun.
10304 </div></div><div class="section" title="5.5. Running a Task"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-bitbake-runtask"></a>5.5. Running a Task</h2></div></div></div><p>
10305 Tasks can either be a shell task or a Python task.
10306 For shell tasks, BitBake writes a shell script to
10307 <code class="filename">${WORKDIR}/temp/run.do_taskname.pid</code> and then executes the script.
10308 The generated shell script contains all the exported variables, and the shell functions
10309 with all variables expanded.
10310 Output from the shell script goes to the file <code class="filename">${WORKDIR}/temp/log.do_taskname.pid</code>.
10311 Looking at the expanded shell functions in the run file and the output in the log files
10312 is a useful debugging technique.
10313 </p><p>
10314 For Python tasks, BitBake executes the task internally and logs information to the
10315 controlling terminal.
10316 Future versions of BitBake will write the functions to files similar to the way
10317 shell tasks are handled.
10318 Logging will be handled in way similar to shell tasks as well.
10319 </p><p>
10320 Once all the tasks have been completed BitBake exits.
10321 </p><p>
10322 When running a task, BitBake tightly controls the execution environment
10323 of the build tasks to make sure unwanted contamination from the build machine
10324 cannot influence the build.
10325 Consequently, if you do want something to get passed into the build
10326 task's environment, you must take a few steps:
10327 </p><div class="orderedlist"><ol class="orderedlist" type="1"><li class="listitem"><p>Tell BitBake to load what you want from the environment
10328 into the data store.
10329 You can do so through the <code class="filename">BB_ENV_WHITELIST</code>
10330 variable.
10331 For example, assume you want to prevent the build system from
10332 accessing your <code class="filename">$HOME/.ccache</code> directory.
10333 The following command tells BitBake to load
10334 <code class="filename">CCACHE_DIR</code> from the environment into the data
10335 store:
10336 </p><pre class="literallayout">
10337 export BB_ENV_EXTRAWHITE="$BB_ENV_EXTRAWHITE CCACHE_DIR"
10338 </pre></li><li class="listitem"><p>Tell BitBake to export what you have loaded into the
10339 environment store to the task environment of every running task.
10340 Loading something from the environment into the data store
10341 (previous step) only makes it available in the datastore.
10342 To export it to the task environment of every running task,
10343 use a command similar to the following in your
10344 <code class="filename">local.conf</code> or distro configuration file:
10345 </p><pre class="literallayout">
10346 export CCACHE_DIR
10347 </pre></li></ol></div><p>
10348 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
10349 A side effect of the previous steps is that BitBake records the variable
10350 as a dependency of the build process in things like the shared state
10351 checksums.
10352 If doing so results in unnecessary rebuilds of tasks, you can whitelist the
10353 variable so that the shared state code ignores the dependency when it creates
10354 checksums.
10355 For information on this process, see the <code class="filename">BB_HASHBASE_WHITELIST</code>
10356 example in the "<a class="link" href="#checksums" title="3.2.2. Checksums (Signatures)">Checksums (Signatures)</a>" section.
10357 </div></div><div class="section" title="5.6. BitBake Command Line"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-bitbake-commandline"></a>5.6. BitBake Command Line</h2></div></div></div><p>
10358 Following is the BitBake help output:
10359 </p><pre class="screen">
10360$ bitbake --help
10361Usage: bitbake [options] [package ...]
10362
10363Executes the specified task (default is 'build') for a given set of BitBake files.
10364It expects that BBFILES is defined, which is a space separated list of files to
10365be executed. BBFILES does support wildcards.
10366Default BBFILES are the .bb files in the current directory.
10367
10368Options:
10369 --version show program's version number and exit
10370 -h, --help show this help message and exit
10371 -b BUILDFILE, --buildfile=BUILDFILE
10372 execute the task against this .bb file, rather than a
10373 package from BBFILES. Does not handle any
10374 dependencies.
10375 -k, --continue continue as much as possible after an error. While the
10376 target that failed, and those that depend on it,
10377 cannot be remade, the other dependencies of these
10378 targets can be processed all the same.
10379 -a, --tryaltconfigs continue with builds by trying to use alternative
10380 providers where possible.
10381 -f, --force force run of specified cmd, regardless of stamp status
10382 -c CMD, --cmd=CMD Specify task to execute. Note that this only executes
10383 the specified task for the providee and the packages
10384 it depends on, i.e. 'compile' does not implicitly call
10385 stage for the dependencies (IOW: use only if you know
10386 what you are doing). Depending on the base.bbclass a
10387 listtasks tasks is defined and will show available
10388 tasks
10389 -r PREFILE, --read=PREFILE
10390 read the specified file before bitbake.conf
10391 -R POSTFILE, --postread=POSTFILE
10392 read the specified file after bitbake.conf
10393 -v, --verbose output more chit-chat to the terminal
10394 -D, --debug Increase the debug level. You can specify this more
10395 than once.
10396 -n, --dry-run don't execute, just go through the motions
10397 -S, --dump-signatures
10398 don't execute, just dump out the signature
10399 construction information
10400 -p, --parse-only quit after parsing the BB files (developers only)
10401 -s, --show-versions show current and preferred versions of all packages
10402 -e, --environment show the global or per-package environment (this is
10403 what used to be bbread)
10404 -g, --graphviz emit the dependency trees of the specified packages in
10405 the dot syntax
10406 -I EXTRA_ASSUME_PROVIDED, --ignore-deps=EXTRA_ASSUME_PROVIDED
10407 Assume these dependencies don't exist and are already
10408 provided (equivalent to ASSUME_PROVIDED). Useful to
10409 make dependency graphs more appealing
10410 -l DEBUG_DOMAINS, --log-domains=DEBUG_DOMAINS
10411 Show debug logging for the specified logging domains
10412 -P, --profile profile the command and print a report
10413 -u UI, --ui=UI userinterface to use
10414 -t SERVERTYPE, --servertype=SERVERTYPE
10415 Choose which server to use, none, process or xmlrpc
10416 --revisions-changed Set the exit code depending on whether upstream
10417 floating revisions have changed or not
10418 </pre></div><div class="section" title="5.7. Fetchers"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-bitbake-fetchers"></a>5.7. Fetchers</h2></div></div></div><p>
10419 BitBake also contains a set of "fetcher" modules that allow
10420 retrieval of source code from various types of sources.
10421 For example, BitBake can get source code from a disk with the metadata, from websites,
10422 from remote shell accounts or from Source Code Management (SCM) systems
10423 like <code class="filename">cvs/subversion/git</code>.
10424 </p><p>
10425 Fetchers are usually triggered by entries in
10426 <code class="filename"><a class="link" href="#var-SRC_URI" title="SRC_URI">SRC_URI</a></code>.
10427 You can find information about the options and formats of entries for specific
10428 fetchers in the <a class="ulink" href="http://docs.openembedded.org/bitbake/html/" target="_top">BitBake manual</a>.
10429 </p><p>
10430 One useful feature for certain Source Code Manager (SCM) fetchers is the ability to
10431 "auto-update" when the upstream SCM changes version.
10432 Since this ability requires certain functionality from the SCM, not all
10433 systems support it.
10434 Currently Subversion, Bazaar and to a limited extent, Git support the ability to "auto-update".
10435 This feature works using the <code class="filename"><a class="link" href="#var-SRCREV" title="SRCREV">SRCREV</a></code>
10436 variable.
10437 See the
10438 "<a class="link" href="#platdev-appdev-srcrev" target="_top">Using an External SCM</a>" section
10439 in the Yocto Project Development Manual for more information.
10440 </p></div></div>
10441
10442 <div class="chapter" title="Chapter 6. Classes"><div class="titlepage"><div><div><h2 class="title"><a id="ref-classes"></a>Chapter 6. Classes</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#ref-classes-base">6.1. The base class - <code class="filename">base.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-autotools">6.2. Autotooled Packages - <code class="filename">autotools.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-update-alternatives">6.3. Alternatives - <code class="filename">update-alternatives.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-update-rc.d">6.4. Initscripts - <code class="filename">update-rc.d.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-binconfig">6.5. Binary config scripts - <code class="filename">binconfig.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-debian">6.6. Debian renaming - <code class="filename">debian.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-pkgconfig">6.7. Pkg-config - <code class="filename">pkgconfig.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-src-distribute">6.8. Distribution of sources - <code class="filename">src_distribute_local.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-perl">6.9. Perl modules - <code class="filename">cpan.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-distutils">6.10. Python extensions - <code class="filename">distutils.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-devshell">6.11. Developer Shell - <code class="filename">devshell.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-package">6.12. Packaging - <code class="filename">package*.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-kernel">6.13. Building kernels - <code class="filename">kernel.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-image">6.14. Creating images - <code class="filename">image.bbclass</code> and <code class="filename">rootfs*.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-sanity">6.15. Host System sanity checks - <code class="filename">sanity.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-insane">6.16. Generated output quality assurance checks - <code class="filename">insane.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-siteinfo">6.17. Autotools configuration data cache - <code class="filename">siteinfo.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-useradd">6.18. Adding Users - <code class="filename">useradd.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-externalsrc">6.19. Using External Source - <code class="filename">externalsrc.bbclass</code></a></span></dt><dt><span class="section"><a href="#ref-classes-others">6.20. Other Classes</a></span></dt></dl></div><p>
10443 Class files are used to abstract common functionality and share it amongst multiple
10444 <code class="filename">.bb</code> files.
10445 Any metadata usually found in a <code class="filename">.bb</code> file can also be placed in a class
10446 file.
10447 Class files are identified by the extension <code class="filename">.bbclass</code> and are usually placed
10448 in a <code class="filename">classes/</code> directory beneath the
10449 <code class="filename">meta*/</code> directory found in the
10450 <a class="link" href="#source-directory" target="_top">source directory</a>.
10451 Class files can also be pointed to by BUILDDIR (e.g. <code class="filename">build/</code>)in the same way as
10452 <code class="filename">.conf</code> files in the <code class="filename">conf</code> directory.
10453 Class files are searched for in <a class="link" href="#var-BBPATH" title="BBPATH"><code class="filename">BBPATH</code></a>
10454 using the same method by which <code class="filename">.conf</code> files are searched.
10455</p><p>
10456 In most cases inheriting the class is enough to enable its features, although
10457 for some classes you might need to set variables or override some of the
10458 default behaviour.
10459</p><div class="section" title="6.1. The base class - base.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-base"></a>6.1. The base class - <code class="filename">base.bbclass</code></h2></div></div></div><p>
10460 The base class is special in that every <code class="filename">.bb</code>
10461 file inherits it automatically.
10462 This class contains definitions for standard basic
10463 tasks such as fetching, unpacking, configuring (empty by default), compiling
10464 (runs any <code class="filename">Makefile</code> present), installing (empty by default) and packaging
10465 (empty by default).
10466 These classes are often overridden or extended by other classes
10467 such as <code class="filename">autotools.bbclass</code> or <code class="filename">package.bbclass</code>.
10468 The class also contains some commonly used functions such as <code class="filename">oe_runmake</code>.
10469 </p></div><div class="section" title="6.2. Autotooled Packages - autotools.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-autotools"></a>6.2. Autotooled Packages - <code class="filename">autotools.bbclass</code></h2></div></div></div><p>
10470 Autotools (<code class="filename">autoconf</code>, <code class="filename">automake</code>,
10471 and <code class="filename">libtool</code>) bring standardization.
10472 This class defines a set of tasks (configure, compile etc.) that
10473 work for all Autotooled packages.
10474 It should usually be enough to define a few standard variables
10475 and then simply <code class="filename">inherit autotools</code>.
10476 This class can also work with software that emulates Autotools.
10477 For more information, see the
10478 "<a class="link" href="#usingpoky-extend-addpkg-autotools" target="_top">Autotooled Package</a>"
10479 section in the Yocto Project Development Manual.
10480 </p><p>
10481 It's useful to have some idea of how the tasks defined by this class work
10482 and what they do behind the scenes.
10483 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename">do_configure</code> ‐ regenerates the
10484 configure script (using <code class="filename">autoreconf</code>) and then launches it
10485 with a standard set of arguments used during cross-compilation.
10486 You can pass additional parameters to <code class="filename">configure</code> through the
10487 <code class="filename"><a class="link" href="#var-EXTRA_OECONF" title="EXTRA_OECONF">EXTRA_OECONF</a></code> variable.
10488 </p></li><li class="listitem"><p><code class="filename">do_compile</code> ‐ runs <code class="filename">make</code> with
10489 arguments that specify the compiler and linker.
10490 You can pass additional arguments through
10491 the <code class="filename"><a class="link" href="#var-EXTRA_OEMAKE" title="EXTRA_OEMAKE">EXTRA_OEMAKE</a></code> variable.
10492 </p></li><li class="listitem"><p><code class="filename">do_install</code> ‐ runs <code class="filename">make install</code>
10493 and passes a DESTDIR option, which takes its value from the standard
10494 <code class="filename"><a class="link" href="#var-DESTDIR" title="DESTDIR">DESTDIR</a></code> variable.
10495 </p></li></ul></div><p>
10496 </p></div><div class="section" title="6.3. Alternatives - update-alternatives.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-update-alternatives"></a>6.3. Alternatives - <code class="filename">update-alternatives.bbclass</code></h2></div></div></div><p>
10497 Several programs can fulfill the same or similar function and be installed with the same name.
10498 For example, the <code class="filename">ar</code> command is available from the
10499 <code class="filename">busybox</code>, <code class="filename">binutils</code> and
10500 <code class="filename">elfutils</code> packages.
10501 The <code class="filename">update-alternatives.bbclass</code> class handles renaming the
10502 binaries so that multiple packages can be installed without conflicts.
10503 The <code class="filename">ar</code> command still works regardless of which packages are installed
10504 or subsequently removed.
10505 The class renames the conflicting binary in each package and symlinks the highest
10506 priority binary during installation or removal of packages.
10507 </p><p>
10508 Four variables control this class:
10509 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename">ALTERNATIVE_NAME</code> ‐ The name of the
10510 binary that is replaced (<code class="filename">ar</code> in this example).</p></li><li class="listitem"><p><code class="filename">ALTERNATIVE_LINK</code> ‐ The path to
10511 the resulting binary (<code class="filename">/bin/ar</code> in this example).</p></li><li class="listitem"><p><code class="filename">ALTERNATIVE_PATH</code> ‐ The path to the
10512 real binary (<code class="filename">/usr/bin/ar.binutils</code> in this example).</p></li><li class="listitem"><p><code class="filename">ALTERNATIVE_PRIORITY</code> ‐ The priority of
10513 the binary.
10514 The version with the most features should have the highest priority.</p></li></ul></div><p>
10515 </p><p>
10516 Currently, the OpenEmbedded build system supports only one binary per package.
10517 </p></div><div class="section" title="6.4. Initscripts - update-rc.d.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-update-rc.d"></a>6.4. Initscripts - <code class="filename">update-rc.d.bbclass</code></h2></div></div></div><p>
10518 This class uses <code class="filename">update-rc.d</code> to safely install an
10519 initialization script on behalf of the package.
10520 The OpenEmbedded build system takes care of details such as making sure the script is stopped before
10521 a package is removed and started when the package is installed.
10522 Three variables control this class:
10523 <code class="filename"><a class="link" href="#var-INITSCRIPT_PACKAGES" title="INITSCRIPT_PACKAGES">INITSCRIPT_PACKAGES</a></code>,
10524 <code class="filename"><a class="link" href="#var-INITSCRIPT_NAME" title="INITSCRIPT_NAME">INITSCRIPT_NAME</a></code> and
10525 <code class="filename"><a class="link" href="#var-INITSCRIPT_PARAMS" title="INITSCRIPT_PARAMS">INITSCRIPT_PARAMS</a></code>.
10526 See the variable links for details.
10527 </p></div><div class="section" title="6.5. Binary config scripts - binconfig.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-binconfig"></a>6.5. Binary config scripts - <code class="filename">binconfig.bbclass</code></h2></div></div></div><p>
10528 Before <code class="filename">pkg-config</code> had become widespread, libraries shipped shell
10529 scripts to give information about the libraries and include paths needed
10530 to build software (usually named <code class="filename">LIBNAME-config</code>).
10531 This class assists any recipe using such scripts.
10532 </p><p>
10533 During staging, BitBake installs such scripts into the
10534 <code class="filename">sysroots/</code> directory.
10535 BitBake also changes all paths to point into the <code class="filename">sysroots/</code>
10536 directory so all builds that use the script will use the correct
10537 directories for the cross compiling layout.
10538 </p></div><div class="section" title="6.6. Debian renaming - debian.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-debian"></a>6.6. Debian renaming - <code class="filename">debian.bbclass</code></h2></div></div></div><p>
10539 This class renames packages so that they follow the Debian naming
10540 policy (i.e. <code class="filename">eglibc</code> becomes <code class="filename">libc6</code>
10541 and <code class="filename">eglibc-devel</code> becomes <code class="filename">libc6-dev</code>.
10542 </p></div><div class="section" title="6.7. Pkg-config - pkgconfig.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-pkgconfig"></a>6.7. Pkg-config - <code class="filename">pkgconfig.bbclass</code></h2></div></div></div><p>
10543 <code class="filename">pkg-config</code> brought standardization and this class aims to make its
10544 integration smooth for all libraries that make use of it.
10545 </p><p>
10546 During staging, BitBake installs <code class="filename">pkg-config</code> data into the
10547 <code class="filename">sysroots/</code> directory.
10548 By making use of sysroot functionality within <code class="filename">pkg-config</code>,
10549 this class no longer has to manipulate the files.
10550 </p></div><div class="section" title="6.8. Distribution of sources - src_distribute_local.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-src-distribute"></a>6.8. Distribution of sources - <code class="filename">src_distribute_local.bbclass</code></h2></div></div></div><p>
10551 Many software licenses require that source files be provided along with the binaries.
10552 To simplify this process, two classes were created:
10553 <code class="filename">src_distribute.bbclass</code> and
10554 <code class="filename">src_distribute_local.bbclass</code>.
10555 </p><p>
10556 The results of these classes are <code class="filename">tmp/deploy/source/</code>
10557 subdirs with sources sorted by
10558 <code class="filename"><a class="link" href="#var-LICENSE" title="LICENSE">LICENSE</a></code> field.
10559 If recipes list few licenses (or have entries like "Bitstream Vera"),
10560 the source archive is placed in each license directory.
10561 </p><p>
10562 This class operates using three modes:
10563 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>copy:</em></span> Copies the files to the
10564 distribute directory.</p></li><li class="listitem"><p><span class="emphasis"><em>symlink:</em></span> Symlinks the files to the
10565 distribute directory.</p></li><li class="listitem"><p><span class="emphasis"><em>move+symlink:</em></span> Moves the files into
10566 the distribute directory and then symlinks them back.</p></li></ul></div><p>
10567 </p></div><div class="section" title="6.9. Perl modules - cpan.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-perl"></a>6.9. Perl modules - <code class="filename">cpan.bbclass</code></h2></div></div></div><p>
10568 Recipes for Perl modules are simple.
10569 These recipes usually only need to point to the source's archive and then inherit the
10570 proper <code class="filename">.bbclass</code> file.
10571 Building is split into two methods depending on which method the module authors used.
10572 </p><p>
10573 Modules that use old <code class="filename">Makefile.PL</code>-based build system require
10574 <code class="filename">cpan.bbclass</code> in their recipes.
10575 </p><p>
10576 Modules that use <code class="filename">Build.PL</code>-based build system require
10577 using <code class="filename">cpan_build.bbclass</code> in their recipes.
10578 </p></div><div class="section" title="6.10. Python extensions - distutils.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-distutils"></a>6.10. Python extensions - <code class="filename">distutils.bbclass</code></h2></div></div></div><p>
10579 Recipes for Python extensions are simple.
10580 These recipes usually only need to point to the source's archive and then inherit
10581 the proper <code class="filename">.bbclass</code> file.
10582 Building is split into two methods dependling on which method the module authors used.
10583 </p><p>
10584 Extensions that use an Autotools-based build system require Autotools and
10585 <code class="filename">distutils</code>-based <code class="filename">.bbclasse</code> files in their recipes.
10586 </p><p>
10587 Extensions that use <code class="filename">distutils</code>-based build systems require
10588 <code class="filename">distutils.bbclass</code> in their recipes.
10589 </p></div><div class="section" title="6.11. Developer Shell - devshell.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-devshell"></a>6.11. Developer Shell - <code class="filename">devshell.bbclass</code></h2></div></div></div><p>
10590 This class adds the <code class="filename">devshell</code> task.
10591 Distribution policy dictates whether to include this class.
10592 See the
10593 "<a class="link" href="#platdev-appdev-devshell" target="_top">Using a Development Shell</a>" section
10594 in the Yocto Project Development Manual for more information about using <code class="filename">devshell</code>.
10595 </p></div><div class="section" title="6.12. Packaging - package*.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-package"></a>6.12. Packaging - <code class="filename">package*.bbclass</code></h2></div></div></div><p>
10596 The packaging classes add support for generating packages from a build's
10597 output.
10598 The core generic functionality is in <code class="filename">package.bbclass</code>.
10599 The code specific to particular package types is contained in various sub-classes such as
10600 <code class="filename">package_deb.bbclass</code>, <code class="filename">package_ipk.bbclass</code>,
10601 and <code class="filename">package_rpm.bbclass</code>.
