documentation: dev-manual - Removed Appendix A.
This appendix is antiquated and needed removed. The BSP development example is now in the BSP guide where it talks about running the yocto-bsp script. (From yocto-docs rev: 892ff450d79a7564a72f11eb7510d349ca71d47a) Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com> Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
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<!DOCTYPE appendix PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
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"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
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[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >
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<appendix id='dev-manual-bsp-appendix'>
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<title>BSP Development Example</title>
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<para>
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This appendix provides a complete BSP development example.
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The example assumes the following:
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<itemizedlist>
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<listitem><para>No previous preparation or use of the Yocto Project.</para></listitem>
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<listitem><para>Use of the Fish River Island 2 Board Support Package (BSP) as a "base" BSP from
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which to work.
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The example begins with the Fish River Island 2 BSP as the starting point
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but ends by building a new 'atom-pc' BSP, which was based on the Fish River Island 2 BSP.
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</para></listitem>
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<listitem><para>Shell commands assume <filename>bash</filename></para></listitem>
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<listitem><para>Example was developed on an Intel-based Core i7 platform running
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Ubuntu 10.04 LTS released in April of 2010.</para></listitem>
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</itemizedlist>
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</para>
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<section id='getting-local-yocto-project-files-and-bsp-files'>
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<title>Getting Local Source Files and BSP Files</title>
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<para>
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You need to have the <link linkend='source-directory'>Source Directory</link>
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available on your host system.
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You can set up this directory through tarball extraction or by cloning the
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<filename>poky</filename> Git repository.
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The following paragraphs describe both methods.
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For additional information, see the bulleted item
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"<link linkend='local-yp-release'>Yocto Project Release</link>".
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</para>
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<para>
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As mentioned, one way to set up the Source Directory is to use Git to clone the
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<filename>poky</filename> repository.
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These commands create a local copy of the Git repository.
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By default, the top-level directory of the repository is named <filename>poky</filename>:
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<literallayout class='monospaced'>
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$ git clone git://git.yoctoproject.org/poky
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$ cd poky
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</literallayout>
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Alternatively, you can start with the downloaded Poky "&DISTRO_NAME;" tarball.
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These commands unpack the tarball into a Source Directory structure.
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By default, the top-level directory of the Source Directory is named
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<filename>&YOCTO_POKY;</filename>:
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<literallayout class='monospaced'>
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$ tar xfj &YOCTO_POKY_TARBALL;
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$ cd &YOCTO_POKY;
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</literallayout>
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<note><para>If you're using the tarball method, you can ignore all the following steps that
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ask you to carry out Git operations.
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You already have the results of those operations
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in the form of the &DISTRO_NAME; release tarballs.
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Consequently, there is nothing left to do other than extract those tarballs into the
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proper locations.</para>
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<para>Once you expand the released tarball, you have a snapshot of the Git repository
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that represents a specific release.
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Fundamentally, this is different than having a local copy of the Poky Git repository.
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Given the tarball method, changes you make are building on top of a release.
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With the Git repository method you have the ability to track development
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and keep changes in revision control.
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See the
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"<link linkend='repositories-tags-and-branches'>Repositories, Tags, and Branches</link>" section
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for more discussion around these differences.</para></note>
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</para>
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<para>
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With the local <filename>poky</filename> Git repository set up,
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you have all the development branches available to you from which you can work.
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Next, you need to be sure that your local repository reflects the exact
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release in which you are interested.
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From inside the repository you can see the development branches that represent
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areas of development that have diverged from the main (master) branch
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at some point, such as a branch to track a maintenance release's development.
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You can also see the tag names used to mark snapshots of stable releases or
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points in the repository.
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Use the following commands to list out the branches and the tags in the repository,
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respectively.
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<literallayout class='monospaced'>
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$ git branch -a
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$ git tag -l
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</literallayout>
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For this example, we are going to use the Yocto Project &DISTRO; Release, which is code
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named "&DISTRO_NAME;".
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To make sure we have a local area (branch in Git terms) on our machine that
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reflects the &DISTRO; release, we can use the following commands:
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<literallayout class='monospaced'>
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$ cd ~/poky
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$ git fetch --tags
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$ git checkout -b &DISTRO_NAME;-&POKYVERSION; origin/&DISTRO_NAME;
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Switched to a new branch '&DISTRO_NAME;-&POKYVERSION;'
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</literallayout>
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The <filename>git fetch --tags</filename> is somewhat redundant since you just set
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up the repository and should have all the tags.
