path: root/documentation/dev-manual/dev-manual-bsp-appendix.xml

<!DOCTYPE appendix PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">

<appendix id='dev-manual-bsp-appendix'>

<title>Development Cases</title>

<para>
    Many development cases exist for which you can use the Yocto Project. 
    However, for the purposes of this manual we are going to focus on two common development cases or groupings:  
    System Development and User Application Development.  
    System Development covers Board Support Package (BSP) development and kernel modification.  
    User Application Development covers development of applications that you intend to run on some 
    target hardware.  
</para>

<para>
    [WRITERS NOTE:  What is undetermined at this point is how much of the entire development process 
    we include in this particular chapter.  
    In other words, do we cover debugging and emulation steps here on a case-specific basis?  
    Or, do we capture that information in the appropriate subsequent chapter by case?]
</para>

<section id='system-development-app'>
    <title>System Development</title>

    <para>
        System development involves modification or creation of an image that you want to run on 
        a specific hardware target.  
        Usually when you want to create an image that runs on embedded hardware the image does 
        not require the same amount of features that a full-fledged Linux distribution provides.  
        Thus, you can create a much smaller image that is designed to just use the hardware 
        features for your particular hardware.
    </para>

    <para>
        To help you understand how system development works in the Yocto Project, this section 
        covers two types of image development:  BSP creation and kernel modification.
    </para>

    <section id='developing-a-board-support-package-bsp-app'>
        <title>Developing a Board Support Package (BSP)</title>

        <para>
            A BSP is a package of recipes that when applied while building an image results in 
            an image you can run on a particular board.  
            Thus, the package, when compiled into the new image, supports the operation of the board.  
        </para>

        <note>
            For a brief list of terms used when describing the development process in the Yocto Project, 
            see <xref linkend='yocto-project-terms'>Yocto Project Terms</xref> in this manual.
        </note>

        <para>
            Here are the basic steps involved in creating a BSP:
            <orderedlist>
                <listitem><para>Be sure your host development system is set up to support 
                    development using the Yocto Project. 
                    See  
                    <ulink url='http://www.yoctoproject.org/docs/1.1/yocto-project-qs/yocto-project-qs.html#the-linux-distro'>
                    The Linux Distributions</ulink> section and  
                    <ulink url='http://www.yoctoproject.org/docs/1.1/yocto-project-qs/yocto-project-qs.html#packages'>
                    The Packages</ulink> section both
                    in the Yocto Project Quick Start for requirements.
                    You will also need a release of Yocto Project installed on the host.</para></listitem>
                <listitem><para>Choose a BSP available with Yocto Project that most closely represents 
                    your hardware.</para></listitem>
                <listitem><para>Get set up with a base BSP.</para></listitem>
                <listitem><para>Make a copy of the existing BSP and isolate your work by creating a layer 
                    for your recipes.</para></listitem>
                <listitem><para>Make configuration and recipe changes to your new BSP layer.</para></listitem>
                <listitem><para>Prepare for the build.</para></listitem>
                <listitem><para>Select and configure the kernel.</para></listitem>
                <listitem><para>Identify the machine branch.</para></listitem>
                <listitem><para>Build the image.</para></listitem>
            </orderedlist>
                You can view a video presentation of the BSP creation process 
                <ulink url='http://free-electrons.com/blog/elc-2011-videos'>here</ulink>.  
                You can also find supplemental information in the 
                <ulink url='http://yoctoproject.org/docs/1.1/bsp-guide/bsp-guide.html'>
                Board Support Package (BSP) Development Guide</ulink>.
                Finally, there is wiki page write up of the example located 
                <ulink url='https://wiki.yoctoproject.org/wiki/Transcript:_creating_one_generic_Atom_BSP_from_another'>
                here</ulink> you might find helpful.
        </para>

        <section id='setting-up-yocto-project-app'>
            <title>Setting Up Yocto Project</title>

