diff options
| author | Richard Purdie <richard.purdie@linuxfoundation.org> | 2011-04-20 14:20:19 +0100 |
|---|---|---|
| committer | Richard Purdie <richard.purdie@linuxfoundation.org> | 2011-04-20 15:49:17 +0100 |
| commit | 50021cba20a09b1ed685db5466f940b17d4880ac (patch) | |
| tree | 3bdafb797e6466ad58727b002f1235933010ab11 /documentation/bsp-guide/bsp.xml | |
| parent | 690e87a2ffe8caa16379be26eb356c5bded17c1f (diff) | |
| download | openembedded-core-50021cba20a09b1ed685db5466f940b17d4880ac.tar.gz openembedded-core-50021cba20a09b1ed685db5466f940b17d4880ac.tar.bz2 openembedded-core-50021cba20a09b1ed685db5466f940b17d4880ac.tar.xz openembedded-core-50021cba20a09b1ed685db5466f940b17d4880ac.zip | |
Drop documentation directory, this is replaced by the new yocto-docs repository
Diffstat (limited to 'documentation/bsp-guide/bsp.xml')
| -rw-r--r-- | documentation/bsp-guide/bsp.xml | 654 |
1 files changed, 0 insertions, 654 deletions
diff --git a/documentation/bsp-guide/bsp.xml b/documentation/bsp-guide/bsp.xml deleted file mode 100644 index 36715f33b..000000000 --- a/documentation/bsp-guide/bsp.xml +++ /dev/null @@ -1,654 +0,0 @@ -<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN" -"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"> - -<chapter id='bsp'> - - <title>Board Support Packages (BSP) - Developers Guide</title> - - <para> - A Board Support Package (BSP) is a collection of information that - defines how to support a particular hardware device, set of devices, or - hardware platform. - The BSP includes information about the hardware features - present on the device and kernel configuration information along with any - additional hardware drivers required. - The BSP also lists any additional software - components required in addition to a generic Linux software stack for both - essential and optional platform features. - </para> - - <para> - 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. - </para> - - <para> - The proposed format does have elements that are specific to the Poky and - OpenEmbedded build systems. - It is intended that this information can be - used by other systems besides Poky and OpenEmbedded and that it will be simple - to extract information and convert it to other formats if required. - Poky, 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. - </para> - - <para> - 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. - </para> - - <section id="bsp-filelayout"> - <title>Example Filesystem Layout</title> - - <para> - The BSP consists of a file structure inside a base directory, which uses the following - naming convention: - <literallayout class='monospaced'> - meta-<bsp_name> - </literallayout> - "bsp_name" is a placeholder for the machine or platform name. - Here are some example base directory names: - <literallayout class='monospaced'> - meta-emenlow - meta-intel_n450 - meta-beagleboard - </literallayout> - </para> - - <para> - Below is the common form for the file structure inside a base directory. - While you can use this basic form for the standard, realize that the actual structures - for specific BSPs could differ. - - <programlisting> -meta-<bsp_name>/ -meta-<bsp_name>/<bsp_license_file> -meta-<bsp_name>/README -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-graphics/* -meta-<bsp_name>/recipes-kernel/linux/linux-yocto_git.bbappend - </programlisting> - </para> - - <para> - Below is an example of the crownbay BSP: - - <programlisting> -meta-crownbay/COPYING.MIT -meta-crownbay/README -meta-crownbay/binary/.gitignore -meta-crownbay/conf/layer.conf -meta-crownbay/conf/machine/crownbay.conf -meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/machconfig -meta-crownbay/recipes-bsp/formfactor/formfactor_0.0.bbappend -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/xcorg.conf -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config_0.1.bbappend -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-emgd-bin/.gitignore -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-emgd-bin_1.7.99.2.bb -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-emgd/crosscompile.patch -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-emgd/fix_open_max_preprocessor_error.patch -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-emgd/macro_tweak.patch -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-emgd/nodolt.patch -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-emgd_1.7.99.2.bb -meta-crownbay/recipes-kernel/linux/linux-yocto_git.bbappend - </programlisting> - </para> - - <para> - The following sections describe each part of the proposed BSP format. - </para> - - <section id="bsp-filelayout-license"> - <title>License Files</title> - <programlisting> -meta-<bsp_name>/<bsp_license_file> - </programlisting> - - <para> - These optional files satisfy licensing requirements for the BSP. - The type or types of files here can vary depending on the licensing requirements. - For example, in the crownbay BSP all licensing requirements are handled with the - <filename>COPYING.MIT</filename> file. - </para> - - <para> - Licensing files can be MIT, BSD, GPLv*, and so forth. - These files are recommended for the BSP but are optional and totally up to the BSP developer. - </para> - </section> - - <section id="bsp-filelayout-readme"> - <title>README File</title> - <programlisting> -meta-<bsp_name>/README - </programlisting> - - <para> - This file provides information on how to boot the live images that are optionally - included in the <filename>/binary</filename> directory. - The <filename>README</filename> file also provides special information needed for - building the image. - </para> - - <para> - Technically speaking a <filename>README</filename> is optional but it is highly - recommended that every BSP has one. - </para> - </section> - - <section id="bsp-filelayout-binary"> - <title>Pre-built User Binaries</title> - <programlisting> -meta-<bsp_name>/binary/<bootable_images> - </programlisting> - - <para> - This optional area contains useful pre-built kernels and user-space filesystem - images appropriate to the target system. - This directory contains the Application Development Toolkit (ADT) and minimal - live images when the BSP is has been "tar-balled" and placed on the Yocto Project website. - You can use these kernels and images to get a system running and quickly get started - on development tasks. - </para> - - <para> - 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 - 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. - </para> - </section> - - <section id='bsp-filelayout-layer'> - <title>Layer Configuration File</title> - <programlisting> -meta-<bsp_name>/conf/layer.conf - </programlisting> - - <para> - This file identifies the structure as a Poky layer, identifies the - contents of the layer, and contains information about how Poky 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). - </para> - - <para> - <programlisting> -# We have a conf directory, add to BBPATH -BBPATH := "${BBPATH}:${LAYERDIR}" - -# We have a recipes directory containing .bb and .bbappend files, add to BBFILES -BBFILES := "${BBFILES} ${LAYERDIR}/recipes/*/*.bb \ ${LAYERDIR}/recipes/*/*.bbappend" - -BBFILE_COLLECTIONS += "bsp" -BBFILE_PATTERN_bsp := "^${LAYERDIR}/" -BBFILE_PRIORITY_bsp = "5" - </programlisting> - </para> - - <para> - This file simply makes BitBake aware of the recipes and configuration directories. - This file must exist so that Poky can recognize the BSP. - </para> - </section> - - <section id="bsp-filelayout-machine"> - <title>Hardware Configuration Options</title> - <programlisting> -meta-<bsp_name>/conf/machine/*.conf - </programlisting> - - <para> - The machine files bind together all the information contained elsewhere - in the BSP into a format that Poky can understand. - 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. - </para> - - <para> - These files define things such as the kernel package to use - (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. - </para> - - <para> - At least one machine file is required for a BSP layer. - However, you can supply more than one file. - </para> - - <para> - This directory could also contain shared hardware "tuning" definitions that are commonly used to - pass specific optimization flags to the compiler. - An example is <filename>tune-atom.inc</filename>: - </para> - <para> - <programlisting> -BASE_PACKAGE_ARCH = "core2" -TARGET_CC_ARCH = "-m32 -march=core2 -msse3 -mtune=generic -mfpmath=sse" - </programlisting> - </para> - <para> - This example defines a new package architecture called "core2" and uses the - specified optimization flags, which are carefully chosen to give best - performance on atom processors. - </para> - <para> - The tune file would be included by the machine definition and can be - contained in the BSP or referenced from one of the standard core set of - files included with Poky itself. - </para> - <para> - Both the base package architecture file and the tune file are optional for a Poky BSP layer. - </para> - </section> - - <section id='bsp-filelayout-misc-recipes'> - <title>Miscellaneous Recipe Files</title> - <programlisting> -meta-<bsp_name>/recipes-bsp/* - </programlisting> - - <para> - This optional directory contains miscellaneous recipe files for the BSP. - Most notably would be the formfactor files. - For example, in the crownbay BSP there is a <filename>machconfig</filename> file and a - <filename>formfactor_0.0.bbappend</filename> file: - <programlisting> -meta-crownbay/recipes-bsp/formfactor/formfactor/crownbay/machconfig -meta-crownbay/recipes-bsp/formfactor/formfactor_0.0.bbappend - </programlisting> - </para> - - <note><para> - If a BSP does not have a formfactor entry, defaults are established according to - the configuration script. - </para></note> - </section> - - <section id='bsp-filelayout-recipes-graphics'> - <title>Display Support Files</title> - <programlisting> -meta-<bsp_name>/recipes-graphics/* - </programlisting> - - <para> - 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, in the crownbay BSP several display support files exist: - <programlisting> -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay/xcorg.conf -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-config_0.1.bbappend -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-emgd-bin/.gitignore -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-emgd-bin_1.7.99.2.bb -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-emgd/crosscompile.patch -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-emgd/fix_open_max_preprocessor_error.patch -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-emgd/macro_tweak.patch -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-emgd/nodolt.patch -meta-crownbay/recipes-graphics/xorg-xserver/xserver-xf86-emgd_1.7.99.2.bb - </programlisting> - </para> - </section> - - <section id='bsp-filelayout-kernel'> - <title>Linux Kernel Configuration</title> - <programlisting> -meta-<bsp_name>/recipes-kernel/linux/linux-yocto_git.bbappend - </programlisting> - - <para> - This file appends your specific changes to the kernel you are using. - </para> - <para> - For your BSP you typically want to use an existing Poky kernel found in the - Poky repository at <filename class='directory'>meta/recipes-kernel/kernel</filename>. - You can append your specific changes to the kernel recipe by using an append file, - which is located in the - <filename class='directory'>meta-<bsp_name>/recipes-kernel/linux</filename> - directory. - </para> - <para> - Suppose you use a BSP that uses the <filename>linux-yocto_git.bb</filename> 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 - <filename><bsp_name>.conf</filename> file by adding the following statement: - <programlisting> -PREFERRED_PROVIDER_virtual/kernel ?