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authorScott Rifenbark <scott.m.rifenbark@intel.com>2013-01-10 18:55:01 -0600
committerRichard Purdie <richard.purdie@linuxfoundation.org>2013-01-27 13:54:09 +0000
commitcdacd8764b26b945253c7a94941806ce34a44da6 (patch)
tree508ebed09bf8c7e1425207236d808963ff16b1f1
parent982637f27ae86d83a7ef425c84ab70345e269451 (diff)
downloadpoky-cdacd8764b26b945253c7a94941806ce34a44da6.tar.gz
profile-manual: Copied in raw "Examples" chapter.
I put the raw text is for chapter 4. No editing. (From yocto-docs rev: e4a017624595394f86f469e15c1c8ad13e82206d) Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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2"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" 2"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
3[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] > 3[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >
4 4
5<chapter id='dev-manual-model'> 5<chapter id='profile-manual-examples'>
6 6
7<title>Common Development Models</title> 7<title>Real-World Examples</title>
8 8
9<para> 9<para>
10 Many development models exist for which you can use the Yocto Project. 10 This chapter contains real-world examples.
11 This chapter overviews simple methods that use tools provided by the
12 Yocto Project:
13 <itemizedlist>
14 <listitem><para><emphasis>System Development:</emphasis>
15 System Development covers Board Support Package (BSP) development and kernel
16 modification or configuration.
17 For an example on how to create a BSP, see the
18 "<ulink url='&YOCTO_DOCS_BSP_URL;#creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a New BSP Layer Using the yocto-bsp Script</ulink>"
19 section in the Yocto Project Board Support Package (BSP) Developer's Guide.
20 </para></listitem>
21 <listitem><para><emphasis>User Application Development:</emphasis>
22 User Application Development covers development of applications that you intend
23 to run on some target hardware.
24 For information on how to set up your host development system for user-space
25 application development, see the
26 <ulink url='&YOCTO_DOCS_ADT_URL;'>Yocto Project Application Developer's Guide</ulink>.
27 For a simple example of user-space application development using the
28 <trademark class='trade'>Eclipse</trademark> IDE, see the
29 "<link linkend='application-development-workflow'>Application
30 Development Workflow</link>" section.
31 </para></listitem>
32 <listitem><para><emphasis>Temporary Source Code Modification:</emphasis>
33 Direct modification of temporary source code is a convenient development model
34 to quickly iterate and develop towards a solution.
35 Once the solution has been implemented, you should of course take steps to
36 get the changes upstream and applied in the affected recipes.</para></listitem>
37 <listitem><para><emphasis>Image Development using Hob:</emphasis>
38 You can use the <ulink url='&YOCTO_HOME_URL;/projects/hob'>Hob</ulink> to build
39 custom operating system images within the build environment.
40 Hob provides an efficient interface to the OpenEmbedded build system.</para></listitem>
41 <listitem><para><emphasis>Using a Development Shell:</emphasis>
42 You can use a <filename>devshell</filename> to efficiently debug commands or simply
43 edit packages.
44 Working inside a development shell is a quick way to set up the OpenEmbedded build
45 environment to work on parts of a project.</para></listitem>
46 </itemizedlist>
47</para> 11</para>
48 12
49<section id='system-development-model'> 13<section id='slow-write-speed-on-live-images'>
50 <title>System Development Workflow</title> 14 <title>Slow Write Speed on Line Images</title>
51 15
52 <para> 16 <para>
53 System development involves modification or creation of an image that you want to run on 17 In one of our previous releases (denzil), users noticed that booting
54 a specific hardware target. 18 off of a live image and writing to disk was noticeably slower.
55 Usually, when you want to create an image that runs on embedded hardware, the image does 19 This included the boot itself, especially the first one, since first
56 not require the same number of features that a full-fledged Linux distribution provides. 20 boots tend to do a significant amount of writing due to certain
57 Thus, you can create a much smaller image that is designed to use only the 21 post-install scripts.
58 features for your particular hardware.
59 </para> 22 </para>
60 23
61 <para> 24 <para>
62 To help you understand how system development works in the Yocto Project, this section 25 The problem (and solution) was discovered by using the Yocto tracing
63 covers two types of image development: BSP creation and kernel modification or 26 tools, in this case 'perf stat', 'perf script', 'perf record'
64 configuration. 27 and 'perf report'.
65 </para> 28 </para>
66 29
67 <section id='developing-a-board-support-package-bsp'>
68 <title>Developing a Board Support Package (BSP)</title>
69
70 <para>
71 A BSP is a package of recipes that, when applied during a build, results in
72 an image that you can run on a particular board.
73 Thus, the package when compiled into the new image, supports the operation of the board.
74 </para>
75
76 <note>
77 For a brief list of terms used when describing the development process in the Yocto Project,
78 see the "<link linkend='yocto-project-terms'>Yocto Project Terms</link>" section.
79 </note>
80
81 <para>
82 The remainder of this section presents the basic steps used to create a BSP
83 using the Yocto Project's
84 <ulink url='&YOCTO_DOCS_BSP_URL;#using-the-yocto-projects-bsp-tools'>BSP Tools</ulink>.
85 For an example that shows how to create a new layer using the tools, see the
86 "<ulink url='&YOCTO_DOCS_BSP_URL;#creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a New BSP Layer Using the yocto-bsp Script</ulink>"
87 section in the Yocto Project Board Support Package (BSP) Developer's Guide.
88 </para>
89
90 <para>
91 The following illustration and list summarize the BSP creation general workflow.
92 </para>
93
94 <para>
95 <imagedata fileref="figures/bsp-dev-flow.png" width="6in" depth="7in" align="center" scalefit="1" />
96 </para>
97
98 <para>
99 <orderedlist>
100 <listitem><para><emphasis>Set up your host development system to support
101 development using the Yocto Project</emphasis>: See the
102 "<ulink url='&YOCTO_DOCS_QS_URL;#the-linux-distro'>The Linux Distributions</ulink>"
103 and the
104 "<ulink url='&YOCTO_DOCS_QS_URL;#packages'>The Packages</ulink>" sections both
105 in the Yocto Project Quick Start for requirements.</para></listitem>
106 <listitem><para><emphasis>Establish a local copy of the project files on your
107 system</emphasis>: You need this <link linkend='source-directory'>Source
108 Directory</link> available on your host system.
109 Having these files on your system gives you access to the build
110 process and to the tools you need.
111 For information on how to set up the
112 <link linkend='source-directory'>Source Directory</link>, see the
113 "<link linkend='getting-setup'>Getting Setup</link>" section.</para></listitem>
114 <listitem><para><emphasis>Establish the <filename>meta-intel</filename>
115 repository on your system</emphasis>: Having local copies of the
116 supported BSP layers on your system gives you access to the build
117 process and to the tools you need for creating a BSP.
118 For information on how to get these files, see the
119 "<link linkend='getting-setup'>Getting Setup</link>" section.</para></listitem>
120 <listitem><para><emphasis>Create your own BSP layer using the
121 <ulink url='&YOCTO_DOCS_BSP_URL;#creating-a-new-bsp-layer-using-the-yocto-bsp-script'><filename>yocto-bsp</filename></ulink> script</emphasis>:
122 Layers are ideal for
123 isolating and storing work for a given piece of hardware.
124 A layer is really just a location or area in which you place the recipes for your BSP.
125 In fact, a BSP is, in itself, a special type of layer.
126 The simplest way to create a new BSP layer that is compliant with the
127 Yocto Project is to use the <filename>yocto-bsp</filename> script.
128 For information about that script, see the
129 "<ulink url='&YOCTO_DOCS_BSP_URL;#creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a New BSP Layer Using the yocto-bsp Script</ulink>"
130 section in the Yocto Project Board Support (BSP) Developer's Guide.
131 </para>
132 <para>
133 Another example that illustrates a layer is an application.
134 Suppose you are creating an application that has library or other dependencies in
135 order for it to compile and run.
136 The layer, in this case, would be where all the recipes that define those dependencies
137 are kept.
138 The key point for a layer is that it is an isolated area that contains
139 all the relevant information for the project that the OpenEmbedded build
140 system knows about.
141 For more information on layers, see the
142 "<link linkend='understanding-and-creating-layers'>Understanding and Creating Layers</link>"
143 section.
144 For more information on BSP layers, see the
145 "<ulink url='&YOCTO_DOCS_BSP_URL;#bsp-layers'>BSP Layers</ulink>" section in the
146 Yocto Project Board Support Package (BSP) Developer's Guide.</para>
147 <note>Four BSPs exist that are part of the
148 Yocto Project release: <filename>atom-pc</filename>, <filename>beagleboard</filename>,
149 <filename>mpc8315e</filename>, and <filename>routerstationpro</filename>.
150 The recipes and configurations for these four BSPs are located and dispersed
151 within the <link linkend='source-directory'>Source Directory</link>.
152 On the other hand, BSP layers for Cedar Trail, Chief River, Crown Bay,
153 Crystal Forest, Emenlow, Fish River, Fish River 2, Jasper Forest, N450,
154 Romley, sys940x, Sugar Bay, and tlk exist in their own separate layers
155 within the larger <filename>meta-intel</filename> layer.</note>
156 <para>When you set up a layer for a new BSP, you should follow a standard layout.
157 This layout is described in the section
158 "<ulink url='&YOCTO_DOCS_BSP_URL;#bsp-filelayout'>Example Filesystem Layout</ulink>"
159 section of the Board Support Package (BSP) Development Guide.
160 In the standard layout, you will notice a suggested structure for recipes and
161 configuration information.
162 You can see the standard layout for a BSP by examining
163 any supported BSP found in the <filename>meta-intel</filename> layer inside
164 the Source Directory.</para></listitem>
165 <listitem><para><emphasis>Make configuration changes to your new BSP
166 layer</emphasis>: The standard BSP layer structure organizes the files you need
167 to edit in <filename>conf</filename> and several <filename>recipes-*</filename>
168 directories within the BSP layer.
169 Configuration changes identify where your new layer is on the local system
170 and identify which kernel you are going to use.
171 When you run the <filename>yocto-bsp</filename> script you are able to interactively
172 configure many things for the BSP (e.g. keyboard, touchscreen, and so forth).
173 </para></listitem>
174 <listitem><para><emphasis>Make recipe changes to your new BSP layer</emphasis>: Recipe
175 changes include altering recipes (<filename>.bb</filename> files), removing
176 recipes you don't use, and adding new recipes or append files
177 (<filename>.bbappend</filename>) that you need to support your hardware.
178 </para></listitem>
179 <listitem><para><emphasis>Prepare for the build</emphasis>: Once you have made all the
180 changes to your BSP layer, there remains a few things
181 you need to do for the OpenEmbedded build system in order for it to create your image.
182 You need to get the build environment ready by sourcing an environment setup script
183 and you need to be sure two key configuration files are configured appropriately:
184 the <filename>conf/local.conf</filename> and the
185 <filename>conf/bblayers.conf</filename> file.
186 You must make the OpenEmbedded build system aware of your new layer.
187 See the
188 "<link linkend='enabling-your-layer'>Enabling Your Layer</link>" section
189 for information on how to let the build system know about your new layer.</para>
190 <para>The entire process for building an image is overviewed in the section
191 "<ulink url='&YOCTO_DOCS_QS_URL;#building-image'>Building an Image</ulink>" section
192 of the Yocto Project Quick Start.
193 You might want to reference this information.</para></listitem>
194 <listitem><para><emphasis>Build the image</emphasis>: The OpenEmbedded build system
195 uses the BitBake tool to build images based on the type of image you want to create.
196 You can find more information about BitBake in the user manual, which is found in the
197 <filename>bitbake/doc/manual</filename> directory of the
198 <link linkend='source-directory'>Source Directory</link>.</para>
199 <para>The build process supports several types of images to satisfy different needs.