            <para>
                You need to have the Yocto Project files available on your host system.  
                You can get files through tarball extraction or by cloning the <filename>poky</filename>
                Git repository.  
                Typically, cloning the Git repository is the method to use.  
                This allows you to maintain a complete history of changes and facilitates you 
                contributing back to the Yocto Project.  
                However, if you just want a hierarchical file structure that contains the recipes
                and metadata that let you develop you can download tarballs from the 
                <ulink url='http://yoctoproject.org/download'>download page</ulink>.
            </para>

            <para>
                Regardless of the method you use this manual will refer to the resulting 
                hierarchical set of files as "the local Yocto Project files."
            </para>

            <para>
                [WRITER'S NOTE: I need to substitute correct and actual filenames for the 
                1.1 release throughout this example once they become available.]
            </para>

            <para>  
                If you download a tarball you can extract it into any directory you want using the 
                tar command.  
                For example, the following command extracts the Yocto Project 1.1 release tarball 
                into the current working directory and sets up a file structure whose top-level 
                directory is named <filename>poky-1.1</filename>:
                <literallayout class='monospaced'>
     $ tar xfj poky-1.1.tar.bz2
                </literallayout>
            </para>

            <para>
                The following transcript shows how to clone the <filename>poky</filename> Git repository
                into the current working directory.  
                The command creates the repository in a directory named <filename>poky</filename>:
                <literallayout class='monospaced'>
     $ git clone git://git.yoctoproject.org/poky
     Initialized empty Git repository in /home/scottrif/poky/.git/
     remote: Counting objects: 107624, done.
     remote: Compressing objects: 100% (37128/37128), done.
     remote: Total 107624 (delta 73393), reused 99851 (delta 67287)
     Receiving objects: 100% (107624/107624), 69.74 MiB | 483 KiB/s, done.
     Resolving deltas: 100% (73393/73393), done.
                </literallayout>
            </para>

            <para>
                Once you have the local <filename>poky</filename> Git repository set up, 
                you have many development branches from which you can work. 
                From inside the repository you can see the branch names and the tag names used 
                in the Git repository using either of the following two commands:
                <literallayout class='monospaced'>
     $ git branch -a
     $ git tag -l
                </literallayout> 
                For this example we are going to use the Yocto Project 1.1 Release, 
                which maps to the <filename>1.1</filename> branch in the repository. 
                These commands create a local branch named <filename>1.1</filename>
                that tracks the remote branch of the same name.
                <literallayout class='monospaced'>
     
     $ cd poky
     $ git checkout -b 1.1 origin/1.1
     Switched to a new branch '1.1'
                </literallayout>
            </para>
        </section>

        <section id='choosing-a-base-bsp-app'>
            <title>Choosing a Base BSP</title>

            <para>
                The Yocto Project ships with several BSPs that support various hardware.  
                It is best to base your new BSP on an existing BSP rather than create all the 
                recipes and configuration files from scratch.  
                While it is possible to create everything from scratch, basing your new BSP 
                on something that is close is much easier.  
                Or, at a minimum, it gives you some structure with which to start.
            </para>

            <para>
                At this point you need to understand your target hardware well enough to determine which 
                existing BSP it most closely matches.  
                Things to consider are your hardware’s on-board features such as CPU type and graphics support.  
                You should look at the README files for supported BSPs to get an idea of which one 
                you could use.  
                A generic Atom-based BSP to consider is the Crown Bay that does not support
                the Intel® Embedded Media Graphics Driver (EMGD).  
                The remainder of this example uses that base BSP. 
            </para>

            <para>
                To see the supported BSPs, go to the Yocto Project
                <ulink url='http://www.yoctoproject.org/download'>download page</ulink> and click 
                on “BSP Downloads.”
            </para>
        </section>

        <section id='getting-your-base-bsp-app'>
            <title>Getting Your Base BSP</title>

            <para>
                You need to have the base BSP layer on your development system.  
                Like the local Yocto Project files, you can get the BSP 
                layer one of two ways:  
                download the BSP tarball and extract it, or set up a local Git repository that 
                has the Yocto Project BSP layers.  
                You should use the same method that you used to get the local Yocto Project files earlier.
            </para>