10602 Most users will want one or more of these classes.
10603 </p><p>
10604 You can control the list of resulting package formats by using the
10605 <code class="filename"><a class="link" href="#var-PACKAGE_CLASSES" title="PACKAGE_CLASSES">PACKAGE_CLASSES</a></code>
10606 variable defined in the <code class="filename">local.conf</code> configuration file,
10607 which is located in the <code class="filename">conf</code> folder of the
10608 <a class="link" href="#source-directory" target="_top">source directory</a>.
10609 When defining the variable, you can specify one or more package types.
10610 Since images are generated from packages, a packaging class is
10611 needed to enable image generation.
10612 The first class listed in this variable is used for image generation.
10613 </p><p>
10614 The package class you choose can affect build-time performance and has space
10615 ramifications.
10616 In general, building a package with RPM takes about thirty percent more time as
10617 compared to using IPK to build the same or similar package.
10618 This comparison takes into account a complete build of the package with all
10619 dependencies previously built.
10620 The reason for this discrepancy is because the RPM package manager creates and
10621 processes more metadata than the IPK package manager.
10622 Consequently, you might consider setting <code class="filename">PACKAGE_CLASSES</code>
10623 to "package_ipk" if you are building smaller systems.
10624 </p><p>
10625 Keep in mind, however, that RPM starts to provide more abilities than IPK due to
10626 the fact that it processes more metadata.
10627 For example, this information includes individual file types, file checksum generation
10628 and evaluation on install, sparse file support, conflict detection and resolution
10629 for multilib systems, ACID style upgrade, and repackaging abilities for rollbacks.
10630 </p><p>
10631 Another consideration for packages built using the RPM package manager is space.
10632 For smaller systems, the extra space used for the Berkley Database and the amount
10633 of metadata can affect your ability to do on-device upgrades.
10634 </p><p>
10635 You can find additional information on the effects of the package class at these
10636 two Yocto Project mailing list links:
10637 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><a class="ulink" href="http://lists.yoctoproject.org/pipermail/poky/2011-May/006362.html" target="_top">
10638 https://lists.yoctoproject.org/pipermail/poky/2011-May/006362.html</a></p></li><li class="listitem"><p><a class="ulink" href="http://lists.yoctoproject.org/pipermail/poky/2011-May/006363.html" target="_top">
10639 https://lists.yoctoproject.org/pipermail/poky/2011-May/006363.html</a></p></li></ul></div><p>
10640 </p></div><div class="section" title="6.13. Building kernels - kernel.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-kernel"></a>6.13. Building kernels - <code class="filename">kernel.bbclass</code></h2></div></div></div><p>
10641 This class handles building Linux kernels.
10642 The class contains code to build all kernel trees.
10643 All needed headers are staged into the
10644 <code class="filename"><a class="link" href="#var-STAGING_KERNEL_DIR" title="STAGING_KERNEL_DIR">STAGING_KERNEL_DIR</a></code>
10645 directory to allow out-of-tree module builds using <code class="filename">module.bbclass</code>.
10646 </p><p>
10647 This means that each built kernel module is packaged separately and inter-module
10648 dependencies are created by parsing the <code class="filename">modinfo</code> output.
10649 If all modules are required, then installing the <code class="filename">kernel-modules</code>
10650 package installs all packages with modules and various other kernel packages
10651 such as <code class="filename">kernel-vmlinux</code>.
10652 </p><p>
10653 Various other classes are used by the kernel and module classes internally including
10654 <code class="filename">kernel-arch.bbclass</code>, <code class="filename">module_strip.bbclass</code>,
10655 <code class="filename">module-base.bbclass</code>, and <code class="filename">linux-kernel-base.bbclass</code>.
10656 </p></div><div class="section" title="6.14. Creating images - image.bbclass and rootfs*.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-image"></a>6.14. Creating images - <code class="filename">image.bbclass</code> and <code class="filename">rootfs*.bbclass</code></h2></div></div></div><p>
10657 These classes add support for creating images in several formats.
10658 First, the root filesystem is created from packages using
10659 one of the <code class="filename">rootfs_*.bbclass</code>
10660 files (depending on the package format used) and then the image is created.
10661 </p><p>
10662 The <code class="filename"><a class="link" href="#var-IMAGE_FSTYPES" title="IMAGE_FSTYPES">IMAGE_FSTYPES</a></code>
10663 variable controls the types of images to generate.
10664 </p><p>
10665 The <code class="filename"><a class="link" href="#var-IMAGE_INSTALL" title="IMAGE_INSTALL">IMAGE_INSTALL</a></code>
10666 variable controls the list of packages to install into the image.
10667 </p></div><div class="section" title="6.15. Host System sanity checks - sanity.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-sanity"></a>6.15. Host System sanity checks - <code class="filename">sanity.bbclass</code></h2></div></div></div><p>
10668 This class checks to see if prerequisite software is present so that
10669 users can be notified of potential problems that might affect their build.
10670 The class also performs basic user configuration checks from
10671 the <code class="filename">local.conf</code> configuration file to
10672 prevent common mistakes that cause build failures.
10673 Distribution policy usually determines whether to include this class.
10674 </p></div><div class="section" title="6.16. Generated output quality assurance checks - insane.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-insane"></a>6.16. Generated output quality assurance checks - <code class="filename">insane.bbclass</code></h2></div></div></div><p>
10675 This class adds a step to the package generation process that sanity checks the
10676 packages generated by the OpenEmbedded build system.
10677 A range of checks are performed that check the build's output
10678 for common problems that show up during runtime.
10679 Distribution policy usually dictates whether to include this class.
10680 </p><p>
10681 You can configure the sanity checks so that specific test failures either raise a warning or
10682 an error message.
10683 Typically, failures for new tests generate a warning.
10684 Subsequent failures for the same test would then generate an error message
10685 once the metadata is in a known and good condition.
10686 You use the <code class="filename">WARN_QA</code> variable to specify tests for which you
10687 want to generate a warning message on failure.
10688 You use the <code class="filename">ERROR_QA</code> variable to specify tests for which you
10689 want to generate an error message on failure.
10690 </p><p>
10691 The following list shows the tests you can list with the <code class="filename">WARN_QA</code>
10692 and <code class="filename">ERROR_QA</code> variables:
10693 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em><code class="filename">ldflags:</code></em></span>
10694 Ensures that the binaries were linked with the
10695 <code class="filename">LDFLAGS</code> options provided by the build system.
10696 If this test fails, check that the <code class="filename">LDFLAGS</code> variable
10697 is being passed to the linker command.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">useless-rpaths:</code></em></span>
10698 Checks for dynamic library load paths (rpaths) in the binaries that
10699 by default on a standard system are searched by the linker (e.g.
10700 <code class="filename">/lib</code> and <code class="filename">/usr/lib</code>).
10701 While these paths will not cause any breakage, they do waste space and
10702 are unnecessary.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">rpaths:</code></em></span>
10703 Checks for rpaths in the binaries that contain build system paths such
10704 as <code class="filename">TMPDIR</code>.
10705 If this test fails, bad <code class="filename">-rpath</code> options are being
10706 passed to the linker commands and your binaries have potential security
10707 issues.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">dev-so:</code></em></span>
10708 Checks that the <code class="filename">.so</code> symbolic links are in the
10709 <code class="filename">-dev</code> package and not in any of the other packages.
10710 In general, these symlinks are only useful for development purposes.
10711 Thus, the <code class="filename">-dev</code> package is the correct location for
10712 them.
10713 Some very rare cases do exist for dynamically loaded modules where
10714 these symlinks are needed instead in the main package.
10715 </p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">debug-files:</code></em></span>
10716 Checks for <code class="filename">.debug</code> directories in anything but the
10717 <code class="filename">-dbg</code> package.
10718 The debug files should all be in the <code class="filename">-dbg</code> package.
10719 Thus, anything packaged elsewhere is incorrect packaging.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">arch:</code></em></span>
10720 Checks the Executable and Linkable Format (ELF) type, bit size and endianness
10721 of any binaries to ensure it matches the target architecture.
10722 This test fails if any binaries don't match the type since there would be an
10723 incompatibility.
10724 Sometimes software, like bootloaders, might need to bypass this check.
10725 </p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">debug-deps:</code></em></span>
10726 Checks that <code class="filename">-dbg</code> packages only depend on other
10727 <code class="filename">-dbg</code> packages and not on any other types of packages,
10728 which would cause a packaging bug.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">dev-deps:</code></em></span>
10729 Checks that <code class="filename">-dev</code> packages only depend on other
10730 <code class="filename">-dev</code> packages and not on any other types of packages,
10731 which would be a packaging bug.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">pkgconfig:</code></em></span>
10732 Checks <code class="filename">.pc</code> files for any
10733 <code class="filename">TMPDIR/WORKDIR</code> paths.
10734 Any <code class="filename">.pc</code> file containing these paths is incorrect
10735 since <code class="filename">pkg-config</code> itself adds the correct sysroot prefix
10736 when the files are accessed.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">la:</code></em></span>
10737 Checks <code class="filename">.la</code> files for any <code class="filename">TMPDIR</code>
10738 paths.
10739 Any <code class="filename">.la</code> file continaing these paths is incorrect since
10740 <code class="filename">libtool</code> adds the correct sysroot prefix when using the
10741 files automatically itself.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">desktop:</code></em></span>
10742 Runs the <code class="filename">desktop-file-validate</code> program against any
10743 <code class="filename">.desktop</code> files to validate their contents against
10744 the specification for <code class="filename">.desktop</code> files.</p></li></ul></div><p>
10745 </p></div><div class="section" title="6.17. Autotools configuration data cache - siteinfo.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-siteinfo"></a>6.17. Autotools configuration data cache - <code class="filename">siteinfo.bbclass</code></h2></div></div></div><p>
10746 Autotools can require tests that must execute on the target hardware.
10747 Since this is not possible in general when cross compiling, site information is
10748 used to provide cached test results so these tests can be skipped over but
10749 still make the correct values available.
10750 The <code class="filename"><a class="link" href="#structure-meta-site" title="4.3.18. meta/site/">meta/site directory</a></code>
10751 contains test results sorted into different categories such as architecture, endianness, and
10752 the <code class="filename">libc</code> used.
10753 Site information provides a list of files containing data relevant to
10754 the current build in the
10755 <code class="filename"><a class="link" href="#var-CONFIG_SITE" title="CONFIG_SITE">CONFIG_SITE</a></code> variable
10756 that Autotools automatically picks up.
10757 </p><p>
10758 The class also provides variables like
10759 <code class="filename"><a class="link" href="#var-SITEINFO_ENDIANNESS" title="SITEINFO_ENDIANNESS">SITEINFO_ENDIANNESS</a></code>
10760 and <code class="filename"><a class="link" href="#var-SITEINFO_BITS" title="SITEINFO_BITS">SITEINFO_BITS</a></code>
10761 that can be used elsewhere in the metadata.
10762 </p><p>
10763 Because this class is included from <code class="filename">base.bbclass</code>, it is always active.
10764 </p></div><div class="section" title="6.18. Adding Users - useradd.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-useradd"></a>6.18. Adding Users - <code class="filename">useradd.bbclass</code></h2></div></div></div><p>
10765 If you have packages that install files that are owned by custom users or groups,
10766 you can use this class to specify those packages and associate the users and groups
10767 with those packages.
10768 The <code class="filename">meta-skeleton/recipes-skeleton/useradd/useradd-example.bb</code>
10769 recipe in the <a class="link" href="#source-directory" target="_top">source directory</a>
10770 provides a simple exmample that shows how to add three
10771 users and groups to two packages.
10772 See the <code class="filename">useradd-example.bb</code> for more information on how to
10773 use this class.
10774 </p></div><div class="section" title="6.19. Using External Source - externalsrc.bbclass"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-externalsrc"></a>6.19. Using External Source - <code class="filename">externalsrc.bbclass</code></h2></div></div></div><p>
10775 You can use this class to build software from source code that is external to the
10776 OpenEmbedded build system.
10777 In other words, your source code resides in an external tree outside of the Yocto Project.
10778 Building software from an external source tree means that the normal fetch, unpack, and
10779 patch process is not used.
10780 </p><p>
10781 To use the class, you need to define the
10782 <a class="link" href="#var-S" title="S"><code class="filename">S</code></a> variable to point to the directory that contains the source files.
10783 You also need to have your recipe inherit the <code class="filename">externalsrc.bbclass</code> class.
10784 </p><p>
10785 This class expects the source code to support recipe builds that use the
10786 <a class="link" href="#var-B" title="B"><code class="filename">B</code></a> variable to point to the directory in
10787 which the OpenEmbedded build system places the generated objects built from the recipes.
10788 By default, the <code class="filename">B</code> directory is set to the following, which is separate from the
10789 source directory (<code class="filename">S</code>):
10790 </p><pre class="literallayout">
10791 ${WORKDIR}/${BPN}-{PV}/
10792 </pre><p>
10793 See the glossary entries for the
10794 <a class="link" href="#var-WORKDIR" title="WORKDIR"><code class="filename">WORKDIR</code></a>,
10795 <a class="link" href="#var-BPN" title="BPN"><code class="filename">BPN</code></a>,
10796 <a class="link" href="#var-PV" title="PV"><code class="filename">PV</code></a>,
10797 <a class="link" href="#var-S" title="S"><code class="filename">S</code></a>, and
10798 <a class="link" href="#var-B" title="B"><code class="filename">B</code></a> for more information.
10799 </p><p>
10800 You can build object files in the external tree by setting the
10801 <code class="filename">B</code> variable equal to <code class="filename">"${S}"</code>.
10802 However, this practice does not work well if you use the source for more than one variant
10803 (i.e., "natives" such as <code class="filename">quilt-native</code>,
10804 or "crosses" such as <code class="filename">gcc-cross</code>).
10805 So, be sure there are no "native", "cross", or "multilib" variants of the recipe.
10806 </p><p>
10807 If you do want to build different variants of a recipe, you can use the
10808 <a class="link" href="#var-BBCLASSEXTEND" title="BBCLASSEXTEND"><code class="filename">BBCLASSEXTEND</code></a> variable.
10809 When you do, the <a class="link" href="#var-B" title="B"><code class="filename">B</code></a> variable must support the
10810 recipe's ability to build variants in different working directories.
10811 Most autotools-based recipes support separating these directories.
10812 The OpenEmbedded build system defaults to using separate directories for <code class="filename">gcc</code>
10813 and some kernel recipes.
10814 Alternatively, you can make sure that separate recipes exist that each
10815 use the <code class="filename">BBCLASSEXTEND</code> variable to build each variant.
10816 The separate recipes can inherit a single target recipe.
10817 </p><p>
10818 For information on how to use this class, see the
10819 "<a class="link" href="#building-software-from-an-external-source" target="_top">Building
10820 Software from an External Source</a>" section in the Yocto Project Development Manual.
10821 </p></div><div class="section" title="6.20. Other Classes"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-classes-others"></a>6.20. Other Classes</h2></div></div></div><p>
10822 Thus far, this chapter has discussed only the most useful and important
10823 classes.
10824 However, other classes exist within the <code class="filename">meta/classes</code> directory
10825 in the <a class="link" href="#source-directory" target="_top">source directory</a>.
10826 You can examine the <code class="filename">.bbclass</code> files directly for more
10827 information.
10828 </p></div></div>
10829
10830 <div class="chapter" title="Chapter 7. Images"><div class="titlepage"><div><div><h2 class="title"><a id="ref-images"></a>Chapter 7. Images</h2></div></div></div><p>
10831 The OpenEmbedded build process supports several types of images to satisfy different needs.
10832 When you issue the <code class="filename">bitbake</code> command you provide a “top-level” recipe
10833 that essentially begins the build for the type of image you want.
10834 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
10835 Building an image without GNU Public License Version 3 (GPLv3) components is
10836 only supported for minimal and base images.
10837 Furthermore, if you are going to build an image using non-GPLv3 components,
10838 you must make the following changes in the <code class="filename">local.conf</code> file
10839 before using the BitBake command to build the minimal or base image:
10840 <pre class="literallayout">
10841 1. Comment out the EXTRA_IMAGE_FEATURES line
10842 2. Set INCOMPATIBLE_LICENSE = "GPLv3"
10843 </pre></div><p>
10844 From within the <code class="filename">poky</code> Git repository, use the following command to list
10845 the supported images:
10846 </p><pre class="literallayout">
10847 $ ls meta*/recipes*/images/*.bb
10848 </pre><p>
10849 These recipes reside in the <code class="filename">meta/recipes-core/images</code>,
10850 <code class="filename">meta/recipes-extended/images</code>,
10851 <code class="filename">meta/recipes-graphics/images</code>, and
10852 <code class="filename">meta/recipes-sato/images</code> directories
10853 within the <a class="link" href="#source-directory" target="_top">source directory</a>.
10854 Although the recipe names are somewhat explanatory, here is a list that describes them:
10855 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-base</code>:</em></span>
10856 A console-only image that fully supports the target device hardware.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-core</code>:</em></span>
10857 An X11 image with simple applications such as terminal, editor, and file manager.
10858 </p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-minimal</code>:</em></span>
10859 A small image just capable of allowing a device to boot.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-minimal-dev</code>:</em></span>
10860 A <code class="filename">core-image-minimal</code> image suitable for development work
10861 using the host.
10862 The image includes headers and libraries you can use in a host development
10863 environment.
10864 </p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-minimal-initramfs</code>:</em></span>
10865 A <code class="filename">core-image-minimal</code> image that has the Minimal RAM-based
10866 Initial Root Filesystem (<code class="filename">initramfs</code>) as part of the kernel,
10867 which allows the system to find the first “init” program more efficiently.
10868 </p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-minimal-mtdutils</code>:</em></span>
10869 A <code class="filename">core-image-minimal</code> image that has support
10870 for the Minimal MTD Utilities, which let the user interact with the
10871 MTD subsystem in the kernel to perform operations on flash devices.
10872 </p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-basic</code>:</em></span>
10873 A foundational basic image without support for X that can be reasonably used for
10874 customization.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-lsb</code>:</em></span>
10875 A <code class="filename">core-image-basic</code> image suitable for implementations
10876 that conform to Linux Standard Base (LSB).</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-lsb-dev</code>:</em></span>
10877 A <code class="filename">core-image-lsb</code> image that is suitable for development work
10878 using the host.
10879 The image includes headers and libraries you can use in a host development
10880 environment.
10881 </p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-lsb-sdk</code>:</em></span>
10882 A <code class="filename">core-image-lsb</code> that includes everything in meta-toolchain
10883 but also includes development headers and libraries to form a complete standalone SDK.
10884 This image is suitable for development using the target.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-clutter</code>:</em></span>
10885 An image with support for the Open GL-based toolkit Clutter, which enables development of
10886 rich and animated graphical user interfaces.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-sato</code>:</em></span>
10887 An image with Sato support, a mobile environment and visual style that works well
10888 with mobile devices.
10889 The image supports X11 with a Sato theme and Pimlico applications and also
10890 contains terminal, editor, and file manager.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-sato-dev</code>:</em></span>
10891 A <code class="filename">core-image-sato</code> image suitable for development
10892 using the host.
10893 The image includes libraries needed to build applications on the device itself,
10894 testing and profiling tools, and debug symbols.
10895 This image was formerly <code class="filename">core-image-sdk</code>.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-sato-sdk</code>:</em></span>
10896 A <code class="filename">core-image-sato</code> image that includes everything in meta-toolchain.
10897 The image also includes development headers and libraries to form a complete standalone SDK
10898 and is suitable for development using the target.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-rt</code>:</em></span>
10899 A <code class="filename">core-image-minimal</code> image plus a real-time test suite and
10900 tools appropriate for real-time use.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-rt-sdk</code>:</em></span>
10901 A <code class="filename">core-image-rt</code> image that includes everything in
10902 <code class="filename">meta-toolchain</code>.
10903 The image also includes development headers and libraries to form a complete
10904 stand-alone SDK and is suitable for development using the target.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">core-image-gtk-directfb</code>:</em></span>
10905 An image that uses <code class="filename">gtk+</code> over <code class="filename">directfb</code>
10906 instead of X11.
10907 In order to build, this image requires specific distro configuration that enables
10908 <code class="filename">gtk</code> over <code class="filename">directfb</code>.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">build-appliance-image</code>:</em></span>
10909 An image you can boot and run using either the
10910 <a class="ulink" href="http://www.vmware.com/products/player/overview.html" target="_top">VMware Player</a>
10911 or <a class="ulink" href="http://www.vmware.com/products/workstation/overview.html" target="_top">VMware Workstation</a>.
10912 For more information on this image, see the
10913 <a class="ulink" href="http://www.yoctoproject.org/documentation/build-appliance" target="_top">Build Appliance</a> page on
10914 the Yocto Project website.</p></li></ul></div><div class="tip" title="Tip" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Tip</h3>
10915 From the Yocto Project release 1.1 onwards, <code class="filename">-live</code> and
10916 <code class="filename">-directdisk</code> images have been replaced by a "live"
10917 option in <code class="filename">IMAGE_FSTYPES</code> that will work with any image to produce an
10918 image file that can be
10919 copied directly to a CD or USB device and run as is.
10920 To build a live image, simply add
10921 "live" to <code class="filename">IMAGE_FSTYPES</code> within the <code class="filename">local.conf</code>
10922 file or wherever appropriate and then build the desired image as normal.