= "linux-yocto" - </programlisting> - You would use the <filename>linux-yocto_git.bbappend</filename> file to append - specific BSP settings to the kernel, thus configuring the kernel for your particular BSP. - </para> - <para> - Now take a look at the existing "crownbay" BSP. - The append file used is: - <programlisting> -meta-crownbay/recipes-kernel/linux/linux-yocto_git.bbappend - </programlisting> - The file contains the following: - <programlisting> -FILESEXTRAPATHS := "${THISDIR}/${PN}" -COMPATIBLE_MACHINE_crownbay = "crownbay" -KMACHINE_crownbay = "yocto/standard/crownbay" - </programlisting> - This append file adds "crownbay" as a compatible machine, - and additionally sets a Yocto Kernel-specific variable that identifies the name of the - BSP branch to use in the GIT repository to find configuration information. - </para> - <para> - One thing missing in this particular BSP, which you will typically need when - developing a BSP, is the kernel configuration (.config) for your BSP. - When developing a BSP, you probably have a kernel configuration file or a set of kernel - configuration files that, when taken together, define the kernel configuration for your BSP. - You can accomplish this definition by putting the configurations in a file or a set of files - inside a directory located at the same level as your append file and having the same name - as the kernel. - With all these conditions met simply reference those files in a SRC_URI statement in the append - file. - </para> - <para> - For example, suppose you had a set of configuration options in a file called - <filename>defconfig</filename>. - If you put that file inside a directory named - <filename class='directory'>/linux-yocto</filename> 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. - <programlisting> -SRC_URI += "file://defconfig" - </programlisting> - </para> - <para> - As mentioned earlier, you can group related configurations into multiple files and - name them all in the SRC_URI statement as well. - For example, you could group separate configurations specifically for Ethernet and graphics - into their own files and add those by using a SRC_URI statement like the - following in your append file: - <programlisting> -SRC_URI += "file://defconfig \ - file://eth.cfg \ - file://gfx.cfg" - </programlisting> - </para> - <para> - 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. - </para> - <note><para> - Other methods exist to accomplish grouping and defining configuration options. - For example, you could directly add configuration options to the Yocto kernel - <filename class='directory'>meta</filename> branch for your BSP. - The configuration options will likely end up in that location anyway if the BSP gets - added to the Yocto Project. - For information on how to add these configurations directly, see the - "Yocto Project Kernel Architecture and Use Manual" on the - <ulink url="http://yoctoproject.org/community/documentation">Yocto Project website - Documentation Page</ulink> - </para> - <para> - In general, however, the Yocto Project maintainers take care of moving the SRC_URI-specified - configuration options to the <filename class='directory'>meta</filename> 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 - the tree are typically using. - This allows for promotion of common configurations into common features. - </para></note> - </section> - -<!-- <section id='bsp-filelayout-packages'> - <title>Other Software (meta-<bsp_name>/recipes-kernel/*)</title> - - <para> - This section describes other pieces of software that the hardware might need for best - operation. - Examples show some of the things you could encounter. - The examples are standard <filename>.bb</filename> file recipes in the - usual Poky format. - You can include the source directly by referring to it in the source control system or - the released tarballs of external software projects. - You only need to provide these types of files if the platform requires them. - </para> - <para> - The following file is a bootloader recipe that can be used to generate a new - bootloader binary. - Sometimes these files are included in the final image format and are needed to re-flash hardware. - </para> - <para> - <programlisting> -meta-Emenlow/recipes-kernel/bootloader/bootloader_0.1.bb - </programlisting> - </para> - <para> - These next two files are examples of a hardware driver and a hardware daemon that might need - to be included in images to make the hardware useful. - Although the example uses "modem" there may be other components needed, such as firmware. - </para> - <para> - <programlisting> -meta-Emenlow/recipes-Emenlow/modem/modem-driver_0.1.bb -meta-Emenlow/recipes-Emenlow/modem/modem-daemon_0.1.bb - </programlisting> - </para> - <para> - Sometimes the device needs an image