From 99e39f6c12375bac757e243b3381a1384f37b74d Mon Sep 17 00:00:00 2001 From: Scott Rifenbark Date: Fri, 15 Jun 2012 05:24:05 -0700 Subject: documentation/bsp-guide/bsp.xml: 1.1.2 variables and updates First pass at implementing the poky.ent variables. Also made some text additions. (From yocto-docs rev: 648f01785fefacbce653473d64e0467bbdaebfde) Signed-off-by: Scott Rifenbark Signed-off-by: Richard Purdie --- documentation/bsp-guide/bsp.xml | 1201 +++++++++++++++++++++++++++++++-------- 1 file changed, 978 insertions(+), 223 deletions(-) (limited to 'documentation') diff --git a/documentation/bsp-guide/bsp.xml b/documentation/bsp-guide/bsp.xml index 631735ea22..d467ceb8fa 100644 --- a/documentation/bsp-guide/bsp.xml +++ b/documentation/bsp-guide/bsp.xml @@ -1,5 +1,6 @@ +"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd" +[ %poky; ] > @@ -18,77 +19,36 @@ - This section (or document if you are reading the BSP Developer's Guide) defines - a structure for these components - so that BSPs follow a commonly understood layout. - Providing a common form allows end-users to understand and become familiar - with the layout. - A common form also encourages standardization - of software support of hardware. + This chapter (or document if you are reading the BSP Developer's Guide) + talks about BSP Layers, defines a structure for components + so that BSPs follow a commonly understood layout, discusses how to customize + a recipe for a BSP, addresses BSP licensing, and provides information that + shows you how to create and manage a + BSP Layer using two Yocto Project + BSP Tools. - - The information here does not provide an example of how to create a BSP. - For examples on how to create a BSP, see the - - BSP Development Example in - - The Yocto Project Development Manual. - You can also see the - - wiki page. - - - - The proposed format does have elements that are specific to the Yocto Project and - OpenEmbedded build systems. - It is intended that this information can be - used by other systems besides Yocto Project and OpenEmbedded and that it will be simple - to extract information and convert it to other formats if required. - Yocto Project, through its standard layers mechanism, can directly accept the format - described as a layer. - The BSP captures all - the hardware-specific details in one place in a standard format, which is - useful for any person wishing to use the hardware platform regardless of - the build system they are using. - - - - The BSP specification does not include a build system or other tools - - it is concerned with the hardware-specific components only. - At the end - distribution point you can ship the BSP combined with a build system - and other tools. - However, it is important to maintain the distinction that these - are separate components that happen to be combined in certain end products. - - -
- Example Filesystem Layout +
+ BSP Layers - The BSP consists of a file structure inside a base directory, which uses the following - naming convention: + The BSP consists of a file structure inside a base directory. + Collectively, you can think of the base directory and the file structure + as a BSP Layer. + BSP Layers use the following naming convention: meta-<bsp_name> - - - "bsp_name" is a placeholder for the machine or platform name. - Here are some example base directory names: - - meta-emenlow - meta-n450 - meta-beagleboard - - The base directory (meta-<bsp_name>) is the root of the BSP layer. - This root is what you add to the BBLAYERS - variable in the build/conf/bblayers.conf file found in the - Yocto Project file's build directory. + The layer's base directory (meta-<bsp_name>) is the root + of the BSP Layer. + This root is what you add to the + BBLAYERS + variable in the conf/bblayers.conf file found in the + Yocto Project Build Directory. Adding the root allows the Yocto Project build system to recognize the BSP definition and from it build an image. Here is an example: @@ -99,15 +59,78 @@ /usr/local/src/yocto/meta-<bsp_name> \ " + + + + Some BSPs require additional layers on + top of the BSP's root layer in order to be functional. + For these cases, you also need to add those layers to the + BBLAYERS variable in order to build the BSP. + You must also specify in the "Dependencies" section of the BSP's + README file any requirements for additional + layers and, preferably, any + build instructions that might be contained elsewhere + in the README file. + + + + Some layers function as a layer to hold other BSP layers. + An example of this type of layer is the meta-intel layer. + The meta-intel layer contains over 10 individual BSP layers. + + + For more detailed information on layers, see the - "BitBake Layers" section of the Yocto Project Reference Manual. + "BitBake Layers" section of the Yocto Project Reference Manual. You can also see the detailed examples in the appendices of - - The Yocto Project Development Manual. + The Yocto Project Development Manual. + +
+ + +