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The <filename>fetch</filename> command makes sure all the tags are available in your
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local repository.
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The Git <filename>checkout</filename> command with the <filename>-b</filename> option
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creates a local branch for you named <filename>&DISTRO_NAME;-&POKYVERSION;</filename>.
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Your local branch begins in the same state as the Yocto Project &DISTRO; released tarball
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marked with the <filename>&DISTRO_NAME;-&POKYVERSION;</filename> tag in the source repositories.
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</para>
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</section>
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<section id='choosing-a-base-bsp-app'>
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<title>Choosing a Base BSP</title>
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<para>
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For this example, the base BSP is the <trademark class='registered'>Intel</trademark>
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<trademark class='trade'>Atom</trademark> Processor E660 with Intel Platform
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Controller Hub EG20T Development Kit, which is otherwise referred to as "Fish River Island 2."
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The BSP layer is <filename>meta-fri2</filename>.
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The base BSP is simply the BSP
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we will be using as a starting point, so don't worry if you don't actually have Fish River Island 2
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hardware.
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The remainder of the example transforms the base BSP into a BSP that should be
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able to boot on generic atom-pc (netbook) hardware.
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</para>
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<para>
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For information on how to choose a base BSP, see
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"<link linkend='developing-a-board-support-package-bsp'>Developing a Board Support Package (BSP)</link>".
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</para>
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</section>
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<section id='getting-your-base-bsp-app'>
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<title>Getting Your Base BSP</title>
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<para>
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You need to have the base BSP layer on your development system.
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Similar to the local <link linkend='source-directory'>Source Directory</link>,
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you can get the BSP
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layer in a couple of different ways:
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download the BSP tarball and extract it, or set up a local Git repository that
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has the BSP layers.
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You should use the same method that you used to set up the Source Directory earlier.
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See "<link linkend='getting-setup'>Getting Setup</link>" for information on how to get
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the BSP files.
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</para>
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<para>
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This example assumes the BSP layer will be located within a directory named
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<filename>meta-intel</filename> contained within the <filename>poky</filename>
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parent directory.
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The following steps will automatically create the
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<filename>meta-intel</filename> directory and the contained
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<filename>meta-fri2</filename> starting point in both the Git and the tarball cases.
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</para>
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<para>
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If you're using the Git method, you could do the following to create
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the starting layout after you have made sure you are in the <filename>poky</filename>
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directory created in the previous steps:
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<literallayout class='monospaced'>
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$ git clone git://git.yoctoproject.org/meta-intel.git
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$ cd meta-intel
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</literallayout>
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Alternatively, you can start with the downloaded Fish River Island 2 tarball.
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You can download the &DISTRO_NAME; version of the BSP tarball from the
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<ulink url='&YOCTO_HOME_URL;/download'>Downloads</ulink> page of the
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Yocto Project website.
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Here is the specific link for the tarball needed for this example:
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<ulink url='&YOCTO_MACHINES_DL_URL;/fri2-noemgd/fri2-noemgd-&DISTRO_NAME;-&POKYVERSION;.tar.bz2'></ulink>.
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Again, be sure that you are already in the <filename>poky</filename> directory
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as described previously before installing the tarball:
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<literallayout class='monospaced'>
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$ tar xfj fri2-noemgd-&DISTRO_NAME;-&POKYVERSION;.tar.bz2
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$ cd meta-intel
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</literallayout>
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</para>
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<para>
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The <filename>meta-intel</filename> directory contains all the metadata
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that supports BSP creation.
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If you're using the Git method, the following
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step will switch to the &DISTRO_NAME; metadata.
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If you're using the tarball method, you already have the correct metadata and can
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skip to the next step.
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Because <filename>meta-intel</filename> is its own Git repository, you will want
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to be sure you are in the appropriate branch for your work.
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For this example we are going to use the <filename>&DISTRO_NAME;</filename>
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branch.
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<literallayout class='monospaced'>
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$ git checkout -b &DISTRO_NAME;-&POKYVERSION; origin/&DISTRO_NAME;
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Branch &DISTRO_NAME;-&POKYVERSION; set up to track remote branch &DISTRO_NAME; from origin.