10923 </div></div>
10924
10925 <div class="chapter" title="Chapter 8. Reference: Features"><div class="titlepage"><div><div><h2 class="title"><a id="ref-features"></a>Chapter 8. Reference: Features</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#ref-features-distro">8.1. Distro</a></span></dt><dt><span class="section"><a href="#ref-features-machine">8.2. Machine</a></span></dt><dt><span class="section"><a href="#ref-features-image">8.3. Reference: Images</a></span></dt></dl></div><p>
10926 Features provide a mechanism for working out which packages
10927 should be included in the generated images.
10928 Distributions can select which features they want to support through the
10929 <code class="filename"><a class="link" href="#var-DISTRO_FEATURES" title="DISTRO_FEATURES">DISTRO_FEATURES</a></code>
10930 variable, which is set in the <code class="filename">poky.conf</code> distribution configuration file.
10931 Machine features are set in the
10932 <code class="filename"><a class="link" href="#var-MACHINE_FEATURES" title="MACHINE_FEATURES">MACHINE_FEATURES</a></code>
10933 variable, which is set in the machine configuration file and
10934 specifies the hardware features for a given machine.
10935 </p><p>
10936 These two variables combine to work out which kernel modules,
10937 utilities, and other packages to include.
10938 A given distribution can support a selected subset of features so some machine features might not
10939 be included if the distribution itself does not support them.
10940 </p><div class="section" title="8.1. Distro"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-features-distro"></a>8.1. Distro</h2></div></div></div><p>
10941 The items below are valid options for
10942 <code class="filename"><a class="link" href="#var-DISTRO_FEATURES" title="DISTRO_FEATURES">DISTRO_FEATURES</a></code>:
10943 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>alsa:</em></span> ALSA support will be included (OSS compatibility
10944 kernel modules will be installed if available).</p></li><li class="listitem"><p><span class="emphasis"><em>bluetooth:</em></span> Include bluetooth support (integrated BT only)
10945 </p></li><li class="listitem"><p><span class="emphasis"><em>ext2:</em></span> Include tools for supporting for devices with internal
10946 HDD/Microdrive for storing files (instead of Flash only devices)
10947 </p></li><li class="listitem"><p><span class="emphasis"><em>irda:</em></span> Include Irda support
10948 </p></li><li class="listitem"><p><span class="emphasis"><em>keyboard:</em></span> Include keyboard support (e.g. keymaps will be
10949 loaded during boot).
10950 </p></li><li class="listitem"><p><span class="emphasis"><em>pci:</em></span> Include PCI bus support
10951 </p></li><li class="listitem"><p><span class="emphasis"><em>pcmcia:</em></span> Include PCMCIA/CompactFlash support
10952 </p></li><li class="listitem"><p><span class="emphasis"><em>usbgadget:</em></span> USB Gadget Device support (for USB
10953 networking/serial/storage)
10954 </p></li><li class="listitem"><p><span class="emphasis"><em>usbhost:</em></span> USB Host support (allows to connect external
10955 keyboard, mouse, storage, network etc)
10956 </p></li><li class="listitem"><p><span class="emphasis"><em>wifi:</em></span> WiFi support (integrated only)
10957 </p></li><li class="listitem"><p><span class="emphasis"><em>cramfs:</em></span> CramFS support
10958 </p></li><li class="listitem"><p><span class="emphasis"><em>ipsec:</em></span> IPSec support
10959 </p></li><li class="listitem"><p><span class="emphasis"><em>ipv6:</em></span> IPv6 support
10960 </p></li><li class="listitem"><p><span class="emphasis"><em>nfs:</em></span> NFS client support (for mounting NFS exports on
10961 device)</p></li><li class="listitem"><p><span class="emphasis"><em>ppp:</em></span> PPP dialup support</p></li><li class="listitem"><p><span class="emphasis"><em>smbfs:</em></span> SMB networks client support (for mounting
10962 Samba/Microsoft Windows shares on device)</p></li></ul></div><p>
10963 </p></div><div class="section" title="8.2. Machine"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-features-machine"></a>8.2. Machine</h2></div></div></div><p>
10964 The items below are valid options for
10965 <code class="filename"><a class="link" href="#var-MACHINE_FEATURES" title="MACHINE_FEATURES">MACHINE_FEATURES</a></code>:
10966 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>acpi:</em></span> Hardware has ACPI (x86/x86_64 only)
10967 </p></li><li class="listitem"><p><span class="emphasis"><em>alsa:</em></span> Hardware has ALSA audio drivers
10968 </p></li><li class="listitem"><p><span class="emphasis"><em>apm:</em></span> Hardware uses APM (or APM emulation)
10969 </p></li><li class="listitem"><p><span class="emphasis"><em>bluetooth:</em></span> Hardware has integrated BT
10970 </p></li><li class="listitem"><p><span class="emphasis"><em>ext2:</em></span> Hardware HDD or Microdrive
10971 </p></li><li class="listitem"><p><span class="emphasis"><em>irda:</em></span> Hardware has Irda support
10972 </p></li><li class="listitem"><p><span class="emphasis"><em>keyboard:</em></span> Hardware has a keyboard
10973 </p></li><li class="listitem"><p><span class="emphasis"><em>pci:</em></span> Hardware has a PCI bus
10974 </p></li><li class="listitem"><p><span class="emphasis"><em>pcmcia:</em></span> Hardware has PCMCIA or CompactFlash sockets
10975 </p></li><li class="listitem"><p><span class="emphasis"><em>screen:</em></span> Hardware has a screen
10976 </p></li><li class="listitem"><p><span class="emphasis"><em>serial:</em></span> Hardware has serial support (usually RS232)
10977 </p></li><li class="listitem"><p><span class="emphasis"><em>touchscreen:</em></span> Hardware has a touchscreen
10978 </p></li><li class="listitem"><p><span class="emphasis"><em>usbgadget:</em></span> Hardware is USB gadget device capable
10979 </p></li><li class="listitem"><p><span class="emphasis"><em>usbhost:</em></span> Hardware is USB Host capable
10980 </p></li><li class="listitem"><p><span class="emphasis"><em>wifi:</em></span> Hardware has integrated WiFi
10981 </p></li></ul></div><p>
10982 </p></div><div class="section" title="8.3. Reference: Images"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-features-image"></a>8.3. Reference: Images</h2></div></div></div><p>
10983 The contents of images generated by the OpenEmbedded build system can be controlled by the
10984 <code class="filename"><a class="link" href="#var-IMAGE_FEATURES" title="IMAGE_FEATURES">IMAGE_FEATURES</a></code>
10985 and <code class="filename"><a class="link" href="#var-EXTRA_IMAGE_FEATURES" title="EXTRA_IMAGE_FEATURES">EXTRA_IMAGE_FEATURES</a></code>
10986 variables that you typically configure in your image recipes.
10987 Through these variables you can add several different
10988 predefined packages such as development utilities or packages with debug
10989 information needed to investigate application problems or profile applications.
10990 </p><p>
10991 Current list of
10992 <code class="filename">IMAGE_FEATURES</code> contains the following:
10993 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em>apps-console-core:</em></span> Core console applications such as
10994 <code class="filename">ssh</code>, <code class="filename">daemon</code>, <code class="filename">avahi daemon</code>,
10995 <code class="filename">portmap</code> (for mounting NFS shares)</p></li><li class="listitem"><p><span class="emphasis"><em>x11-base:</em></span> X11 server + minimal desktop</p></li><li class="listitem"><p><span class="emphasis"><em>x11-sato:</em></span> OpenedHand Sato environment</p></li><li class="listitem"><p><span class="emphasis"><em>apps-x11-core:</em></span> Core X11 applications such as an
10996 X Terminal, file manager, and file editor</p></li><li class="listitem"><p><span class="emphasis"><em>apps-x11-games:</em></span> A set of X11 games</p></li><li class="listitem"><p><span class="emphasis"><em>tools-sdk:</em></span> A full SDK that runs on the device
10997 </p></li><li class="listitem"><p><span class="emphasis"><em>tools-debug:</em></span> Debugging tools such as
10998 <code class="filename">strace</code> and <code class="filename">gdb</code>
10999 </p></li><li class="listitem"><p><span class="emphasis"><em>tools-profile:</em></span> Profiling tools such as
11000 <code class="filename">oprofile</code>, <code class="filename">exmap</code>, and
11001 <code class="filename">LTTng</code></p></li><li class="listitem"><p><span class="emphasis"><em>tools-testapps:</em></span> Device testing tools (e.g.
11002 touchscreen debugging)</p></li><li class="listitem"><p><span class="emphasis"><em>nfs-server:</em></span> NFS server (exports / over NFS
11003 to everybody)</p></li><li class="listitem"><p><span class="emphasis"><em>dev-pkgs:</em></span> Development packages (headers and
11004 extra library links) for all packages installed in a given image</p></li><li class="listitem"><p><span class="emphasis"><em>dbg-pkgs:</em></span> Debug packages for all packages
11005 installed in a given image</p></li></ul></div><p>
11006 </p></div></div>
11007
11008 <div class="chapter" title="Chapter 9. Variables Glossary"><div class="titlepage"><div><div><h2 class="title"><a id="ref-variables-glos"></a>Chapter 9. Variables Glossary</h2></div></div></div><div class="toc"><dl><dt><span class="glossary"><a href="#ref-variables-glossary">Glossary</a></span></dt></dl></div><p>
11009 This chapter lists common variables used in the OpenEmbedded build system and gives an overview
11010 of their function and contents.
11011</p><div class="glossary" title="Glossary"><div class="titlepage"><div><div><h2 class="title"><a id="ref-variables-glossary"></a>Glossary</h2></div></div></div><p>
11012 <a class="link" href="#var-ALLOW_EMPTY" title="ALLOW_EMPTY">A</a>
11013 <a class="link" href="#var-B" title="B">B</a>
11014 <a class="link" href="#var-CFLAGS" title="CFLAGS">C</a>
11015 <a class="link" href="#var-D" title="D">D</a>
11016 <a class="link" href="#var-ENABLE_BINARY_LOCALE_GENERATION" title="ENABLE_BINARY_LOCALE_GENERATION">E</a>
11017 <a class="link" href="#var-FILES" title="FILES">F</a>
11018
11019 <a class="link" href="#var-HOMEPAGE" title="HOMEPAGE">H</a>
11020 <a class="link" href="#var-IMAGE_FEATURES" title="IMAGE_FEATURES">I</a>
11021
11022 <a class="link" href="#var-KBRANCH" title="KBRANCH">K</a>
11023 <a class="link" href="#var-LAYERDIR" title="LAYERDIR">L</a>
11024 <a class="link" href="#var-MACHINE" title="MACHINE">M</a>
11025
11026
11027 <a class="link" href="#var-PACKAGE_ARCH" title="PACKAGE_ARCH">P</a>
11028
11029 <a class="link" href="#var-RCONFLICTS" title="RCONFLICTS">R</a>
11030 <a class="link" href="#var-S" title="S">S</a>
11031 <a class="link" href="#var-TARGET_ARCH" title="TARGET_ARCH">T</a>
11032
11033
11034 <a class="link" href="#var-WORKDIR" title="WORKDIR">W</a>
11035
11036
11037
11038 </p><div class="glossdiv" title="A"><h3 class="title">A</h3><dl><dt><a id="var-ALLOW_EMPTY"></a>ALLOW_EMPTY</dt><dd><p>
11039 Specifies if an output package should still be produced if it is empty.
11040 By default, BitBake does not produce empty packages.
11041 This default behavior can cause issues when there is an
11042 <a class="link" href="#var-RDEPENDS" title="RDEPENDS"><code class="filename">RDEPENDS</code></a> or
11043 some other runtime hard-requirement on the existence of the package.
11044 </p><p>
11045 Like all package-controlling variables, you must always use them in
11046 conjunction with a package name override.
11047 Here is an example:
11048 </p><pre class="literallayout">
11049 ALLOW_EMPTY_${PN}
11050 </pre><p>
11051 </p></dd><dt><a id="var-AUTHOR"></a>AUTHOR</dt><dd><p>The email address used to contact the original author or authors in
11052 order to send patches, forward bugs, etc.</p></dd><dt><a id="var-AUTOREV"></a>AUTOREV</dt><dd><p>Specifies to use the current (newest) source revision.
11053 This variable is with the <code class="filename"><a class="link" href="#var-SRCREV" title="SRCREV">SRCREV</a></code>
11054 variable.</p></dd></dl></div><div class="glossdiv" title="B"><h3 class="title">B</h3><dl><dt><a id="var-B"></a>B</dt><dd><p>
11055 The directory in which the OpenEmbedded build system places
11056 generated objects during a recipe's build process.
11057 By default, this directory is the same as the <a class="link" href="#var-S" title="S"><code class="filename">S</code></a>
11058 directory:
11059 </p><pre class="literallayout">
11060 B = ${WORKDIR}/${BPN}-{PV}/
11061 </pre><p>
11062 You can separate the source directory (<code class="filename">S</code>) and the directory pointed to
11063 by the <code class="filename">B</code> variable.
11064 Most autotools-based recipes support separating these directories.
11065 The build system defaults to using separate directories for <code class="filename">gcc</code>
11066 and some kernel recipes.
11067 </p></dd><dt><a id="var-BAD_RECOMMENDATIONS"></a>BAD_RECOMMENDATIONS</dt><dd><p>
11068 A list of packages not to install despite being recommended by a recipe.
11069 Support for this variable exists only for images that use the
11070 <code class="filename">ipkg</code> packaging system.
11071 </p></dd><dt><a id="var-BBCLASSEXTEND"></a>BBCLASSEXTEND</dt><dd><p>
11072 Allows you to extend a recipe so that it builds variants of the software.
11073 Common variants for recipes exist such as "natives" like <code class="filename">quilt-native</code>,
11074 which is a copy of quilt built to run on the build system;
11075 "crosses" such as <code class="filename">gcc-cross</code>,
11076 which is a compiler built to run on the build machine but produces binaries
11077 that run on the target <a class="link" href="#var-MACHINE" title="MACHINE"><code class="filename">MACHINE</code></a>;
11078 "nativesdk", which targets the SDK machine instead of <code class="filename">MACHINE</code>;
11079 and "mulitlibs" in the form "<code class="filename">multilib:&lt;multilib_name&gt;</code>".
11080 </p><p>
11081 To build a different variant of the recipe with a minimal amount of code, it usually
11082 is as simple as adding the following to your recipe:
11083 </p><pre class="literallayout">
11084 BBCLASSEXTEND =+ "native nativesdk"
11085 BBCLASSEXTEND =+ "multilib:&lt;multilib_name&gt;"
11086 </pre><p>
11087 </p></dd><dt><a id="var-BBMASK"></a>BBMASK</dt><dd><p>Prevents BitBake from processing recipes and recipe append files.
11088 You can use the <code class="filename">BBMASK</code> variable to "hide"
11089 these <code class="filename">.bb</code> and <code class="filename">.bbappend</code> files.
11090 BitBake ignores any recipe or recipe append files that match the expression.
11091 It is as if BitBake does not see them at all.
11092 Consequently, matching files are not parsed or otherwise used by
11093 BitBake.</p><p>The value you provide is passed to python's regular expression compiler.
11094 For complete syntax information, see python's documentation at
11095 <a class="ulink" href="http://docs.python.org/release/2.3/lib/re-syntax.html" target="_top">http://docs.python.org/release/2.3/lib/re-syntax.html</a>.
11096 The expression is compared against the full paths to the files.
11097 For example, the following uses a complete regular expression to tell
11098 BitBake to ignore all recipe and recipe append files in the
11099 <code class="filename">.*/meta-ti/recipes-misc/</code> directory:
11100 </p><pre class="literallayout">
11101 BBMASK = ".*/meta-ti/recipes-misc/"
11102 </pre><p>Use the <code class="filename">BBMASK</code> variable from within the
11103 <code class="filename">conf/local.conf</code> file found
11104 in the <a class="link" href="#build-directory" target="_top">build directory</a>.</p></dd><dt><a id="var-BB_NUMBER_THREADS"></a>BB_NUMBER_THREADS</dt><dd><p>The maximum number of tasks BitBake should run in parallel at any one time.
11105 If your host development system supports multiple cores a good rule of thumb
11106 is to set this variable to twice the number of cores.</p></dd><dt><a id="var-BBFILE_COLLECTIONS"></a>BBFILE_COLLECTIONS</dt><dd><p>Lists the names of configured layers.
11107 These names are used to find the other <code class="filename">BBFILE_*</code>
11108 variables.
11109 Typically, each layer will append its name to this variable in its
11110 <code class="filename">conf/layer.conf</code> file.
11111 </p></dd><dt><a id="var-BBFILE_PATTERN"></a>BBFILE_PATTERN</dt><dd><p>Variable that expands to match files from <code class="filename">BBFILES</code> in a particular layer.
11112 This variable is used in the <code class="filename">conf/layer.conf</code> file and must
11113 be suffixed with the name of the specific layer (e.g.
11114 <code class="filename">BBFILE_PATTERN_emenlow</code>).</p></dd><dt><a id="var-BBFILE_PRIORITY"></a>BBFILE_PRIORITY</dt><dd><p>Assigns the priority for recipe files in each layer.</p><p>This variable is useful in situations where the same package appears in
11115 more than one layer.
11116 Setting this variable allows you to prioritize a
11117 layer against other layers that contain the same package - effectively
11118 letting you control the precedence for the multiple layers.
11119 The precedence established through this variable stands regardless of a
11120 layer's package version (<code class="filename">PV</code> variable).
11121 For example, a layer that has a package with a higher <code class="filename">PV</code> value but for
11122 which the <code class="filename">BBFILE_PRIORITY</code> is set to have a lower precedence still has a
11123 lower precedence.</p><p>A larger value for the <code class="filename">BBFILE_PRIORITY</code> variable results in a higher
11124 precedence.
11125 For example, the value 6 has a higher precedence than the value 5.
11126 If not specified, the <code class="filename">BBFILE_PRIORITY</code> variable is set based on layer
11127 dependencies (see the
11128 <code class="filename"><a class="link" href="#var-LAYERDEPENDS" title="LAYERDEPENDS">LAYERDEPENDS</a></code> variable for
11129 more information.
11130 The default priority, if unspecified
11131 for a layer with no dependencies, is the lowest defined priority + 1
11132 (or 1 if no priorities are defined).</p><div class="tip" title="Tip" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Tip</h3>
11133 You can use the command <code class="filename">bitbake-layers show_layers</code> to list
11134 all configured layers along with their priorities.
11135 </div></dd><dt><a id="var-BBFILES"></a>BBFILES</dt><dd><p>List of recipe files used by BitBake to build software</p></dd><dt><a id="var-BBPATH"></a>BBPATH</dt><dd><p>Used by BitBake to locate <code class="filename">.bbclass</code> and configuration files.
11136 This variable is analogous to the <code class="filename">PATH</code> variable.</p></dd><dt><a id="var-BBINCLUDELOGS"></a>BBINCLUDELOGS</dt><dd><p>Variable that controls how BitBake displays logs on build failure.</p></dd><dt><a id="var-BBLAYERS"></a>BBLAYERS</dt><dd><p>Lists the layers to enable during the build.
11137 This variable is defined in the <code class="filename">bblayers.conf</code> configuration
11138 file in the <a class="link" href="#build-directory" target="_top">build directory</a>.
11139 Here is an example:
11140 </p><pre class="literallayout">
11141 BBLAYERS = " \
11142 /home/scottrif/poky/meta \
11143 /home/scottrif/poky/meta-yocto \
11144 /home/scottrif/poky/meta-mykernel \
11145 "
11146 </pre><p>
11147 This example enables three layers, one of which is a custom, user-defined layer
11148 named <code class="filename">meta-mykernel</code>.
11149 </p></dd><dt><a id="var-BPN"></a>BPN</dt><dd><p>Bare name of package with any suffixes like -cross -native removed.</p></dd></dl></div><div class="glossdiv" title="C"><h3 class="title">C</h3><dl><dt><a id="var-CFLAGS"></a>CFLAGS</dt><dd><p>
11150 Flags passed to C compiler for the target system.
11151 This variable evaluates to the same as
11152 <code class="filename"><a class="link" href="#var-TARGET_CFLAGS" title="TARGET_CFLAGS">TARGET_CFLAGS</a></code>.
11153 </p></dd><dt><a id="var-COMPATIBLE_MACHINE"></a>COMPATIBLE_MACHINE</dt><dd><p>A regular expression which evaluates to match the machines the recipe
11154 works with.
11155 It stops recipes being run on machines for which they are not compatible.
11156 This is particularly useful with kernels.
11157 It also helps to increase parsing speed as further parsing of the recipe is skipped
11158 if it is found the current machine is not compatible.</p></dd><dt><a id="var-CONFFILES"></a>CONFFILES</dt><dd><p>
11159 Identifies editable or configurable files that are part of a package.
11160 If the Package Management System (PMS) is being used to update
11161 packages on the target system, it is possible that
11162 configuration files you have changed after the original installation
11163 and that you now want to remain unchanged are overwritten.
11164 In other words, editable files might exist in the package that you do not
11165 want reset as part of the package update process.
11166 You can use the <code class="filename">CONFFILES</code> variable to list the files in the
11167 package that you wish to prevent the PMS from overwriting during this update process.
11168 </p><p>
11169 To use the <code class="filename">CONFFILES</code> variable, provide a package name
11170 override that identifies the package.
11171 Then, provide a space-separated list of files.
11172 Here is an example:
11173 </p><pre class="literallayout">
11174 CONFFILES_${PN} += "${sysconfdir}/file1 \
11175 ${sysconfdir}/file2 ${sysconfdir}/file3"
11176 </pre><p>
11177 </p><p>
11178 A relationship exists between the <code class="filename">CONFFILES</code> and
11179 <code class="filename"><a class="link" href="#var-FILES" title="FILES">FILES</a></code> variables.