            <para>
                If you are using tarball extraction, simply download the tarball for the base 
                BSP you chose in the previous step and then extract it into any directory 
                you choose using the tar command.  
                Upon extraction, the BSP source directory (layer) will be named 
                <filename>meta-&lt;BSP_name&gt;</filename>.  
                The following command extracts the Crown Bay BSP into the current directory and names it 
                <filename>meta-crownbay</filename>:
                <literallayout class='monospaced'>
     $ tar xjf crownbay-noemgd-1.1.tar.bz2
                </literallayout>
            </para>

            <para>
                If you cloned a <filename>poky</filename> Git repository
                then you need to set up a different local Git repository 
                (<filename>meta-intel</filename>) for the BSP.  
                The <filename>meta-intel</filename> Git repository contains all the metadata 
                that supports BSP creation.
                When you set up the <filename>meta-intel</filename> Git repository you can 
                set it up anywhere you want.
                We will set up the repository inside the 
                <filename>poky</filename> Git repository in this example.  
            </para>

            <para>
                The following transcript shows the steps to clone the <filename>meta-intel</filename>
                Git repository inside the <filename>poky</filename> Git repository created earlier in this 
                example.
                <literallayout class='monospaced'>
     $cd poky
     $ git clone git://git.yoctoproject.org/meta-intel.git
     Initialized empty Git repository in /home/scottrif/poky/meta-intel/.git/
     remote: Counting objects: 1325, done.
     remote: Compressing objects: 100% (1078/1078), done.
     remote: Total 1325 (delta 546), reused 85 (delta 27)
     Receiving objects: 100% (1325/1325), 1.56 MiB | 330 KiB/s, done.
     Resolving deltas: 100% (546/546), done.
                </literallayout>
            </para>

            <para>
                Because <filename>meta-intel</filename> is its own Git repository you will want
                to be sure you are in the appropriate branch for your work.
                For this example we are going to use the <filename>1.1</filename> branch. 
                <literallayout class='monospaced'>
     $ cd meta-intel
     $ git checkout -b 1.1 origin/1.1
     Switched to a new branch 'bernard'
                </literallayout>
            </para>
        </section>

        <section id='making-a-copy-of-the-base bsp-to-create-your-new-bsp-layer-app'>
            <title>Making a Copy of the Base BSP to Create Your New BSP Layer</title>

            <para>
                Now that you have the local Yocto Project files and the base BSP files you need to create a 
                new layer for your BSP.
            </para>

            <para>
                Layers are ideal for isolating and storing work for a given piece of hardware.  
                A layer is really just a location or area in which you place the recipes for your BSP.  
                In fact, a BSP is, in itself, a special type of layer.   
                Consider an application as another example that illustrates a layer.  
                Suppose you are creating an application that has library or other dependencies in 
                order for it to compile and run.  
                The layer, in this case, would be where all the recipes that define those dependencies 
                are kept.  The key point for a layer is that it is an isolated area that contains 
                all the relevant information for the project that the Yocto Project build system knows about.
            </para>

            <note>
                The Yocto Project supports four BSPs that are part of the 
                Yocto Project release: <filename>atom-pc</filename>, <filename>beagleboard</filename>,
                <filename>mpc8315e</filename>, and <filename>routerstationpro</filename>.  
                The recipes and configurations for these four BSPs are located and dispersed 
                within local Yocto Project files.
                Consequently, they are not totally isolated in the spirit of layers unless you think 
                of <filename>meta-yocto</filename> as a layer itself.  
                On the other hand, BSP layers for Crown Bay, Emenlow, Jasper Forest, 
                N450, and Sugar Bay are isolated.
            </note>

            <para>
                When you set up a layer for a new BSP you should follow a standard layout.  
                This layout is described in the
                <ulink url='http://www.yoctoproject.org/docs/1.1/bsp-guide/bsp-guide.html#bsp-filelayout'>
                Example Filesystem Layout</ulink> section of the Board Support Package (BSP) Development
                Guide.  
                In the standard layout you will notice a suggested structure for recipes and  
                configuration information.  
                You can see the standard layout for the Crown Bay BSP in this example by examining the 
                directory structure of the <filename>meta-crownbay</filename> layer inside the 
                local Yocto Project files.
            </para>