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Switched to a new branch '&DISTRO_NAME;-&POKYVERSION;'
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</literallayout>
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</para>
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</section>
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<section id='making-a-copy-of-the-base bsp-to-create-your-new-bsp-layer-app'>
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<title>Making a Copy of the Base BSP to Create Your New BSP Layer</title>
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<para>
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Now that you have set up the Source Directory and included the base BSP files, you need to
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create a new layer for your BSP.
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To create your BSP layer, you simply copy the <filename>meta-fri2</filename>
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layer to a new layer.
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</para>
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<para>
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For this example, the new layer will be named <filename>meta-mymachine</filename>.
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The name should follow the BSP layer naming convention, which is
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<filename>meta-<name></filename>.
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The following assumes your working directory is <filename>meta-intel</filename>
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inside your Source Directory.
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To start your new layer, just copy the new layer alongside the existing
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BSP layers in the <filename>meta-intel</filename> directory:
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<literallayout class='monospaced'>
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$ cp -a meta-fri2/ meta-mymachine
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</literallayout>
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</para>
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</section>
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<section id='making-changes-to-your-bsp-app'>
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<title>Making Changes to Your BSP</title>
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<para>
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Right now you have two identical BSP layers with different names:
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<filename>meta-fri2</filename> and <filename>meta-mymachine</filename>.
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You need to change your configurations so that they work for your new BSP and
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your particular hardware.
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The following sections look at each of these areas of the BSP.
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</para>
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<section id='changing-the-bsp-configuration'>
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<title>Changing the BSP Configuration</title>
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<para>
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We will look first at the configurations, which are all done in the layer’s
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<filename>conf</filename> directory.
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</para>
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<para>
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First, since in this example the new BSP will not support EMGD, we will get rid of the
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<filename>fri2.conf</filename> file and then rename the
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<filename>fri2-noemgd.conf</filename> file to <filename>mymachine.conf</filename>.
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Much of what we do in the configuration directory is designed to help the OpenEmbedded
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build system work with the new layer and to be able to find and use the right software.
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The following two commands result in a single machine configuration file named
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<filename>mymachine.conf</filename>.
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<literallayout class='monospaced'>
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$ rm meta-mymachine/conf/machine/fri2.conf
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$ mv meta-mymachine/conf/machine/fri2-noemgd.conf \
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meta-mymachine/conf/machine/mymachine.conf
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</literallayout>
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</para>
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<para>
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Next, we need to make changes to the <filename>mymachine.conf</filename> itself.
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The only changes we want to make for this example are to the comment lines.
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Changing comments, of course, is never strictly necessary, but it's always good form to make
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them reflect reality as much as possible.
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Here, simply substitute the Fish River Island 2 name with an appropriate name for the BSP
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(<filename>mymachine</filename> in this case) and change the description to
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something that describes your hardware.
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</para>
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<para>
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Note that inside the <filename>mymachine.conf</filename> is the
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<filename>PREFERRED_VERSION_linux-yocto</filename> statement.
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This statement identifies the kernel that the BSP is going to use.
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In this case, the BSP is using <filename>linux-yocto</filename>, which is the
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current Yocto Project kernel based on the Linux 3.4 release.
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</para>
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<para>
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The next configuration file in the new BSP layer we need to edit is
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<filename>meta-mymachine/conf/layer.conf</filename>.
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This file identifies build information needed for the new layer.
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You can see the
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"<ulink url='&YOCTO_DOCS_BSP_URL;#bsp-filelayout-layer'>Layer Configuration File</ulink>" section
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in The Board Support Packages (BSP) Development Guide for more information on this configuration file.
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Basically, we are changing the existing statements to work with our BSP.
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</para>
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<para>
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The file contains these statements that reference the Fish River Island 2 BSP:
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<literallayout class='monospaced'>
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BBFILE_COLLECTIONS += "fri2"
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BBFILE_PATTERN_fri2 := "^${LAYERDIR}/"
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BBFILE_PRIORITY_fri2 = "6"
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LAYERDEPENDS_fri2 = "intel"
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</literallayout>
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</para>
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<para>
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Simply substitute the machine string name <filename>fri2</filename>
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with the new machine name <filename>mymachine</filename> to get the following:
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<literallayout class='monospaced'>
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BBFILE_COLLECTIONS += "mymachine"
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BBFILE_PATTERN_mymachine := "^${LAYERDIR}/"
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BBFILE_PRIORITY_mymachine = "6"
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LAYERDEPENDS_mymachine = "intel"
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</literallayout>
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</para>
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</section>
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<section id='changing-the-recipes-in-your-bsp'>
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<title>Changing the Recipes in Your BSP</title>
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<para>
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Now we will take a look at the recipes in your new layer.