in a very specific format so that the update - mechanism can accept and re-flash it. - Recipes to build the tools needed to do this can be included with the BSP. - Following is an example. - </para> - <para> - <programlisting> -meta-Emenlow/recipes-Emenlow/image-creator/image-creator-native_0.1.bb - </programlisting> - </para> - </section> - - <section id='bs-filelayout-bbappend'> - <title>Append BSP-Specific Information to Existing Recipes</title> - <para> - Suppose you have a recipe such as "pointercal" that requires machine-specific information. - At the same time, you have your new BSP code nicely partitioned into a layer through which - you would also like to specify any machine-specific information associated with your new machine. - Before the <filename>.bbappend</filename> extension was introduced, you would have to copy the whole - pointercal recipe and files into your layer and then add the single file for your machine. - </para> - <para> - With the <filename>.bbappend</filename> extension, however, your work becomes much easier. - This extension allows you to easily merge BSP-specific information with the original recipe. - Whenever BitBake finds any <filename>.bbappend</filename> files BitBake will include them after - it loads the associated <filename>.bb</filename> file but before any finalize - or anonymous methods are run. - This allows the BSP layer to do whatever it might want to do to customize the original recipe. - </para> - <para> - If your recipe needs to reference extra files it can use the FILESEXTRAPATHS variable - to specify their location. - The example below shows extra files contained in a folder called ${PN} (the package name). - </para> - <programlisting> -FILESEXTRAPATHS := "${THISDIR}/${PN}" - </programlisting> - <para> - This technique allows the BSP to add machine-specific configuration files to the layer directory, - which will be picked up by BitBake. - For an example see <filename>meta-emenlow/packages/formfactor</filename>. - </para> - </section> - - <section id="bsp-filelayout-prebuilds"> - <title>Pre-build Data (meta-<bsp_name>/prebuilds/*)</title> - <para> - This location can contain precompiled representations of the source code - contained elsewhere in the BSP layer. - Assuming a compatible configuration is used, Poky can process and use these optional pre-compiled - representations to provide much faster build times. - </para> - </section> --> - </section> - - <section id='bsp-click-through-licensing'> - <title>BSP 'Click-Through' Licensing Procedure</title> - - <note><para> This section describes how - click-through licensing is expected to work. - Currently, this functionality is not yet implemented. - </para></note> - - <para> - 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 - Poky 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. - </para> - - <para> - For cases where you can substitute something and still maintain functionality, - the Yocto Project website at - <ulink url='http://yoctoproject.org/download/board-support-package-bsp-downloads'></ulink> - will make available a 'de-featured' BSP completely free of the encumbered IP. - In that case you can use the substitution directly and without any further licensing - requirements. - If present, this fully 'de-featured' BSP will be named appropriately different - than the normal encumbered BSP. - If available, this substitution is the simplest and most preferred option. - This, of course, assumes the resulting functionality meets requirements. - </para> - - <para> - If however, a non-encumbered version is unavailable or the 'free' version - would provide unsuitable functionality or quality, you can use - an encumbered version. - </para> - - <para> - Several methods exist within the Poky build system to satisfy the licensing - requirements for an encumbered BSP. - The following list describes them in preferential order: - </para> - - <orderedlist> - <listitem> - - <para> - 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. - </para> - -<!-- - <ulink url='https://pokylinux.org/bsp-keys.html'>https://pokylinux.org/bsp-keys.html</ulink> - and give the name of the BSP and your e-mail address in the web form. - </para> - - COMMENT: This link is not implemented at this point. - - <programlisting> - [screenshot of dialog box] - </programlisting> - ---> - - <para> - 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: - </para> - - <programlisting> - $ BSPKEY_<keydomain>=<key> bitbake poky-image-sato - </programlisting> - - <para> - These steps allow the encumbered image to be built - with no change at all to the normal build process. - </para> - - <para> - Equivalently and probably more conveniently, a line - for each key can instead be put into the user's - <filename>local.conf</filename> file. - </para> - - <para> - 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 <filename>local.conf</filename> or - supplied on the command-line. - </para> - </listitem> - <listitem> - <para> - 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 <filename>poky/build/downloads</filename>). - 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. - </para> - </listitem> - <listitem> - <para> - 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 - <ulink url='http://yoctoproject.org/download/board-support-package-bsp-downloads'></ulink>. - 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. - </para> - </listitem> - </orderedlist> - <para> - 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. - </para> - </section> - -</chapter> |