11180 The files listed within <code class="filename">CONFFILES</code> must be a subset of
11181 the files listed within <code class="filename">FILES</code>.
11182 Because the configuration files you provide with <code class="filename">CONFFILES</code>
11183 are simply being identified so that the PMS will not overwrite them,
11184 it makes sense that
11185 the files must already be included as part of the package through the
11186 <code class="filename">FILES</code> variable.
11187 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
11188 When specifying paths as part of the <code class="filename">CONFFILES</code> variable,
11189 it is good practice to use appropriate path variables.
11190 For example, <code class="filename">${sysconfdir}</code> rather than
11191 <code class="filename">/etc</code> or <code class="filename">${bindir}</code> rather
11192 than <code class="filename">/usr/bin</code>.
11193 You can find a list of these variables at the top of the
11194 <code class="filename">/meta/conf/bitbake.conf</code> file in the
11195 <a class="link" href="#source-directory" target="_top">source directory</a>.
11196 </div></dd><dt><a id="var-CONFIG_SITE"></a>CONFIG_SITE</dt><dd><p>
11197 A list of files that contains <code class="filename">autoconf</code> test results relevant
11198 to the current build.
11199 This variable is used by the Autotools utilities when running
11200 <code class="filename">configure</code>.
11201 </p></dd><dt><a id="var-CORE_IMAGE_EXTRA_INSTALL"></a>CORE_IMAGE_EXTRA_INSTALL</dt><dd><p>
11202 Specifies the list of packages to be added to the image.
11203 This variable should only be set in the <code class="filename">local.conf</code>
11204 configuration file found in the
11205 <a class="link" href="#build-directory" target="_top">build directory</a>.
11206 </p><p>
11207 This variable replaces <code class="filename">POKY_EXTRA_INSTALL</code>, which is no longer supported.
11208 </p></dd></dl></div><div class="glossdiv" title="D"><h3 class="title">D</h3><dl><dt><a id="var-D"></a>D</dt><dd><p>The destination directory.</p></dd><dt><a id="var-DEBUG_BUILD"></a>DEBUG_BUILD</dt><dd><p>
11209 Specifies to build packages with debugging information.
11210 This influences the value of the
11211 <code class="filename"><a class="link" href="#var-SELECTED_OPTIMIZATION" title="SELECTED_OPTIMIZATION">SELECTED_OPTIMIZATION</a></code>
11212 variable.
11213 </p></dd><dt><a id="var-DEBUG_OPTIMIZATION"></a>DEBUG_OPTIMIZATION</dt><dd><p>
11214 The options to pass in
11215 <code class="filename"><a class="link" href="#var-TARGET_CFLAGS" title="TARGET_CFLAGS">TARGET_CFLAGS</a></code>
11216 and <code class="filename"><a class="link" href="#var-CFLAGS" title="CFLAGS">CFLAGS</a></code> when compiling
11217 a system for debugging.
11218 This variable defaults to "-O -fno-omit-frame-pointer -g".
11219 </p></dd><dt><a id="var-DEFAULT_PREFERENCE"></a>DEFAULT_PREFERENCE</dt><dd><p>Specifies the priority of recipes.</p></dd><dt><a id="var-DEPENDS"></a>DEPENDS</dt><dd><p>
11220 A list of build-time dependencies for a given recipe.
11221 The variable indicates recipes that must have been staged before a
11222 particular recipe can configure.
11223 </p></dd><dt><a id="var-DESCRIPTION"></a>DESCRIPTION</dt><dd><p>The package description used by package managers.</p></dd><dt><a id="var-DESTDIR"></a>DESTDIR</dt><dd><p>the destination directory.</p></dd><dt><a id="var-DISTRO"></a>DISTRO</dt><dd><p>The short name of the distribution.</p></dd><dt><a id="var-DISTRO_EXTRA_RRECOMMENDS"></a>DISTRO_EXTRA_RRECOMMENDS</dt><dd><p></p><p>The list of packages which extend usability of the image.
11224 Those packages will automatically be installed but can be removed by user.</p></dd><dt><a id="var-DISTRO_FEATURES"></a>DISTRO_FEATURES</dt><dd><p>The features of the distribution.</p></dd><dt><a id="var-DISTRO_NAME"></a>DISTRO_NAME</dt><dd><p>The long name of the distribution.</p></dd><dt><a id="var-DISTRO_PN_ALIAS"></a>DISTRO_PN_ALIAS</dt><dd><p>Alias names used for the recipe in various Linux distributions.</p><p>See the
11225 "<a class="link" href="#usingpoky-configuring-DISTRO_PN_ALIAS" target="_top">Handling
11226 a Package Name Alias</a>" section in the Yocto Project Development
11227 Manual for more information.</p></dd><dt><a id="var-DISTRO_VERSION"></a>DISTRO_VERSION</dt><dd><p>the version of the distribution.</p></dd><dt><a id="var-DL_DIR"></a>DL_DIR</dt><dd><p>
11228 The central download directory used by the build process to store downloads.
11229 You can set this directory by defining the <code class="filename">DL_DIR</code>
11230 variable in the <code class="filename">/conf/local.conf</code> file.
11231 This directory is self-maintaining and you should not have
11232 to touch it.
11233 By default, the directory is <code class="filename">downloads</code> in the
11234 <a class="link" href="#build-directory" target="_top">build directory</a>.
11235 </p><pre class="literallayout">
11236 #DL_DIR ?= "${TOPDIR}/downloads"
11237 </pre><p>
11238 To specify a different download directory, simply uncomment the line
11239 and provide your directory.
11240 </p><p>
11241 During a first build, the system downloads many different source code
11242 tarballs from various upstream projects.
11243 Downloading can take a while, particularly if your network
11244 connection is slow.
11245 Tarballs are all stored in the directory defined by
11246 <code class="filename">DL_DIR</code> and the build system looks there first
11247 to find source tarballs.
11248 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
11249 When wiping and rebuilding, you can preserve this directory to speed
11250 up this part of subsequent builds.
11251 </div><p>
11252 </p><p>
11253 You can safely share this directory between multiple builds on the
11254 same development machine.
11255 For additional information on how the build process gets source files
11256 when working behind a firewall or proxy server, see the
11257 "<a class="link" href="#how-does-the-yocto-project-obtain-source-code-and-will-it-work-behind-my-firewall-or-proxy-server">FAQ</a>"
11258 chapter.
11259 </p></dd></dl></div><div class="glossdiv" title="E"><h3 class="title">E</h3><dl><dt><a id="var-ENABLE_BINARY_LOCALE_GENERATION"></a>ENABLE_BINARY_LOCALE_GENERATION</dt><dd><p></p><p>Variable that controls which locales for <code class="filename">eglibc</code> are
11260 to be generated during the build (useful if the target device has 64Mbytes
11261 of RAM or less).</p></dd><dt><a id="var-EXTRA_IMAGE_FEATURES"></a>EXTRA_IMAGE_FEATURES</dt><dd><p>Allows extra packages to be added to the generated images.
11262 You set this variable in the <code class="filename">local.conf</code>
11263 configuration file.
11264 Note that some image features are also added using the
11265 <code class="filename"><a class="link" href="#var-IMAGE_FEATURES" title="IMAGE_FEATURES">IMAGE_FEATURES</a></code>
11266 variable generally configured in image recipes.
11267 You can use this variable to add more features in addition to those.
11268 Here are some examples of features you can add:</p><pre class="literallayout">
11269"dbg-pkgs" - Adds -dbg packages for all installed packages
11270 including symbol information for debugging and
11271 profiling.
11272
11273"dev-pkgs" - Adds -dev packages for all installed packages.
11274 This is useful if you want to develop against
11275 the libraries in the image.
11276
11277"tools-sdk" - Adds development tools such as gcc, make,
11278 pkgconfig and so forth.
11279
11280"tools-debug" - Adds debugging tools such as gdb and
11281 strace.
11282
11283"tools-profile" - Adds profiling tools such as oprofile,
11284 exmap, lttng and valgrind (x86 only).
11285
11286"tools-testapps" - Adds useful testing tools such as
11287 ts_print, aplay, arecord and so
11288 forth.
11289
11290"debug-tweaks" - Makes an image suitable for development.
11291 For example, ssh root access has a blank
11292 password. You should remove this feature
11293 before you produce a production image.
11294
11295 There are other application targets too, see
11296 <code class="filename">meta/classes/poky-image.bbclass</code>
11297 and <code class="filename">meta/packages/tasks/task-poky.bb</code>
11298 for more details.
11299 </pre></dd><dt><a id="var-EXTRA_IMAGEDEPENDS"></a>EXTRA_IMAGEDEPENDS</dt><dd><p>A list of recipes to be built that do not provide packages to be installed in
11300 the root filesystem.
11301 </p><p>Sometimes a recipe is required to build the final image but is not
11302 needed in the root filesystem.
11303 You can use the <code class="filename">EXTRA_IMAGEDEPENDS</code> variable to
11304 list these recipes and thus, specify the dependencies.
11305 A typical example is a required bootloader in a machine configuration.
11306 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
11307 To add packages to the root filesystem, see the various
11308 <code class="filename">*DEPENDS</code> and <code class="filename">*RECOMMENDS</code>
11309 variables.
11310 </div></dd><dt><a id="var-EXTRA_OECMAKE"></a>EXTRA_OECMAKE</dt><dd><p>Additional <code class="filename">cmake</code> options.</p></dd><dt><a id="var-EXTRA_OECONF"></a>EXTRA_OECONF</dt><dd><p>Additional <code class="filename">configure</code> script options.</p></dd><dt><a id="var-EXTRA_OEMAKE"></a>EXTRA_OEMAKE</dt><dd><p>Additional GNU <code class="filename">make</code> options.</p></dd></dl></div><div class="glossdiv" title="F"><h3 class="title">F</h3><dl><dt><a id="var-FILES"></a>FILES</dt><dd><p>
11311 The list of directories or files that are placed in packages.
11312 </p><p>
11313 To use the <code class="filename">FILES</code> variable, provide a package name
11314 override that identifies the package.
11315 Then, provide a space-separated list of files or paths that identifies the
11316 files you want included as part of the package.
11317 Here is an example:
11318 </p><pre class="literallayout">
11319 FILES_${PN} += "${bindir}/mydir1/ ${bindir}/mydir2/myfile"
11320 </pre><p>
11321 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
11322 When specifying paths as part of the <code class="filename">FILES</code> variable,
11323 it is good practice to use appropriate path variables.
11324 For example, <code class="filename">${sysconfdir}</code> rather than
11325 <code class="filename">/etc</code> or <code class="filename">${bindir}</code> rather
11326 than <code class="filename">/usr/bin</code>.
11327 You can find a list of these variables at the top of the
11328 <code class="filename">/meta/conf/bitbake.conf</code> file in the
11329 <a class="link" href="#source-directory" target="_top">source directory</a>.
11330 </div><p>
11331 If some of the files you provide with the <code class="filename">FILES</code> variable
11332 are editable and you know they should not be
11333 overwritten during the package update process by the Package Management
11334 System (PMS), you can identify these files so that the PMS will not
11335 overwrite them.
11336 See the <code class="filename"><a class="link" href="#var-CONFFILES" title="CONFFILES">CONFFILES</a></code>
11337 variable for information on how to identify these files to the PMS.
11338 </p></dd><dt><a id="var-FILESEXTRAPATHS"></a>FILESEXTRAPATHS</dt><dd><p>
11339 Extends the search path the OpenEmbedded build system uses when
11340 looking for files and patches as it processes recipes.
11341 The directories BitBake uses when it processes recipes is defined by the
11342 <a class="link" href="#var-FILESPATH" title="FILESPATH"><code class="filename">FILESPATH</code></a> variable.
11343 You can add directories to the search path by defining the
11344 <code class="filename">FILESEXTRAPATHS</code> variable.
11345 </p><p>
11346 To add paths to the search order, provide a list of directories and separate
11347 each path using a colon character as follows:
11348 </p><pre class="literallayout">
11349 FILESEXTRAPATHS_prepend := "path_1:path_2:path_3:"
11350 </pre><p>
11351 Typically, you want your directories search first.
11352 To make sure that happens, use <code class="filename">_prepend</code> and
11353 the immediate expansion (<code class="filename">:=</code>) operator as shown in the
11354 previous example.
11355 Finally, to maintain the integrity of the <code class="filename">FILESPATH</code> variable,
11356 you must include the appropriate beginning or ending (as needed) colon character.
11357 </p><p>
11358 The <code class="filename">FILESEXTRAPATHS</code> variable is intended for use in
11359 <code class="filename">.bbappend</code> files to include any additional files provided in that layer.
11360 You typically accomplish this with the following:
11361 </p><pre class="literallayout">
11362 FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
11363 </pre><p>
11364 </p></dd><dt><a id="var-FILESPATH"></a>FILESPATH</dt><dd><p>
11365 The default set of directories the OpenEmbedded build system uses
11366 when searching for patches and files.
11367 During the build process, BitBake searches each directory in
11368 <code class="filename">FILESPATH</code> in the specified order when looking for
11369 files and patches specified by each <code class="filename">file://</code> URI in a recipe.
11370 </p><p>
11371 The default value for the <code class="filename">FILESPATH</code> variable is defined
11372 in the <code class="filename">base.bbclass</code> class found in
11373 <code class="filename">meta/classes</code> in the
11374 <a class="link" href="#source-directory" target="_top">source directory</a>:
11375 </p><pre class="literallayout">
11376FILESPATH = "${@base_set_filespath([ "${FILE_DIRNAME}/${PF}", \
11377 "${FILE_DIRNAME}/${P}", "${FILE_DIRNAME}/${PN}", \
11378 "${FILE_DIRNAME}/${BP}", "${FILE_DIRNAME}/${BPN}", \
11379 "${FILE_DIRNAME}/files", "${FILE_DIRNAME}" ], d)}"
11380 </pre><p>
11381 Do not hand-edit the <code class="filename">FILESPATH</code> variable.
11382 If you want to extend the set of pathnames that BitBake uses when searching for
11383 files and patches, use the
11384 <a class="link" href="#var-FILESEXTRAPATHS" title="FILESEXTRAPATHS"><code class="filename">FILESEXTRAPATHS</code></a> variable.
11385 </p></dd><dt><a id="var-FILESYSTEM_PERMS_TABLES"></a>FILESYSTEM_PERMS_TABLES</dt><dd><p>Allows you to define your own file permissions settings table as part of
11386 your configuration for the packaging process.
11387 For example, suppose you need a consistent set of custom permissions for
11388 a set of groups and users across an entire work project.
11389 It is best to do this in the packages themselves but this is not always
11390 possible.
11391 </p><p>
11392 By default, the OpenEmbedded build system uses the <code class="filename">fs-perms.txt</code>, which
11393 is located in the <code class="filename">meta/files</code> folder in the
11394 <a class="link" href="#source-directory" target="_top">source directory</a>.
11395 If you create your own file permissions setting table, you should place it in your
11396 layer or the distros layer.
11397 </p><p>
11398 You define the <code class="filename">FILESYSTEM_PERMS_TABLES</code> variable in the
11399 <code class="filename">conf/local.conf</code> file, which is found in the
11400 <a class="link" href="#build-directory" target="_top">build directory</a>, to
11401 point to your custom <code class="filename">fs-perms.txt</code>.
11402 You can specify more than a single file permissions setting table.
11403 The paths you specify to these files must be defined within the
11404 <code class="filename">BBPATH</code> variable.
11405 </p><p>
11406 For guidance on how to create your own file permissions settings table file,
11407 examine the existing <code class="filename">fs-perms.txt</code>.
11408 </p></dd><dt><a id="var-FULL_OPTIMIZATION"></a>FULL_OPTIMIZATION</dt><dd><p>
11409 The options to pass in
11410 <code class="filename"><a class="link" href="#var-TARGET_CFLAGS" title="TARGET_CFLAGS">TARGET_CFLAGS</a></code>
11411 and <code class="filename"><a class="link" href="#var-CFLAGS" title="CFLAGS">CFLAGS</a></code>
11412 when compiling an optimized system.
11413 This variable defaults to
11414 "-fexpensive-optimizations -fomit-frame-pointer -frename-registers -O2".
11415 </p></dd></dl></div><div class="glossdiv" title="H"><h3 class="title">H</h3><dl><dt><a id="var-HOMEPAGE"></a>HOMEPAGE</dt><dd><p>Website where more info about package can be found</p></dd></dl></div><div class="glossdiv" title="I"><h3 class="title">I</h3><dl><dt><a id="var-IMAGE_FEATURES"></a>IMAGE_FEATURES</dt><dd><p>The list of features present in images.
11416 Typically, you configure this variable in image recipes.
11417 Note that you can add extra features to the image by using the
11418 <code class="filename"><a class="link" href="#var-EXTRA_IMAGE_FEATURES" title="EXTRA_IMAGE_FEATURES">EXTRA_IMAGE_FEATURES</a></code> variable.
11419 See the "<a class="link" href="#ref-features-image" title="8.3. Reference: Images">Images</a>" chapter for the
11420 list of features present in images built by the OpenEmbedded build system.</p></dd><dt><a id="var-IMAGE_FSTYPES"></a>IMAGE_FSTYPES</dt><dd><p>Formats of root filesystem images that you want to have created.</p></dd><dt><a id="var-IMAGE_INSTALL"></a>IMAGE_INSTALL</dt><dd><p>
11421 Specifies the packages to install into an image.
11422 The <code class="filename">IMAGE_INSTALL</code> variable is a mechanism for an image
11423 recipe and you should use it with care to avoid ordering issues.
11424 </p><p>
11425 Image recipes set <code class="filename">IMAGE_INSTALL</code> to specify the
11426 packages to install into an image through <code class="filename">image.bbclass</code>.
11427 Additionally, "helper" classes exist, such as <code class="filename">core-image.bbclass</code>,
11428 that can take
11429 <code class="filename"><a class="link" href="#var-IMAGE_FEATURES" title="IMAGE_FEATURES">IMAGE_FEATURES</a></code> lists
11430 and turn these into auto-generated entries in
11431 <code class="filename">IMAGE_INSTALL</code> in addition to its default contents.
11432 </p><p>
11433 Using <code class="filename">IMAGE_INSTALL</code> with the <code class="filename">+=</code>
11434 operator from the <code class="filename">/conf/local.conf</code> file or from within
11435 an image recipe is not recommended as it can cause ordering issues.
11436 Since <code class="filename">core-image.bbclass</code> sets <code class="filename">IMAGE_INSTALL</code>
11437 to a default value using the <code class="filename">?=</code> operator, using a
11438 <code class="filename">+=</code> operation against <code class="filename">IMAGE_INSTALL</code>
11439 will result in unexpected behavior when used in
11440 <code class="filename">/conf/local.conf</code>.
11441 Furthermore, the same operation from with an image recipe may or may not
11442 succeed depending on the specific situation.
11443 In both these cases, the behavior is contrary to how most users expect
11444 the <code class="filename">+=</code> operator to work.
11445 </p><p>
11446 When you use this variable, it is best to use it as follows:
11447 </p><pre class="literallayout">
11448 IMAGE_INSTALL_append = " package-name"
11449 </pre><p>
11450 Be sure to include the space between the quotation character and the start of the
11451 package name.
11452 </p></dd><dt><a id="var-IMAGE_OVERHEAD_FACTOR"></a>IMAGE_OVERHEAD_FACTOR</dt><dd><p>
11453 Defines a multiplier that the build system applies to the initial image
11454 size for cases when the multiplier times the returned disk usage value
11455 for the image is greater than the sum of
11456 <code class="filename"><a class="link" href="#var-IMAGE_ROOTFS_SIZE" title="IMAGE_ROOTFS_SIZE">IMAGE_ROOTFS_SIZE</a></code>
11457 and
11458 <code class="filename"><a class="link" href="#var-IMAGE_ROOTFS_EXTRA_SPACE" title="IMAGE_ROOTFS_EXTRA_SPACE">IMAGE_ROOTFS_EXTRA_SPACE</a></code>.
11459 The result of the multiplier applied to the initial image size creates
11460 free disk space in the image as overhead.
11461 By default, the build process uses a multiplier of 1.3 for this variable.
11462 This default value results in 30% free disk space added to the image when this
11463 method is used to determine the final generated image size.
11464 You should be aware that post install scripts and the package management
11465 system uses disk space inside this overhead area.
11466 Consequently, the multiplier does not produce an image with
11467 all the theoretical free disk space.
11468 See <code class="filename"><a class="link" href="#var-IMAGE_ROOTFS_SIZE" title="IMAGE_ROOTFS_SIZE">IMAGE_ROOTFS_SIZE</a></code>
11469 for information on how the build system determines the overall image size.
11470 </p><p>
11471 The default 30% free disk space typically gives the image enough room to boot
11472 and allows for basic post installs while still leaving a small amount of
11473 free disk space.
11474 If 30% free space is inadequate, you can increase the default value.
11475 For example, the following setting gives you 50% free space added to the image:
11476 </p><pre class="literallayout">
11477 IMAGE_OVERHEAD_FACTOR = "1.5"
11478 </pre><p>
11479 </p><p>
11480 Alternatively, you can ensure a specific amount of free disk space is added
11481 to the image by using
11482 <code class="filename"><a class="link" href="#var-IMAGE_ROOTFS_EXTRA_SPACE" title="IMAGE_ROOTFS_EXTRA_SPACE">IMAGE_ROOTFS_EXTRA_SPACE</a></code>
11483 the variable.