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The standard BSP structure has areas for BSP, graphics, core, and kernel recipes.
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When you create a BSP, you use these areas for appropriate recipes and append files.
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Recipes take the form of <filename>.bb</filename> files, while append files take
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the form of <filename>.bbappend</filename> files.
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If you want to leverage the existing recipes the OpenEmbedded build system uses
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but change those recipes, you can use <filename>.bbappend</filename> files.
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All new recipes and append files for your layer must go in the layer’s
|
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<filename>recipes-bsp</filename>, <filename>recipes-kernel</filename>,
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<filename>recipes-core</filename>, and
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<filename>recipes-graphics</filename> directories.
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</para>
|
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<section id='changing-recipes-bsp'>
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<title>Changing <filename>recipes-bsp</filename></title>
|
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<para>
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First, let's look at <filename>recipes-bsp</filename>.
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For this example we are not adding any new BSP recipes.
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And, we only need to remove the formfactor we do not want and change the name of
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the remaining one that doesn't support EMGD.
|
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These commands take care of the <filename>recipes-bsp</filename> recipes:
|
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<literallayout class='monospaced'>
|
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$ rm -rf meta-mymachine/recipes-bsp/formfactor/formfactor/fri2
|
||||
$ mv meta-mymachine/recipes-bsp/formfactor/formfactor/fri2-noemgd/ \
|
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meta-mymachine/recipes-bsp/formfactor/formfactor/mymachine
|
||||
</literallayout>
|
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</para>
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||||
</section>
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<section id='changing-recipes-graphics'>
|
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<title>Changing <filename>recipes-graphics</filename></title>
|
||||
|
||||
<para>
|
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Now let's look at <filename>recipes-graphics</filename>.
|
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For this example we want to remove anything that supports EMGD and
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be sure to rename remaining directories appropriately.
|
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The following commands clean up the <filename>recipes-graphics</filename> directory:
|
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<literallayout class='monospaced'>
|
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$ rm -rf meta-mymachine/recipes-graphics/xorg-xserver/xserver-xf86-config/fri2
|
||||
$ mv meta-mymachine/recipes-graphics/xorg-xserver/xserver-xf86-config/fri2-noemgd \
|
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meta-mymachine/recipes-graphics/xorg-xserver/xserver-xf86-config/mymachine
|
||||
</literallayout>
|
||||
</para>
|
||||
|
||||
<para>
|
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At this point the <filename>recipes-graphics</filename> directory just has files that
|
||||
support Video Electronics Standards Association (VESA) graphics modes and not EMGD.
|
||||
</para>
|
||||
</section>
|
||||
|
||||
<section id='changing-recipes-kernel'>
|
||||
<title>Changing <filename>recipes-kernel</filename></title>
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||||
|
||||
<para>
|
||||
Finally, let's look at <filename>recipes-kernel</filename> changes.
|
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Recall that the BSP uses the <filename>linux-yocto</filename> kernel as determined
|
||||
earlier in the <filename>mymachine.conf</filename>.
|
||||
The recipe for that kernel is not located in the
|
||||
BSP layer but rather in the Source Directory at
|
||||
<filename>meta/recipes-kernel/linux</filename> and is
|
||||
named <filename>linux-yocto_3.4.bb</filename>.
|
||||
The <filename>SRCREV_machine</filename> and <filename>SRCREV_meta</filename>
|
||||
statements point to the exact commits used by the Yocto Project development team
|
||||
in their source repositories that identify the right kernel for our hardware.
|
||||
In other words, the <filename>SRCREV</filename> values are simply Git commit
|
||||
IDs that identify which commit on each
|
||||
of the kernel branches (machine and meta) will be checked out and used to build
|
||||
the kernel.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
However, in the <filename>meta-mymachine</filename> layer in
|
||||
<filename>recipes-kernel/linux</filename> resides a <filename>.bbappend</filename>
|
||||
file named <filename>linux-yocto_3.4.bbappend</filename> that
|
||||
appends the information to the recipe of the same name
|
||||
that is found in <filename>meta/recipes-kernel/linux</filename>.