+ Example Filesystem Layout + + + Providing a common form allows end-users to understand and become familiar + with the layout. + A common format also encourages standardization of software support of hardware. + + + + The proposed form does have elements that are specific to the Yocto Project and + OpenEmbedded build systems. + It is intended that this information can be + used by other systems besides Yocto Project and OpenEmbedded and that it will be simple + to extract information and convert it to other formats if required. + Yocto Project, through its standard layers mechanism, can directly accept the format + described as a layer. + The BSP captures all + the hardware-specific details in one place in a standard format, which is + useful for any person wishing to use the hardware platform regardless of + the build system they are using. + + + + The BSP specification does not include a build system or other tools - + it is concerned with the hardware-specific components only. + At the end-distribution point, you can ship the BSP combined with a build system + and other tools. + However, it is important to maintain the distinction that these + are separate components that happen to be combined in certain end products. - Below is the common form for the file structure inside a base directory. + Before looking at the common form for the file structure inside a BSP Layer, + you should be aware that some requirements do exist in order for a BSP to + be considered compliant with the Yocto Project. + For that list of requirements, see the + "Released BSP Requirements" + section. + + + + Below is the common form for the file structure inside a BSP Layer. While you can use this basic form for the standard, realize that the actual structures for specific BSPs could differ. @@ -115,10 +138,12 @@ meta-<bsp_name>/ meta-<bsp_name>/<bsp_license_file> meta-<bsp_name>/README + meta-<bsp_name>/README.sources meta-<bsp_name>/binary/<bootable_images> meta-<bsp_name>/conf/layer.conf meta-<bsp_name>/conf/machine/*.conf meta-<bsp_name>/recipes-bsp/* + meta-<bsp_name>/recipes-core/* meta-<bsp_name>/recipes-graphics/* meta-<bsp_name>/recipes-kernel/linux/linux-yocto_<kernel_rev>.bbappend @@ -130,7 +155,8 @@ meta-crownbay/COPYING.MIT meta-crownbay/README - meta-crownbay/binary + meta-crownbay/README.sources + meta-crownbay/binary/ meta-crownbay/conf/ meta-crownbay/conf/layer.conf meta-crownbay/conf/machine/ @@ -171,7 +197,7 @@ License Files - You can find these files in the Yocto Project file's directory structure at: + You can find these files in the BSP Layer at: meta-<bsp_name>/<bsp_license_file> @@ -193,7 +219,7 @@
README File - You can find these files in the Yocto Project file's directory structure at: + You can find this file in the BSP Layer at: meta-<bsp_name>/README @@ -201,21 +227,41 @@ This file provides information on how to boot the live images that are optionally - included in the /binary directory. + included in the binary/ directory. The README file also provides special information needed for building the image. - Technically speaking a README is optional but it is highly - recommended that every BSP has one. + At a minimum, the README file must + contain a list of dependencies, such as the names of + any other layers on which the BSP depends and the name of + the BSP maintainer with his or her contact information. + +
+ +
+ README.sources File + + You can find this file in the BSP Layer at: + + meta-<bsp_name>/README.sources + + + + + This file provides information on where to locate the BSP source files. + For example, information provides where to find the sources that comprise + the images shipped with the BSP. + Information is also included to help you find the metadata used to generate the images + that ship with the BSP.
Pre-built User Binaries - You can find these files in the Yocto Project file's directory structure at: + You can find these files in the BSP Layer at: meta-<bsp_name>/binary/<bootable_images> @@ -225,24 +271,25 @@ This optional area contains useful pre-built kernels and user-space filesystem images appropriate to the target system. This directory typically contains graphical (e.g. sato) and minimal live images - when the BSP tarball has been created and made available in the Yocto Project website. + when the BSP tarball has been created and made available in the + Yocto Project website. You can use these kernels and images to get a system running and quickly get started on development tasks. The exact types of binaries present are highly hardware-dependent. - However, a README file should be present in the BSP file structure that explains how to use + However, a README file should be present in the BSP Layer that explains how to use the kernels and images with the target hardware. If pre-built binaries are present, source code to meet licensing requirements must also - be provided in some form. + exist in some form.
Layer Configuration File - You can find this file in the Yocto Project file's directory structure at: + You can find this file in the BSP Layer at: meta-<bsp_name>/conf/layer.conf @@ -253,13 +300,14 @@ Project layer, identifies the contents of the layer, and contains information about how Yocto Project should use it. Generally, a standard boilerplate file such as the following works. - In the following example you would replace "bsp" and "_bsp" with the actual name - of the BSP (i.e. <bsp_name> from the example template). + In the following example, you would replace "bsp" and + "_bsp" with the actual name + of the BSP (i.e. <bsp_name> from the example template). - # We have a conf directory, add to BBPATH + # We have a conf and classes directory, add to BBPATH BBPATH := "${BBPATH}:${LAYERDIR}" # We have a recipes directory containing .bb and .bbappend files, add to BBFILES @@ -272,16 +320,26 @@ + + To illustrate the string substitutions, here are the last three statements from the Crown + Bay conf/layer.conf file: + + BBFILE_COLLECTIONS += "crownbay" + BBFILE_PATTERN_crownbay := "^${LAYERDIR}/" + BBFILE_PRIORITY_crownbay = "6" + + + This file simply makes BitBake aware of the recipes and configuration directories. - This file must exist so that the Yocto Project build system can recognize the BSP. + The file must exist so that the Yocto Project build system can recognize the BSP.