11484 </p></dd><dt><a id="var-IMAGE_ROOTFS_EXTRA_SPACE"></a>IMAGE_ROOTFS_EXTRA_SPACE</dt><dd><p>
11485 Defines additional free disk space created in the image in Kbytes.
11486 By default, this variable is set to "0".
11487 This free disk space is added to the image after the build system determines
11488 the image size as described in
11489 <code class="filename"><a class="link" href="#var-IMAGE_ROOTFS_SIZE" title="IMAGE_ROOTFS_SIZE">IMAGE_ROOTFS_SIZE</a></code>.
11490 </p><p>
11491 This variable is particularly useful when you want to ensure that a
11492 specific amount of free disk space is available on a device after an image
11493 is installed and running.
11494 For example, to be sure 5 Gbytes of free disk space is available, set the
11495 variable as follows:
11496 </p><pre class="literallayout">
11497 IMAGE_ROOTFS_EXTRA_SPACE = "5242880"
11498 </pre><p>
11499 </p></dd><dt><a id="var-IMAGE_ROOTFS_SIZE"></a>IMAGE_ROOTFS_SIZE</dt><dd><p>
11500 Defines the size in Kbytes for the generated image.
11501 The OpenEmbedded build system determines the final size for the generated
11502 image using an algorithm that takes into account the initial disk space used
11503 for the generated image, a requested size for the image, and requested
11504 additional free disk space to be added to the image.
11505 Programatically, the build system determines the final size of the
11506 generated image as follows:
11507 </p><pre class="literallayout">
11508 if (image-du * overhead) &lt; rootfs-size:
11509 internal-rootfs-size = rootfs-size + xspace
11510 else:
11511 internal-rootfs-size = (image-du * overhead) + xspace
11512
11513 where:
11514
11515 image-du = Returned value of the du command on
11516 the image.
11517
11518 overhead = IMAGE_OVERHEAD_FACTOR
11519
11520 rootfs-size = IMAGE_ROOTFS_SIZE
11521
11522 internal-rootfs-size = Initial root filesystem
11523 size before any modifications.
11524
11525 xspace = IMAGE_ROOTFS_EXTRA_SPACE
11526 </pre><p>
11527
11528 </p></dd><dt><a id="var-INC_PR"></a>INC_PR</dt><dd><p>Defines the Package revision.
11529 You manually combine values for <code class="filename">INC_PR</code> into the
11530 <a class="link" href="#var-PR" title="PR"><code class="filename">PR</code></a> field of the parent recipe.
11531 When you change this variable, you change the <code class="filename">PR</code>
11532 value for every person that includes the file.</p><p>
11533 The following example shows how to use the <code class="filename">INC_PR</code> variable
11534 given a common <code class="filename">.inc</code> file that defines the variable.
11535 Once defined, you can use the variable to set the
11536 <code class="filename">PR</code> value:
11537 </p><pre class="literallayout">
11538recipes-graphics/xorg-font/encodings_1.0.4.bb:PR = "${INC_PR}.1"
11539recipes-graphics/xorg-font/font-util_1.3.0.bb:PR = "${INC_PR}.0"
11540recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
11541recipes-graphics/xorg-font/xorg-font-common.inc:INC_PR = "r2"
11542 </pre></dd><dt><a id="var-INHIBIT_PACKAGE_STRIP"></a>INHIBIT_PACKAGE_STRIP</dt><dd><p>
11543 Causes the build to not strip binaries in resulting packages.
11544 </p></dd><dt><a id="var-INHERIT"></a>INHERIT</dt><dd><p>
11545 Causes the named class to be inherited at
11546 this point during parsing.
11547 The variable is only valid in configuration files.
11548 </p></dd><dt><a id="var-INITSCRIPT_PACKAGES"></a>INITSCRIPT_PACKAGES</dt><dd><p>
11549 A list of the packages that contain initscripts.
11550 If multiple packages are specified, you need to append the package name
11551 to the other <code class="filename">INITSCRIPT_*</code> as an override.</p><p>
11552 This variable is used in recipes when using <code class="filename">update-rc.d.bbclass</code>.
11553 The variable is optional and defaults to the <code class="filename">PN</code> variable.
11554 </p></dd><dt><a id="var-INITSCRIPT_NAME"></a>INITSCRIPT_NAME</dt><dd><p>
11555 The filename of the initscript (as installed to <code class="filename">${etcdir}/init.d)</code>.
11556 </p><p>
11557 This variable is used in recipes when using <code class="filename">update-rc.d.bbclass</code>.
11558 The variable is Mandatory.
11559 </p></dd><dt><a id="var-INITSCRIPT_PARAMS"></a>INITSCRIPT_PARAMS</dt><dd><p>
11560 Specifies the options to pass to <code class="filename">update-rc.d</code>.
11561 An example is <code class="filename">start 99 5 2 . stop 20 0 1 6 .</code>, which gives the script a
11562 runlevel of 99, starts the script in initlevels 2 and 5, and
11563 stops the script in levels 0, 1 and 6.
11564 </p><p>
11565 The variable is mandatory and is used in recipes when using
11566 <code class="filename">update-rc.d.bbclass</code>.
11567 </p></dd></dl></div><div class="glossdiv" title="K"><h3 class="title">K</h3><dl><dt><a id="var-KBRANCH"></a>KBRANCH</dt><dd><p>
11568 A regular expression used by the build process to explicitly identify the kernel
11569 branch that is validated, patched and configured during a build.
11570 The <code class="filename">KBRANCH</code> variable is optional.
11571 You can use it to trigger checks to ensure the exact kernel branch you want is
11572 being used by the build process.
11573 </p><p>
11574 Values for this variable are set in the kernel's recipe file and the kernel's
11575 append file.
11576 For example, if you are using the Yocto Project kernel that is based on the
11577 Linux 3.2 kernel, the kernel recipe file is the
11578 <code class="filename">meta/recipes-kernel/linux/linux-yocto_3.2.bb</code> file.
11579 Following is the default value for <code class="filename">KBRANCH</code> and the five overrides
11580 for the architectures the Yocto Project supports:
11581 </p><pre class="literallayout">
11582 KBRANCH = "standard/default/base"
11583 KBRANCH_qemux86 = "standard/default/common-pc/base"
11584 KBRANCH_qemux86-64 = "standard/default/common-pc-64/base"
11585 KBRANCH_qemuppc = "standard/default/qemu-ppc32"
11586 KBRANCH_qemumips = "standard/default/mti-malta32-be"
11587 KBRANCH_qemuarm = "standard/default/arm-versatile-926ejs"
11588 </pre><p>
11589 Each of the above branches exist in the <code class="filename">linux-yocto-3.2</code> kernel Git
11590 repository <a class="ulink" href="http://git.yoctoproject.org/cgit.cgi/linux-yocto-3.2/refs/heads" target="_top">http://git.yoctoproject.org/cgit.cgi/linux-yocto-3.2/refs/heads</a>.
11591 </p><p>
11592 This variable is also used from the kernel's append file to identify the kernel
11593 branch specific to a particular machine or target hardware.
11594 The kernel's append file is located in the BSP layer for a given machine.
11595 For example, the kernel append file for the Crown Bay BSP is in the
11596 <code class="filename">meta-intel</code> Git repository and is named
11597 <code class="filename">meta-crownbay/recipes-kernel/linux/linux-yocto_3.2.bbappend</code>.
11598 Here are the related statements from the append file:
11599 </p><pre class="literallayout">
11600 COMPATIBLE_MACHINE_crownbay = "crownbay"
11601 KMACHINE_crownbay = "crownbay"
11602 KBRANCH_crownbay = "standard/default/crownbay"
11603
11604 COMPATIBLE_MACHINE_crownbay-noemgd = "crownbay-noemgd"
11605 KMACHINE_crownbay-noemgd = "crownbay"
11606 KBRANCH_crownbay-noemgd = "standard/default/crownbay"
11607 </pre><p>
11608 The <code class="filename">KBRANCH_*</code> statements identify the kernel branch to
11609 use when building for the Crown Bay BSP.
11610 In this case there are two identical statements: one for each type of
11611 Crown Bay machine.
11612 </p></dd><dt><a id="var-KERNEL_FEATURES"></a>KERNEL_FEATURES</dt><dd><p>Includes additional metadata from the Yocto Project kernel Git repository.
11613 In the OpenEmbedded build system, the default Board Support Packages (BSPs)
11614 metadata is provided through
11615 the <code class="filename">KMACHINE</code> and <code class="filename">KBRANCH</code> variables.
11616 You can use the <code class="filename">KERNEL_FEATURES</code> variable to further
11617 add metadata for all BSPs.</p><p>The metadata you add through this variable includes config fragments and
11618 features descriptions,
11619 which usually includes patches as well as config fragments.
11620 You typically override the <code class="filename">KERNEL_FEATURES</code> variable
11621 for a specific machine.
11622 In this way, you can provide validated, but optional, sets of kernel
11623 configurations and features.</p><p>For example, the following adds <code class="filename">netfilter</code> to all
11624 the Yocto Project kernels and adds sound support to the <code class="filename">qemux86</code>
11625 machine:
11626 </p><pre class="literallayout">
11627 # Add netfilter to all linux-yocto kernels
11628 KERNEL_FEATURES="features/netfilter"
11629
11630 # Add sound support to the qemux86 machine
11631 KERNEL_FEATURES_append_qemux86="cfg/sound"
11632 </pre></dd><dt><a id="var-KERNEL_IMAGETYPE"></a>KERNEL_IMAGETYPE</dt><dd><p>The type of kernel to build for a device, usually set by the
11633 machine configuration files and defaults to "zImage".
11634 This variable is used
11635 when building the kernel and is passed to <code class="filename">make</code> as the target to
11636 build.</p></dd><dt><a id="var-KMACHINE"></a>KMACHINE</dt><dd><p>
11637 The machine as known by the kernel.
11638 Sometimes the machine name used by the kernel does not match the machine name
11639 used by the OpenEmbedded build system.
11640 For example, the machine name that the OpenEmbedded build system understands as
11641 <code class="filename">qemuarm</code> goes by a different name in the Linux Yocto kernel.
11642 The kernel understands that machine as <code class="filename">arm_versatile926ejs</code>.
11643 For cases like these, the <code class="filename">KMACHINE</code> variable maps the
11644 kernel machine name to the OpenEmbedded build system machine name.
11645 </p><p>
11646 Kernel machine names are initially defined in the
11647 <a class="link" href="#local-kernel-files" target="_top">Yocto Project Kernel</a> in
11648 the <code class="filename">meta/cfg/kernel-cache/bsp/&lt;bsp_name&gt;/&lt;bsp-name&gt;-&lt;kernel-type&gt;.scc</code> file.
11649 For example, in the <code class="filename">linux-yocto-3.4</code> kernel in the
11650 <code class="filename">meta/cfg/kernel-cache/bsp/cedartrail/cedartrail-standard.scc</code> file,
11651 has the following:
11652 </p><pre class="literallayout">
11653 define KMACHINE cedartrail
11654 define KTYPE standard
11655 define KARCH i386
11656
11657 include ktypes/standard
11658 branch cedartrail
11659
11660 include cedartrail.scc
11661 </pre><p>
11662 You can see that the kernel understands the machine name for the Cedar Trail BSP as
11663 <code class="filename">cedartrail</code>.
11664 </p><p>
11665 If you look in the Cedar Trail BSP layer in the <code class="filename">meta-intel</code> source
11666 repository at <code class="filename">meta-cedartrail/recipes-kernel/linux/linux-yocto_3.0.bbappend</code>,
11667 you will find the following statements among others:
11668 </p><pre class="literallayout">
11669 COMPATIBLE_MACHINE_cedartrail = "cedartrail"
11670 KMACHINE_cedartrail = "cedartrail"
11671 KBRANCH_cedartrail = "yocto/standard/cedartrail"
11672 KERNEL_FEATURES_append_cedartrail += "bsp/cedartrail/cedartrail-pvr-merge.scc"
11673 KERNEL_FEATURES_append_cedartrail += "cfg/efi-ext.scc"
11674
11675 COMPATIBLE_MACHINE_cedartrail-nopvr = "cedartrail"
11676 KMACHINE_cedartrail-nopvr = "cedartrail"
11677 KBRANCH_cedartrail-nopvr = "yocto/standard/cedartrail"
11678 KERNEL_FEATURES_append_cedartrail-nopvr += " cfg/smp.scc"
11679 </pre><p>
11680 The <code class="filename">KMACHINE</code> statements in the kernel's append file make sure that
11681 the OpenEmbedded build system and the Yocto Linux kernel understand the same machine
11682 names.
11683 </p><p>
11684 This append file uses two <code class="filename">KMACHINE</code> statements.
11685 The first is not really necessary but does ensure that the machine known to the
11686 OpenEmbedded build system as <code class="filename">cedartrail</code> maps to the machine
11687 in the kernel also known as <code class="filename">cedartrail</code>:
11688 </p><pre class="literallayout">
11689 KMACHINE_cedartrail = "cedartrail"
11690 </pre><p>
11691 </p><p>
11692 The second statement is a good example of why the <code class="filename">KMACHINE</code> variable
11693 is needed.
11694 In this example, the OpenEmbedded build system uses the <code class="filename">cedartrail-nopvr</code>
11695 machine name to refer to the Cedar Trail BSP that does not support the propriatory
11696 PowerVR driver.
11697 The kernel, however, uses the machine name <code class="filename">cedartrail</code>.
11698 Thus, the append file must map the <code class="filename">cedartrail-nopvr</code> machine name to
11699 the kernel's <code class="filename">cedartrail</code> name:
11700 </p><pre class="literallayout">
11701 KMACHINE_cedartrail-nopvr = "cedartrail"
11702 </pre><p>
11703 </p><p>
11704 BSPs that ship with the Yocto Project release provide all mappings between the Yocto
11705 Project kernel machine names and the OpenEmbedded machine names.
11706 Be sure to use the <code class="filename">KMACHINE</code> if you create a BSP and the machine
11707 name you use is different than that used in the kernel.
11708 </p></dd></dl></div><div class="glossdiv" title="L"><h3 class="title">L</h3><dl><dt><a id="var-LAYERDEPENDS"></a>LAYERDEPENDS</dt><dd><p>Lists the layers that this recipe depends upon, separated by spaces.
11709 Optionally, you can specify a specific layer version for a dependency
11710 by adding it to the end of the layer name with a colon, (e.g. "anotherlayer:3"
11711 to be compared against <code class="filename">LAYERVERSION_anotherlayer</code> in this case).
11712 An error will be produced if any dependency is missing or
11713 the version numbers do not match exactly (if specified).
11714 This variable is used in the <code class="filename">conf/layer.conf</code> file
11715 and must be suffixed with the name of the specific layer (e.g.
11716 <code class="filename">LAYERDEPENDS_mylayer</code>).</p></dd><dt><a id="var-LAYERDIR"></a>LAYERDIR</dt><dd><p>When used inside the <code class="filename">layer.conf</code> configuration
11717 file, this variable provides the path of the current layer.
11718 This variable requires immediate expansion
11719 (see the BitBake manual) as lazy expansion can result in
11720 the expansion happening in the wrong directory and therefore
11721 giving the wrong value.</p></dd><dt><a id="var-LAYERVERSION"></a>LAYERVERSION</dt><dd><p>Optionally specifies the version of a layer as a single number.
11722 You can use this within <code class="filename">LAYERDEPENDS</code> for another layer in order to
11723 depend on a specific version of the layer.
11724 This variable is used in the <code class="filename">conf/layer.conf</code> file
11725 and must be suffixed with the name of the specific layer (e.g.
11726 <code class="filename">LAYERVERSION_mylayer</code>).</p></dd><dt><a id="var-LIC_FILES_CHKSUM"></a>LIC_FILES_CHKSUM</dt><dd><p>Checksums of the license text in the recipe source code.</p><p>This variable tracks changes in license text of the source
11727 code files.
11728 If the license text is changed, it will trigger a build
11729 failure, which gives the developer an opportunity to review any
11730 license change.</p><p>
11731 This variable must be defined for all recipes (unless <code class="filename">LICENSE</code>
11732 is set to "CLOSED")</p><p>For more information, see the
11733 <a class="link" href="#usingpoky-configuring-LIC_FILES_CHKSUM" title="3.4.1. Tracking License Changes">
11734 Tracking License Changes</a> section</p></dd><dt><a id="var-LICENSE"></a>LICENSE</dt><dd><p>The list of package source licenses.</p></dd><dt><a id="var-LICENSE_DIR"></a>LICENSE_DIR</dt><dd><p>Path to additional licenses used during the build.
11735 By default, the OpenEmbedded build system uses <code class="filename">COMMON_LICENSE_DIR</code>
11736 to define the directory that holds common license text used during the build.
11737 The <code class="filename">LICENSE_DIR</code> variable allows you to extend that
11738 location to other areas that have additional licenses:
11739 </p><pre class="literallayout">
11740 LICENSE_DIR += "/path/to/additional/common/licenses"
11741 </pre></dd></dl></div><div class="glossdiv" title="M"><h3 class="title">M</h3><dl><dt><a id="var-MACHINE"></a>MACHINE</dt><dd><p>Specifies the target device.</p></dd><dt><a id="var-MACHINE_ESSENTIAL_EXTRA_RDEPENDS"></a>MACHINE_ESSENTIAL_EXTRA_RDEPENDS</dt><dd><p></p><p>
11742 A list of required packages to install as part of the package being
11743 built.
11744 The build process depends on these packages being present.
11745 Furthermore, because this is a "machine essential" variable, the list of
11746 packages are essential for the machine to boot.
11747 The impact of this variable affects images based on <code class="filename">task-core-boot</code>,
11748 including the <code class="filename">core-image-minimal</code> image.
11749 </p><p>
11750 This variable is similar to the
11751 <code class="filename"><a class="link" href="#var-MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS" title="MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS">MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS</a></code>
11752 variable with the exception that the package being built has a build
11753 dependency on the variable's list of packages.
11754 In other words, the image will not build if a file in this list is not found.
11755 </p><p>
11756 For example, suppose you are building a runtime package that depends
11757 on a certain disk driver.
11758 In this case, you would use the following:
11759 </p><pre class="literallayout">
11760 MACHINE_ESSENTIAL_EXTRA_RDEPENDS += "&lt;disk_driver&gt;"
11761 </pre><p>
11762 </p></dd><dt><a id="var-MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS"></a>MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS</dt><dd><p></p><p>
11763 A list of recommended packages to install as part of the package being
11764 built.
11765 The build process does not depend on these packages being present.
11766 Furthermore, because this is a "machine essential" variable, the list of
11767 packages are essential for the machine to boot.
11768 The impact of this variable affects images based on <code class="filename">task-core-boot</code>,
11769 including the <code class="filename">core-image-minimal</code> image.
11770 </p><p>
11771 This variable is similar to the
11772 <code class="filename"><a class="link" href="#var-MACHINE_ESSENTIAL_EXTRA_RDEPENDS" title="MACHINE_ESSENTIAL_EXTRA_RDEPENDS">MACHINE_ESSENTIAL_EXTRA_RDEPENDS</a></code>
11773 variable with the exception that the package being built does not have a build
11774 dependency on the variable's list of packages.
11775 In other words, the image will build if a file in this list is not found.
11776 However, because this is one of the "essential" variables, the resulting image
11777 might not boot on the machine.
11778 Or, if the machine does boot using the image, the machine might not be fully
11779 functional.
11780 </p><p>
11781 Consider an example where you have a custom kernel with a disk driver
11782 built into the kernel itself, rather than using the driver built as a module.
11783 If you include the package that has the driver module as part of
11784 the variable's list, the
11785 build process will not find that package.
11786 However, because these packages are "recommends" packages, the build will
11787 not fail due to the missing package.
11788 Not accounting for any other problems, the custom kernel would still boot the machine.
11789 </p><p>
11790 Some example packages of these machine essentials are flash, screen, keyboard, mouse,
11791 or touchscreen drivers (depending on the machine).
11792 </p><p>
11793 For example, suppose you are building a runtime package that depends
11794 on a mouse driver.
11795 In this case, you would use the following:
11796 </p><pre class="literallayout">
11797 MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS += "&lt;mouse_driver&gt;"
11798 </pre><p>
11799 </p></dd><dt><a id="var-MACHINE_EXTRA_RDEPENDS"></a>MACHINE_EXTRA_RDEPENDS</dt><dd><p>
11800 A list of optional but non-machine essential packages to install as
11801 part of the package being built.
11802 Even though these packages are not essential for the machine to boot,
11803 the build process depends on them being present.
11804 The impact of this variable affects all images based on
11805 <code class="filename">task-base</code>, which does not include the
11806 <code class="filename">core-image-minimal</code> or <code class="filename">core-image-basic</code>
11807 images.
11808 </p><p>
11809 This variable is similar to the
11810 <code class="filename"><a class="link" href="#var-MACHINE_EXTRA_RRECOMMENDS" title="MACHINE_EXTRA_RRECOMMENDS">MACHINE_EXTRA_RRECOMMENDS</a></code>
11811 variable with the exception that the package being built has a build
11812 dependency on the variable's list of packages.