|
||||
Thus, the <filename>SRCREV</filename> statements in our
|
||||
<filename>mymachine</filename> append file override
|
||||
the more general statements found in the more general recipe.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
The <filename>SRCREV</filename> statements in the
|
||||
<filename>mymachine</filename> append file currently identify
|
||||
the kernel that supports the Fish River Island 2 BSP with and without EMGD support.
|
||||
Here are the statements:
|
||||
<note>The commit ID strings used in this manual might not match the actual commit
|
||||
ID strings found in the <filename>linux-yocto_3.4.bbappend</filename> file.
|
||||
For the example, this difference does not matter.</note>
|
||||
<literallayout class='monospaced'>
|
||||
SRCREV_machine_pn-linux-yocto_fri2 ?= \
|
||||
"59c3ff750831338d05ab67d5efd7fc101c451aff"
|
||||
#SRCREV_meta_pn-linux-yocto_fri2 ?= \
|
||||
"c5bddf8ea379406ffec550528e17b777a0eba24b"
|
||||
|
||||
SRCREV_machine_pn-linux-yocto_fri2-noemgd ?= \
|
||||
"59c3ff750831338d05ab67d5efd7fc101c451aff"
|
||||
#SRCREV_meta_pn-linux-yocto_fir2-noemgd ?= \
|
||||
"c5bddf8ea379406ffec550528e17b777a0eba24b"
|
||||
</literallayout>
|
||||
<note>The <filename>SRCREV_meta_pn-linux-yocto_fir2-noemgd</filename>
|
||||
statements in the <filename>mymachine</filename> append file,
|
||||
which originated from the Fish River Island 2 BSP, are
|
||||
commented out.
|
||||
The reason they are not used is because the commit IDs are identical to
|
||||
those in the general <filename>linux-yocto_3.4.bbappend</filename> recipe,
|
||||
which is found in <filename>meta/recipes-kernel/linux</filename>.
|
||||
</note>
|
||||
</para>
|
||||
|
||||
<para>
|
||||
You will notice that there are two pairs of <filename>SRCREV</filename> statements.
|
||||
The top pair identifies the kernel that supports
|
||||
EMGD, which we don’t care about in this example.
|
||||
The bottom pair identifies the kernel that we will use:
|
||||
<filename>linux-yocto</filename>.
|
||||
At this point though, the unique commit strings all are still associated with
|
||||
Fish River Island 2 and not <filename>meta-mymachine</filename>.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
To fix this situation in <filename>linux-yocto_3.4.bbappend</filename>
|
||||
for <filename>mymachine</filename>,
|
||||
we delete the two <filename>SRCREV</filename> statements that support
|
||||
EMGD (the top pair).
|
||||
We also change the remaining pair to specify <filename>mymachine</filename>
|
||||
and insert the commit identifiers to identify the kernel in which we
|
||||
are interested, which will be based on the <filename>atom-pc-standard</filename>
|
||||
kernel.
|
||||
In this case, because we're working with the &DISTRO_NAME; branch of everything, we
|
||||
need to use the <filename>SRCREV</filename> values for the atom-pc branch
|
||||
that are associated with the &DISTRO_NAME; release.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
To find the machine value, we need to find the <filename>SRCREV</filename>
|
||||
value that &DISTRO_NAME; uses for the atom-pc branch, which we find in the
|
||||
<filename>poky/meta-yocto-bsp/recipes-kernel/linux/linux-yocto_3.4.bbappend</filename>
|
||||
file.
|
||||
The machine <filename>SRCREV</filename> we want is in the
|
||||
<filename>SRCREV_machine_atom-pc</filename> variable.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
The meta <filename>SRCREV</filename> isn't specified in this file, so if you
|
||||
needed it, you would find it in the base kernel recipe in the
|
||||
<filename>poky/meta/recipes-kernel/linux/linux-yocto_3.4.bb</filename>.