200 See the
201 "<ulink url='&YOCTO_DOCS_REF_URL;#ref-images'>Images</ulink>" chapter
202 in the Yocto Project Reference Manual for information on
203 supported images.</para></listitem>
204 </orderedlist>
205 </para>
206
207 <para>
208 You can view a video presentation on "Building Custom Embedded Images with Yocto"
209 at <ulink url='http://free-electrons.com/blog/elc-2011-videos'>Free Electrons</ulink>.
210 You can also find supplemental information in
211 <ulink url='&YOCTO_DOCS_BSP_URL;'>
212 The Board Support Package (BSP) Development Guide</ulink>.
213 Finally, there is wiki page write up of the example also located
214 <ulink url='&YOCTO_WIKI_URL;/wiki/Transcript:_creating_one_generic_Atom_BSP_from_another'>
215 here</ulink> that you might find helpful.
216 </para>
217 </section>
218
219 <section id='modifying-the-kernel'>
220 <title><anchor id='kernel-spot' />Modifying the Kernel</title>
221
222 <para>
223 Kernel modification involves changing the Yocto Project kernel, which could involve changing
224 configuration options as well as adding new kernel recipes.
225 Configuration changes can be added in the form of configuration fragments, while recipe
226 modification comes through the kernel's <filename>recipes-kernel</filename> area
227 in a kernel layer you create.
228 </para>
229
230 <para>
231 The remainder of this section presents a high-level overview of the Yocto Project
232 kernel architecture and the steps to modify the kernel.
233 For a complete discussion of the kernel, see the
234 <ulink url='&YOCTO_DOCS_KERNEL_URL;'>Yocto Project Kernel Architecture and Use Manual</ulink>.
235 You can reference the
236 "<link linkend='patching-the-kernel'>Patching the Kernel</link>" section
237 for an example that changes the source code of the kernel.
238 For information on how to configure the kernel, see the
239 "<link linkend='configuring-the-kernel'>Configuring the Kernel</link>" section.
240 </para>
241
242 <section id='kernel-overview'>
243 <title>Kernel Overview</title>
244
245 <para>
246 Traditionally, when one thinks of a patched kernel, they think of a base kernel
247 source tree and a fixed structure that contains kernel patches.
248 The Yocto Project, however, employs mechanisms, that in a sense, result in a kernel source
249 generator.
250 By the end of this section, this analogy will become clearer.
251 </para>
252
253 <para>
254 You can find a web interface to the Yocto Project kernel source repositories at
255 <ulink url='&YOCTO_GIT_URL;'></ulink>.
256 If you look at the interface, you will see to the left a grouping of
257 Git repositories titled "Yocto Linux Kernel."
258 Within this group, you will find several kernels supported by
259 the Yocto Project:
260 <itemizedlist>
261 <listitem><para><emphasis><filename>linux-yocto-2.6.34</filename></emphasis> - The
262 stable Yocto Project kernel that is based on the Linux 2.6.34 released kernel.</para></listitem>
263 <listitem><para><emphasis><filename>linux-yocto-2.6.37</filename></emphasis> - The
264 stable Yocto Project kernel that is based on the Linux 2.6.37 released kernel.</para></listitem>
265 <listitem><para><emphasis><filename>linux-yocto-3.0</filename></emphasis> - The stable
266 Yocto Project kernel that is based on the Linux 3.0 released kernel.</para></listitem>
267 <listitem><para><emphasis><filename>linux-yocto-3.0-1.1.x</filename></emphasis> - The
268 stable Yocto Project kernel to use with the Yocto Project Release 1.1.x. This kernel
269 is based on the Linux 3.0 released kernel.</para></listitem>
270 <listitem><para><emphasis><filename>linux-yocto-3.2</filename></emphasis> - The
271 stable Yocto Project kernel to use with the Yocto Project Release 1.2. This kernel
272 is based on the Linux 3.2 released kernel.</para></listitem>
273 <listitem><para><emphasis><filename>linux-yocto-3.4</filename></emphasis> - The
274 stable Yocto Project kernel to use with the Yocto Project Release 1.3. This kernel
275 is based on the Linux 3.4 released kernel.</para></listitem>
276 <listitem><para><emphasis><filename>linux-yocto-dev</filename></emphasis> - A development
277 kernel based on the latest upstream release candidate available.</para></listitem>
278 </itemizedlist>
279 </para>
280
281 <para>
282 The kernels are maintained using the Git revision control system
283 that structures them using the familiar "tree", "branch", and "leaf" scheme.
284 Branches represent diversions from general code to more specific code, while leaves
285 represent the end-points for a complete and unique kernel whose source files
286 when gathered from the root of the tree to the leaf accumulate to create the files
287 necessary for a specific piece of hardware and its features.
288 The following figure displays this concept:
289 <para>
290 <imagedata fileref="figures/kernel-overview-1.png"
291 width="6in" depth="6in" align="center" scale="100" />
292 </para>
293
294 <para>
295 Within the figure, the "Kernel.org Branch Point" represents the point in the tree
296 where a supported base kernel is modified from the Linux kernel.
297 For example, this could be the branch point for the <filename>linux-yocto-3.0</filename>
298 kernel.
299 Thus, everything further to the right in the structure is based on the
300 <filename>linux-yocto-3.0</filename> kernel.
301 Branch points to right in the figure represent where the
302 <filename>linux-yocto-3.0</filename> kernel is modified for specific hardware
303 or types of kernels, such as real-time kernels.
304 Each leaf thus represents the end-point for a kernel designed to run on a specific
305 targeted device.
306 </para>
307
308 <para>
309 The overall result is a Git-maintained repository from which all the supported
310 kernel types can be derived for all the supported devices.
311 A big advantage to this scheme is the sharing of common features by keeping them in
312 "larger" branches within the tree.
313 This practice eliminates redundant storage of similar features shared among kernels.
314 </para>
315
316 <note>
317 Keep in mind the figure does not take into account all the supported Yocto
318 Project kernel types, but rather shows a single generic kernel just for conceptual purposes.
319 Also keep in mind that this structure represents the Yocto Project source repositories
320 that are either pulled from during the build or established on the host development system
321 prior to the build by either cloning a particular kernel's Git repository or by
322 downloading and unpacking a tarball.
323 </note>
324
325 <para>
326 Upstream storage of all the available kernel source code is one thing, while
327 representing and using the code on your host development system is another.
328 Conceptually, you can think of the kernel source repositories as all the
329 source files necessary for all the supported kernels.
330 As a developer, you are just interested in the source files for the kernel on
331 on which you are working.
332 And, furthermore, you need them available on your host system.
333 </para>
334
335 <para>
336 Kernel source code is available on your host system a couple of different
337 ways.
338 If you are working in the kernel all the time, you probably would want
339 to set up your own local Git repository of the kernel tree.
340 If you just need to make some patches to the kernel, you can get at
341 temporary kernel source files extracted and used during the OpenEmbedded
342 build system.
343 We will just talk about working with the temporary source code.
344 </para>
345
346 <para>
347 What happens during the build?
348 When you build the kernel on your development system, all files needed for the build
349 are taken from the source repositories pointed to by the
350 <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink> variable
351 and gathered in a temporary work area
352 where they are subsequently used to create the unique kernel.
353 Thus, in a sense, the process constructs a local source tree specific to your
354 kernel to generate the new kernel image - a source generator if you will.
355 </para>
356 The following figure shows the temporary file structure
357 created on your host system when the build occurs.
358 This
359 <link linkend='build-directory'>Build Directory</link> contains all the
360 source files used during the build.
361 </para>
362
363 <para>
364 <imagedata fileref="figures/kernel-overview-2-generic.png"
365 width="6in" depth="5in" align="center" scale="100" />
366 </para>
367
368 <para>
369 Again, for a complete discussion of the Yocto Project kernel's architecture and its
370 branching strategy, see the
371 <ulink url='&YOCTO_DOCS_KERNEL_URL;'>Yocto Project Kernel Architecture and Use Manual</ulink>.
372 You can also reference the
373 "<link linkend='patching-the-kernel'>Patching the Kernel</link>"
374 section for a detailed example that modifies the kernel.
375 </para>
376 </section>
377
378 <section id='kernel-modification-workflow'>
379 <title>Kernel Modification Workflow</title>
380
381 <para>
382 This illustration and the following list summarizes the kernel modification general workflow.
383 </para>
384
385 <para>
386 <imagedata fileref="figures/kernel-dev-flow.png"
387 width="6in" depth="5in" align="center" scalefit="1" />
388 </para>
389
390 <para>
391 <orderedlist>
392 <listitem><para><emphasis>Set up your host development system to support
393 development using the Yocto Project</emphasis>: See
394 "<ulink url='&YOCTO_DOCS_QS_URL;#the-linux-distro'>The Linux Distributions</ulink>" and
395 "<ulink url='&YOCTO_DOCS_QS_URL;#packages'>The Packages</ulink>" sections both
396 in the Yocto Project Quick Start for requirements.</para></listitem>
397 <listitem><para><emphasis>Establish a local copy of project files on your
398 system</emphasis>: Having the <link linkend='source-directory'>Source
399 Directory</link> on your system gives you access to the build process and tools
400 you need.
401 For information on how to get these files, see the bulleted item
402 "<link linkend='local-yp-release'>Yocto Project Release</link>" earlier in this manual.
403 </para></listitem>
404 <listitem><para><emphasis>Establish the temporary kernel source files</emphasis>:
405 Temporary kernel source files are kept in the Build Directory created by the
406 OpenEmbedded build system when you run BitBake.
407 If you have never built the kernel you are interested in, you need to run
408 an initial build to establish local kernel source files.</para>
409 <para>If you are building an image for the first time, you need to get the build
410 environment ready by sourcing
411 the environment setup script.
412 You also need to be sure two key configuration files
413 (<filename>local.conf</filename> and <filename>bblayers.conf</filename>)
414 are configured appropriately.</para>
415 <para>The entire process for building an image is overviewed in the
416 "<ulink url='&YOCTO_DOCS_QS_URL;#building-image'>Building an Image</ulink>"
417 section of the Yocto Project Quick Start.
418 You might want to reference this information.
419 You can find more information on BitBake in the user manual, which is found in the
420 <filename>bitbake/doc/manual</filename> directory of the
421 <link linkend='source-directory'>Source Directory</link>.</para>
422 <para>The build process supports several types of images to satisfy different needs.
423 See the "<ulink url='&YOCTO_DOCS_REF_URL;#ref-images'>Images</ulink>" chapter in
424 the Yocto Project Reference Manual for information on supported images.
425 </para></listitem>
426 <listitem><para><emphasis>Make changes to the kernel source code if
427 applicable</emphasis>: Modifying the kernel does not always mean directly
428 changing source files.
429 However, if you have to do this, you make the changes to the files in the
430 Build directory.</para></listitem>
431 <listitem><para><emphasis>Make kernel configuration changes
432 if applicable</emphasis>:
433 If your situation calls for changing the kernel's configuration, you can
434 use the <filename>yocto-kernel</filename> script or <filename>menuconfig</filename>
435 to enable and disable kernel configurations.
436 Using the script lets you interactively set up kernel configurations.
437 Using <filename>menuconfig</filename> allows you to interactively develop and test the
438 configuration changes you are making to the kernel.
439 When saved, changes using <filename>menuconfig</filename> update the kernel's
440 <filename>.config</filename>.
441 Try to resist the temptation of directly editing the <filename>.config</filename>
442 file found in the
443 <link linkend='build-directory'>Build Directory</link> at
444 <filename>tmp/sysroots/&lt;machine-name&gt;/kernel</filename>.