11813 In other words, the image will not build if a file in this list is not found.
11814 </p><p>
11815 An example is a machine that might or might not have a WiFi card.
11816 The package containing the WiFi support is not essential for the
11817 machine to boot the image.
11818 If it is not there, the machine will boot but not be able to use the
11819 WiFi functionality.
11820 However, if you include the package with the WiFi support as part of the
11821 variable's package list, the build
11822 process depends on finding the package.
11823 In this case, you would use the following:
11824 </p><pre class="literallayout">
11825 MACHINE_EXTRA_RDEPENDS += "&lt;wifi_driver&gt;"
11826 </pre><p>
11827 </p></dd><dt><a id="var-MACHINE_EXTRA_RRECOMMENDS"></a>MACHINE_EXTRA_RRECOMMENDS</dt><dd><p></p><p>
11828 A list of optional but non-machine essential packages to install as
11829 part of the package being built.
11830 The package being built has no build dependency on the list of packages
11831 with this variable.
11832 The impact of this variable affects only images based on
11833 <code class="filename">task-base</code>, which does not include the
11834 <code class="filename">core-image-minimal</code> or <code class="filename">core-image-basic</code>
11835 images.
11836 </p><p>
11837 This variable is similar to the
11838 <code class="filename"><a class="link" href="#var-MACHINE_EXTRA_RDEPENDS" title="MACHINE_EXTRA_RDEPENDS">MACHINE_EXTRA_RDEPENDS</a></code>
11839 variable with the exception that the package being built does not have a build
11840 dependency on the variable's list of packages.
11841 In other words, the image will build if a file in this list is not found.
11842 </p><p>
11843 An example is a machine that might or might not have a WiFi card.
11844 The package containing the WiFi support is not essential for the
11845 machine to boot the image.
11846 If it is not there, the machine will boot but not be able to use the
11847 WiFi functionality.
11848 You are free to either include or not include the
11849 the package with the WiFi support as part of the
11850 variable's package list, the build
11851 process does not depend on finding the package.
11852 If you include the package, you would use the following:
11853 </p><pre class="literallayout">
11854 MACHINE_EXTRA_RRECOMMENDS += "&lt;wifi_driver&gt;"
11855 </pre><p>
11856 </p></dd><dt><a id="var-MACHINE_FEATURES"></a>MACHINE_FEATURES</dt><dd><p>Specifies the list of device features.
11857 See the <a class="link" href="#ref-features-machine" title="8.2. Machine">Machine</a> section for
11858 more information.</p></dd><dt><a id="var-MAINTAINER"></a>MAINTAINER</dt><dd><p>The email address of the distribution maintainer.</p></dd></dl></div><div class="glossdiv" title="P"><h3 class="title">P</h3><dl><dt><a id="var-PACKAGE_ARCH"></a>PACKAGE_ARCH</dt><dd><p>The architecture of the resulting package.</p></dd><dt><a id="var-PACKAGE_CLASSES"></a>PACKAGE_CLASSES</dt><dd><p>This variable, which is set in the <code class="filename">local.conf</code> configuration
11859 file found in the <code class="filename">conf</code> folder of the
11860 <a class="link" href="#source-directory" target="_top">source directory</a>,
11861 specifies the package manager to use when packaging data.
11862 You can provide one or more arguments for the variable with the first
11863 argument being the package manager used to create images:
11864 </p><pre class="literallayout">
11865 PACKAGE_CLASSES ?= "package_rpm package_deb package_ipk"
11866 </pre><p>
11867 For information on build performance effects as a result of the
11868 package manager use, see
11869 <a class="link" href="#ref-classes-package" title="6.12. Packaging - package*.bbclass">Packaging - <code class="filename">package*.bbclass</code></a>
11870 in this manual.
11871 </p></dd><dt><a id="var-PACKAGE_EXTRA_ARCHS"></a>PACKAGE_EXTRA_ARCHS</dt><dd><p>Specifies the list of architectures compatible with the device CPU.
11872 This variable is useful when you build for several different devices that use
11873 miscellaneous processors such as XScale and ARM926-EJS).</p></dd><dt><a id="var-PACKAGES"></a>PACKAGES</dt><dd><p>The list of packages to be created from the recipe.
11874 The default value is "${PN}-dbg ${PN} ${PN}-doc ${PN}-dev".</p></dd><dt><a id="var-PARALLEL_MAKE"></a>PARALLEL_MAKE</dt><dd><p>Specifies extra options that are passed to the <code class="filename">make</code> command during the
11875 compile tasks.
11876 This variable is usually in the form <code class="filename">-j 4</code>, where the number
11877 represents the maximum number of parallel threads make can run.
11878 If you development host supports multiple cores a good rule of thumb is to set
11879 this variable to twice the number of cores on the host.</p></dd><dt><a id="var-PN"></a>PN</dt><dd><p>The name of the package.
11880 </p></dd><dt><a id="var-PR"></a>PR</dt><dd><p>The revision of the package.
11881 The default value for this variable is "r0".
11882 </p></dd><dt><a id="var-PV"></a>PV</dt><dd><p>The version of the package.
11883 The version is normally extracted from the recipe name.
11884 For example, if the recipe is named
11885 <code class="filename">expat_2.0.1.bb</code>, then <code class="filename">PV</code>
11886 will be <code class="filename">2.0.1</code>.
11887 <code class="filename">PV</code> is generally not overridden within
11888 a recipe unless it is building an unstable version from a source code repository
11889 (e.g. Git or Subversion).
11890 </p></dd><dt><a id="var-PE"></a>PE</dt><dd><p>
11891 the epoch of the package.
11892 The default value is "0".
11893 The field is used to make upgrades possible when the versioning scheme changes in
11894 some backwards incompatible way.
11895 </p></dd><dt><a id="var-PREFERRED_PROVIDER"></a>PREFERRED_PROVIDER</dt><dd><p>
11896 If multiple recipes provide an item, this variable
11897 determines which recipe should be given preference.
11898 The variable must always be suffixed with the name of the
11899 provided item, and should be set to the
11900 <code class="filename">$PN</code> of the recipe
11901 to which you want to give precedence.
11902 Here is an example:
11903 </p><pre class="literallayout">
11904 PREFERRED_PROVIDER_virtual/xserver = "xserver-xf86"
11905 </pre><p>
11906 </p></dd><dt><a id="var-PREFERRED_VERSION"></a>PREFERRED_VERSION</dt><dd><p>
11907 If there are multiple versions of recipes available, this
11908 variable determines which recipe should be given preference.
11909 The variable must always be suffixed with the <code class="filename">$PN</code>
11910 for which to select, and should be set to the
11911 <code class="filename">$PV</code> to which you want to give precedence.
11912 You can use the "<code class="filename">%</code>" character as a wildcard
11913 to match any number of characters, which can be useful when
11914 specifying versions that contain long revision number that could
11915 potentially change.
11916 Here are two examples:
11917 </p><pre class="literallayout">
11918 PREFERRED_VERSION_python = "2.6.6"
11919 PREFERRED_VERSION_linux-yocto = "3.0+git%"
11920 </pre><p>
11921 </p></dd></dl></div><div class="glossdiv" title="R"><h3 class="title">R</h3><dl><dt><a id="var-RCONFLICTS"></a>RCONFLICTS</dt><dd><p>The list of packages that conflict with this package.
11922 Note that the package will not be installed if the conflicting packages are not
11923 first removed.</p></dd><dt><a id="var-RDEPENDS"></a>RDEPENDS</dt><dd><p>
11924 A list of packages that must be installed as part of a package being built.
11925 The package being built has a runtime dependency on the packages in the
11926 variable's list.
11927 In other words, in order for the package being built to run correctly,
11928 it depends on these listed packages.
11929 If a package in this list cannot be found during the build, the build
11930 will not complete.
11931 </p><p>
11932 Because the <code class="filename">RDEPENDS</code> variable applies to packages
11933 being built, you should
11934 always attach an override to the variable to specify the particular runtime package
11935 that has the dependency.
11936 For example, suppose you are building a development package that depends
11937 on the <code class="filename">perl</code> package.
11938 In this case, you would use the following <code class="filename">RDEPENDS</code>
11939 statement:
11940 </p><pre class="literallayout">
11941 RDEPENDS_${PN}-dev += "perl"
11942 </pre><p>
11943 In the example, the package name (<code class="filename">${PN}-dev</code>) must
11944 appear as it would in the
11945 <code class="filename"><a class="link" href="#var-PACKAGES" title="PACKAGES">PACKAGES</a></code> namespace before any
11946 renaming of the output package by classes like <code class="filename">debian.bbclass</code>.
11947 </p><p>
11948 Some automatic handling occurs around the <code class="filename">RDEPENDS</code>
11949 variable:
11950 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em><code class="filename">shlibdeps</code></em></span>: If a runtime
11951 package contains a shared library (<code class="filename">.so</code>), the build
11952 processes the library in order to determine other libraries to which it
11953 is dynamically linked.
11954 The build process adds these libraries to <code class="filename">RDEPENDS</code>
11955 to create the runtime package.</p></li><li class="listitem"><p><span class="emphasis"><em><code class="filename">pcdeps</code></em></span>: If the package
11956 ships a <code class="filename">pkg-config</code> information file, the build process
11957 uses this file to add items to the <code class="filename">RDEPENDS</code>
11958 variable to create the runtime packages.
11959 </p></li></ul></div><p>
11960 </p></dd><dt><a id="var-RRECOMMENDS"></a>RRECOMMENDS</dt><dd><p>
11961 A list of packages that extend the usability of a package being
11962 built.
11963 The package being built does not depend on this list of packages in
11964 order to successfully build, but needs them for the extended usability.
11965 To specify runtime dependencies for packages, see the
11966 <code class="filename"><a class="link" href="#var-RDEPENDS" title="RDEPENDS">RDEPENDS</a></code> variable.
11967 </p><p>
11968 The OpenEmbedded build process automatically installs the list of packages
11969 as part of the built package.
11970 However, you can remove them later if you want.
11971 If, during the build, a package from the list cannot be found, the build
11972 process continues without an error.
11973 </p><p>
11974 Because the <code class="filename">RRECOMMENDS</code> variable applies to packages
11975 being built, you should
11976 always attach an override to the variable to specify the particular package
11977 whose usability is being extended.
11978 For example, suppose you are building a development package that is extended
11979 to support wireless functionality.
11980 In this case, you would use the following:
11981 </p><pre class="literallayout">
11982 RRECOMMENDS_${PN}-dev += "&lt;wireless_package_name&gt;"
11983 </pre><p>
11984 In the example, the package name (<code class="filename">${PN}-dev</code>) must
11985 appear as it would in the
11986 <code class="filename"><a class="link" href="#var-PACKAGES" title="PACKAGES">PACKAGES</a></code> namespace before any
11987 renaming of the output package by classes like <code class="filename">debian.bbclass</code>.
11988 </p></dd><dt><a id="var-RREPLACES"></a>RREPLACES</dt><dd><p>The list of packages that are replaced with this package.</p></dd></dl></div><div class="glossdiv" title="S"><h3 class="title">S</h3><dl><dt><a id="var-S"></a>S</dt><dd><p>
11989 The location in the <a class="link" href="#build-directory" target="_top">build directory</a>
11990 where unpacked package source code resides.
11991 This location is within the working directory
11992 (<code class="filename"><a class="link" href="#var-WORKDIR" title="WORKDIR">WORKDIR</a></code>), which
11993 is not static.
11994 The unpacked source location depends on the package name
11995 (<code class="filename"><a class="link" href="#var-PN" title="PN">PN</a></code>) and
11996 package version (<code class="filename"><a class="link" href="#var-PV" title="PV">PV</a></code>) as
11997 follows:
11998 </p><pre class="literallayout">
11999 ${WORKDIR}/${PN}-${PV}
12000 </pre><p>
12001 As an example, assume a
12002 <a class="link" href="#source-directory" target="_top">source directory</a> top-level
12003 folder named <code class="filename">poky</code>
12004 and a default <a class="link" href="#build-directory" target="_top">build directory</a>
12005 at <code class="filename">poky/build</code>.
12006 In this case, the working directory the build system uses to build
12007 the <code class="filename">db</code> package is the following:
12008 </p><pre class="literallayout">
12009 ~/poky/build/tmp/work/qemux86-poky-linux/db-5.1.19-r3/db-5.1.19
12010 </pre><p>
12011 </p></dd><dt><a id="var-SECTION"></a>SECTION</dt><dd><p>The section where package should be put.
12012 Package managers use this variable.</p></dd><dt><a id="var-SELECTED_OPTIMIZATION"></a>SELECTED_OPTIMIZATION</dt><dd><p>
12013 The variable takes the value of
12014 <code class="filename"><a class="link" href="#var-FULL_OPTIMIZATION" title="FULL_OPTIMIZATION">FULL_OPTIMIZATION</a></code>
12015 unless <code class="filename"><a class="link" href="#var-DEBUG_BUILD" title="DEBUG_BUILD">DEBUG_BUILD</a></code> = "1".
12016 In this case the value of
12017 <code class="filename"><a class="link" href="#var-DEBUG_OPTIMIZATION" title="DEBUG_OPTIMIZATION">DEBUG_OPTIMIZATION</a></code> is used.
12018 </p></dd><dt><a id="var-SERIAL_CONSOLE"></a>SERIAL_CONSOLE</dt><dd><p>The speed and device for the serial port used to attach the serial console.
12019 This variable is given to the kernel as the "console"
12020 parameter and after booting occurs <code class="filename">getty</code> is started on that port
12021 so remote login is possible.</p></dd><dt><a id="var-SSTATE_DIR"></a>SSTATE_DIR</dt><dd><p>The directory for the shared state.</p></dd><dt><a id="var-SITEINFO_ENDIANNESS"></a>SITEINFO_ENDIANNESS</dt><dd><p>
12022 Specifies the endian byte order of the target system.
12023 The variable is either "le" for little-endian or "be" for big-endian.
12024 </p></dd><dt><a id="var-SITEINFO_BITS"></a>SITEINFO_BITS</dt><dd><p>
12025 Specifies the number of bits for the target system CPU.
12026 The variable is either "32" or "64".
12027 </p></dd><dt><a id="var-SRC_URI"></a>SRC_URI</dt><dd><p>The list of source files - local or remote.</p></dd><dt><a id="var-SRC_URI_OVERRIDES_PACKAGE_ARCH"></a>SRC_URI_OVERRIDES_PACKAGE_ARCH</dt><dd><p></p><p>
12028 By default, the OpenEmbedded build system automatically detects whether
12029 <code class="filename"><a class="link" href="#var-SRC_URI" title="SRC_URI">SRC_URI</a></code>
12030 contains files that are machine-specific.
12031 If so, the build system automatically changes
12032 <code class="filename"><a class="link" href="#var-PACKAGE_ARCH" title="PACKAGE_ARCH">PACKAGE_ARCH</a></code>.
12033 Setting this variable to "0" disables this behavior.
12034 </p></dd><dt><a id="var-SRCDATE"></a>SRCDATE</dt><dd><p>
12035 The date of the source code used to build the package.
12036 This variable applies only if the source was fetched from a Source Code Manager (SCM).
12037 </p></dd><dt><a id="var-SRCREV"></a>SRCREV</dt><dd><p>
12038 The revision of the source code used to build the package.
12039 This variable applies to Subversion, Git, Mercurial and Bazaar
12040 only.
12041 Note that if you wish to build a fixed revision and you wish
12042 to avoid performing a query on the remote repository every time
12043 BitBake parses your recipe, you should specify a <code class="filename">SRCREV</code> that is a
12044 full revision identifier and not just a tag.
12045 </p></dd><dt><a id="var-STAGING_KERNEL_DIR"></a>STAGING_KERNEL_DIR</dt><dd><p>
12046 The directory with kernel headers that are required to build out-of-tree
12047 modules.
12048 </p></dd><dt><a id="var-STAMP"></a>STAMP</dt><dd><p>
12049 The directory (usually <code class="filename">TMPDIR/stamps</code>) with timestamps of
12050 executed tasks.
12051 </p></dd><dt><a id="var-SUMMARY"></a>SUMMARY</dt><dd><p>The short (72 characters or less) summary of the binary package for packaging
12052 systems such as <code class="filename">ipkg</code>, <code class="filename">rpm</code> or
12053 <code class="filename">debian</code>.
12054 By default, this variable inherits <code class="filename">DESCRIPTION</code>.</p></dd></dl></div><div class="glossdiv" title="T"><h3 class="title">T</h3><dl><dt><a id="var-TARGET_ARCH"></a>TARGET_ARCH</dt><dd><p>The architecture of the device being built.
12055 While a number of values are possible, the OpenEmbedded build system primarily supports
12056 <code class="filename">arm</code> and <code class="filename">i586</code>.</p></dd><dt><a id="var-TARGET_CFLAGS"></a>TARGET_CFLAGS</dt><dd><p>
12057 Flags passed to the C compiler for the target system.
12058 This variable evaluates to the same as
12059 <code class="filename"><a class="link" href="#var-CFLAGS" title="CFLAGS">CFLAGS</a></code>.
12060 </p></dd><dt><a id="var-TARGET_FPU"></a>TARGET_FPU</dt><dd><p>Specifies the method for handling FPU code.
12061 For FPU-less targets, which include most ARM CPUs, the variable must be
12062 set to "soft".
12063 If not, the kernel emulation gets used, which results in a performance penalty.</p></dd><dt><a id="var-TARGET_OS"></a>TARGET_OS</dt><dd><p>Specifies the target's operating system.
12064 The variable can be set to "linux" for <code class="filename">eglibc</code>-based systems and
12065 to "linux-uclibc" for <code class="filename">uclibc</code>.
12066 For ARM/EABI targets, there are also "linux-gnueabi" and
12067 "linux-uclibc-gnueabi" values possible.</p></dd><dt><a id="var-TCLIBC"></a>TCLIBC</dt><dd><p>
12068 Specifies which variant of the GNU standard C library (<code class="filename">libc</code>)
12069 to use during the build process.
12070 This variable replaces <code class="filename">POKYLIBC</code>, which is no longer
12071 supported.
12072 </p><p>
12073 You can select <code class="filename">eglibc</code> or <code class="filename">uclibc</code>.
12074 </p><div class="note" title="Note" style="margin-left: 0.5in; margin-right: 0.5in;"><h3 class="title">Note</h3>
12075 This release of the Yocto Project does not support the
12076 <code class="filename">glibc</code> implementation of <code class="filename">libc</code>.
12077 </div><p>
12078 </p></dd><dt><a id="var-TCMODE"></a>TCMODE</dt><dd><p>
12079 The toolchain selector.
12080 This variable replaces <code class="filename">POKYMODE</code>, which is no longer
12081 supported.
12082 </p><p>
12083 The <code class="filename">TCMODE</code> variable selects the external toolchain
12084 built using the OpenEmbedded build system or a few supported combinations of
12085 the upstream GCC or CodeSourcery Labs toolchain.
12086 The variable determines which of the <code class="filename">tcmode-*</code> files in
12087 the <code class="filename">meta/conf/distro/include</code> directory, which is found in the
12088 <a class="link" href="#source-directory" target="_top">source directory</a>,
12089 is used.
12090 </p><p>
12091 By default, <code class="filename">TCMODE</code> is set to "default", which
12092 chooses the <code class="filename">tcmode-default.inc</code> file.
12093 The variable is similar to
12094 <a class="link" href="#var-TCLIBC" title="TCLIBC"><code class="filename">TCLIBC</code></a>, which controls
12095 the variant of the GNU standard C library (<code class="filename">libc</code>)
12096 used during the build process: <code class="filename">eglibc</code> or <code class="filename">uclibc</code>.
12097 </p></dd><dt><a id="var-TMPDIR"></a>TMPDIR</dt><dd><p>
12098 This variable is the temporary directory the OpenEmbedded build system
12099 uses when it does its work building images.
12100 By default, the <code class="filename">TMPDIR</code> variable is named
12101 <code class="filename">tmp</code> within the
12102 <a class="link" href="#build-directory" target="_top">build directory</a>.
12103 </p><p>
12104 If you want to establish this directory in a location other than the
12105 default, you can uncomment the following statement in the
12106 <code class="filename">conf/local.conf</code> file in the
12107 <a class="link" href="#source-directory" target="_top">source directory</a>:
12108 </p><pre class="literallayout">
12109 #TMPDIR = "${TOPDIR}/tmp"
12110 </pre><p>
12111 </p></dd><dt><a id="var-TOPDIR"></a>TOPDIR</dt><dd><p>
12112 This variable is the
12113 <a class="link" href="#build-directory" target="_top">build directory</a>.
12114 BitBake automatically sets this variable.
12115 The OpenEmbedded build system uses the build directory when building images.
12116 </p></dd></dl></div><div class="glossdiv" title="W"><h3 class="title">W</h3><dl><dt><a id="var-WORKDIR"></a>WORKDIR</dt><dd><p>
12117 The pathname of the working directory in which the OpenEmbedded build system
12118 builds packages.
12119 This directory is located within the
12120 <a class="link" href="#var-TMPDIR" title="TMPDIR"><code class="filename">TMPDIR</code></a> directory structure and changes
12121 as different packages are built.