Hardware Configuration Options - You can find these files in the Yocto Project file's directory structure at: + You can find these files in the BSP Layer at: meta-<bsp_name>/conf/machine/*.conf @@ -293,19 +351,20 @@ If the BSP supports multiple machines, multiple machine configuration files can be present. These filenames correspond to the values to which users have set the - MACHINE variable. + MACHINE variable. These files define things such as the kernel package to use - (PREFERRED_PROVIDER of virtual/kernel), the hardware drivers to + (PREFERRED_PROVIDER + of virtual/kernel), the hardware drivers to include in different types of images, any special software components that are needed, any bootloader information, and also any special image format requirements. - At least one machine file is required for a BSP layer. + Each BSP Layer requires at least one machine file. However, you can supply more than one file. For example, in the Crown Bay BSP shown earlier in this section, the conf/machine directory contains two configuration files: @@ -321,7 +380,7 @@ This crownbay.conf file could also include a hardware "tuning" file that is commonly used to - define the the package architecture and specify + define the package architecture and specify optimization flags, which are carefully chosen to give best performance on a given processor. @@ -341,7 +400,7 @@
Miscellaneous Recipe Files - You can find these files in the Yocto Project file's directory structure at: + You can find these files in the BSP Layer at: meta-<bsp_name>/recipes-bsp/* @@ -356,7 +415,10 @@ Furthermore, there are machine-specific settings used during the build that are defined by the machconfig files. In the Crown Bay example, two machconfig files exist: - one that supports the Intel EMGD and one that does not: + one that supports the + Intel Embedded + Media and Graphics Driver (Intel + EMGD) and one that does not: meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/machconfig meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay-noemgd/machconfig @@ -373,14 +435,16 @@
Core Recipe Files - You can find these files in the Yocto Project file's directory structure at: + You can find these files in the BSP Layer at: meta-<bsp_name>/recipes-core/* - This directory contains recipe files for the core. + This directory contains recipe files that are almost always necessary to build a + useful, working Linux image. + Thus, the term "core" is used to group these recipes. For example, in the Crown Bay BSP there is the task-core-tools.bbappend file, which is an append file used to recommend that the SystemTap package be included as a package when the image @@ -391,7 +455,7 @@
Display Support Files - You can find these files in the Yocto Project file's directory structure at: + You can find these files in the BSP Layer at: meta-<bsp_name>/recipes-graphics/* @@ -401,8 +465,12 @@ This optional directory contains recipes for the BSP if it has special requirements for graphics support. All files that are needed for the BSP to support a display are kept here. - For example, the Crown Bay BSP contains the following files that support - building a BSP that supports and does not support the Intel EMGD: + For example, the Crown Bay BSP contains two versions of the + xorg.conf file. + The version in crownbay builds a BSP that supports the + Intel Embedded Media Graphics Driver (EMGD), + while the version in crownbay-noemgd builds + a BSP that supports Video Electronics Standards Association (VESA) graphics only: meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config_0.1.bbappend meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/xorg.conf @@ -414,7 +482,7 @@
Linux Kernel Configuration - You can find these files in the Yocto Project file's directory structure at: + You can find these files in the BSP Layer at: meta-<bsp_name>/recipes-kernel/linux/linux-yocto_*.bbappend @@ -427,12 +495,11 @@ For your BSP, you typically want to use an existing Yocto Project kernel found in the Yocto Project repository at meta/recipes-kernel/linux. You can append your specific changes to the kernel recipe by using a - similarly named append file, which is located in the - meta-<bsp_name>/recipes-kernel/linux - directory. + similarly named append file, which is located in the BSP Layer (e.g. + the meta-<bsp_name>/recipes-kernel/linux directory). - Suppose you use a BSP that uses the linux-yocto_3.0.bb kernel, + Suppose the BSP uses the linux-yocto_3.0.bb kernel, which is the preferred kernel to use for developing a new BSP using the Yocto Project. In other words, you have selected the kernel in your <bsp_name>.conf file by adding the following statements: @@ -449,7 +516,10 @@ meta-crownbay/recipes-kernel/linux/linux-yocto_3.0.bbappend - The file contains the following: + The following listing shows the file. + Be aware that the actual commit ID strings in this example listing might be different + than the actual strings in the file from the meta-intel + Git source repository. FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:" @@ -467,8 +537,8 @@ SRCREV_machine_pn-linux-yocto_crownbay-noemgd ?= "2247da9131ea7e46ed4766a69bb1353dba22f873" SRCREV_meta_pn-linux-yocto_crownbay-noemgd ?= "d05450e4aef02c1b7137398ab3a9f8f96da74f52" - This append file contains statements used to support the Crown Bay BSP for both - Intel EMGD and non-EMGD. + This append file contains statements used to support the Crown Bay BSP for both + Intel EMGD and the VESA graphics. The build process, in this case, recognizes and uses only the statements that apply to the defined machine name - crownbay in this case. So, the applicable statements in the linux-yocto_3.0.bbappend @@ -503,14 +573,14 @@ For example, suppose you had a set of configuration options in a file called - defconfig. + myconfig. If you put that file inside a directory named /linux-yocto and then added a SRC_URI statement such as the following to the append file, those configuration options will be picked up and applied when the kernel is built. - SRC_URI += "file://defconfig" + SRC_URI += "file://myconfig" @@ -520,20 +590,26 @@ into their own files and add those by using a SRC_URI statement like the following in your append file: - SRC_URI += "file://defconfig \ + SRC_URI += "file://myconfig \ file://eth.cfg \ file://gfx.cfg" - The FILESEXTRAPATHS variable is in boilerplate form here - in order to make it easy to do that. - It basically allows those configuration files to be found by the build process. + The FILESEXTRAPATHS variable is in boilerplate form