445 Doing so, can produce unexpected results when the OpenEmbedded build system
446 regenerates the configuration file.</para>
447 <para>Once you are satisfied with the configuration changes made using
448 <filename>menuconfig</filename>, you can directly examine the
449 <filename>.config</filename> file against a saved original and gather those
450 changes into a config fragment to be referenced from within the kernel's
451 <filename>.bbappend</filename> file.</para></listitem>
452 <listitem><para><emphasis>Rebuild the kernel image with your changes</emphasis>:
453 Rebuilding the kernel image applies your changes.</para></listitem>
454 </orderedlist>
455 </para>
456 </section>
457 </section>
458</section>
459
460<section id='application-development-workflow'>
461 <title>Application Development Workflow</title>
462
463 <para> 30 <para>
464 Application development involves creating an application that you want 31 See all the unvarnished details of how this bug was diagnosed and
465 to run on your target hardware, which is running a kernel image created using the 32 solved here: Yocto Bug #3049
466 OpenEmbedded build system.
467 The Yocto Project provides an Application Development Toolkit (ADT) and
468 stand-alone cross-development toolchains that
469 facilitate quick development and integration of your application into its run-time environment.
470 Using the ADT and toolchains, you can compile and link your application.
471 You can then deploy your application to the actual hardware or to the QEMU emulator for testing.
472 If you are familiar with the popular <trademark class='trade'>Eclipse</trademark> IDE,
473 you can use an Eclipse Yocto Plug-in to
474 allow you to develop, deploy, and test your application all from within Eclipse.
475 </para> 33 </para>
476
477 <para>
478 While we strongly suggest using the ADT to develop your application, this option might not
479 be best for you.
480 If this is the case, you can still use pieces of the Yocto Project for your development process.
481 However, because the process can vary greatly, this manual does not provide detail on the process.
482 </para>
483
484 <section id='workflow-using-the-adt-and-eclipse'>
485 <title>Workflow Using the ADT and <trademark class='trade'>Eclipse</trademark></title>
486
487 <para>
488 To help you understand how application development works using the ADT, this section
489 provides an overview of the general development process and a detailed example of the process
490 as it is used from within the Eclipse IDE.
491 </para>
492
493 <para>
494 The following illustration and list summarize the application development general workflow.
495 </para>
496
497 <para>
498 <imagedata fileref="figures/app-dev-flow.png"
499 width="7in" depth="8in" align="center" scale="100" />
500 </para>
501
502 <para>
503 <orderedlist>
504 <listitem><para><emphasis>Prepare the Host System for the Yocto Project</emphasis>:
505 See
506 "<ulink url='&YOCTO_DOCS_QS_URL;#the-linux-distro'>The Linux Distributions</ulink>" and
507 "<ulink url='&YOCTO_DOCS_QS_URL;#packages'>The Packages</ulink>" sections both
508 in the Yocto Project Quick Start for requirements.</para></listitem>
509 <listitem><para><emphasis>Secure the Yocto Project Kernel Target Image</emphasis>:
510 You must have a target kernel image that has been built using the OpenEmbeded
511 build system.</para>
512 <para>Depending on whether the Yocto Project has a pre-built image that matches your target
513 architecture and where you are going to run the image while you develop your application
514 (QEMU or real hardware), the area from which you get the image differs.
515 <itemizedlist>
516 <listitem><para>Download the image from
517 <ulink url='&YOCTO_MACHINES_DL_URL;'><filename>machines</filename></ulink>
518 if your target architecture is supported and you are going to develop
519 and test your application on actual hardware.</para></listitem>
520 <listitem><para>Download the image from the
521 <ulink url='&YOCTO_QEMU_DL_URL;'>
522 <filename>machines/qemu</filename></ulink> if your target architecture is supported
523 and you are going to develop and test your application using the QEMU
524 emulator.</para></listitem>
525 <listitem><para>Build your image if you cannot find a pre-built image that matches
526 your target architecture.
527 If your target architecture is similar to a supported architecture, you can
528 modify the kernel image before you build it.
529 See the
530 "<link linkend='patching-the-kernel'>Patching the Kernel</link>"
531 section for an example.</para></listitem>
532 </itemizedlist></para>
533 <para>For information on pre-built kernel image naming schemes for images
534 that can run on the QEMU emulator, see the
535 "<ulink url='&YOCTO_DOCS_QS_URL;#downloading-the-pre-built-linux-kernel'>Downloading the Pre-Built Linux Kernel</ulink>"
536 section in the Yocto Project Quick Start.</para></listitem>
537 <listitem><para><emphasis>Install the ADT</emphasis>:
538 The ADT provides a target-specific cross-development toolchain, the root filesystem,
539 the QEMU emulator, and other tools that can help you develop your application.
540 While it is possible to get these pieces separately, the ADT Installer provides an
541 easy method.
542 You can get these pieces by running an ADT installer script, which is configurable.
543 For information on how to install the ADT, see the
544 "<ulink url='&YOCTO_DOCS_ADT_URL;#using-the-adt-installer'>Using the ADT Installer</ulink>"
545 section
546 in the Yocto Project Application Developer's Guide.</para></listitem>
547 <listitem><para><emphasis>If Applicable, Secure the Target Root Filesystem
548 and the Cross-development Toolchain</emphasis>:
549 If you choose not to install the ADT using the ADT Installer,
550 you need to find and download the appropriate root filesystem and
551 the cross-development toolchain.</para>
552 <para>You can find the tarballs for the root filesystem in the same area used
553 for the kernel image.
554 Depending on the type of image you are running, the root filesystem you need differs.
555 For example, if you are developing an application that runs on an image that
556 supports Sato, you need to get root filesystem that supports Sato.</para>
557 <para>You can find the cross-development toolchains at
558 <ulink url='&YOCTO_TOOLCHAIN_DL_URL;'><filename>toolchains</filename></ulink>.
559 Be sure to get the correct toolchain for your development host and your
560 target architecture.
561 See the "<ulink url='&YOCTO_DOCS_ADT_URL;#using-an-existing-toolchain-tarball'>Using a Cross-Toolchain Tarball</ulink>"
562 section in the Yocto Project Application Developer's Guide for information
563 and the
564 "<ulink url='&YOCTO_DOCS_QS_URL;#installing-the-toolchain'>Installing the Toolchain</ulink>"
565 in the Yocto Project Quick Start for information on finding and installing
566 the correct toolchain based on your host development system and your target
567 architecture.
568 </para></listitem>
569 <listitem><para><emphasis>Create and Build your Application</emphasis>:
570 At this point, you need to have source files for your application.
571 Once you have the files, you can use the Eclipse IDE to import them and build the
572 project.
573 If you are not using Eclipse, you need to use the cross-development tools you have
574 installed to create the image.</para></listitem>
575 <listitem><para><emphasis>Deploy the Image with the Application</emphasis>:
576 If you are using the Eclipse IDE, you can deploy your image to the hardware or to
577 QEMU through the project's preferences.
578 If you are not using the Eclipse IDE, then you need to deploy the application
579 to the hardware using other methods.
580 Or, if you are using QEMU, you need to use that tool and load your image in for testing.
581 </para></listitem>
582 <listitem><para><emphasis>Test and Debug the Application</emphasis>:
583 Once your application is deployed, you need to test it.
584 Within the Eclipse IDE, you can use the debugging environment along with the
585 set of user-space tools installed along with the ADT to debug your application.
586 Of course, the same user-space tools are available separately if you choose
587 not to use the Eclipse IDE.</para></listitem>
588 </orderedlist>
589 </para>
590 </section>
591
592 <section id='adt-eclipse'>
593 <title>Working Within Eclipse</title>
594
595 <para>
596 The Eclipse IDE is a popular development environment and it fully supports
597 development using the Yocto Project.
598 <note>This release of the Yocto Project supports both the Juno and Indigo versions
599 of the Eclipse IDE.
600 Thus, the following information provides setup information for both versions.
601 </note>
602 </para>
603
604 <para>
605 When you install and configure the Eclipse Yocto Project Plug-in into
606 the Eclipse IDE, you maximize your Yocto Project experience.
607 Installing and configuring the Plug-in results in an environment that
608 has extensions specifically designed to let you more easily develop software.
609 These extensions allow for cross-compilation, deployment, and execution of
610 your output into a QEMU emulation session.
611 You can also perform cross-debugging and profiling.
612 The environment also supports a suite of tools that allows you to perform
613 remote profiling, tracing, collection of power data, collection of
614 latency data, and collection of performance data.
615 </para>
616
617 <para>
618 This section describes how to install and configure the Eclipse IDE
619 Yocto Plug-in and how to use it to develop your application.
620 </para>
621
622 <section id='setting-up-the-eclipse-ide'>
623 <title>Setting Up the Eclipse IDE</title>
624
625 <para>
626 To develop within the Eclipse IDE, you need to do the following:
627 <orderedlist>
628 <listitem><para>Install the optimal version of the Eclipse IDE.</para></listitem>
629 <listitem><para>Configure the Eclipse IDE.</para></listitem>
630 <listitem><para>Install the Eclipse Yocto Plug-in.</para></listitem>
631 <listitem><para>Configure the Eclipse Yocto Plug-in.</para></listitem>
632 </orderedlist>
633 <note>
634 Do not install Eclipse from your distribution's package repository.
635 Be sure to install Eclipse from the official Eclipse download site as directed
636 in the next section.
637 </note>
638 </para>
639
640 <section id='installing-eclipse-ide'>
641 <title>Installing the Eclipse IDE</title>
642
643 <para>
644 It is recommended that you have the Juno 4.2 version of the
645 Eclipse IDE installed on your development system.
646 However, if you currently have the Indigo 3.7.2 version installed and you do
647 not want to upgrade the IDE, you can configure Indigo to work with the
648 Yocto Project.
649 See the
650 "<link linkend='configuring-the-eclipse-ide-indigo'>Configuring the Eclipse IDE (Indigo)</link>"
651 section.
652 </para>
653
654 <para>
655 If you don’t have the Juno 4.2 Eclipse IDE installed, you can find the tarball at
656 <ulink url='&ECLIPSE_MAIN_URL;'></ulink>.
657 From that site, choose the Eclipse Classic version particular to your development
658 host.
659 This version contains the Eclipse Platform, the Java Development
660 Tools (JDT), and the Plug-in Development Environment.
661 </para>
662
663 <para>
664 Once you have downloaded the tarball, extract it into a clean
665 directory.
666 For example, the following commands unpack and install the
667 downloaded Eclipse IDE tarball into a clean directory
668 using the default name <filename>eclipse</filename>:
669 <literallayout class='monospaced'>
670 $ cd ~
671 $ tar -xzvf ~/Downloads/eclipse-SDK-4.2-linux-gtk-x86_64.tar.gz
672 </literallayout>
673 </para>
674
675 <para>
676 If you have the Indigo 3.7.2 Eclipse IDE already installed and you want to use that
677 version, one issue exists that you need to be aware of regarding the Java
678 Virtual machine’s garbage collection (GC) process.
679 The GC process does not clean up the permanent generation
680 space (PermGen).
681 This space stores metadata descriptions of classes.
682 The default value is set too small and it could trigger an
683 out-of-memory error such as the following:
684 <literallayout class='monospaced'>
685 Java.lang.OutOfMemoryError: PermGen space
686 </literallayout>
687 </para>
688
689 <para>
690 This error causes the application to hang.
691 </para>
692
693 <para>
694 To fix this issue, you can use the <filename>--vmargs</filename>
695 option when you start the Indigo 3.7.2 Eclipse IDE
696 to increase the size of the permanent generation space:
697 <literallayout class='monospaced'>
698 eclipse --vmargs --XX:PermSize=256M
699 </literallayout>
700 </para>
701 </section>
702
703 <section id='configuring-the-eclipse-ide-juno'>
704 <title>Configuring the Eclipse IDE (Juno)</title>
705
706 <para>
707 This section presents the steps needed to configure the Juno 4.2 Eclipse IDE.
708 If you are using Indigo 3.7.2, see the
709 "<link linkend='configuring-the-eclipse-ide-indigo'>Configuring the Eclipse IDE (Indigo)</link>".
710 </para>
711
712 <para>
713 Before installing and configuring the Eclipse Yocto Plug-in, you need to configure
714 the Juno 4.2 Eclipse IDE.