|
||||
Recall that for this example the commit ID's for the <filename>SRCREV</filename>
|
||||
meta statements are identical and do not have to be used in the
|
||||
<filename>mymachine</filename> append file.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Here are the final <filename>SRCREV</filename> statements for the
|
||||
<filename>mymachine</filename> append file:
|
||||
<literallayout class='monospaced'>
|
||||
SRCREV_machine_pn-linux-yocto_mymachine ?= \
|
||||
"0985844fa6235422c67ef269952fa4e765f252f9"
|
||||
#SRCREV_meta_pn-linux-yocto_mymachine ?= \
|
||||
"c5bddf8ea379406ffec550528e17b777a0eba24b"
|
||||
</literallayout>
|
||||
</para>
|
||||
|
||||
<para>
|
||||
In this example, we're using the <filename>SRCREV</filename> values we
|
||||
found already captured in the &DISTRO_NAME; release because we're creating a BSP based on
|
||||
&DISTRO_NAME;.
|
||||
If, instead, we had based our BSP on the master branches, we would want to use
|
||||
the most recent <filename>SRCREV</filename> values taken directly from the kernel's
|
||||
repository.
|
||||
We will not be doing that for this example.
|
||||
However, if you do base a future BSP on master and
|
||||
if you are familiar with Git repositories, you probably won’t have trouble locating the
|
||||
exact commit strings in the Yocto Project source repositories you need to change
|
||||
the <filename>SRCREV</filename> statements.
|
||||
You can find all the <filename>machine</filename> and <filename>meta</filename>
|
||||
branch points (commits) for the <filename>linux-yocto-3.4</filename> kernel at
|
||||
<ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi/linux-yocto-3.4'></ulink>.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
If you need a little more assistance after going to the link then do the following:
|
||||
<orderedlist>
|
||||
<listitem><para>Expand the list of branches by clicking <filename>[…]</filename></para></listitem>
|
||||
<listitem><para>Click on the <filename>standard/default/common-pc/atom-pc</filename>
|
||||
branch</para></listitem>
|
||||
<listitem><para>Click on the commit column header to view the top commit</para></listitem>
|
||||
<listitem><para>Copy the commit string for use in the
|
||||
<filename>linux-yocto_3.4.bbappend</filename> file</para></listitem>
|
||||
</orderedlist>
|
||||
</para>
|
||||
|
||||
<para>
|
||||
For the <filename>SRCREV</filename> statement that points to the <filename>meta</filename>
|
||||
branch use the same procedure except expand the <filename>meta</filename>
|
||||
branch in step 2 above.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Also in the <filename>linux-yocto_3.4.bbappend</filename> file are
|
||||
<ulink url='&YOCTO_DOCS_REF_URL;#var-COMPATIBLE_MACHINE'><filename>COMPATIBLE_MACHINE</filename></ulink>,
|
||||
<ulink url='&YOCTO_DOCS_REF_URL;#var-KMACHINE'><filename>KMACHINE</filename></ulink>,
|
||||
and
|
||||
<ulink url='&YOCTO_DOCS_REF_URL;#var-KBRANCH'><filename>KBRANCH</filename></ulink> statements.
|
||||
Two sets of these exist: one set supports EMGD and one set does not.
|
||||
Because we are not interested in supporting EMGD those three can be deleted.
|
||||
The remaining three must be changed so that <filename>mymachine</filename> replaces
|
||||
<filename>fri2-noemgd</filename> and <filename>fri2</filename>.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Because we are using the <filename>atom-pc</filename> branch for this new BSP, we can also find
|
||||
the exact branch we need for the <filename>KMACHINE</filename>
|
||||
and <filename>KBRANCH</filename> variables in our new BSP from the value
|
||||
we find in the
|
||||
<filename>poky/meta-yocto-bsp/recipes-kernel/linux/linux-yocto_3.4.bbappend</filename>
|
||||
file we looked at in a previous step.
|
||||
In this case, the values we want are in the <filename>KMACHINE_atom-pc</filename> variable
|
||||
and the <filename>KBRANCH_atom-pc</filename> variables in that file.
|
||||
Here is the final <filename>linux-yocto_3.4.bbappend</filename> file after all
|
||||
the edits:
|
||||
<literallayout class='monospaced'>
|
||||
FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"
|
||||
|
||||
COMPATIBLE_MACHINE_mymachine = "mymachine"
|
||||
KMACHINE_mymachine = "atom-pc"
|
||||
KBRANCH_mymachine = "standard/default/common-pc/atom-pc"
|
||||
|
||||
SRCREV_machine_pn-linux-yocto_mymachine ?= \
|
||||
"f29531a41df15d74be5ad47d958e4117ca9e489e"
|
||||
SRCREV_meta_pn-linux-yocto_mymachine ?= \
|
||||
"b14a08f5c7b469a5077c10942f4e1aec171faa9d"
|
||||
</literallayout>
|
||||
</para>
|
||||
</section>
|
||||
</section>
|
||||
|
||||
<section id='bsp-recipe-change-summary'>
|
||||
<title>BSP Recipe Change Summary</title>
|
||||
|
||||
<para>
|
||||
In summary, the edits to the layer’s recipe files result in removal of any files and
|
||||
statements that do not support your targeted hardware in addition to the inclusion
|
||||
of any new recipes you might need.