in the + previous example in order to make it easy to do that. + This variable must be in your layer or BitBake will not find the patches or + configurations even if you have them in your SRC_URI. + The FILESEXTRAPATHS variable enables the build process to + find those configuration files. Other methods exist to accomplish grouping and defining configuration options. - For example, you could directly add configuration options to the Yocto kernel + For example, if you are working with a local clone of the kernel repository, + you could checkout the kernel's meta branch, make your changes, + and then push the changes to the local bare clone of the kernel. + The result is that you directly add configuration options to the Yocto kernel meta branch for your BSP. The configuration options will likely end up in that location anyway if the BSP gets added to the Yocto Project. @@ -543,7 +619,7 @@ In general, however, the Yocto Project maintainers take care of moving the SRC_URI-specified - configuration options to the meta branch. + configuration options to the kernel's meta branch. Not only is it easier for BSP developers to not have to worry about putting those configurations in the branch, but having the maintainers do it allows them to apply 'global' knowledge about the kinds of common configuration options multiple BSPs in @@ -553,136 +629,815 @@
-
- BSP 'Click-Through' Licensing Procedure +
+ Requirements and Recommendations for Released BSPs - This section describes how - click-through licensing is expected to work. - Currently, this functionality is not yet implemented. - + + Certain requirements exist for a released BSP to be considered + compliant with the Yocto Project. + Additionally, a single recommendation also exists. + This section describes the requirements and recommendation for + released BSPs. + + +
+ Released BSP Requirements + + + Before looking at BSP requirements, you should consider the following: + + The requirements here assume the BSP layer is a well-formed, "legal" + layer that can be added to the Yocto Project. + For guidelines on creating a Yocto Project layer that meets these base requirements, see the + "BSP Layers" and the + "Understanding + and Creating Layers" in the Yocto Project Development Manual. + The requirements in this section apply regardless of how you + ultimately package a BSP. + You should consult the packaging and distribution guidelines for your + specific release process. + For an example of packaging and distribution requirements, see the + Third + Party BSP Release Process wiki page. + The requirements for the BSP as it is made available to a developer + are completely independent of the released form of the BSP. + For example, the BSP metadata can be contained within a Git repository + and could have a directory structure completely different from what appears + in the officially released BSP layer. + It is not required that specific packages or package + modifications exist in the BSP layer, beyond the requirements for general + compliance with the Yocto Project. + For example, no requirement exists dictating that a specific kernel or + kernel version be used in a given BSP. + + + + + Following are the requirements for a released BSP that conforms to the + Yocto Project: + + Layer Name: + The BSP must have a layer name that follows the Yocto + Project standards. + For information on BSP layer names, see the + "BSP Layers" section. + + File System Layout: + When possible, use the same directory names in your + BSP layer as listed in the recipes.txt file. + In particular, you should place recipes + (.bb files) and recipe + modifications (.bbappend files) into + recipes-* subdirectories by functional area + as outlined in recipes.txt. + If you cannot find a category in recipes.txt + to fit a particular recipe, you can make up your own + recipe-* subdirectory. + You can find recipes.txt in the + meta directory of the + Yocto + Project Files, or in the OpenEmbedded Core Layer + (openembedded-core) found at + . + + Within any particular recipes-* category, the layout + should match what is found in the OpenEmbedded Core + Git repository (openembedded-core) + or the Yocto Project Files (poky). + In other words, make sure you place related files in appropriately + related recipes-* subdirectories specific to the + recipe's function, or within a subdirectory containing a set of closely-related + recipes. + The recipes themselves should follow the general guidelines + for recipes used in the Yocto Project found in the + Yocto + Recipe and Patch Style Guide. + License File: + You must include a license file in the + meta-<bsp_name> directory. + This license covers the BSP metadata as a whole. + You must specify which license to use since there is no + default license if one is not specified. + See the + COPYING.MIT + file for the Fish River BSP in the meta-fishriver BSP layer + as an example. + README File: + You must include a README file in the + meta-<bsp_name> directory. + See the + README + file for the Fish River BSP in the meta-fishriver BSP layer + as an example. + At a minimum, the README file should + contain the following: + + A brief description about the hardware the BSP + targets. + A list of all the dependencies a + on which a BSP layer depends. + These dependencies are typically a list of required layers needed + to build the BSP. + However, the dependencies should also contain information regarding + any other dependencies the BSP might have. + Any required special licensing information. + For example, this information includes information on + special variables needed to satisfy a EULA, + or instructions on information needed to build or distribute + binaries built from the BSP metadata. + The name and contact information for the + BSP layer maintainer. + This is the person to whom patches and questions should + be sent. + Instructions on how to build the BSP using the BSP + layer. + Instructions on how to boot the BSP build from + the BSP layer. + Instructions on how to boot the binary images + contained in the /binary directory, + if present. + Information on any known bugs or issues that users + should know about when either building or booting the BSP + binaries. + + README.sources File: + You must include a README.sources in the + meta-<bsp_name> directory. + This file specifies exactly where you can find the sources used to + generate the binary images contained in the + /binary directory, if present. + See the + README.sources + file for the Fish River BSP in the meta-fishriver