715 Follow these general steps:
716 <orderedlist>
717 <listitem><para>Start the Eclipse IDE.</para></listitem>
718 <listitem><para>Make sure you are in your Workbench and select
719 "Install New Software" from the "Help" pull-down menu.
720 </para></listitem>
721 <listitem><para>Select <filename>Juno - &ECLIPSE_JUNO_URL;</filename>
722 from the "Work with:" pull-down menu.</para></listitem>
723 <listitem><para>Expand the box next to "Linux Tools" and select the
724 "LTTng - Linux Tracing Toolkit" boxes.</para></listitem>
725 <listitem><para>Expand the box next to "Mobile and Device Development" and select the
726 following boxes:
727 <itemizedlist>
728 <listitem><para><filename>C/C++ Remote Launch</filename></para></listitem>
729 <listitem><para><filename>Remote System Explorer End-user Runtime</filename></para></listitem>
730 <listitem><para><filename>Remote System Explorer User Actions</filename></para></listitem>
731 <listitem><para><filename>Target Management Terminal</filename></para></listitem>
732 <listitem><para><filename>TCF Remote System Explorer add-in</filename></para></listitem>
733 <listitem><para><filename>TCF Target Explorer</filename></para></listitem>
734 </itemizedlist></para></listitem>
735 <listitem><para>Expand the box next to <filename>Programming Languages</filename>
736 and select the <filename>Autotools Support for CDT</filename>
737 and <filename>C/C++ Development Tools</filename> boxes.</para></listitem>
738 <listitem><para>Complete the installation and restart the Eclipse IDE.</para></listitem>
739 </orderedlist>
740 </para>
741 </section>
742
743 <section id='configuring-the-eclipse-ide-indigo'>
744 <title>Configuring the Eclipse IDE (Indigo)</title>
745
746 <para>
747 This section presents the steps needed to configure the Indigo 3.7.2 Eclipse IDE.
748 If you are using Juno 4.2, see the
749 "<link linkend='configuring-the-eclipse-ide-juno'>Configuring the Eclipse IDE (Juno)</link>".
750 </para>
751
752 <para>
753 Before installing and configuring the Eclipse Yocto Plug-in, you need to configure
754 the Indigo 3.7.2 Eclipse IDE.
755 Follow these general steps:
756 <orderedlist>
757 <listitem><para>Start the Eclipse IDE.</para></listitem>
758 <listitem><para>Make sure you are in your Workbench and select
759 "Install New Software" from the "Help" pull-down menu.
760 </para></listitem>
761 <listitem><para>Select <filename>indigo - &ECLIPSE_INDIGO_URL;</filename>
762 from the "Work with:" pull-down menu.</para></listitem>
763 <listitem><para>Expand the box next to <filename>Programming Languages</filename>
764 and select the <filename>Autotools Support for CDT (incubation)</filename>
765 and <filename>C/C++ Development Tools</filename> boxes.</para></listitem>
766 <listitem><para>Expand the box next to "Linux Tools" and select the
767 "LTTng - Linux Tracing Toolkit(incubation)" boxes.</para></listitem>
768 <listitem><para>Complete the installation and restart the Eclipse IDE.</para></listitem>
769 <listitem><para>After the Eclipse IDE restarts and from the Workbench, select
770 "Install New Software" from the "Help" pull-down menu.</para></listitem>
771 <listitem><para>Click the
772 "Available Software Sites" link.</para></listitem>
773 <listitem><para>Check the box next to
774 <filename>&ECLIPSE_UPDATES_URL;</filename>
775 and click "OK".</para></listitem>
776 <listitem><para>Select <filename>&ECLIPSE_UPDATES_URL;</filename>
777 from the "Work with:" pull-down menu.</para></listitem>
778 <listitem><para>Check the box next to <filename>TM and RSE Main Features</filename>.
779 </para></listitem>
780 <listitem><para>Expand the box next to <filename>TM and RSE Optional Add-ons</filename>
781 and select every item except <filename>RSE Unit Tests</filename> and
782 <filename>RSE WinCE Services (incubation)</filename>.</para></listitem>
783 <listitem><para>Complete the installation and restart the Eclipse IDE.</para></listitem>
784 <listitem><para>If necessary, select
785 "Install New Software" from the "Help" pull-down menu so you can click the
786 "Available Software Sites" link again.</para></listitem>
787 <listitem><para>After clicking "Available Software Sites", check the box next to
788 <filename>http://download.eclipse.org/tools/cdt/releases/indigo</filename>
789 and click "OK".</para></listitem>
790 <listitem><para>Select <filename>&ECLIPSE_INDIGO_CDT_URL;</filename>
791 from the "Work with:" pull-down menu.</para></listitem>
792 <listitem><para>Check the box next to <filename>CDT Main Features</filename>.
793 </para></listitem>
794 <listitem><para>Expand the box next to <filename>CDT Optional Features</filename>
795 and select <filename>C/C++ Remote Launch</filename> and
796 <filename>Target Communication Framework (incubation)</filename>.</para></listitem>
797 <listitem><para>Complete the installation and restart the Eclipse IDE.</para></listitem>
798 </orderedlist>
799 </para>
800 </section>
801
802 <section id='installing-the-eclipse-yocto-plug-in'>
803 <title>Installing or Accessing the Eclipse Yocto Plug-in</title>
804
805 <para>
806 You can install the Eclipse Yocto Plug-in into the Eclipse IDE
807 one of two ways: use the Yocto Project's Eclipse Update site to install the pre-built plug-in,
808 or build and install the plug-in from the latest source code.
809 If you don't want to permanently install the plug-in but just want to try it out
810 within the Eclipse environment, you can import the plug-in project from the
811 Yocto Project's Source Repositories.
812 </para>
813
814 <section id='new-software'>
815 <title>Installing the Pre-built Plug-in from the Yocto Project Eclipse Update Site</title>
816
817 <para>
818 To install the Eclipse Yocto Plug-in from the update site,
819 follow these steps:
820 <orderedlist>
821 <listitem><para>Start up the Eclipse IDE.</para></listitem>
822 <listitem><para>In Eclipse, select "Install New Software" from the "Help" menu.</para></listitem>
823 <listitem><para>Click "Add..." in the "Work with:" area.</para></listitem>
824 <listitem><para>Enter
825 <filename>&ECLIPSE_DL_PLUGIN_URL;</filename>
826 in the URL field and provide a meaningful name in the "Name" field.</para></listitem>
827 <listitem><para>Click "OK" to have the entry added to the "Work with:"
828 drop-down list.</para></listitem>
829 <listitem><para>Select the entry for the plug-in from the "Work with:" drop-down
830 list.</para></listitem>
831 <listitem><para>Check the box next to <filename>Development tools and SDKs for Yocto Linux</filename>.
832 </para></listitem>
833 <listitem><para>Complete the remaining software installation steps and
834 then restart the Eclipse IDE to finish the installation of the plug-in.
835 </para></listitem>
836 </orderedlist>
837 </para>
838 </section>
839
840 <section id='zip-file-method'>
841 <title>Installing the Plug-in Using the Latest Source Code</title>
842
843 <para>
844 To install the Eclipse Yocto Plug-in from the latest source code, follow these steps:
845 <orderedlist>
846 <listitem><para>Open a shell and create a Git repository with:
847 <literallayout class='monospaced'>
848 $ git clone git://git.yoctoproject.org/eclipse-poky yocto-eclipse
849 </literallayout>
850 For this example, the repository is named
851 <filename>~/yocto-eclipse</filename>.</para></listitem>
852 <listitem><para>Change to the directory where you set up
853 the Git repository:
854 <literallayout class='monospaced'>
855 $ cd ~/yocto-eclipse
856 </literallayout></para></listitem>
857 <listitem><para>Be sure you are in the right branch for your Git repository.
858 For this release set the branch to <filename>&DISTRO_NAME;</filename>:
859 <literallayout class='monospaced'>
860 $ git checkout -b &DISTRO_NAME; origin/&DISTRO_NAME;
861 </literallayout></para></listitem>
862 <listitem><para>Change to the <filename>scripts</filename>
863 directory within the Git repository:
864 <literallayout class='monospaced'>
865 $ cd scripts
866 </literallayout></para></listitem>
867 <listitem><para>Set up the local build environment by running the
868 setup script:
869 <literallayout class='monospaced'>
870 $ ./setup.sh
871 </literallayout></para></listitem>
872 <listitem><para>When the script finishes execution, it prompts
873 you with instructions on how to run the
874 <filename>build.sh</filename> script, which is also in
875 the <filename>scripts</filename> of the
876 Git repository created earlier.
877 </para></listitem>
878 <listitem><para>Run the <filename>build.sh</filename> script
879 as directed.
880 Be sure to provide the name of the Git branch along with the
881 Yocto Project release you are using.
882 Here is an example that uses the <filename>&DISTRO_NAME;</filename> branches:
883 <literallayout class='monospaced'>
884 $ ECLIPSE_HOME=/home/scottrif/yocto-eclipse/scripts/eclipse ./build.sh &DISTRO_NAME; &DISTRO_NAME;
885 </literallayout>
886 After running the script, the file
887 <filename>org.yocto.sdk-&lt;release&gt;-&lt;date&gt;-archive.zip</filename>
888 is in the current directory.</para></listitem>
889 <listitem><para>If necessary, start the Eclipse IDE and be sure you are in the
890 Workbench.</para></listitem>
891 <listitem><para>Select "Install New Software" from the "Help" pull-down menu.
892 </para></listitem>
893 <listitem><para>Click "Add".</para></listitem>
894 <listitem><para>Provide anything you want in the "Name" field.</para></listitem>
895 <listitem><para>Click "Archive" and browse to the ZIP file you built
896 in step seven.
897 This ZIP file should not be "unzipped", and must be the
898 <filename>*archive.zip</filename> file created by running the
899 <filename>build.sh</filename> script.</para></listitem>
900 <listitem><para>Click through the "Okay" buttons.</para></listitem>
901 <listitem><para>Check the box next to the new entry in the installation window and complete
902 the installation.</para></listitem>
903 <listitem><para>Restart the Eclipse IDE if necessary.</para></listitem>
904 </orderedlist>
905 </para>
906
907 <para>
908 At this point you should be able to configure the Eclipse Yocto Plug-in as described in the
909 "<link linkend='configuring-the-eclipse-yocto-plug-in'>Configuring the Eclipse Yocto Plug-in</link>"
910 section.</para>
911 </section>
912
913 <section id='yocto-project-source'>
914 <title>Importing the Plug-in Project into the Eclipse Environment</title>
915
916 <para>
917 Importing the Eclipse Yocto Plug-in project from the Yocto Project source repositories
918 is useful when you want to try out the latest plug-in from the tip of plug-in's
919 development tree.
920 It is important to understand when you import the plug-in you are not installing
921 it into the Eclipse application.
922 Rather, you are importing the project and just using it.
923 To import the plug-in project, follow these steps:
924 <orderedlist>
925 <listitem><para>Open a shell and create a Git repository with:
926 <literallayout class='monospaced'>
927 $ git clone git://git.yoctoproject.org/eclipse-poky yocto-eclipse
928 </literallayout>
929 For this example, the repository is named
930 <filename>~/yocto-eclipse</filename>.</para></listitem>
931 <listitem><para>In Eclipse, select "Import" from the "File" menu.</para></listitem>
932 <listitem><para>Expand the "General" box and select "existing projects into workspace"
933 and then click "Next".</para></listitem>
934 <listitem><para>Select the root directory and browse to
935 <filename>~/yocto-eclipse/plugins</filename>.</para></listitem>
936 <listitem><para>Three plug-ins exist: "org.yocto.bc.ui", "org.yocto.sdk.ide", and
937 "org.yocto.sdk.remotetools".