            <para>
                To create your BSP layer you simply copy the <filename>meta-crownbay</filename>
                layer to a new layer.  
                For this example the new layer will be named <filename>meta-mymachine</filename>.  
                The name must follow the BSP layer naming convention, which is 
                <filename>meta-&lt;name&gt;</filename>.  
                The following example assumes your working directory is <filename>meta-intel</filename> 
                inside the local Yocto Project files.  
                If you downloaded and expanded a Crown Bay tarball then you simply copy the resulting 
                <filename>meta-crownbay</filename> directory structure to a location of your choice.
                Good practice for a Git repository, however, is to just copy the new layer alongside 
                the existing
                BSP layers in the <filename>meta-intel</filename> Git repository:
                <literallayout class='monospaced'>
     $ cp -a meta-crownbay/ meta-mymachine 
                </literallayout>
            </para>
        </section>

        <section id='making-changes-to-your-bsp-app'>
            <title>Making Changes to Your BSP</title>

            <para>
                Right now you have two identical BSP layers with different names:  
                <filename>meta-crownbay</filename> and <filename>meta-mymachine</filename>.  
                You need to change your configurations so that they work for your new BSP and 
                your particular hardware.  
                We will look first at the configurations, which are all done in the layer’s 
                <filename>conf</filename> directory.
            </para>

            <para>
                First, since in this example the new BSP will not support EMGD we will get rid of the 
                <filename>crownbay.conf</filename> file and then rename the 
                <filename>crownbay-noemgd.conf</filename> file to <filename>mymachine.conf</filename>.  
                Much of what we do in the configuration directory is designed to help the Yocto Project 
                build system work with the new layer and to be able to find and use the right software.  
                The following two commands result in a single machine configuration file named 
                <filename>mymachine.conf</filename>.  
                <literallayout class='monospaced'>
     $ rm meta-mymachine/conf/machine/crownbay.conf
     $ mv meta-mymachine/conf/machine/crownbay-noemgd.conf \
     meta-mymachine/conf/machine/mymachine.conf
                </literallayout>
            </para>

            <para>
                The next step makes changes to <filename>mymachine.conf</filename> itself.  
                The only changes needed for this example are changes to the comment lines.
                Here we simply substitute the Crown Bay name with an appropriate name.
            </para>

            <para>
                Note that inside the <filename>mymachine.conf</filename> is the 
                <filename>PREFERRED_PROVIDER_virtual/kernel</filename> statement. 
                This statement identifies the kernel that the BSP is going to use.
                In this case the BSP is using <filename>linux-yocto</filename>, which is the 
                current Linux Yocto kernel based on the Linux 2.6.37 release. 
            </para>

            <para>
                The next configuration file in the new BSP layer we need to edit is <filename>layer.conf</filename>.
                This file identifies build information needed for the new layer.  
                You can see the 
                <ulink url='http://www.yoctoproject.org/docs/1.1/bsp-guide/bsp-guide.html#bsp-filelayout-layer'>
                Layer Configuration File</ulink> section in the Board Support Packages (BSP) Development Guide
                for more information on this configuration file.  
                Basically, we are changing the existing statements to work with our BSP. 
            </para>

            <para>
                The file contains these statements that reference the Crown Bay BSP:
                <literallayout class='monospaced'>
     BBFILE_COLLECTIONS += "crownbay"
     BBFILE_PATTERN_crownbay := "^${LAYERDIR}/"
     BBFILE_PRIORITY_crownbay = "6"
                </literallayout>
            </para>

            <para>
                Simply substitute the machine string name <filename>crownbay</filename>
                with the new machine name <filename>mymachine</filename> to get the following:
                <literallayout class='monospaced'>
     BBFILE_COLLECTIONS_mymachine += "mymachine"
     BBFILE_PATTERN_mymachine := "^${LAYERDIR}/"
     BBFILE_PRIORITY_mymachine = "6"
                </literallayout>
            </para>