BSP layer + as an example. + Layer Configuration File: + You must include a conf/layer.conf in the + meta-<bsp_name> directory. + This file identifies the meta-<bsp_name> + BSP layer as a layer to the build system. + Machine Configuration File: + You must include a conf/machine/<bsp_name>.conf + in the meta-<bsp_name> directory. + This configuration file defines a machine target that can be built + using the BSP layer. + Multiple machine configuration files define variations of machine + configurations that are supported by the BSP. + If a BSP supports more multiple machine variations, you need to + adequately describe each variation in the BSP + README file. + Do not use multiple machine configuration files to describe disparate + hardware. + Multiple machine configuration files should describe very similar targets. + If you do have very different targets, you should create a separate + BSP. + It is completely possible for a developer to structure the + working repository as a conglomeration of unrelated BSP + files, and to possibly generate specifically targeted 'release' BSPs + from that directory using scripts or some other mechanism. + Such considerations are outside the scope of this document. + + + +
+ +
+ Released BSP Recommendations + + + Following are recommendations for a released BSP that conforms to the + Yocto Project: + + Bootable Images: + BSP releases + can contain one or more bootable images. + Including bootable images allows users to easily try out the BSP + on their own hardware. + In some cases, it might not be convenient to include a + bootable image. + In this case, you might want to make two versions of the + BSP available: one that contains binary images, and one + that does not. + The version that does not contain bootable images avoids + unnecessary download times for users not interested in the images. + + If you need to distribute a BSP and include bootable images or build kernel and + filesystems meant to allow users to boot the BSP for evaluation + purposes, you should put the images and artifacts within a + binary/ subdirectory located in the + meta-<bsp_name> directory. + If you do include a bootable image as part of the BSP and the image + was built by software covered by the GPL or other open source licenses, + it is your responsibility to understand + and meet all licensing requirements, which could include distribution + of source files. + Use a Yocto Linux Kernel: + Kernel recipes in the BSP should be based on a Yocto Linux kernel. + Basing your recipes on these kernels reduces the costs for maintaining + the BSP and increases its scalability. + See the Yocto Linux Kernel category in the + Yocto Source Repositories + for these kernels. + + +
+
+ +
+ Customizing a Recipe for a BSP - In some cases, a BSP contains separately licensed IP - (Intellectual Property) for a component that imposes - upon the user a requirement to accept the terms of a - 'click-through' license. - Once the license is accepted the - Yocto Project build system can then build and include the - corresponding component in the final BSP image. - Some affected components might be essential to the normal - functioning of the system and have no 'free' replacement - (i.e. the resulting system would be non-functional - without them). - On the other hand, other components might be simply - 'good-to-have' or purely elective, or if essential - nonetheless have a 'free' (possibly less-capable) - version that could be used as a in the BSP recipe. + If you plan on customizing a recipe for a particular BSP, you need to do the + following: + + Include within the BSP layer a .bbappend + file for the modified recipe. + Place the BSP-specific file in the BSP's recipe + .bbappend file path under a directory named + after the machine. + + + + + To better understand this, consider an example that customizes a recipe by adding + a BSP-specific configuration file named interfaces to the + netbase_4.47.bb recipe for machine "xyz". + Do the following: + + Edit the netbase_4.47.bbappend file so that it + contains the following: + + FILESEXTRAPATHS_prepend := "${THISDIR}/files:" + PRINC := "${@int(PRINC) + 2}" + + Create and place the new interfaces + configuration file in the BSP's layer here: + + meta-xyz/recipes-core/netbase/files/xyz/interfaces + + +
+ +
+ BSP Licensing Considerations - For cases where you can substitute something and still maintain functionality, - the Yocto Project website's - BSP Download Page - makes available 'de-featured' BSPs that are completely free of any IP encumbrances. - For these cases you can use the substitution directly and without any further licensing - requirements. - If present, these fully 'de-featured' BSPs are named appropriately different - as compared to the names of the respective encumbered BSPs. - If available, these substitutions are the simplest and most preferred options. - This, of course, assumes the resulting functionality meets requirements. + In some cases, a BSP contains separately licensed Intellectual Property (IP) + for a component or components. + For these cases, you are required to accept the terms of a commercial or other + type of license that requires some kind of explicit End User License Agreement (EULA). + Once the license is accepted, the Yocto Project build system can then build and + include the corresponding component in the final BSP image. + If the BSP is available as a pre-built image, you can download the image after + agreeing to the license or EULA. - If however, a non-encumbered version is unavailable or the 'free' version - would provide unsuitable functionality or quality, you can use - an encumbered version. + You could find that some separately licensed components that are essential + for normal operation of the system might not have an unencumbered (or free) + substitute. + Without these essential components, the system would be non-functional. + Then again, you might find that other licensed components that are simply + 'good-to-have' or purely elective do have an unencumbered, free replacement + component that you can use rather than agreeing to the separately licensed component. + Even for components essential to the system, you might find an unencumbered component + that is not identical but will work as a less-capable version of the + licensed version in the BSP recipe. - - Several methods exist within the Yocto Project build system to satisfy the licensing - requirements for an encumbered BSP. - The following list describes them in preferential order: + + For