12122 </p><p>
12123 The actual <code class="filename">WORKDIR</code> directory depends on several things:
12124 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem">The temporary directory - <a class="link" href="#var-TMPDIR" title="TMPDIR"><code class="filename">TMPDIR</code></a></li><li class="listitem">The package architecture - <a class="link" href="#var-PACKAGE_ARCH" title="PACKAGE_ARCH"><code class="filename">PACKAGE_ARCH</code></a></li><li class="listitem">The target machine - <a class="link" href="#var-MACHINE" title="MACHINE"><code class="filename">MACHINE</code></a></li><li class="listitem">The target operating system - <a class="link" href="#var-TARGET_OS" title="TARGET_OS"><code class="filename">TARGET_OS</code></a></li><li class="listitem">The package name - <a class="link" href="#var-PN" title="PN"><code class="filename">PN</code></a></li><li class="listitem">The package version - <a class="link" href="#var-PV" title="PV"><code class="filename">PV</code></a></li><li class="listitem">The package revision - <a class="link" href="#var-PR" title="PR"><code class="filename">PR</code></a></li></ul></div><p>
12125 </p><p>
12126 For packages that are not dependent on a particular machine,
12127 <code class="filename">WORKDIR</code> is defined as follows:
12128 </p><pre class="literallayout">
12129 ${TMPDIR}/work/${PACKAGE_ARCH}-poky-${TARGET_OS}/${PN}-${PV}-${PR}
12130 </pre><p>
12131 As an example, assume a
12132 <a class="link" href="#source-directory" target="_top">source directory</a> top-level
12133 folder name <code class="filename">poky</code> and a default
12134 <a class="link" href="#build-directory" target="_top">build directory</a>
12135 at <code class="filename">poky/build</code>.
12136 In this case, the working directory the build system uses to build
12137 the <code class="filename">v86d</code> package is the following:
12138 </p><pre class="literallayout">
12139 ~/poky/build/tmp/work/qemux86-poky-linux/v86d-01.9-r0
12140 </pre><p>
12141 </p><p>
12142 For packages that are dependent on a particular machine, <code class="filename">WORKDIR</code>
12143 is defined slightly different:
12144 </p><pre class="literallayout">
12145 ${TMPDIR}/work/${MACHINE}-poky-${TARGET_OS}/${PN}-${PV}-${PR}
12146 </pre><p>
12147 As an example, again assume a source directory top-level folder
12148 named <code class="filename">poky</code> and a default build directory
12149 at <code class="filename">poky/build</code>.
12150 In this case, the working directory the build system uses to build
12151 the <code class="filename">acl</code> package, which is dependent on a
12152 MIPS-based device, is the following:
12153 </p><pre class="literallayout">
12154 ~/poky/build/tmp/work/mips-poky-linux/acl-2.2.51-r2
12155 </pre><p>
12156 </p></dd></dl></div></div></div>
12157
12158 <div class="chapter" title="Chapter 10. Variable Context"><div class="titlepage"><div><div><h2 class="title"><a id="ref-varlocality"></a>Chapter 10. Variable Context</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#ref-varlocality-configuration">10.1. Configuration</a></span></dt><dd><dl><dt><span class="section"><a href="#ref-varlocality-config-distro">10.1.1. Distribution (Distro)</a></span></dt><dt><span class="section"><a href="#ref-varlocality-config-machine">10.1.2. Machine</a></span></dt><dt><span class="section"><a href="#ref-varlocality-config-local">10.1.3. Local</a></span></dt></dl></dd><dt><span class="section"><a href="#ref-varlocality-recipes">10.2. Recipes</a></span></dt><dd><dl><dt><span class="section"><a href="#ref-varlocality-recipe-required">10.2.1. Required</a></span></dt><dt><span class="section"><a href="#ref-varlocality-recipe-dependencies">10.2.2. Dependencies</a></span></dt><dt><span class="section"><a href="#ref-varlocality-recipe-paths">10.2.3. Paths</a></span></dt><dt><span class="section"><a href="#ref-varlocality-recipe-build">10.2.4. Extra Build Information</a></span></dt></dl></dd></dl></div><p>
12159 While most variables can be used in almost any context such as
12160 <code class="filename">.conf</code>, <code class="filename">.bbclass</code>,
12161 <code class="filename">.inc</code>, and <code class="filename">.bb</code> files,
12162 some variables are often associated with a particular locality or context.
12163 This chapter describes some common associations.
12164 </p><div class="section" title="10.1. Configuration"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-varlocality-configuration"></a>10.1. Configuration</h2></div></div></div><p>
12165 The following subsections provide lists of variables whose context is
12166 configuration: distribution, machine, and local.
12167 </p><div class="section" title="10.1.1. Distribution (Distro)"><div class="titlepage"><div><div><h3 class="title"><a id="ref-varlocality-config-distro"></a>10.1.1. Distribution (Distro)</h3></div></div></div><p>
12168 This section lists variables whose context is the distribution, or distro.
12169 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename"><a class="link" href="#var-DISTRO" title="DISTRO">DISTRO</a></code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-DISTRO_NAME" title="DISTRO_NAME">DISTRO_NAME</a></code>
12170 </p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-DISTRO_VERSION" title="DISTRO_VERSION">DISTRO_VERSION</a>
12171 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-MAINTAINER" title="MAINTAINER">MAINTAINER</a></code>
12172 </p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-PACKAGE_CLASSES" title="PACKAGE_CLASSES">PACKAGE_CLASSES</a>
12173 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-TARGET_OS" title="TARGET_OS">TARGET_OS</a></code>
12174 </p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-TARGET_FPU" title="TARGET_FPU">TARGET_FPU</a></code>
12175 </p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-TCMODE" title="TCMODE">TCMODE</a></code>
12176 </p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-TCLIBC" title="TCLIBC">TCLIBC</a></code>
12177 </p></li></ul></div><p>
12178 </p></div><div class="section" title="10.1.2. Machine"><div class="titlepage"><div><div><h3 class="title"><a id="ref-varlocality-config-machine"></a>10.1.2. Machine</h3></div></div></div><p>
12179 This section lists variables whose context is the machine.
12180 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename"><a class="link" href="#var-TARGET_ARCH" title="TARGET_ARCH">TARGET_ARCH</a></code>
12181 </p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-SERIAL_CONSOLE" title="SERIAL_CONSOLE">SERIAL_CONSOLE</a>
12182 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-PACKAGE_EXTRA_ARCHS" title="PACKAGE_EXTRA_ARCHS">PACKAGE_EXTRA_ARCHS</a>
12183 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-IMAGE_FSTYPES" title="IMAGE_FSTYPES">IMAGE_FSTYPES</a>
12184 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-MACHINE_FEATURES" title="MACHINE_FEATURES">MACHINE_FEATURES</a>
12185 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-MACHINE_EXTRA_RDEPENDS" title="MACHINE_EXTRA_RDEPENDS">MACHINE_EXTRA_RDEPENDS
12186 </a></code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-MACHINE_EXTRA_RRECOMMENDS" title="MACHINE_EXTRA_RRECOMMENDS">MACHINE_EXTRA_RRECOMMENDS
12187 </a></code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-MACHINE_ESSENTIAL_EXTRA_RDEPENDS" title="MACHINE_ESSENTIAL_EXTRA_RDEPENDS">MACHINE_ESSENTIAL_EXTRA_RDEPENDS
12188 </a></code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS" title="MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS">
12189 MACHINE_ESSENTIAL_EXTRA_RRECOMMENDS</a></code></p></li></ul></div><p>
12190 </p></div><div class="section" title="10.1.3. Local"><div class="titlepage"><div><div><h3 class="title"><a id="ref-varlocality-config-local"></a>10.1.3. Local</h3></div></div></div><p>
12191 This section lists variables whose context is the local configuration through the
12192 <code class="filename">local.conf</code> file.
12193 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename"><a class="link" href="#var-DISTRO" title="DISTRO">DISTRO</a></code>
12194 </p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-MACHINE" title="MACHINE">MACHINE</a></code>
12195 </p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-DL_DIR" title="DL_DIR">DL_DIR</a></code>
12196 </p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-BBFILES" title="BBFILES">BBFILES</a></code>
12197 </p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-EXTRA_IMAGE_FEATURES" title="EXTRA_IMAGE_FEATURES">EXTRA_IMAGE_FEATURES
12198 </a></code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-PACKAGE_CLASSES" title="PACKAGE_CLASSES">PACKAGE_CLASSES</a>
12199 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-BB_NUMBER_THREADS" title="BB_NUMBER_THREADS">BB_NUMBER_THREADS</a>
12200 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-BBINCLUDELOGS" title="BBINCLUDELOGS">BBINCLUDELOGS</a>
12201 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-ENABLE_BINARY_LOCALE_GENERATION" title="ENABLE_BINARY_LOCALE_GENERATION">
12202 ENABLE_BINARY_LOCALE_GENERATION</a></code></p></li></ul></div><p>
12203 </p></div></div><div class="section" title="10.2. Recipes"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="ref-varlocality-recipes"></a>10.2. Recipes</h2></div></div></div><p>
12204 The following subsections provide lists of variables whose context is
12205 recipes: required, dependencies, path, and extra build information.
12206 </p><div class="section" title="10.2.1. Required"><div class="titlepage"><div><div><h3 class="title"><a id="ref-varlocality-recipe-required"></a>10.2.1. Required</h3></div></div></div><p>
12207 This section lists variables that are required for recipes.
12208 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename"><a class="link" href="#var-DESCRIPTION" title="DESCRIPTION">DESCRIPTION</a>
12209 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-LICENSE" title="LICENSE">LICENSE</a>
12210 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-LIC_FILES_CHKSUM" title="LIC_FILES_CHKSUM">LIC_FILES_CHKSUM</a>
12211 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-SECTION" title="SECTION">SECTION</a>
12212 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-HOMEPAGE" title="HOMEPAGE">HOMEPAGE</a>
12213 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-AUTHOR" title="AUTHOR">AUTHOR</a>
12214 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-SRC_URI" title="SRC_URI">SRC_URI</a>
12215 </code></p></li></ul></div><p>
12216 </p></div><div class="section" title="10.2.2. Dependencies"><div class="titlepage"><div><div><h3 class="title"><a id="ref-varlocality-recipe-dependencies"></a>10.2.2. Dependencies</h3></div></div></div><p>
12217 This section lists variables that define recipe dependencies.
12218 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename"><a class="link" href="#var-DEPENDS" title="DEPENDS">DEPENDS</a>
12219 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-RDEPENDS" title="RDEPENDS">RDEPENDS</a>
12220 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-RRECOMMENDS" title="RRECOMMENDS">RRECOMMENDS</a>
12221 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-RCONFLICTS" title="RCONFLICTS">RCONFLICTS</a>
12222 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-RREPLACES" title="RREPLACES">RREPLACES</a>
12223 </code></p></li></ul></div><p>
12224 </p></div><div class="section" title="10.2.3. Paths"><div class="titlepage"><div><div><h3 class="title"><a id="ref-varlocality-recipe-paths"></a>10.2.3. Paths</h3></div></div></div><p>
12225 This section lists variables that define recipe paths.
12226 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename"><a class="link" href="#var-WORKDIR" title="WORKDIR">WORKDIR</a>
12227 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-S" title="S">S</a>
12228 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-FILES" title="FILES">FILES</a>
12229 </code></p></li></ul></div><p>
12230 </p></div><div class="section" title="10.2.4. Extra Build Information"><div class="titlepage"><div><div><h3 class="title"><a id="ref-varlocality-recipe-build"></a>10.2.4. Extra Build Information</h3></div></div></div><p>
12231 This section lists variables that define extra build information for recipes.
12232 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename"><a class="link" href="#var-DISTRO_PN_ALIAS" title="DISTRO_PN_ALIAS">DISTRO_PN_ALIAS</a>
12233 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-EXTRA_OECMAKE" title="EXTRA_OECMAKE">EXTRA_OECMAKE</a>
12234 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-EXTRA_OECONF" title="EXTRA_OECONF">EXTRA_OECONF</a>
12235 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-EXTRA_OEMAKE" title="EXTRA_OEMAKE">EXTRA_OEMAKE</a>
12236 </code></p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-PACKAGES" title="PACKAGES">PACKAGES</a></code>
12237 </p></li><li class="listitem"><p><code class="filename"><a class="link" href="#var-DEFAULT_PREFERENCE" title="DEFAULT_PREFERENCE">DEFAULT_PREFERENCE
12238 </a></code></p></li></ul></div><p>
12239 </p></div></div></div>
12240
12241 <div class="chapter" title="Chapter 11. FAQ"><div class="titlepage"><div><div><h2 class="title"><a id="faq"></a>Chapter 11. FAQ</h2></div></div></div><div class="qandaset" title="Frequently Asked Questions"><a id="id1519542"></a><table border="0" width="100%" summary="Q and A Set"><col align="left" width="1%" /><col /><tbody><tr class="question" title="11.1."><td align="left" valign="top"><a id="id1519546"></a><a id="id1519547"></a><p><b>11.1.</b></p></td><td align="left" valign="top"><p>
12242 How does Poky differ from <a class="ulink" href="http://www.openembedded.org" target="_top">OpenEmbedded</a>?
12243 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12244 The term "Poky" is sometimes used to refer to the build system that the
12245 Yocto Project uses.
12246 The build system used in the Yocto project is referred to as the
12247 OpenEmbedded build system because "Poky" was derived from <a class="ulink" href="http://www.openembedded.org" target="_top">OpenEmbedded</a>.
12248 Poky is a stable, smaller subset focused on the mobile environment.
12249 Development in the Yocto Project using Poky is closely tied to OpenEmbedded with
12250 features being merged regularly between the two for mutual benefit.
12251 For a fuller description of the term "Poky", see the
12252 <a class="link" href="#poky" target="_top">poky</a> term in the Yocto Project
12253 Development Manual.
12254 </p></td></tr><tr class="question" title="11.2."><td align="left" valign="top"><a id="id1519579"></a><a id="id1519580"></a><p><b>11.2.</b></p></td><td align="left" valign="top"><p>
12255 I only have Python 2.4 or 2.5 but BitBake requires Python 2.6 or 2.7.
12256 Can I still use the Yocto Project?
12257 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12258 You can use a stand-alone tarball to provide Python 2.6.
12259 You can find pre-built 32 and 64-bit versions of Python 2.6 at the following locations:
12260 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><a class="ulink" href="http://downloads.yoctoproject.org/releases/miscsupport/python-nativesdk-standalone-i686.tar.bz2" target="_top">32-bit tarball</a></p></li><li class="listitem"><p><a class="ulink" href="http://downloads.yoctoproject.org/releases/miscsupport/python-nativesdk-standalone-x86_64.tar.bz2" target="_top">64-bit tarball</a></p></li></ul></div><p>
12261 </p><p>
12262 These tarballs are self-contained with all required libraries and should work
12263 on most Linux systems.
12264 To use the tarballs extract them into the root
12265 directory and run the appropriate command:
12266 </p><pre class="literallayout">
12267 $ export PATH=/opt/poky/sysroots/i586-pokysdk-linux/usr/bin/:$PATH
12268 $ export PATH=/opt/poky/sysroots/x86_64-pokysdk-linux/usr/bin/:$PATH
12269 </pre><p>
12270 </p><p>
12271 Once you run the command, BitBake uses Python 2.6.
12272 </p></td></tr><tr class="question" title="11.3."><td align="left" valign="top"><a id="id1519623"></a><a id="id1519624"></a><p><b>11.3.</b></p></td><td align="left" valign="top"><p>
12273 How can you claim Poky is stable?
12274 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12275 There are three areas that help with stability;
12276 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>The Yocto Project team keeps
12277 <a class="link" href="#poky" target="_top">Poky</a> small and focused.
12278 It contains around 650 packages as compared to over 5000 for full
12279 OpenEmbedded.</p></li><li class="listitem"><p>The Yocto Project only supports hardware that the
12280 team has access to for testing.</p></li><li class="listitem"><p>The Yocto Project uses an an autobuilder,
12281 which provides continuous build and integration tests.</p></li></ul></div><p>
12282 </p></td></tr><tr class="question" title="11.4."><td align="left" valign="top"><a id="id1519656"></a><a id="id1519657"></a><p><b>11.4.</b></p></td><td align="left" valign="top"><p>
12283 How do I get support for my board added to the Yocto Project?
12284 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12285 There are two main ways to get a board supported in the Yocto Project;
12286 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>Send the Yocto Project team information on the board
12287 and if the team does not have it yet they will consider adding it.</p></li><li class="listitem"><p>Send the Yocto Project team the BitBake recipes if you have them.
12288 </p></li></ul></div><p>
12289 Usually, if the board is not completely exotic, adding support in
12290 the Yocto Project is fairly straightforward.
12291 </p></td></tr><tr class="question" title="11.5."><td align="left" valign="top"><a id="id1519678"></a><a id="id1519679"></a><p><b>11.5.</b></p></td><td align="left" valign="top"><p>
12292 Are there any products using the OpenEmbedded build system (poky)?
12293 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12294 The <a class="ulink" href="http://vernier.com/labquest/" target="_top">Vernier LabQuest</a> is using
12295 the OpenEmbedded build system.
12296 See the <a class="ulink" href="http://www.vernier.com/products/interfaces/labq/" target="_top">Vernier LabQuest</a>
12297 for more information.
12298 There are a number of pre-production devices using the OpenEmbedded build system
12299 and the Yocto Project team
12300 announces them as soon as they are released.
12301 </p></td></tr><tr class="question" title="11.6."><td align="left" valign="top"><a id="id1519700"></a><a id="id1519702"></a><p><b>11.6.</b></p></td><td align="left" valign="top"><p>
12302 What does the OpenEmbedded build system produce as output?
12303 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12304 Because the same set of recipes can be used to create output of various formats, the
12305 output of an OpenEmbedded build depends on how it was started.
12306 Usually, the output is a flashable image ready for the target device.
12307 </p></td></tr><tr class="question" title="11.7."><td align="left" valign="top"><a id="id1519711"></a><a id="id1519712"></a><p><b>11.7.</b></p></td><td align="left" valign="top"><p>
12308 How do I add my package to the Yocto Project?
12309 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12310 To add a package, you need to create a BitBake recipe.
12311 For information on how to add a package, see the section
12312 "<a class="link" href="#usingpoky-extend-addpkg" target="_top">Adding a Package</a>"
12313 in the Yocto Project Development Manual.
12314 </p></td></tr><tr class="question" title="11.8."><td align="left" valign="top"><a id="id1519726"></a><a id="id1519727"></a><p><b>11.8.</b></p></td><td align="left" valign="top"><p>
12315 Do I have to reflash my entire board with a new Yocto Project image when recompiling
12316 a package?
12317 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12318 The OpenEmbedded build system can build packages in various formats such as
12319 <code class="filename">ipk</code> for <code class="filename">ipkg</code>/<code class="filename">opkg</code>,
12320 Debian package (<code class="filename">.deb</code>), or RPM.
12321 The packages can then be upgraded using the package tools on the device, much like
12322 on a desktop distribution such as Ubuntu or Fedora.
12323 </p></td></tr><tr class="question" title="11.9."><td align="left" valign="top"><a id="id1519761"></a><a id="id1519762"></a><p><b>11.9.</b></p></td><td align="left" valign="top"><p>
12324 What is GNOME Mobile and what is the difference between GNOME Mobile and GNOME?
12325 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12326 GNOME Mobile is a subset of the <a class="ulink" href="http://www.gnome.org" target="_top">GNOME</a>
12327 platform targeted at mobile and embedded devices.
12328 The the main difference between GNOME Mobile and standard GNOME is that
12329 desktop-orientated libraries have been removed, along with deprecated libraries,
12330 creating a much smaller footprint.
12331 </p></td></tr><tr class="question" title="11.10."><td align="left" valign="top"><a id="id1519778"></a><a id="id1519780"></a><p><b>11.10.</b></p></td><td align="left" valign="top"><p>
12332 I see the error '<code class="filename">chmod: XXXXX new permissions are r-xrwxrwx, not r-xr-xr-x</code>'.
12333 What is wrong?
12334 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12335 You are probably running the build on an NTFS filesystem.
12336 Use <code class="filename">ext2</code>, <code class="filename">ext3</code>, or <code class="filename">ext4</code> instead.
12337 </p></td></tr><tr class="question" title="11.11."><td align="left" valign="top"><a id="id1519811"></a><a id="id1519812"></a><p><b>11.11.</b></p></td><td align="left" valign="top"><p>
12338 How do I make the Yocto Project work in RHEL/CentOS?
12339 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12340 To get the Yocto Project working under RHEL/CentOS 5.1 you need to first
12341 install some required packages.
12342 The standard CentOS packages needed are:
12343 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p>"Development tools" (selected during installation)</p></li><li class="listitem"><p><code class="filename">texi2html</code></p></li><li class="listitem"><p><code class="filename">compat-gcc-34</code></p></li></ul></div><p>
12344 On top of these, you need the following external packages:
12345 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename">python-sqlite2</code> from
12346 <a class="ulink" href="http://dag.wieers.com/rpm/packages/python-sqlite2/" target="_top">DAG repository</a>
12347 </p></li><li class="listitem"><p><code class="filename">help2man</code> from
12348 <a class="ulink" href="http://centos.karan.org/el4/extras/stable/x86_64/RPMS/repodata/repoview/help2man-0-1.33.1-2.html" target="_top">Karan repository</a></p></li></ul></div><p>
12349 </p><p>
12350 Once these packages are installed, the OpenEmbedded build system will be able
12351 to build standard images.