|
||||
In this example, it was simply a matter of ridding the new layer
|
||||
<filename>meta-mymachine</filename> of any code that supported the EMGD features
|
||||
and making sure we were identifying the kernel that supports our example, which
|
||||
is the <filename>atom-pc-standard</filename> kernel.
|
||||
We did not introduce any new recipes to the layer.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Finally, it is also important to update the layer’s <filename>README</filename>
|
||||
file so that the information in it reflects your BSP.
|
||||
</para>
|
||||
</section>
|
||||
</section>
|
||||
|
||||
<section id='preparing-for-the-build-app'>
|
||||
<title>Preparing for the Build</title>
|
||||
|
||||
<para>
|
||||
To get ready to build your image that uses the new layer you need to do the following:
|
||||
<orderedlist>
|
||||
<listitem><para>Get the environment ready for the build by sourcing the environment
|
||||
script.
|
||||
The environment script is in the top-level of the Source Directory.
|
||||
The script has the string
|
||||
<filename>init-build-env</filename> in the file’s name.
|
||||
For this example, the following command gets the build environment ready:
|
||||
<literallayout class='monospaced'>
|
||||
$ source oe-init-build-env yocto-build
|
||||
</literallayout>
|
||||
When you source the script, a build directory is created in the current
|
||||
working directory.
|
||||
In our example we were in the <filename>poky</filename> directory.
|
||||
Thus, entering the previous command created the <filename>yocto-build</filename> directory.
|
||||
If you do not provide a name for the build directory it defaults to
|
||||
<filename>build</filename>.
|
||||
The <filename>yocto-build</filename> directory contains a
|
||||
<filename>conf</filename> directory that has
|
||||
two configuration files you will need to check: <filename>bblayers.conf</filename>
|
||||
and <filename>local.conf</filename>.</para></listitem>
|
||||
<listitem><para>Check and edit the resulting <filename>local.conf</filename> file.
|
||||
This file minimally identifies the machine for which to build the image by
|
||||
configuring the <filename>MACHINE</filename> variable.
|
||||
For this example you must set the variable to mymachine as follows:
|
||||
<literallayout class='monospaced'>
|
||||
MACHINE ??= “mymachine”
|
||||
</literallayout>
|
||||
You should also be sure any other variables in which you are interested are set.
|
||||
Some variables to consider are <filename>BB_NUMBER_THREADS</filename>
|
||||
and <filename>PARALLEL_MAKE</filename>, both of which can greatly reduce your build time
|
||||
if your development system supports multiple cores.
|
||||
For development systems that support multiple cores, a good rule of thumb is to set
|
||||
both the <filename>BB_NUMBER_THREADS</filename> and <filename>PARALLEL_MAKE</filename>
|
||||
variables to twice the number of cores your system supports.</para></listitem>
|
||||
<listitem><para>Update the <filename>bblayers.conf</filename> file so that it includes
|
||||
both the path to your new BSP layer and the path to the
|
||||
<filename>meta-intel</filename> layer.
|
||||
In this example, you need to include both these paths as part of the
|
||||
<filename>BBLAYERS</filename> variable:
|
||||
<literallayout class='monospaced'>
|
||||
$HOME/poky/meta-intel
|
||||
$HOME/poky/meta-intel/meta-mymachine
|
||||
</literallayout></para></listitem>
|
||||
</orderedlist>
|
||||
</para>
|
||||
|
||||
<para>
|
||||
The
|
||||
<ulink url='&YOCTO_DOCS_REF_URL;#ref-variables-glos'>Variables Glossary</ulink> chapter in the
|
||||
Yocto Project Reference Manual has more information on configuration variables.
|
||||
</para>
|
||||
</section>
|
||||
|
||||
<section id='building-the-image-app'>
|
||||
<title>Building and Booting the Image</title>
|
||||
|
||||
<para>
|
||||
To build the image for our <filename>meta-mymachine</filename> BSP enter the following command
|
||||
from the same shell from which you ran the setup script.