cases where you can substitute a free component and still + maintain the system's functionality, the Yocto Project website's + BSP + Download Page makes available de-featured BSPs + that are completely free of any IP encumbrances. + For these cases, you can use the substitution directly and + without any further licensing requirements. + If present, these fully de-featured BSPs are named appropriately + different as compared to the names of the respective + encumbered BSPs. + If available, these substitutions are your + simplest and most preferred options. + Use of these substitutions of course assumes the resulting functionality meets + system requirements. + + + + If however, a non-encumbered version is unavailable or + it provides unsuitable functionality or quality, you can use an encumbered + version. + + + + A couple different methods exist within the Yocto + Project build system to satisfy the licensing + requirements for an encumbered BSP. + The following list describes them in order of preference: + + Use the LICENSE_FLAGS variable + to define the Yocto Project recipes that have commercial or other types of + specially-licensed packages: + For each of those recipes, you can + specify a matching license string in a + local.conf variable named + LICENSE_FLAGS_WHITELIST. + Specifying the matching license string signifies that you agree to the license. + Thus, the build system can build the corresponding recipe and include + the component in the image. + See the + "Enabling + Commercially Licensed Recipes" section in the Yocto Project Reference + Manual for details on how to use these variables. + If you build as you normally would, without + specifying any recipes in the + LICENSE_FLAGS_WHITELIST, the build stops and + provides you with the list of recipes that you have + tried to include in the image that need entries in + the LICENSE_FLAGS_WHITELIST. + Once you enter the appropriate license flags into the whitelist, + restart the build to continue where it left off. + During the build, the prompt will not appear again + since you have satisfied the requirement. + Once the appropriate license flags are on the white list + in the LICENSE_FLAGS_WHITELIST variable, you + can build the encumbered image with no change at all + to the normal build process. + Get a pre-built version of the BSP: + You can get this type of BSP by visiting the Yocto Project website's + Download + page and clicking on "BSP Downloads". + You can download BSP tarballs that contain proprietary components + after agreeing to the licensing + requirements of each of the individually encumbered + packages as part of the download process. + Obtaining the BSP this way allows you to access an encumbered + image immediately after agreeing to the + click-through license agreements presented by the + website. + Note that if you want to build the image + yourself using the recipes contained within the BSP + tarball, you will still need to create an + appropriate LICENSE_FLAGS_WHITELIST to match the + encumbered recipes in the BSP. + + + + + Pre-compiled images are bundled with + a time-limited kernel that runs for a + predetermined amount of time (10 days) before it forces + the system to reboot. + This limitation is meant to discourage direct redistribution + of the image. + You must eventually rebuild the image if you want to remove this restriction. + +
+ +
+ Using the Yocto Project's BSP Tools + + + The Yocto Project includes a couple of tools that enable + you to create a BSP layer + from scratch and do basic configuration and maintenance + of the kernel without ever looking at a Yocto Project metadata file. + These tools are yocto-bsp and yocto-kernel, + respectively. + + + + The following sections describe the common location and help features as well + as details for the yocto-bsp and yocto-kernel + tools. - - +
+ Common Features - - Get a license key (or keys) for the encumbered BSP by visiting - a website and providing the name of the BSP and your email address - through a web form. + + Designed to have a command interface somewhat like + Git, each + tool is structured as a set of sub-commands under a + top-level command. + The top-level command (yocto-bsp + or yocto-kernel) itself does + nothing but invoke or provide help on the sub-commands + it supports. - - - After agreeing to any applicable license terms, the - BSP key(s) will be immediately sent to the address - you gave and you can use them by specifying BSPKEY_<keydomain> - environment variables when building the image: - - - - $ BSPKEY_<keydomain>=<key> bitbake core-image-sato - - - - These steps allow the encumbered image to be built - with no change at all to the normal build process. - - - - Equivalently and probably more conveniently, a line - for each key can instead be put into the user's - local.conf file found in the Yocto Project file's - build directory. - - - - The <keydomain> component of the - BSPKEY_<keydomain> is required because there - might be multiple licenses in effect for a given BSP. - In such cases, a given <keydomain> corresponds to - a particular license. In order for an encumbered - BSP that encompasses multiple key domains to be built - successfully, a <keydomain> entry for each - applicable license must be present in local.conf or - supplied on the command-line. - - - - - Do nothing - build as you normally would. - When a license is needed the build will stop and prompt you with instructions. - Follow the license prompts that originate from the - encumbered BSP. - These prompts usually take the form of instructions - needed to manually fetch the encumbered package(s) - and md5 sums into the required directory - (e.g. the yocto/build/downloads). - Once the manual package fetch has been - completed, restart the build to continue where - it left off. - During the build the prompt will not appear again since you have satisfied the - requirement. - - - - - Get a full-featured BSP recipe rather than a key. - You can do this by visiting the applicable BSP download page from the Yocto - Project website at - . - BSP tarballs that have proprietary information can be downloaded after agreeing - to licensing requirements as part of the download process. - Obtaining the code this way allows you to build an encumbered image with - no changes at all as compared to the normal build. + + + Both tools reside in the scripts/ subdirectory + of the Yocto Project + Files. + Consequently, to use the scripts, you must source the + environment just as you would when invoking a build: + + $ source oe-init-build-env [build_dir] + - - - - Note that the third method is also the only option available - when downloading pre-compiled images generated from non-free BSPs. - Those images are likewise available at from the Yocto Project website. - -