938 Select and import all of them.</para></listitem>
939 </orderedlist>
940 </para>
941
942 <para>
943 The left navigation pane in the Eclipse application shows the default projects.
944 Right-click on one of these projects and run it as an Eclipse application.
945 This brings up a second instance of Eclipse IDE that has the Yocto Plug-in.
946 </para>
947 </section>
948 </section>
949
950 <section id='configuring-the-eclipse-yocto-plug-in'>
951 <title>Configuring the Eclipse Yocto Plug-in</title>
952
953 <para>
954 Configuring the Eclipse Yocto Plug-in involves setting the Cross
955 Compiler options and the Target options.
956 The configurations you choose become the default settings for all projects.
957 You do have opportunities to change them later when
958 you configure the project (see the following section).
959 </para>
960
961 <para>
962 To start, you need to do the following from within the Eclipse IDE:
963 <itemizedlist>
964 <listitem><para>Choose <filename>Windows -&gt; Preferences</filename> to display
965 the <filename>Preferences</filename> Dialog</para></listitem>
966 <listitem><para>Click <filename>Yocto Project ADT</filename></para></listitem>
967 </itemizedlist>
968 </para>
969
970 <section id='configuring-the-cross-compiler-options'>
971 <title>Configuring the Cross-Compiler Options</title>
972
973 <para>
974 To configure the Cross Compiler Options, you must select the type of toolchain,
975 point to the toolchain, specify the sysroot location, and select the target architecture.
976 <itemizedlist>
977 <listitem><para><emphasis>Selecting the Toolchain Type:</emphasis>
978 Choose between <filename>Standalone pre-built toolchain</filename>
979 and <filename>Build system derived toolchain</filename> for Cross
980 Compiler Options.
981 <itemizedlist>
982 <listitem><para><emphasis>
983 <filename>Standalone Pre-built Toolchain:</filename></emphasis>
984 Select this mode when you are using a stand-alone cross-toolchain.
985 For example, suppose you are an application developer and do not
986 need to build a target image.
987 Instead, you just want to use an architecture-specific toolchain on an
988 existing kernel and target root filesystem.
989 </para></listitem>
990 <listitem><para><emphasis>
991 <filename>Build System Derived Toolchain:</filename></emphasis>
992 Select this mode if the cross-toolchain has been installed and built
993 as part of the Build Directory.
994 When you select <filename>Build system derived toolchain</filename>,
995 you are using the toolchain bundled
996 inside the Build Directory.
997 </para></listitem>
998 </itemizedlist>
999 </para></listitem>
1000 <listitem><para><emphasis>Point to the Toolchain:</emphasis>
1001 If you are using a stand-alone pre-built toolchain, you should be pointing to the
1002 <filename>&YOCTO_ADTPATH_DIR;</filename> directory.
1003 This is the location for toolchains installed by the ADT Installer or by hand.
1004 Sections "<ulink url='&YOCTO_DOCS_ADT_URL;#configuring-and-running-the-adt-installer-script'>Configuring
1005 and Running the ADT Installer Script</ulink>" and
1006 "<ulink url='&YOCTO_DOCS_ADT_URL;#using-an-existing-toolchain-tarball'>Using a Cross-Toolchain Tarball</ulink>"
1007 in the Yocto Project Application Developer's Guide
1008 describe two ways to install a stand-alone cross-toolchain in the
1009 <filename>/opt/poky</filename> directory.
1010 <note>It is possible to install a stand-alone cross-toolchain in a directory
1011 other than <filename>/opt/poky</filename>.
1012 However, doing so is discouraged.</note></para>
1013 <para>If you are using a system-derived toolchain, the path you provide
1014 for the <filename>Toolchain Root Location</filename>
1015 field is the Build Directory.
1016 See the "<ulink url='&YOCTO_DOCS_ADT_URL;#using-the-toolchain-from-within-the-build-tree'>Using
1017 BitBake and the Build Directory</ulink>" section in the Yocto Project Application
1018 Developer's Guide for information on how to install the toolchain into the build
1019directory.</para></listitem>
1020 <listitem><para><emphasis>Specify the Sysroot Location:</emphasis>
1021 This location is where the root filesystem for the target hardware resides.
1022 If you used the ADT Installer, then the location is
1023 <filename>/opt/poky/&lt;release&gt;</filename>.
1024 Additionally, when you use the ADT Installer, the same location is used for
1025 the QEMU user-space tools and the NFS boot process.</para>
1026 <para>If you used either of the other two methods to install the toolchain, then the
1027 location of the sysroot filesystem depends on where you separately
1028 extracted and intalled the filesystem.</para>
1029 <para>For information on how to install the toolchain and on how to extract
1030 and install the sysroot filesystem, see the
1031 "<ulink url='&YOCTO_DOCS_ADT_URL;#installing-the-adt'>Installing the ADT and Toolchains</ulink>" section.
1032 </para></listitem>
1033 <listitem><para><emphasis>Select the Target Architecture:</emphasis>
1034 The target architecture is the type of hardware you are
1035 going to use or emulate.
1036 Use the pull-down <filename>Target Architecture</filename> menu to make
1037 your selection.
1038 The pull-down menu should have the supported architectures.
1039 If the architecture you need is not listed in the menu, you
1040 will need to build the image.
1041 See the "<ulink url='&YOCTO_DOCS_QS_URL;#building-image'>Building an Image</ulink>" section
1042 of the Yocto Project Quick Start for more information.</para></listitem>
1043 </itemizedlist>
1044 </para>
1045 </section>
1046
1047 <section id='configuring-the-target-options'>
1048 <title>Configuring the Target Options</title>
1049
1050 <para>
1051 You can choose to emulate hardware using the QEMU emulator, or you
1052 can choose to run your image on actual hardware.
1053 <itemizedlist>
1054 <listitem><para><emphasis><filename>QEMU:</filename></emphasis> Select this option if
1055 you will be using the QEMU emulator.
1056 If you are using the emulator, you also need to locate the kernel
1057 and specify any custom options.</para>
1058 <para>If you selected <filename>Build system derived toolchain</filename>,
1059 the target kernel you built will be located in the
1060 Build Directory in <filename>tmp/deploy/images</filename> directory.
1061 If you selected <filename>Standalone pre-built toolchain</filename>, the
1062 pre-built image you downloaded is located
1063 in the directory you specified when you downloaded the image.</para>
1064 <para>Most custom options are for advanced QEMU users to further
1065 customize their QEMU instance.
1066 These options are specified between paired angled brackets.
1067 Some options must be specified outside the brackets.
1068 In particular, the options <filename>serial</filename>,
1069 <filename>nographic</filename>, and <filename>kvm</filename> must all
1070 be outside the brackets.
1071 Use the <filename>man qemu</filename> command to get help on all the options
1072 and their use.
1073 The following is an example:
1074 <literallayout class='monospaced'>
1075 serial ‘&lt;-m 256 -full-screen&gt;’
1076 </literallayout></para>
1077 <para>
1078 Regardless of the mode, Sysroot is already defined as part of the
1079 Cross Compiler Options configuration in the
1080 <filename>Sysroot Location:</filename> field.</para></listitem>
1081 <listitem><para><emphasis><filename>External HW:</filename></emphasis> Select this option
1082 if you will be using actual hardware.</para></listitem>
1083 </itemizedlist>
1084 </para>
1085
1086 <para>
1087 Click the <filename>OK</filename> button to save your plug-in configurations.
1088 </para>
1089 </section>
1090 </section>
1091 </section>
1092
1093 <section id='creating-the-project'>
1094 <title>Creating the Project</title>
1095
1096 <para>
1097 You can create two types of projects: Autotools-based, or Makefile-based.
1098 This section describes how to create Autotools-based projects from within
1099 the Eclipse IDE.
1100 For information on creating Makefile-based projects in a terminal window, see the section
1101 "<ulink url='&YOCTO_DOCS_ADT_URL;#using-the-command-line'>Using the Command Line</ulink>"
1102 in the Yocto Project Application Developer's Guide.
1103 </para>
1104
1105 <para>
1106 To create a project based on a Yocto template and then display the source code,
1107 follow these steps:
1108 <orderedlist>
1109 <listitem><para>Select <filename>File -&gt; New -&gt; Project</filename>.</para></listitem>
1110 <listitem><para>Double click <filename>CC++</filename>.</para></listitem>
1111 <listitem><para>Double click <filename>C Project</filename> to create the project.</para></listitem>
1112 <listitem><para>Expand <filename>Yocto Project ADT Project</filename>.</para></listitem>
1113 <listitem><para>Select <filename>Hello World ANSI C Autotools Project</filename>.
1114 This is an Autotools-based project based on a Yocto template.</para></listitem>
1115 <listitem><para>Put a name in the <filename>Project name:</filename> field.
1116 Do not use hyphens as part of the name.</para></listitem>
1117 <listitem><para>Click <filename>Next</filename>.</para></listitem>
1118 <listitem><para>Add information in the <filename>Author</filename> and
1119 <filename>Copyright notice</filename> fields.</para></listitem>
1120 <listitem><para>Be sure the <filename>License</filename> field is correct.</para></listitem>
1121 <listitem><para>Click <filename>Finish</filename>.</para></listitem>
1122 <listitem><para>If the "open perspective" prompt appears, click "Yes" so that you
1123 in the C/C++ perspective.</para></listitem>
1124 <listitem><para>The left-hand navigation pane shows your project.
1125 You can display your source by double clicking the project's source file.
1126 </para></listitem>
1127 </orderedlist>
1128 </para>
1129 </section>
1130
1131 <section id='configuring-the-cross-toolchains'>
1132 <title>Configuring the Cross-Toolchains</title>
1133
1134 <para>
1135 The earlier section, "<link linkend='configuring-the-eclipse-yocto-plug-in'>Configuring
1136 the Eclipse Yocto Plug-in</link>", sets up the default project
1137 configurations.
1138 You can override these settings for a given project by following these steps:
1139 <orderedlist>
1140 <listitem><para>Select <filename>Project -&gt; Change Yocto Project Settings</filename>:
1141 This selection brings up the <filename>Yocot Project Settings</filename> Dialog
1142 and allows you to make changes specific to an individual project.
1143 </para>
1144 <para>By default, the Cross Compiler Options and Target Options for a project
1145 are inherited from settings you provide using the <filename>Preferences</filename>
1146 Dialog as described earlier
1147 in the "<link linkend='configuring-the-eclipse-yocto-plug-in'>Configuring the Eclipse
1148 Yocto Plug-in</link>" section.
1149 The <filename>Yocto Project Settings</filename>
1150 Dialog allows you to override those default settings
1151 for a given project.</para></listitem>
1152 <listitem><para>Make your configurations for the project and click "OK".
1153 If you are running the Juno version of Eclipse, you can skip down to the next
1154 section where you build the project.
1155 If you are not working with Juno, you need to reconfigure the project as
1156 described in the next step.</para></listitem>
1157 <listitem><para>Select <filename>Project -&gt; Reconfigure Project</filename>:
1158 This selection reconfigures the project by running
1159 <filename>autogen.sh</filename> in the workspace for your project.
1160 The script also runs <filename>libtoolize</filename>, <filename>aclocal</filename>,
1161 <filename>autoconf</filename>, <filename>autoheader</filename>,
1162 <filename>automake --a</filename>, and
1163 <filename>./configure</filename>.
1164 Click on the <filename>Console</filename> tab beneath your source code to
1165 see the results of reconfiguring your project.</para></listitem>
1166 </orderedlist>
1167 </para>
1168 </section>
1169
1170 <section id='building-the-project'>
1171 <title>Building the Project</title>
1172
1173 <para>
1174 To build the project in Juno, right click on the project in the navigator pane and select
1175 <filename>Build Project</filename>.
1176 If you are not running Juno, select <filename>Project -&gt; Build Project</filename>.
1177 The console should update and you can note the cross-compiler you are using.
1178 </para>
1179 </section>
1180
1181 <section id='starting-qemu-in-user-space-nfs-mode'>
1182 <title>Starting QEMU in User Space NFS Mode</title>
1183
1184 <para>
1185 To start the QEMU emulator from within Eclipse, follow these steps:
1186 <orderedlist>
1187 <listitem><para>Expose the <filename>Run -&gt; External Tools</filename> menu.