12352 However, there might be a problem with the QEMU emulator segfaulting.
12353 You can either disable the generation of binary locales by setting
12354 <code class="filename"><a class="link" href="#var-ENABLE_BINARY_LOCALE_GENERATION" title="ENABLE_BINARY_LOCALE_GENERATION">ENABLE_BINARY_LOCALE_GENERATION</a>
12355 </code> to "0" or by removing the <code class="filename">linux-2.6-execshield.patch</code>
12356 from the kernel and rebuilding it since that is the patch that causes the problems with QEMU.
12357 </p></td></tr><tr class="question" title="11.12."><td align="left" valign="top"><a id="id1519899"></a><a id="id1519900"></a><p><b>11.12.</b></p></td><td align="left" valign="top"><p>
12358 I see lots of 404 responses for files on
12359 <code class="filename">http://www.yoctoproject.org/sources/*</code>. Is something wrong?
12360 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12361 Nothing is wrong.
12362 The OpenEmbedded build system checks any configured source mirrors before downloading
12363 from the upstream sources.
12364 The build system does this searching for both source archives and
12365 pre-checked out versions of SCM managed software.
12366 These checks help in large installations because it can reduce load on the SCM servers
12367 themselves.
12368 The address above is one of the default mirrors configured into the
12369 build system.
12370 Consequently, if an upstream source disappears, the team
12371 can place sources there so builds continue to work.
12372 </p></td></tr><tr class="question" title="11.13."><td align="left" valign="top"><a id="id1519919"></a><a id="id1519920"></a><p><b>11.13.</b></p></td><td align="left" valign="top"><p>
12373 I have machine-specific data in a package for one machine only but the package is
12374 being marked as machine-specific in all cases, how do I prevent this?
12375 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12376 Set <code class="filename"><a class="link" href="#var-SRC_URI_OVERRIDES_PACKAGE_ARCH" title="SRC_URI_OVERRIDES_PACKAGE_ARCH">SRC_URI_OVERRIDES_PACKAGE_ARCH</a>
12377 </code> = "0" in the <code class="filename">.bb</code> file but make sure the package is
12378 manually marked as
12379 machine-specific in the case that needs it.
12380 The code that handles <code class="filename">SRC_URI_OVERRIDES_PACKAGE_ARCH</code> is in <code class="filename">base.bbclass</code>.
12381 </p></td></tr><tr class="question" title="11.14."><td align="left" valign="top"><a id="id1519958"></a><a id="id1519959"></a><p><b>11.14.</b></p></td><td align="left" valign="top"><p>
12382 I'm behind a firewall and need to use a proxy server. How do I do that?
12383 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12384 Most source fetching by the OpenEmbedded build system is done by <code class="filename">wget</code>
12385 and you therefore need to specify the proxy settings in a
12386 <code class="filename">.wgetrc</code> file in your home directory.
12387 Example settings in that file would be
12388 </p><pre class="literallayout">
12389 http_proxy = http://proxy.yoyodyne.com:18023/
12390 ftp_proxy = http://proxy.yoyodyne.com:18023/
12391 </pre><p>
12392 The Yocto Project also includes a <code class="filename">site.conf.sample</code>
12393 file that shows how to configure CVS and Git proxy servers
12394 if needed.
12395 </p></td></tr><tr class="question" title="11.15."><td align="left" valign="top"><a id="id1519996"></a><a id="id1519997"></a><p><b>11.15.</b></p></td><td align="left" valign="top"><p>
12396 I'm using Ubuntu Intrepid and am seeing build failures. What’s wrong?
12397 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12398 In Intrepid, Ubuntu turns on by default the normally optional compile-time security features
12399 and warnings.
12400 There are more details at
12401 <a class="ulink" href="https://wiki.ubuntu.com/CompilerFlags" target="_top">https://wiki.ubuntu.com/CompilerFlags</a>.
12402 You can work around this problem by disabling those options by adding
12403 the following to the <code class="filename">BUILD_CPPFLAGS</code> variable in the
12404 <code class="filename">conf/bitbake.conf</code> file.
12405 </p><pre class="literallayout">
12406 " -Wno-format-security -U_FORTIFY_SOURCE"
12407 </pre><p>
12408 </p></td></tr><tr class="question" title="11.16."><td align="left" valign="top"><a id="id1520034"></a><a id="id1520035"></a><p><b>11.16.</b></p></td><td align="left" valign="top"><p>
12409 What’s the difference between <code class="filename">foo</code> and <code class="filename">foo-native</code>?
12410 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12411 The <code class="filename">*-native</code> targets are designed to run on the system
12412 being used for the build.
12413 These are usually tools that are needed to assist the build in some way such as
12414 <code class="filename">quilt-native</code>, which is used to apply patches.
12415 The non-native version is the one that runs on the target device.
12416 </p></td></tr><tr class="question" title="11.17."><td align="left" valign="top"><a id="id1520068"></a><a id="id1520070"></a><p><b>11.17.</b></p></td><td align="left" valign="top"><p>
12417 I'm seeing random build failures. Help?!
12418 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12419 If the same build is failing in totally different and random ways,
12420 the most likely explanation is that either the hardware you're running the
12421 build on has some problem, or, if you are running the build under virtualisation,
12422 the virtualisation probably has bugs.
12423 The OpenEmbedded build system processes a massive amount of data causing lots of network, disk and
12424 CPU activity and is sensitive to even single bit failures in any of these areas.
12425 True random failures have always been traced back to hardware or virtualisation issues.
12426 </p></td></tr><tr class="question" title="11.18."><td align="left" valign="top"><a id="id1520082"></a><a id="id1520083"></a><p><b>11.18.</b></p></td><td align="left" valign="top"><p>
12427 What do we need to ship for license compliance?
12428 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12429 This is a difficult question and you need to consult your lawyer for the answer
12430 for your specific case.
12431 It is worth bearing in mind that for GPL compliance there needs to be enough
12432 information shipped to allow someone else to rebuild the same end result
12433 you are shipping.
12434 This means sharing the source code, any patches applied to it, and also any
12435 configuration information about how that package was configured and built.
12436 </p></td></tr><tr class="question" title="11.19."><td align="left" valign="top"><a id="id1520094"></a><a id="id1520095"></a><p><b>11.19.</b></p></td><td align="left" valign="top"><p>
12437 How do I disable the cursor on my touchscreen device?
12438 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12439 You need to create a form factor file as described in the
12440 "<a class="link" href="#bsp-filelayout-misc-recipes" target="_top">Miscellaneous Recipe Files</a>"
12441 section and set the <code class="filename">HAVE_TOUCHSCREEN</code> variable equal to one as follows:
12442 </p><pre class="literallayout">
12443 HAVE_TOUCHSCREEN=1
12444 </pre><p>
12445 </p></td></tr><tr class="question" title="11.20."><td align="left" valign="top"><a id="id1520125"></a><a id="id1520126"></a><p><b>11.20.</b></p></td><td align="left" valign="top"><p>
12446 How do I make sure connected network interfaces are brought up by default?
12447 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12448 The default interfaces file provided by the netbase recipe does not
12449 automatically bring up network interfaces.
12450 Therefore, you will need to add a BSP-specific netbase that includes an interfaces
12451 file.
12452 See the "<a class="link" href="#bsp-filelayout-misc-recipes" target="_top">Miscellaneous Recipe Files</a>"
12453 section for information on creating these types of miscellaneous recipe files.
12454 </p><p>
12455 For example, add the following files to your layer:
12456 </p><pre class="literallayout">
12457 meta-MACHINE/recipes-bsp/netbase/netbase/MACHINE/interfaces
12458 meta-MACHINE/recipes-bsp/netbase/netbase_4.44.bbappend
12459 </pre><p>
12460 </p></td></tr><tr class="question" title="11.21."><td align="left" valign="top"><a id="id1520156"></a><a id="id1520157"></a><p><b>11.21.</b></p></td><td align="left" valign="top"><p>
12461 How do I create images with more free space?
12462 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12463 Images are created to be 1.2 times the size of the populated root filesystem.
12464 To modify this ratio so that there is more free space available, you need to
12465 set the configuration value <code class="filename">IMAGE_OVERHEAD_FACTOR</code>.
12466 For example, setting <code class="filename">IMAGE_OVERHEAD_FACTOR</code> to 1.5 sets
12467 the image size ratio to one and a half times the size of the populated
12468 root filesystem.
12469 </p><pre class="literallayout">
12470 IMAGE_OVERHEAD_FACTOR = "1.5"
12471 </pre><p>
12472 </p></td></tr><tr class="question" title="11.22."><td align="left" valign="top"><a id="id1520188"></a><a id="id1520190"></a><p><b>11.22.</b></p></td><td align="left" valign="top"><p>
12473 Why don't you support directories with spaces in the pathnames?
12474 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12475 The Yocto Project team has tried to do this before but too many of the tools
12476 the OpenEmbedded build system depends on such as <code class="filename">autoconf</code>
12477 break when they find spaces in pathnames.
12478 Until that situation changes, the team will not support spaces in pathnames.
12479 </p></td></tr><tr class="question" title="11.23."><td align="left" valign="top"><a id="id1520206"></a><a id="id1520207"></a><p><b>11.23.</b></p></td><td align="left" valign="top"><p>
12480 How do I use an external toolchain?
12481 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12482 The toolchain configuration is very flexible and customizable.
12483 It is primarily controlled with the
12484 <code class="filename"><a class="link" href="#var-TCMODE" title="TCMODE">TCMODE</a></code> variable.
12485 This variable controls which <code class="filename">tcmode-*.inc</code> file to include
12486 from the <code class="filename">meta/conf/distro/include</code> directory within the
12487 <a class="link" href="#source-directory" target="_top">source directory</a>.
12488 </p><p>
12489 The default value of <code class="filename">TCMODE</code> is "default"
12490 (i.e. <code class="filename">tcmode-default.inc</code>).
12491 However, other patterns are accepted.
12492 In particular, "external-*" refers to external toolchains of which there are some
12493 basic examples included in the OpenEmbedded Core (<code class="filename">meta</code>).
12494 You can use your own custom toolchain definition in your own layer
12495 (or as defined in the <code class="filename">local.conf</code> file) at the location
12496 <code class="filename">conf/distro/include/tcmode-*.inc</code>.
12497 </p><p>
12498 In addition to the toolchain configuration, you also need a corresponding toolchain recipe file.
12499 This recipe file needs to package up any pre-built objects in the toolchain such as
12500 <code class="filename">libgcc</code>, <code class="filename">libstdcc++</code>,
12501 any locales, and <code class="filename">libc</code>.
12502 An example is the <code class="filename">external-sourcery-toolchain.bb</code>, which is located
12503 in <code class="filename">meta/recipes-core/meta/</code> within the source directory.
12504 </p></td></tr><tr class="question" title="11.24."><td align="left" valign="top"><a id="id1520281"></a><a id="id1520316"></a><p><b>11.24.</b></p></td><td align="left" valign="top"><p><a id="how-does-the-yocto-project-obtain-source-code-and-will-it-work-behind-my-firewall-or-proxy-server"></a>
12505 How does the OpenEmbedded build system obtain source code and will it work behind my
12506 firewall or proxy server?
12507 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12508 The way the build system obtains source code is highly configurable.
12509 You can setup the build system to get source code in most environments if
12510 HTTP transport is available.
12511 </p><p>
12512 When the build system searches for source code, it first tries the local download directory.
12513 If that location fails, Poky tries PREMIRRORS, the upstream source,
12514 and then MIRRORS in that order.
12515 </p><p>
12516 By default, the OpenEmbedded build system uses the Yocto Project source PREMIRRORS
12517 for SCM-based sources,
12518 upstreams for normal tarballs, and then falls back to a number of other mirrors
12519 including the Yocto Project source mirror if those fail.
12520 </p><p>
12521 As an example, you could add a specific server for Poky to attempt before any
12522 others by adding something like the following to the <code class="filename">local.conf</code>
12523 configuration file:
12524 </p><pre class="literallayout">
12525 PREMIRRORS_prepend = "\
12526 git://.*/.* http://www.yoctoproject.org/sources/ \n \
12527 ftp://.*/.* http://www.yoctoproject.org/sources/ \n \
12528 http://.*/.* http://www.yoctoproject.org/sources/ \n \
12529 https://.*/.* http://www.yoctoproject.org/sources/ \n"
12530 </pre><p>
12531 </p><p>
12532 These changes cause Poky to intercept Git, FTP, HTTP, and HTTPS
12533 requests and direct them to the <code class="filename">http://</code> sources mirror.
12534 You can use <code class="filename">file://</code> URLs to point to local directories
12535 or network shares as well.
12536 </p><p>
12537 Aside from the previous technique, these options also exist:
12538 </p><pre class="literallayout">
12539 BB_NO_NETWORK = "1"
12540 </pre><p>
12541 This statement tells BitBake to throw an error instead of trying to access the
12542 Internet.
12543 This technique is useful if you want to ensure code builds only from local sources.
12544 </p><p>
12545 Here is another technique:
12546 </p><pre class="literallayout">
12547 BB_FETCH_PREMIRRORONLY = "1"
12548 </pre><p>
12549 This statement limits Poky to pulling source from the PREMIRRORS only.
12550 Again, this technique is useful for reproducing builds.
12551 </p><p>
12552 Here is another technique:
12553 </p><pre class="literallayout">
12554 BB_GENERATE_MIRROR_TARBALLS = "1"
12555 </pre><p>
12556 This statement tells Poky to generate mirror tarballs.
12557 This technique is useful if you want to create a mirror server.
12558 If not, however, the technique can simply waste time during the build.
12559 </p><p>
12560 Finally, consider an example where you are behind an HTTP-only firewall.
12561 You could make the following changes to the <code class="filename">local.conf</code>
12562 configuration file as long as the PREMIRROR server is up to date:
12563 </p><pre class="literallayout">
12564 PREMIRRORS_prepend = "\
12565 ftp://.*/.* http://www.yoctoproject.org/sources/ \n \
12566 http://.*/.* http://www.yoctoproject.org/sources/ \n \
12567 https://.*/.* http://www.yoctoproject.org/sources/ \n"
12568 BB_FETCH_PREMIRRORONLY = "1"
12569 </pre><p>
12570 These changes would cause Poky to successfully fetch source over HTTP and
12571 any network accesses to anything other than the PREMIRROR would fail.
12572 </p><p>
12573 The build system also honors the standard shell environment variables
12574 <code class="filename">http_proxy</code>, <code class="filename">ftp_proxy</code>,
12575 <code class="filename">https_proxy</code>, and <code class="filename">all_proxy</code>
12576 to redirect requests through proxy servers.
12577 </p></td></tr><tr class="question" title="11.25."><td align="left" valign="top"><a id="id1520463"></a><a id="id1520464"></a><p><b>11.25.</b></p></td><td align="left" valign="top"><p>
12578 Can I get rid of build output so I can start over?
12579 </p></td></tr><tr class="answer"><td align="left" valign="top"></td><td align="left" valign="top"><p>
12580 Yes - you can easily do this.
12581 When you use BitBake to build an image, all the build output goes into the
12582 directory created when you source the <code class="filename">oe-init-build-env</code>
12583 setup file.
12584 By default, this <a class="link" href="#build-directory" target="_top">build directory</a>
12585 is named <code class="filename">build</code> but can be named
12586 anything you want.
12587 </p><p>
12588 Within the build directory is the <code class="filename">tmp</code> directory.
12589 To remove all the build output yet preserve any source code or downloaded files
12590 from previous builds, simply remove the <code class="filename">tmp</code> directory.
12591 </p></td></tr></tbody></table></div></div>
12592
12593 <div class="chapter" title="Chapter 12. Contributing to the Yocto Project"><div class="titlepage"><div><div><h2 class="title"><a id="resources"></a>Chapter 12. Contributing to the Yocto Project</h2></div></div></div><div class="toc"><dl><dt><span class="section"><a href="#resources-intro">12.1. Introduction</a></span></dt><dt><span class="section"><a href="#resources-bugtracker">12.2. Tracking Bugs</a></span></dt><dt><span class="section"><a href="#resources-mailinglist">12.3. Mailing lists</a></span></dt><dt><span class="section"><a href="#resources-irc">12.4. Internet Relay Chat (IRC)</a></span></dt><dt><span class="section"><a href="#resources-links">12.5. Links</a></span></dt><dt><span class="section"><a href="#resources-contributions">12.6. Contributions</a></span></dt></dl></div><div class="section" title="12.1. Introduction"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="resources-intro"></a>12.1. Introduction</h2></div></div></div><p>
12594 The Yocto Project team is happy for people to experiment with the Yocto Project.
12595 A number of places exist to find help if you run into difficulties or find bugs.
12596 To find out how to download source code,
12597 see the "<a class="link" href="#local-yp-release" target="_top">Yocto Project Release</a>"
12598 list item in the Yocto Project Development Manual.
12599 </p></div><div class="section" title="12.2. Tracking Bugs"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="resources-bugtracker"></a>12.2. Tracking Bugs</h2></div></div></div><p>
12600 If you find problems with the Yocto Project, you should report them using the
12601 Bugzilla application at <a class="ulink" href="http://bugzilla.yoctoproject.org" target="_top">http://bugzilla.yoctoproject.org</a>.
12602 </p></div><div class="section" title="12.3. Mailing lists"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="resources-mailinglist"></a>12.3. Mailing lists</h2></div></div></div><p>
12603 There are a number of mailing lists maintained by the Yocto Project as well as
12604 related OpenEmbedded mailing lists for discussion, patch submission and announcements.
12605 To subscribe to one of the following mailing lists, click on the appropriate URL
12606 in the following list and follow the instructions:
12607 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><a class="ulink" href="http://lists.yoctoproject.org/listinfo/yocto" target="_top">http://lists.yoctoproject.org/listinfo/yocto</a> -
12608 General Yocto Project discussion mailing list. </p></li><li class="listitem"><p><a class="ulink" href="http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-core" target="_top">http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-core</a> -
12609 Discussion mailing list about OpenEmbedded-Core (the core metadata).</p></li><li class="listitem"><p><a class="ulink" href="http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-devel" target="_top">http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/openembedded-devel</a> -
12610 Discussion mailing list about OpenEmbedded.</p></li><li class="listitem"><p><a class="ulink" href="http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/bitbake-devel" target="_top">http://lists.linuxtogo.org/cgi-bin/mailman/listinfo/bitbake-devel</a> -
12611 Discussion mailing list about the BitBake build tool.</p></li><li class="listitem"><p><a class="ulink" href="http://lists.yoctoproject.org/listinfo/poky" target="_top">http://lists.yoctoproject.org/listinfo/poky</a> -
12612 Discussion mailing list about Poky.</p></li><li class="listitem"><p><a class="ulink" href="http://lists.yoctoproject.org/listinfo/yocto-announce" target="_top">http://lists.yoctoproject.org/listinfo/yocto-announce</a> -
12613 Mailing list to receive official Yocto Project release and milestone
12614 announcements.</p></li></ul></div><p>
12615 </p></div><div class="section" title="12.4. Internet Relay Chat (IRC)"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="resources-irc"></a>12.4. Internet Relay Chat (IRC)</h2></div></div></div><p>
12616 Two IRC channels on freenode are available for the Yocto Project and Poky discussions:
12617 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><code class="filename">#yocto</code></p></li><li class="listitem"><p><code class="filename">#poky</code></p></li></ul></div><p>
12618 </p></div><div class="section" title="12.5. Links"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="resources-links"></a>12.5. Links</h2></div></div></div><p>
12619 Following is a list of resources you will find helpful:
12620 </p><div class="itemizedlist"><ul class="itemizedlist" type="disc"><li class="listitem"><p><span class="emphasis"><em><a class="ulink" href="http://www.yoctoproject.org" target="_top">The Yocto Project website</a>:
12621 </em></span> The home site for the Yocto Project.</p></li><li class="listitem"><p><span class="emphasis"><em><a class="ulink" href="http://www.intel.com/" target="_top">Intel Corporation</a>:</em></span>
12622 The company who acquired OpenedHand in 2008 and began development on the
12623 Yocto Project.</p></li><li class="listitem"><p><span class="emphasis"><em><a class="ulink" href="http://www.openembedded.org" target="_top">OpenEmbedded</a>:</em></span>
12624 The upstream, generic, embedded distribution used as the basis for the build system in the
12625 Yocto Project.
12626 Poky derives from and contributes back to the OpenEmbedded project.</p></li><li class="listitem"><p><span class="emphasis"><em><a class="ulink" href="http://developer.berlios.de/projects/bitbake/" target="_top">
12627 BitBake</a>:</em></span> The tool used to process metadata.</p></li><li class="listitem"><p><span class="emphasis"><em><a class="ulink" href="http://docs.openembedded.org/bitbake/html/" target="_top">
12628 BitBake User Manual</a>:</em></span> A comprehensive guide to the BitBake tool.
12629 </p></li><li class="listitem"><p><span class="emphasis"><em><a class="ulink" href="http://wiki.qemu.org/Index.html" target="_top">QEMU</a>:
12630 </em></span> An open source machine emulator and virtualizer.</p></li></ul></div><p>
12631 </p></div><div class="section" title="12.6. Contributions"><div class="titlepage"><div><div><h2 class="title" style="clear: both"><a id="resources-contributions"></a>12.6. Contributions</h2></div></div></div><p>
12632 The Yocto Project gladly accepts contributions.
12633 You can submit changes to the project either by creating and sending pull requests,
12634 or by submitting patches through email.
12635 For information on how to do both, see the
12636 "<a class="link" href="#how-to-submit-a-change" target="_top">How to Submit a Change</a>"
12637 section in the Yocto Project Development Manual.
12638 </p></div></div>
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