|
||||
You should run the <filename>bitbake</filename> command without any intervening shell commands.
|
||||
For example, moving your working directory around could cause problems.
|
||||
Here is the command for this example:
|
||||
<literallayout class='monospaced'>
|
||||
$ bitbake -k core-image-sato
|
||||
</literallayout>
|
||||
</para>
|
||||
|
||||
<para>
|
||||
This command specifies an image that has Sato support and that can be run from a USB device or
|
||||
from a CD without having to first install anything.
|
||||
The build process takes significant time and includes thousands of tasks, which are reported
|
||||
at the console.
|
||||
If the build results in any type of error you should check for misspellings in the
|
||||
files you changed or problems with your host development environment such as missing packages.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Finally, once you have an image, you can try booting it from a device
|
||||
(e.g. a USB device).
|
||||
To prepare a bootable USB device, insert a USB flash drive into your build system and
|
||||
copy the <filename>.hddimg</filename> file, located in the
|
||||
<filename>poky/build/tmp/deploy/images</filename>
|
||||
directory after a successful build to the flash drive.
|
||||
Assuming the USB flash drive takes device <filename>/dev/sdf</filename>,
|
||||
use <filename>dd</filename> to copy the live image to it.
|
||||
For example:
|
||||
<literallayout class='monospaced'>
|
||||
# dd if=core-image-sato-mymachine-20111101223904.hddimg of=/dev/sdf
|
||||
# sync
|
||||
# eject /dev/sdf
|
||||
</literallayout>
|
||||
You should now have a bootable USB flash device.
|
||||
</para>
|
||||
|
||||
<para>
|
||||
Insert the device
|
||||
into a bootable USB socket on the target, and power it on.
|
||||
The system should boot to the Sato graphical desktop.
|
||||
<footnote><para>Because
|
||||
this new image is not in any way tailored to the system you're
|
||||
booting it on, which is assumed to be some sort of atom-pc (netbook) system for this
|
||||
example, it might not be completely functional though it should at least boot to a text
|
||||
prompt.
|
||||
Specifically, it might fail to boot into graphics without some tweaking.
|
||||
If this ends up being the case, a possible next step would be to replace the
|
||||
<filename>mymachine.conf</filename>
|
||||
contents with the contents of <filename>atom-pc.conf</filename> and replace
|
||||
<filename>xorg.conf</filename> with <filename>atom-pc xorg.conf</filename>
|
||||
in <filename>meta-yocto</filename> and see if it fares any better.
|
||||
In any case, following the previous steps will give you a buildable image that
|
||||
will probably boot on most systems.
|
||||
Getting things working like you want
|
||||
them to for your hardware will normally require some amount of experimentation with
|
||||
configuration settings.</para></footnote>
|
||||
</para>
|
||||
|
||||
<para>
|
||||
For reference, the sato image produced by the previous steps for &DISTRO_NAME;
|
||||
should look like the following in terms of size.
|
||||
If your sato image is much different from this,
|
||||
you probably made a mistake in one of the above steps:
|
||||
<literallayout class='monospaced'>
|
||||
260538368 2012-04-27 01:44 core-image-sato-mymachine-20120427025051.hddimg
|
||||
</literallayout>
|
||||
<note>The previous instructions are also present in the README that was copied
|
||||
from meta-fri2, which should also be updated to reflect the specifics of your
|
||||
new BSP.
|
||||
That file and the <filename>README.hardware</filename> file in the top-level
|
||||
<filename>poky</filename> directory
|
||||
also provides some suggestions for things to try if booting fails and produces
|
||||
strange error messages.</note>
|
||||
</para>
|
||||
</section>
|
||||
</appendix>
|
||||
|
||||
|
||||
<!--
|
||||
vim: expandtab tw=80 ts=4
|
||||
-->
|
|
@ -80,8 +80,6 @@
|
|||
|
||||
<xi:include href="dev-manual-model.xml"/>
|
||||
|
||||
<xi:include href="dev-manual-bsp-appendix.xml"/>
|
||||
|
||||
<xi:include href="dev-manual-kernel-appendix.xml"/>
|
||||
|
||||
</book>
|
||||
|
|
Loading…
Reference in New Issue