1188 Your image should appear as a selectable menu item.
1189 </para></listitem>
1190 <listitem><para>Select your image from the menu to launch the
1191 emulator in a new window.</para></listitem>
1192 <listitem><para>If needed, enter your host root password in the shell window at the prompt.
1193 This sets up a <filename>Tap 0</filename> connection needed for running in user-space
1194 NFS mode.</para></listitem>
1195 <listitem><para>Wait for QEMU to launch.</para></listitem>
1196 <listitem><para>Once QEMU launches, you can begin operating within that
1197 environment.
1198 For example, you could determine the IP Address
1199 for the user-space NFS by using the <filename>ifconfig</filename> command.
1200 </para></listitem>
1201 </orderedlist>
1202 </para>
1203 </section>
1204
1205 <section id='deploying-and-debugging-the-application'>
1206 <title>Deploying and Debugging the Application</title>
1207
1208 <para>
1209 Once the QEMU emulator is running the image, using the Eclipse IDE
1210 you can deploy your application and use the emulator to perform debugging.
1211 Follow these steps to deploy the application.
1212 <orderedlist>
1213 <listitem><para>Select <filename>Run -&gt; Debug Configurations...</filename></para></listitem>
1214 <listitem><para>In the left area, expand <filename>C/C++Remote Application</filename>.</para></listitem>
1215 <listitem><para>Locate your project and select it to bring up a new
1216 tabbed view in the <filename>Debug Configurations</filename> Dialog.</para></listitem>
1217 <listitem><para>Enter the absolute path into which you want to deploy
1218 the application.
1219 Use the <filename>Remote Absolute File Path for C/C++Application:</filename> field.
1220 For example, enter <filename>/usr/bin/&lt;programname&gt;</filename>.</para></listitem>
1221 <listitem><para>Click on the <filename>Debugger</filename> tab to see the cross-tool debugger
1222 you are using.</para></listitem>
1223 <listitem><para>Click on the <filename>Main</filename> tab.</para></listitem>
1224 <listitem><para>Create a new connection to the QEMU instance
1225 by clicking on <filename>new</filename>.</para></listitem>
1226 <listitem><para>Select <filename>TCF</filename>, which means Target Communication
1227 Framework.</para></listitem>
1228 <listitem><para>Click <filename>Next</filename>.</para></listitem>
1229 <listitem><para>Clear out the <filename>host name</filename> field and enter the IP Address
1230 determined earlier.</para></listitem>
1231 <listitem><para>Click <filename>Finish</filename> to close the
1232 <filename>New Connections</filename> Dialog.</para></listitem>
1233 <listitem><para>Use the drop-down menu now in the <filename>Connection</filename> field and pick
1234 the IP Address you entered.</para></listitem>
1235 <listitem><para>Click <filename>Run</filename> to bring up a login screen
1236 and login.</para></listitem>
1237 <listitem><para>Accept the debug perspective.</para></listitem>
1238 </orderedlist>
1239 </para>
1240 </section>
1241
1242 <section id='running-user-space-tools'>
1243 <title>Running User-Space Tools</title>
1244
1245 <para>
1246 As mentioned earlier in the manual, several tools exist that enhance
1247 your development experience.
1248 These tools are aids in developing and debugging applications and images.
1249 You can run these user-space tools from within the Eclipse IDE through the
1250 <filename>YoctoTools</filename> menu.
1251 </para>
1252
1253 <para>
1254 Once you pick a tool, you need to configure it for the remote target.
1255 Every tool needs to have the connection configured.
1256 You must select an existing TCF-based RSE connection to the remote target.
1257 If one does not exist, click <filename>New</filename> to create one.
1258 </para>
1259
1260 <para>
1261 Here are some specifics about the remote tools:
1262 <itemizedlist>
1263 <listitem><para><emphasis><filename>OProfile</filename>:</emphasis> Selecting this tool causes
1264 the <filename>oprofile-server</filename> on the remote target to launch on
1265 the local host machine.
1266 The <filename>oprofile-viewer</filename> must be installed on the local host machine and the
1267 <filename>oprofile-server</filename> must be installed on the remote target,
1268 respectively, in order to use.
1269 You must compile and install the <filename>oprofile-viewer</filename> from the source code
1270 on your local host machine.
1271 Furthermore, in order to convert the target's sample format data into a form that the
1272 host can use, you must have <filename>oprofile</filename> version 0.9.4 or
1273 greater installed on the host.</para>
1274 <para>You can locate both the viewer and server from
1275 <ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi/oprofileui/'></ulink>.
1276 <note>The <filename>oprofile-server</filename> is installed by default on
1277 the <filename>core-image-sato-sdk</filename> image.</note></para></listitem>
1278 <listitem><para><emphasis><filename>Lttng2.0 ust trace import</filename>:</emphasis>
1279 Selecting this tool transfers the remote target's
1280 <filename>Lttng</filename> tracing data back to the local host machine
1281 and uses the <filename>Lttng</filename> Eclipse plug-in to graphically
1282 display the output.
1283 For information on how to use <filename>Lttng</filename> to trace an application,
1284 see <ulink url='http://lttng.org/documentation'></ulink>.
1285 <note>Do not use <filename>Lttng-user space (legacy)</filename> tool.
1286 This tool no longer has any upstream support.</note>
1287 </para>
1288 <para>Before you use the <filename>Lttng2.0 ust trace import</filename> tool,
1289 you need to setup the <filename>Lttng</filename> Eclipse plug-in and create a
1290 <filename>Tracing</filename> project.
1291 Do the following:
1292 <orderedlist>
1293 <listitem><para>Select <filename>Window -> Open Perspective -> Other</filename>
1294 and then select <filename>Tracing</filename>.</para></listitem>
1295 <listitem><para>Click <filename>OK</filename> to change the Eclipse perspective
1296 into the <filename>Tracing</filename> perspective.</para></listitem>
1297 <listitem><para>Create a new <filename>Tracing</filename> project by selecting
1298 <filename>File -> New -> Project</filename>.</para></listitem>
1299 <listitem><para>Choose <filename>Tracing -> Tracing Project</filename>.
1300 </para></listitem>
1301 <listitem><para>Generate your tracing data on the remote target.
1302 </para></listitem>
1303 <listitem><para>Click
1304 <filename>Yocto Project Tools -> Lttng2.0 ust trace import</filename>
1305 to start the data import process.</para></listitem>
1306 <listitem><para>Specify your remote connection name.</para></listitem>
1307 <listitem><para>For the Ust directory path, specify the location of
1308 your remote tracing data.
1309 Make sure the location ends with <filename>ust</filename> (e.g.
1310 <filename>/usr/mysession/ust</filename>.</para></listitem>
1311 <listitem><para>Click <filename>OK</filename> to complete the import process.
1312 The data is now in the local tracing project you created.</para></listitem>
1313 <listitem><para>Right click on the data and then use the menu to
1314 <filename>Select Trace Type... -> Common Trace Format -> Generic CTF Trace</filename>
1315 to map the tracing type.</para></listitem>
1316 <listitem><para>Right click the mouse and select <filename>Open</filename>
1317 to bring up the Eclipse <filename>Lttng</filename> Trace Viewer so you
1318 view the tracing data.</para></listitem>
1319 </orderedlist></para></listitem>
1320 <listitem><para><emphasis><filename>PowerTOP</filename>:</emphasis> Selecting this tool runs
1321 <filename>powertop</filename> on the remote target machine and displays the results in a
1322 new view called <filename>powertop</filename>.</para>
1323 <para><filename>Time to gather data(sec):</filename> is the time passed in seconds before data
1324 is gathered from the remote target for analysis.</para>
1325 <para><filename>show pids in wakeups list:</filename> corresponds to the
1326 <filename>-p</filename> argument
1327 passed to <filename>powertop</filename>.</para></listitem>
1328 <listitem><para><emphasis><filename>LatencyTOP and Perf</filename>:</emphasis>
1329 <filename>latencytop</filename> identifies system latency, while
1330 <filename>perf</filename> monitors the system's
1331 performance counter registers.
1332 Selecting either of these tools causes an RSE terminal view to appear
1333 from which you can run the tools.
1334 Both tools refresh the entire screen to display results while they run.</para></listitem>
1335 </itemizedlist>
1336 </para>
1337 </section>
1338
1339 <section id='customizing-an-image-using-a-bitbake-commander-project-and-hob'>
1340 <title>Customizing an Image Using a BitBake Commander Project and Hob</title>
1341
1342 <para>
1343 Within Eclipse, you can create a Yocto BitBake Commander project,
1344 edit the metadata, and then use the
1345 <ulink url='&YOCTO_HOME_URL;/projects/hob'>Hob</ulink> to build a customized
1346 image all within one IDE.
1347 </para>
1348
1349 <section id='creating-the-yocto-bitbake-commander-project'>
1350 <title>Creating the Yocto BitBake Commander Project</title>
1351
1352 <para>
1353 To create a Yocto BitBake Commander project, follow these steps:
1354 <orderedlist>
1355 <listitem><para>Select <filename>Window -> Open Perspective -> Other</filename>
1356 and then choose <filename>Bitbake Commander</filename>.</para></listitem>
1357 <listitem><para>Click <filename>OK</filename> to change the Eclipse perspective into the
1358 Bitbake Commander perspective.</para></listitem>
1359 <listitem><para>Select <filename>File -> New -> Project</filename> to create a new Yocto
1360 Bitbake Commander project.</para></listitem>
1361 <listitem><para>Choose <filename>Yocto Project Bitbake Commander -> New Yocto Project</filename>
1362 and click <filename>Next</filename>.</para></listitem>
1363 <listitem><para>Enter the Project Name and choose the Project Location.
1364 The Yocto project's metadata files will be put under the directory
1365 <filename>&lt;project_location&gt;/&lt;project_name&gt;</filename>.
1366 If that directory does not exist, you need to check
1367 the "Clone from Yocto Git Repository" box, which would execute a
1368 <filename>git clone</filename> command to get the project's metadata files.
1369 </para></listitem>
1370 <listitem><para>Select <filename>Finish</filename> to create the project.</para></listitem>
1371 </orderedlist>
1372 </para>
1373 </section>
1374
1375 <section id='editing-the-metadata-files'>
1376 <title>Editing the Metadata Files</title>
1377
1378 <para>
1379 After you create the Yocto Bitbake Commander project, you can modify the metadata files
1380 by opening them in the project.
1381 When editing recipe files (<filename>.bb</filename> files), you can view BitBake
1382 variable values and information by hovering the mouse pointer over the variable name and
1383 waiting a few seconds.
1384 </para>
1385
1386 <para>
1387 To edit the metadata, follow these steps:
1388 <orderedlist>
1389 <listitem><para>Select your Yocto Bitbake Commander project.</para></listitem>
1390 <listitem><para>Select <filename>File -> New -> Yocto BitBake Commander -> BitBake Recipe</filename>
1391 to open a new recipe wizard.</para></listitem>
1392 <listitem><para>Point to your source by filling in the "SRC_URL" field.
1393 For example, you can add a recipe to your
1394 <link linkend='source-directory'>Source Directory</link>
1395 by defining "SRC_URL" as follows:
1396 <literallayout class='monospaced'>
1397 ftp://ftp.gnu.org/gnu/m4/m4-1.4.9.tar.gz
1398 </literallayout></para></listitem>
1399 <listitem><para>Click "Populate" to calculate the archive md5, sha256,
1400 license checksum values and to auto-generate the recipe filename.</para></listitem>
1401 <listitem><para>Fill in the "Description" field.</para></listitem>
1402 <listitem><para>Be sure values for all required fields exist.</para></listitem>
1403 <listitem><para>Click <filename>Finish</filename>.</para></listitem>
1404 </orderedlist>
1405 </para>
1406 </section>
1407
1408 <section id='buiding-and-customizing-the-image'>
1409 <title>Building and Customizing the Image</title>
1410
1411 <para>
1412 To build and customize the image in Eclipse, follow these steps:
1413 <orderedlist>
1414 <listitem><para>Select your Yocto Bitbake Commander project.</para></listitem>
1415 <listitem><para>Select <filename>Project -> Launch HOB</filename>.</para></listitem>
1416 <listitem><para>Enter the Build Directory where you want to put your final images.</para></listitem>
1417 <listitem><para>Click <filename>OK</filename> to launch Hob.</para></listitem>
1418 <listitem><para>Use Hob to customize and build your own images.