            <para>
                Now we will take a look at the recipes in your new layer.  
                The standard BSP structure has areas for BSP, graphics, core, and kernel recipes.  
                When you create a BSP you use these areas for appropriate recipes and append files.  
                Recipes take the form of <filename>.bb</filename> files.  
                If you want to leverage the existing recipes the Yocto Project build system uses
                but change those recipes you can use <filename>.bbappend</filename> files.  
                All new recipes and append files for your layer must go in the layer’s 
                <filename>recipes-bsp</filename>, <filename>recipes-kernel</filename>, 
                <filename>recipes-core</filename>, and 
                <filename>recipes-graphics</filename> directories.    
            </para>

            <para>
                First, let's look at <filename>recipes-bsp</filename>.
                For this example we are not adding any new BSP recipes.  
                And, we only need to remove the formfactor we do not want and change the name of 
                the remaining one that doesn't support EMGD.  
                These commands take care of the <filename>recipes-bsp</filename> recipes:
                <literallayout class='monospaced'>
     $ rm &dash;rf meta-mymachine/recipes-graphics/xorg-xserver/*emgd*
     $ mv meta-mymachine/recipes-bsp/formfactor/formfactor/crownbay-noemgd/ \
     meta-mymachine/recipes-bsp/formfactor/formfactor/mymachine
                </literallayout>
            </para>

            <para>
                Now let's look at <filename>recipes-graphics</filename>.
                For this example we want to remove anything that supports EMGD and 
                be sure to rename remaining directories appropriately.  
                The following commands clean up the <filename>recipes-graphics</filename> directory:
                <literallayout class='monospaced'>
     $ rm &dash;rf meta-mymachine/recipes-graphics/xorg-xserver/xserver-xf86-emgd*
     $ rm &dash;rf meta-mymachine/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay
     $ mv meta-mymachine/recipes-graphics/xorg-xserver/xserver-xf86-config/crownbay-noemgd \
        meta-mymachine/recipes-graphics/xorg-xserver/xserver-xf86-config/mymachine   
                </literallayout>
            </para>

            <para>
                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>

            <para>
                Now let's look at changes in <filename>recipes-core</filename>.
                The file <filename>task-core-tools.bbappend</filename> in 
                <filename>recipes-core/tasks</filename> appends the similarly named recipe
                located in the local Yocto Project files at 
                <filename>meta/recipes-core/tasks</filename>.
                The "append" file in our layer right now is Crown Bay-specific and supports 
                EMGD and non-EMGD.
                Here are the contents of the file:
                <literallayout class='monospaced'>
     RRECOMMENDS_task-core-tools-profile_append_crownbay = " systemtap"
     RRECOMMENDS_task-core-tools-profile_append_crownbay-noemgd = " systemtap"
                </literallayout>
            </para>

            <para>
                The <filename>RRECOMMENDS</filename> statements list packages that 
                extend usability.
                The first <filename>RRECOMMENDS</filename> statement can be removed, while the 
                second one can be changed to reflect <filename>meta-mymachine</filename>:
                <literallayout class='monospaced'>
     RRECOMMENDS_task-core-tools-profile_append_mymachine = " systemtap"
                </literallayout>
            </para>

            <para>
                Finally, let's look at <filename>recipes-kernel</filename> changes.
                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 local Yocto Project files at 
                <filename>meta/recipes-kernel/linux</filename> and is 
                named <filename>linux-yocto-2.6.37.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.
            </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-2.6.37.bbappend</filename> that 
                is appended to the recipe of the same name in <filename>meta/recipes-kernel/link</filename>.
                Thus, the <filename>SRCREV</filename> statements in the "append" file override
                the more general statements found in <filename>meta</filename>.
            </para>

            <para>
                The <filename>SRCREV</filename> statements in the "append" file currently identify
                the kernel that supports the Crown Bay BSP with and without EMGD support.
                Here are the statements: 
                <literallayout class='monospaced'>
     SRCREV_machine_pn-linux-yocto_crownbay ?= \
        "372c0ab135978bd8ca3a77c88816a25c5ed8f303"
     SRCREV_meta_pn-linux-yocto_crownbay ?= \
        "d5d3c6480d61f83503ccef7fbcd765f7aca8b71b"