+ + The most immediately useful function is to get help on both tools. + The built-in help system makes it easy to drill down at + any time and view the syntax required for any specific command. + Simply enter the name of the command, or the command along with + help to display a list of the available sub-commands. + Here is an example: + + $ yocto-bsp + $ yocto-bsp help + + Usage: + + Create a customized Yocto BSP layer. + + usage: yocto-bsp [--version] [--help] COMMAND [ARGS] + + The most commonly used 'yocto-bsp' commands are: + create Create a new Yocto BSP + list List available values for options and BSP properties + + See 'yocto-bsp help COMMAND' for more information on a specific command. + + + Options: + --version show program's version number and exit + -h, --help show this help message and exit + -D, --debug output debug information + + + + + Similarly, entering just the name of a sub-command shows the detailed usage + for that sub-command: + + $ yocto-bsp create + + Usage: + + Create a new Yocto BSP + usage: yocto-bsp create <bsp-name> <karch> [-o <DIRNAME> | --outdir <DIRNAME>] + [-i <JSON PROPERTY FILE> | --infile <JSON PROPERTY_FILE>] + + This command creates a Yocto BSP based on the specified parameters. + The new BSP will be a new Yocto BSP layer contained by default within + the top-level directory specified as 'meta-bsp-name'. The -o option + can be used to place the BSP layer in a directory with a different + name and location. + + ... + + + + + For any sub-command, you can also use the word 'help' just before the + sub-command to get more extensive documentation: + + $ yocto-bsp help create + + NAME + yocto-bsp create - Create a new Yocto BSP + + SYNOPSIS + yocto-bsp create <bsp-name> <karch> [-o <DIRNAME> | --outdir <DIRNAME>] + [-i <JSON PROPERTY FILE> | --infile <JSON PROPERTY_FILE>] + + DESCRIPTION + This command creates a Yocto BSP based on the specified + parameters. The new BSP will be a new Yocto BSP layer contained + by default within the top-level directory specified as + 'meta-bsp-name'. The -o option can be used to place the BSP layer + in a directory with a different name and location. + + The value of the 'karch' parameter determines the set of files + that will be generated for the BSP, along with the specific set of + 'properties' that will be used to fill out the BSP-specific + portions of the BSP. + + ... + + NOTE: Once created, you should add your new layer to your + bblayers.conf file in order for it to be subsequently seen and + modified by the yocto-kernel tool. + + NOTE for x86- and x86_64-based BSPs: The generated BSP assumes the + presence of the of the meta-intel layer, so you should also have a + meta-intel layer present and added to your bblayers.conf as well. + + + + + Now that you know where these two commands reside and how to access information + on them, you should find it relatively straightforward to discover the commands + necessary to create a BSP and perform basic kernel maintenance on that BSP using + the tools. + The next sections provide a concrete starting point to expand on a few points that + might not be immediately obvious or that could use further explanation. + +
+ + +
+ Creating a new BSP Layer Using the yocto-bsp Script + + + The yocto-bsp script creates a new + BSP layer for any architecture supported + by the Yocto Project, as well as QEMU versions of the same. + The default mode of the script's operation is to prompt you for information needed + to generate the BSP layer. + For the current set of BSPs, the script prompts you for various important + parameters such as: + + which kernel to use + which branch of that kernel to use (or re-use) + whether or not to use X, and if so, which drivers to use + whether to turn on SMP + whether the BSP has a keyboard + whether the BSP has a touchscreen + any remaining configurable items associated with the BSP + + + + + You use the yocto-bsp create sub-command to create + a new BSP layer. + This command requires you to specify a particular architecture on which to + base the BSP. + Assuming you have sourced the environment, you can use the + yocto-bsp list karch sub-command to list the + architectures available for BSP creation as follows: + + $ yocto-bsp list karch + Architectures available: + arm + powerpc + i386 + mips + x86_64 + qemu + + + + + The remainder of this section presents an example that uses + myarm as the machine name and qemu + as the machine architecture. + Of the available architectures, qemu is the only architecture + that causes the script to prompt you further for an actual architecture. + In every other way, this architecture is representative of how creating a BSP for + a 'real' machine would work. + The reason the example uses this architecture is because it is an emulated architecture + and can easily be followed without requiring actual hardware. + + + + As the yocto-bsp create command runs, default values for + the prompts appear in brackets. + Pressing enter without supplying anything on the command line or pressing enter + and providing an invalid response causes the script to accept the default value. + + + + Following is the complete example: + + $ yocto-bsp create myarm qemu + Which qemu architecture would you like to use? [default: x86] + 1) common 32-bit x86 + 2) common 64-bit x86 + 3) common 32-bit ARM + 4) common 32-bit PowerPC + 5) common 32-bit MIPS + 3 + Would you like to use the default (3.2) kernel? (Y/n) + Do you need a new machine branch for this BSP (the alternative is to re-use an existing branch)? [Y/n] + Getting branches from remote repo git://git.yoctoproject.org/linux-yocto-3.2... + Please choose a machine branch to base this BSP on => [default: standard/default/common-pc] + 1) base + 2) standard/base + 3) standard/default/arm-versatile-926ejs + 4) standard/default/base + 5) standard/default/beagleboard + 6) standard/default/cedartrailbsp (copy).xml + 7) standard/default/common-pc-64/base + 8) standard/default/common-pc-64/jasperforest + 9) standard/default/common-pc-64/romley + 10) standard/default/common-pc-64/sugarbay + 11) standard/default/common-pc/atom-pc + 12) standard/default/common-pc/base + 13) standard/default/crownbay + 14) standard/default/emenlow + 15) standard/default/fishriver + 16) standard/default/fri2 + 