1419 For information on Hob, see the
1420 <ulink url='&YOCTO_HOME_URL;/projects/hob'>Hob Project Page</ulink> on the
1421 Yocto Project website.</para></listitem>
1422 </orderedlist>
1423 </para>
1424 </section>
1425 </section>
1426 </section>
1427
1428 <section id='workflow-using-stand-alone-cross-development-toolchains'>
1429 <title>Workflow Using Stand-alone Cross-development Toolchains</title>
1430
1431 <para>
1432 If you want to develop an application without prior installation of the ADT, you
1433 still can employ the cross-development toolchain, the QEMU emulator, and a number of supported
1434 target image files.
1435 You just need to follow these general steps:
1436 <orderedlist>
1437 <listitem><para><emphasis>Install the cross-development toolchain for your target hardware:</emphasis>
1438 For information on how to install the toolchain, see the
1439 "<ulink url='&YOCTO_DOCS_ADT_URL;#using-an-existing-toolchain-tarball'>Using a Cross-Toolchain Tarball</ulink>"
1440 section
1441 in the Yocto Project Application Developer's Guide.</para></listitem>
1442 <listitem><para><emphasis>Download the Target Image:</emphasis> The Yocto Project supports
1443 several target architectures and has many pre-built kernel images and root filesystem
1444 images.</para>
1445 <para>If you are going to develop your application on hardware, go to the
1446 <ulink url='&YOCTO_MACHINES_DL_URL;'><filename>machines</filename></ulink>
1447 download area and choose a target machine area
1448 from which to download the kernel image and root filesystem.
1449 This download area could have several files in it that support development using
1450 actual hardware.
1451 For example, the area might contain <filename>.hddimg</filename> files that combine the
1452 kernel image with the filesystem, boot loaders, etc.
1453 Be sure to get the files you need for your particular development process.</para>
1454 <para>If you are going to develop your application and then run and test it using the QEMU
1455 emulator, go to the
1456 <ulink url='&YOCTO_QEMU_DL_URL;'><filename>machines/qemu</filename></ulink>
1457 download area.
1458 From this area, go down into the directory for your target architecture
1459 (e.g. <filename>qemux86_64</filename> for an
1460 <trademark class='registered'>Intel</trademark>-based 64-bit architecture).
1461 Download kernel, root filesystem, and any other files you need for your process.
1462 <note>In order to use the root filesystem in QEMU, you need to extract it.
1463 See the
1464 "<ulink url='&YOCTO_DOCS_ADT_URL;#extracting-the-root-filesystem'>Extracting the Root Filesystem</ulink>"
1465 section for information on how to extract the root filesystem.</note></para></listitem>
1466 <listitem><para><emphasis>Develop and Test your Application:</emphasis> At this point,
1467 you have the tools to develop your application.
1468 If you need to separately install and use the QEMU emulator, you can go to
1469 <ulink url='http://www.qemu.org'>QEMU Home Page</ulink> to download and learn about the
1470 emulator.</para></listitem>
1471 </orderedlist>
1472 </para>
1473 </section>
1474</section>
1475
1476<section id="modifying-temporary-source-code">
1477 <title>Modifying Temporary Source Code</title>
1478
1479 <para>
1480 You might
1481 find it helpful during development to modify the temporary source code used by recipes
1482 to build packages.
1483 For example, suppose you are developing a patch and you need to experiment a bit
1484 to figure out your solution.
1485 After you have initially built the package, you can iteratively tweak the
1486 source code, which is located in the
1487 <link linkend='build-directory'>Build Directory</link>, and then
1488 you can force a re-compile and quickly test your altered code.
1489 Once you settle on a solution, you can then preserve your changes in the form of
1490 patches.
1491 You can accomplish these steps all within either a
1492 <ulink url='http://savannah.nongnu.org/projects/quilt'>Quilt</ulink> or
1493 <link linkend='git'>Git</link> workflow.
1494 </para>
1495
1496 <section id='finding-the-temporary-source-code'>
1497 <title>Finding the Temporary Source Code</title>
1498
1499 <para>
1500 During a build, the unpacked temporary source code used by recipes
1501 to build packages is available in the Build Directory as
1502 defined by the
1503 <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-S'>S</ulink></filename> variable.
1504 Below is the default value for the <filename>S</filename> variable as defined in the
1505 <filename>meta/conf/bitbake.conf</filename> configuration file in the
1506 <link linkend='source-directory'>Source Directory</link>:
1507 <literallayout class='monospaced'>
1508 S = ${WORKDIR}/${BP}
1509 </literallayout>
1510 You should be aware that many recipes override the <filename>S</filename> variable.
1511 For example, recipes that fetch their source from Git usually set
1512 <filename>S</filename> to <filename>${WORKDIR}/git</filename>.
1513 <note>
1514 The
1515 <ulink url='&YOCTO_DOCS_REF_URL;#var-BP'><filename>BP</filename></ulink>
1516 represents the base recipe name, which consists of the name and version:
1517 <literallayout class='monospaced'>
1518 BP = ${BPN}-${PV}
1519 </literallayout>
1520 </note>
1521 </para>
1522
1523 <para>
1524 The path to the work directory for the recipe
1525 (<ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink>) depends
1526 on the recipe name and the architecture of the target device.
1527 For example, here is the work directory for recipes and resulting packages that are
1528 not device-dependent:
1529 <literallayout class='monospaced'>
1530 ${TMPDIR}/work/${PACKAGE_ARCH}-poky-${TARGET_OS}/${PN}-${PV}-${PR}
1531 </literallayout>
1532 Let's look at an example without variables.
1533 Assuming a top-level <link linkend='source-directory'>Source Directory</link>
1534 named <filename>poky</filename>
1535 and a default Build Directory of <filename>poky/build</filename>,
1536 the following is the work directory for the <filename>acl</filename> recipe that
1537 creates the <filename>acl</filename> package:
1538 <literallayout class='monospaced'>
1539 ~/poky/build/tmp/work/i586-poky-linux/acl-2.2.51-r3
1540 </literallayout>
1541 </para>
1542
1543 <para>
1544 If your resulting package is dependent on the target device,
1545 the work directory varies slightly:
1546 <literallayout class='monospaced'>
1547 ${TMPDIR}/work/${MACHINE}-poky-${TARGET_OS}/${PN}-${PV}-${PR}
1548 </literallayout>
1549 Again, assuming top-level Source Directory named <filename>poky</filename>
1550 and a default Build Directory of <filename>poky/build</filename>, the
1551 following are the work and temporary source directories, respectively,
1552 for the <filename>acl</filename> package that is being
1553 built for a MIPS-based device:
1554 <literallayout class='monospaced'>
1555 ~/poky/build/tmp/work/mips-poky-linux/acl-2.2.51-r2
1556 ~/poky/build/tmp/work/mips-poky-linux/acl-2.2.51-r2/acl-2.2.51
1557 </literallayout>
1558 </para>
1559
1560 <note>
1561 To better understand how the OpenEmbedded build system resolves directories during the
1562 build process, see the glossary entries for the
1563 <ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink>,
1564 <ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink>,
1565 <ulink url='&YOCTO_DOCS_REF_URL;#var-TOPDIR'><filename>TOPDIR</filename></ulink>,
1566 <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_ARCH'><filename>PACKAGE_ARCH</filename></ulink>,
1567 <ulink url='&YOCTO_DOCS_REF_URL;#var-TARGET_OS'><filename>TARGET_OS</filename></ulink>,
1568 <ulink url='&YOCTO_DOCS_REF_URL;#var-PN'><filename>PN</filename></ulink>,
1569 <ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink>,
1570 and
1571 <ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink>
1572 variables in the Yocto Project Reference Manual.
1573 </note>
1574
1575 <para>
1576 Now that you know where to locate the directory that has the temporary source code,
1577 you can use a Quilt or Git workflow to make your edits, test the changes,
1578 and preserve the changes in the form of patches.
1579 </para>
1580 </section>
1581
1582 <section id="using-a-quilt-workflow">
1583 <title>Using a Quilt Workflow</title>
1584
1585 <para>
1586 <ulink url='http://savannah.nongnu.org/projects/quilt'>Quilt</ulink>
1587 is a powerful tool that allows you to capture source code changes without having
1588 a clean source tree.
1589 This section outlines the typical workflow you can use to modify temporary source code,
1590 test changes, and then preserve the changes in the form of a patch all using Quilt.
1591 </para>
1592
1593 <para>
1594 Follow these general steps:
1595 <orderedlist>
1596 <listitem><para><emphasis>Find the Source Code:</emphasis>
1597 The temporary source code used by the OpenEmbedded build system is kept in the
1598 Build Directory.
1599 See the
1600 "<link linkend='finding-the-temporary-source-code'>Finding the Temporary Source Code</link>"
1601 section to learn how to locate the directory that has the temporary source code for a
1602 particular package.</para></listitem>
1603 <listitem><para><emphasis>Change Your Working Directory:</emphasis>
1604 You need to be in the directory that has the temporary source code.
1605 That directory is defined by the
1606 <ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink>
1607 variable.</para></listitem>
1608 <listitem><para><emphasis>Create a New Patch:</emphasis>
1609 Before modifying source code, you need to create a new patch.
1610 To create a new patch file, use <filename>quilt new</filename> as below:
1611 <literallayout class='monospaced'>
1612 $ quilt new my_changes.patch
1613 </literallayout></para></listitem>
1614 <listitem><para><emphasis>Notify Quilt and Add Files:</emphasis>
1615 After creating the patch, you need to notify Quilt about the files
1616 you plan to edit.
1617 You notify Quilt by adding the files to the patch you just created:
1618 <literallayout class='monospaced'>
1619 $ quilt add file1.c file2.c file3.c
1620 </literallayout>
1621 </para></listitem>
1622 <listitem><para><emphasis>Edit the Files:</emphasis>
1623 Make your changes in the temporary source code to the files you added
1624 to the patch.</para></listitem>
1625 <listitem><para><emphasis>Test Your Changes:</emphasis>
1626 Once you have modified the source code, the easiest way to test your changes
1627 is by calling the <filename>compile</filename> task as shown in the following example:
1628 <literallayout class='monospaced'>
1629 $ bitbake -c compile -f &lt;name_of_package&gt;
1630 </literallayout>
1631 The <filename>-f</filename> or <filename>--force</filename>
1632 option forces re-execution of the specified task.
1633 If you find problems with your code, you can just keep editing and
1634 re-testing iteratively until things work as expected.
1635 <note>All the modifications you make to the temporary source code
1636 disappear once you <filename>-c clean</filename> or
1637 <filename>-c cleanall</filename> with BitBake for the package.
1638 Modifications will also disappear if you use the <filename>rm_work</filename>
1639 feature as described in the
1640 "<ulink url='&YOCTO_DOCS_QS_URL;#building-image'>Building an Image</ulink>"
1641 section of the Yocto Project Quick Start.
1642 </note></para></listitem>
1643 <listitem><para><emphasis>Generate the Patch:</emphasis>
1644 Once your changes work as expected, you need to use Quilt to generate the final patch that
1645 contains all your modifications.
1646 <literallayout class='monospaced'>
1647 $ quilt refresh
1648 </literallayout>
1649 At this point the <filename>my_changes.patch</filename> file has all your edits made
1650 to the <filename>file1.c</filename>, <filename>file2.c</filename>, and
1651 <filename>file3.c</filename> files.</para>
1652 <para>You can find the resulting patch file in the <filename>patches/</filename>
1653 subdirectory of the source (<filename>S</filename>) directory.</para></listitem>
1654 <listitem><para><emphasis>Copy the Patch File:</emphasis>
1655 For simplicity, copy the patch file into a directory named <filename>files</filename>,
1656 which you can create in the same directory that holds the recipe
1657 (<filename>.bb</filename>) file or the
1658 append (<filename>.bbappend</filename>) file.
1659 Placing the patch here guarantees that the OpenEmbedded build system will find
1660 the patch.
1661 Next, add the patch into the
1662 <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'>SRC_URI</ulink></filename>
1663 of the recipe.
1664 Here is an example:
1665 <literallayout class='monospaced'>
1666 SRC_URI += "file://my_changes.patch"
1667 </literallayout></para></listitem>
1668 <listitem><para><emphasis>Increment the Recipe Revision Number:</emphasis>
1669 Finally, don't forget to 'bump' the
1670 <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PR'>PR</ulink></filename>
1671 value in the recipe since the resulting packages have changed.</para></listitem>
1672 </orderedlist>
1673 </para> </section>
1674
1675 <section id='using-a-git-workflow'>
1676 <title>Using a Git Workflow</title>
1677 <para>
1678 Git is an even more powerful tool that allows you to capture source code changes without having
1679 a clean source tree.
1680 This section outlines the typical workflow you can use to modify temporary source code,
1681 test changes, and then preserve the changes in the form of a patch all using Git.
1682 For general information on Git as it is used in the Yocto Project, see the
1683 "<link linkend='git'>Git</link>" section.
1684 </para>
1685
1686 <note>
1687 This workflow uses Git only for its ability to manage local changes to the source code
1688 and produce patches independent of any version control system used with the Yocto Project.
1689 </note>
1690
1691 <para>
1692 Follow these general steps:
1693 <orderedlist>
1694 <listitem><para><emphasis>Find the Source Code:</emphasis>
1695 The temporary source code used by the OpenEmbedded build system is kept in the
1696 Build Directory.
1697 See the
1698 "<link linkend='finding-the-temporary-source-code'>Finding the Temporary Source Code</link>"
1699 section to learn how to locate the directory that has the temporary source code for a
1700 particular package.</para></listitem>
1701 <listitem><para><emphasis>Change Your Working Directory:</emphasis>
1702 You need to be in the directory that has the temporary source code.
1703 That directory is defined by the
1704 <ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink>
1705 variable.</para></listitem>
1706 <listitem><para><emphasis>If needed, initialize a Git Repository:</emphasis>
1707 If the recipe you are working with does not use a Git fetcher,
1708 you need to set up a Git repository as follows:
1709 <literallayout class='monospaced'>
1710 $ git init
1711 $ git add *
1712 $ git commit -m "initial revision"
1713 </literallayout>
1714 The above Git commands initialize a Git repository that is based on the
1715 files in your current working directory, stage all the files, and commit
1716 the files.
1717 At this point, your Git repository is aware of all the source code files.
1718 Any edits you now make to files can be committed later and will be tracked by
1719 Git.</para></listitem>
1720 <listitem><para><emphasis>Edit the Files:</emphasis>
1721 Make your changes to the temporary source code.</para></listitem>
1722 <listitem><para><emphasis>Test Your Changes:</emphasis>
1723 Once you have modified the source code, the easiest way to test your changes
1724 is by calling the <filename>compile</filename> task as shown in the following example:
1725 <literallayout class='monospaced'>
1726 $ bitbake -c compile -f &lt;name_of_package&gt;
1727 </literallayout>
1728 The <filename>-f</filename> or <filename>--force</filename>
1729 option forces re-execution of the specified task.
1730 If you find problems with your code, you can just keep editing and
1731 re-testing iteratively until things work as expected.
1732 <note>All the modifications you make to the temporary source code
1733 disappear once you <filename>-c clean</filename>, <filename>-c cleansstate</filename>,
1734 or <filename>-c cleanall</filename> with BitBake for the package.
1735 Modifications will also disappear if you use the <filename>rm_work</filename>
1736 feature as described in the
1737 "<ulink url='&YOCTO_DOCS_QS_URL;#building-image'>Building an Image</ulink>"
1738 section of the Yocto Project Quick Start.
1739 </note></para></listitem>
1740 <listitem><para><emphasis>See the List of Files You Changed:</emphasis>
1741 Use the <filename>git status</filename> command to see what files you have actually edited.
1742 The ability to have Git track the files you have changed is an advantage that this
1743 workflow has over the Quilt workflow.
1744 Here is the Git command to list your changed files:
1745 <literallayout class='monospaced'>
1746 $ git status
1747 </literallayout></para></listitem>
1748 <listitem><para><emphasis>Stage the Modified Files:</emphasis>
1749 Use the <filename>git add</filename> command to stage the changed files so they
1750 can be committed as follows:
1751 <literallayout class='monospaced'>
1752 $ git add file1.c file2.c file3.c
1753 </literallayout></para></listitem>
1754 <listitem><para><emphasis>Commit the Staged Files and View Your Changes:</emphasis>
1755 Use the <filename>git commit</filename> command to commit the changes to the
1756 local repository.
1757 Once you have committed the files, you can use the <filename>git log</filename>
1758 command to see your changes:
1759 <literallayout class='monospaced'>
1760 $ git commit -m "&lt;commit-summary-message&gt;"
1761 $ git log
1762 </literallayout>
1763 <note>The name of the patch file created in the next step is based on your
1764 <filename>commit-summary-message</filename>.</note></para></listitem>
1765 <listitem><para><emphasis>Generate the Patch:</emphasis>
1766 Once the changes are committed, use the <filename>git format-patch</filename>
1767 command to generate a patch file:
1768 <literallayout class='monospaced'>
1769 $ git format-patch -1
1770 </literallayout>
1771 Specifying "-1" causes Git to generate the
1772 patch file for the most recent commit.</para>
1773 <para>At this point, the patch file has all your edits made
1774 to the <filename>file1.c</filename>, <filename>file2.c</filename>, and
1775 <filename>file3.c</filename> files.
1776 You can find the resulting patch file in the current directory and it
1777 is named according to the <filename>git commit</filename> summary line.
1778 The patch file ends with <filename>.patch</filename>.</para></listitem>
1779 <listitem><para><emphasis>Copy the Patch File:</emphasis>
1780 For simplicity, copy the patch file into a directory named <filename>files</filename>,
1781 which you can create in the same directory that holds the recipe
1782 (<filename>.bb</filename>) file or the
1783 append (<filename>.bbappend</filename>) file.
1784 Placing the patch here guarantees that the OpenEmbedded build system will find
1785 the patch.
1786 Next, add the patch into the
1787 <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'>SRC_URI</ulink></filename>
1788 of the recipe.
1789 Here is an example:
1790 <literallayout class='monospaced'>
1791 SRC_URI += "file://0001-&lt;commit-summary-message&gt;.patch"
1792 </literallayout></para></listitem>
1793 <listitem><para><emphasis>Increment the Recipe Revision Number:</emphasis>
1794 Finally, don't forget to 'bump' the
1795 <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PR'>PR</ulink></filename>
1796 value in the recipe since the resulting packages have changed.</para></listitem>
1797 </orderedlist>
1798 </para>
1799 </section>
1800</section>
1801
1802<section id='image-development-using-hob'>
1803 <title>Image Development Using Hob</title>
1804
1805 <para>
1806 The <ulink url='&YOCTO_HOME_URL;/projects/hob'>Hob</ulink> is a graphical user interface for the
1807 OpenEmbedded build system, which is based on BitBake.
1808 You can use the Hob to build custom operating system images within the Yocto Project build environment.
1809 Hob simply provides a friendly interface over the build system used during system development.
1810 In other words, building images with the Hob lets you take care of common build tasks more easily.
1811 </para>
1812
1813 <para>
1814 For a better understanding of Hob, see the project page at
1815 <ulink url='&YOCTO_HOME_URL;/projects/hob'></ulink> on the Yocto Project website.
1816 The page has a short introductory training video on Hob.
1817 The following lists some features of Hob:
1818 <itemizedlist>
1819 <listitem><para>You can setup and run Hob using these commands:
1820 <literallayout class='monospaced'>
1821 $ source oe-init-build-env
1822 $ hob
1823 </literallayout></para></listitem>
1824 <listitem><para>You can set the
1825 <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
1826 for which you are building the image.</para></listitem>
1827 <listitem><para>You can modify various policy settings such as the package format used to build with,
1828 the parrallelism BitBake uses, whether or not to build an external toolchain, and which host
1829 to build against.</para></listitem>
1830 <listitem><para>You can manage
1831 <link linkend='understanding-and-creating-layers'>layers</link>.</para></listitem>
1832 <listitem><para>You can select a base image and then add extra packages for your custom build.
1833 </para></listitem>
1834 <listitem><para>You can launch and monitor the build from within Hob.</para></listitem>
1835 </itemizedlist>
1836 </para>
1837</section>
1838
1839<section id="platdev-appdev-devshell">
1840 <title>Using a Development Shell</title>
1841
1842 <para>
1843 When debugging certain commands or even when just editing packages,
1844 <filename>devshell</filename> can be a useful tool.
1845 When you invoke <filename>devshell</filename>, source files are
1846 extracted into your working directory and patches are applied.
1847 Then, a new terminal is opened and you are placed in the working directory.
1848 In the new terminal, all the OpenEmbedded build-related environment variables are
1849 still defined so you can use commands such as <filename>configure</filename> and
1850 <filename>make</filename>.
1851 The commands execute just as if the OpenEmbedded build system were executing them.
1852 Consequently, working this way can be helpful when debugging a build or preparing
1853 software to be used with the OpenEmbedded build system.
1854 </para>
1855
1856 <para>
1857 Following is an example that uses <filename>devshell</filename> on a target named
1858 <filename>matchbox-desktop</filename>:
1859 <literallayout class='monospaced'>
1860 $ bitbake matchbox-desktop -c devshell
1861 </literallayout>
1862 </para>
1863
1864 <para>
1865 This command spawns a terminal with a shell prompt within the OpenEmbedded build environment.
1866 The <ulink url='&YOCTO_DOCS_REF_URL;#var-OE_TERMINAL'><filename>OE_TERMINAL</filename></ulink>
1867 controls what type of shell is opened.
1868 </para>
1869
1870 <para>
1871 For spawned terminals, the following occurs:
1872 <itemizedlist>
1873 <listitem><para>The <filename>PATH</filename> variable includes the
1874 cross-toolchain.</para></listitem>
1875 <listitem><para>The <filename>pkgconfig</filename> variables find the correct
1876 <filename>.pc</filename> files.</para></listitem>
1877 <listitem><para>The <filename>configure</filename> command finds the
1878 Yocto Project site files as well as any other necessary files.</para></listitem>
1879 </itemizedlist>
1880 </para>
1881
1882 <para>
1883 Within this environment, you can run configure or compile
1884 commands as if they were being run by
1885 the OpenEmbedded build system itself.
1886 As noted earlier, the working directory also automatically changes to the
1887 Source Directory (<ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink>).
1888 </para>
1889
1890 <para>
1891 When you are finished, you just exit the shell or close the terminal window.
1892 </para>
1893
1894 <note>
1895 <para>
1896 It is worth remembering that when using <filename>devshell</filename>
1897 you need to use the full compiler name such as <filename>arm-poky-linux-gnueabi-gcc</filename>
1898 instead of just using <filename>gcc</filename>.
1899 The same applies to other applications such as <filename>binutils</filename>,
1900 <filename>libtool</filename> and so forth.
1901 BitBake sets up environment variables such as <filename>CC</filename>
1902 to assist applications, such as <filename>make</filename> to find the correct tools.
1903 </para>
1904
1905 <para>
1906 It is also worth noting that <filename>devshell</filename> still works over
1907 X11 forwarding and similar situations
1908 </para>
1909 </note>
1910</section> 34</section>
1911 35
1912</chapter> 36</chapter>
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