17) standard/default/fsl-mpc8315e-rdb + 18) standard/default/mti-malta32-be + 19) standard/default/mti-malta32-le + 20) standard/default/preempt-rt + 21) standard/default/qemu-ppc32 + 22) standard/default/routerstationpro + 23) standard/preempt-rt/base + 24) standard/preempt-rt/qemu-ppc32 + 25) standard/preempt-rt/routerstationpro + 26) standard/tiny + 3 + Do you need SMP support? (Y/n) + Does your BSP have a touchscreen? (y/N) + Does your BSP have a keyboard? (Y/n) + New qemu BSP created in meta-myarm + + Let's take a closer look at the example now: + + For the qemu architecture, + the script first prompts you for which emulated architecture to use. + In the example, we use the arm architecture. + + The script then prompts you for the kernel. + The default kernel is 3.2 and is acceptable. + So, the example accepts the default. + If you enter 'n', the script prompts you to further enter the kernel + you do want to use (e.g. 3.0, 3.2_preempt-rt, etc.). + Next, the script asks whether you would like to have a new + branch created especially for your BSP in the local + Linux Yocto Kernel + Git repository . + If not, then the script re-uses an existing branch. + In this example, the default (or 'yes') is accepted. + Thus, a new branch is created for the BSP rather than using a common, shared + branch. + The new branch is the branch committed to for any patches you might later add. + The reason a new branch is the default is that typically + new BSPs do require BSP-specific patches. + The tool thus assumes that most of time a new branch is required. + In the current implementation, creation or re-use of a branch does + not actually matter. + The reason is because the generated BSPs assume that patches and + configurations live in recipe-space, which is something that can be done + with or without a dedicated branch. + Generated BSPs, however, are different. + This difference becomes significant once the tool's 'publish' functionality + is implemented. + Regardless of which choice is made in the previous step, + you are now given the opportunity to select a particular machine branch on + which to base your new BSP-specific machine branch on + (or to re-use if you had elected to not create a new branch). + Because this example is generating an arm BSP, the example + uses #3 at the prompt, which selects the arm-versatile branch. + + The remainder of the prompts are routine. + Defaults are accepted for each. + By default, the script creates the new BSP Layer in the + Yocto Project + Build Directory. + + + + + Once the BSP Layer is created, you must add it to your + bblayers.conf file. + Here is an example: + + BBLAYERS = " \ + /usr/local/src/yocto/meta \ + /usr/local/src/yocto/meta-yocto \ + /usr/local/src/yocto/meta-myarm \ + " + + Adding the layer to this file allows the build system to build the BSP and + the yocto-kernel tool to be able to find the layer and + other metadata it needs on which to operate. + +
+ +
+ Managing Kernel Patches and Config Items with yocto-kernel + + + Assuming you have created a Yocto Project + BSP Layer using + + yocto-bsp and you added it to your + BBLAYERS + variable in the bblayers.conf file, you can now use + the yocto-kernel script to add patches and configuration + items to the BSP's kernel. + + + + The yocto-kernel script allows you to add, remove, and list patches + and kernel config settings to a Yocto Project BSP's kernel + .bbappend file. + All you need to do is use the appropriate sub-command. + Recall that the easiest way to see exactly what sub-commands are available + is to use the yocto-kernel built-in help as follows: + + $ yocto-kernel + Usage: + + Modify and list Yocto BSP kernel config items and patches. + + usage: yocto-kernel [--version] [--help] COMMAND [ARGS] + + The most commonly used 'yocto-kernel' commands are: + config list List the modifiable set of bare kernel config options for a BSP + config add Add or modify bare kernel config options for a BSP + config rm Remove bare kernel config options from a BSP + patch list List the patches associated with a BSP + patch add Patch the Yocto kernel for a BSP + patch rm Remove patches from a BSP + + See 'yocto-kernel help COMMAND' for more information on a specific command. + + + + + The yocto-kernel patch add sub-command allows you to add a + patch to a BSP. + The following example adds two patches to the myarm BSP: + + $ yocto-kernel patch add myarm ~/test.patch + Added patches: + test.patch + + $ yocto-kernel patch add myarm ~/yocto-testmod.patch + Added patches: + yocto-testmod.patch + + Although the previous example adds patches one at a time, it is possible + to add multiple patches at the same time. + + + + You can verify patches have been added by using the + yocto-kernel patch list sub-command. + Here is an example: + + $ yocto-kernel patch list myarm + The current set of machine-specific patches for myarm is: + 1) test.patch + 2) yocto-testmod.patch + + + + + You can also use the yocto-kernel script to + remove a patch using the yocto-kernel patch rm sub-command. + Here is an example: + + $ yocto-kernel patch rm myarm + Specify the patches to remove: + 1) test.patch + 2) yocto-testmod.patch + 1 + Removed patches: + test.patch + + + + + Again, using the yocto-kernel patch list sub-command, + you can verify that the patch was in fact removed: + + $ yocto-kernel patch list myarm + The current set of machine-specific patches for myarm is: + 1) yocto-testmod.patch + + + + + In a completely similar way, you can use the yocto-kernel config add + sub-command to add one or more kernel config item settings to a BSP. + The following commands add a couple of config items to the + myarm BSP: + + $ yocto-kernel config add myarm CONFIG_MISC_DEVICES=y + Added items: + CONFIG_MISC_DEVICES=y + + $ yocto-kernel config add myarm KCONFIG_YOCTO_TESTMOD=y + Added items: + CONFIG_YOCTO_TESTMOD=y + + Although the previous example adds config items one at a time, it is possible + to add multiple config items at the same time. + + + + You can list the config items now associated with the BSP. + Doing so shows you the config items you added as well as others associated + with the BSP: + + $ yocto-kernel config list myarm + The current set of machine-specific kernel config items for myarm is: + 1) CONFIG_MISC_DEVICES=y + 2) CONFIG_YOCTO_TESTMOD=y + + + + + Finally, you can remove one or more config items using the + yocto-kernel config rm sub-command in a manner + completely analogous to yocto-kernel patch rm. + +
+
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