     SRCREV_machine_pn-linux-yocto_crownbay-noemgd ?= \
        "372c0ab135978bd8ca3a77c88816a25c5ed8f303"
     SRCREV_meta_pn-linux-yocto_crownbay-noemgd ?= \
        "d5d3c6480d61f83503ccef7fbcd765f7aca8b71b"
                </literallayout>
            </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 
                Crown Bay and not <filename>meta-mymachine</filename>.
            </para>

            <para>  
                To fix this situation in <filename>linux-yocto-2.6.37.bbappend</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.
                Here are the final <filename>SRCREV</filename> statements:
                <literallayout class='monospaced'>
     SRCREV_machine_pn-linux-yocto-_mymachine ?= \ 
        "fce17f046d3756045e4dfb49221d1cf60fcae329"
     SRCREV_meta_pn-linux-yocto-stable_mymachine ?= \ 
        "84f1a422d7e21fbc23a687035bdf9d42471f19e0"
                </literallayout>
            </para>

            <para>
                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-2.6.37</filename> kernel 
                <ulink url='http://git.yoctoproject.org/cgit/cgit.cgi/linux-yocto-2.6.37'>here</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>yocto/standard/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-2.6.37.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-2.6.37.bbappend</filename> file are 
                <filename>COMPATIBLE_MACHINE</filename>, <filename>KMACHINE</filename>, 
                and <filename>KERNEL_FEATURES</filename> 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>crownbay-noemgd</filename> and <filename>crownbay</filename>.
                Here is the final <filename>linux-yocto-2.6.37.bbappend</filename> file after all 
                the edits:
                <literallayout class='monospaced'>
     FILESEXTRAPATHS_prepend := "${THISDIR}/${PN}:"

     COMPATIBLE_MACHINE_mymachine = "mymachine"
     KMACHINE_mymachine  = "yocto/standard/mymachine"
     KERNEL_FEATURES_append_mymachine += " cfg/smp.scc"

     SRCREV_machine_pn-linux-yocto_mymachine ?= \
        "fce17f046d3756045e4dfb49221d1cf60fcae329"
     SRCREV_meta_pn-linux-yocto_mymachine ?= \
        "84f1a422d7e21fbc23a687035bdf9d42471f19e0"
                </literallayout>
            </para>

            <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-machine</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 id='preparing-for-the-build-app'>
            <title>Preparing for the Build</title>

            <para>
                Once you have made all the changes to your BSP layer there remains a few things 
                you need to do for the Yocto Project build system in order for it to create your image.  
                You need to get the build environment ready by sourcing an environment setup script 
                and you need to be sure two key configuration files are configured appropriately.
            </para>

            <para>
                The entire process for building an image is overviewed in the 
                <ulink url='http://www.yoctoproject.org/docs/1.1/yocto-project-qs/yocto-project-qs.html#building-image'>
                Building an Image</ulink> section of the Yocto Project Quick Start.    
                You might want to reference this information.  
                The remainder of this section will apply to our example of the 
                <filename>meta-mymachine</filename> layer.
            </para>

            <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 local Yocto Project files
                       directory structure.
                       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>yocot-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 you are using a multi-threaded development system (e.g. values of 
                       <filename>8</filename> and <filename>j 6</filename>, respectively are optimal 
                       for a development machine that has four available cores).</para></listitem>
                   <listitem><para>Update the <filename>bblayers.conf</filename> file so that it includes 
                       the path to your new BSP layer.  
                       In this example you need to include the pathname to <filename>meta-mymachine</filename>.
                       For this example the 
                       <filename>BBLAYERS</filename> variable in the file would need to include the following path:
                       <literallayout class='monospaced'>
     $HOME/poky/meta-intel/meta-mymachine
                       </literallayout></para></listitem>
               </orderedlist>
            </para>

            <para>
                The appendix 
                <ulink url='http://www.yoctoproject.org/docs/1.1/poky-ref-manual/poky-ref-manual.html#ref-variables-glos'>
                Reference: Variables Glossary</ulink> in the Yocto Project Reference Manual has more information 
                on configuration variables.
            </para>
        </section>

        <section id='building-the-image-app'>
            <title>Building the Image</title>

            <para>
                The Yocto Project uses the BitBake tool to build images based on the type of image 
                you want to create.  
                You can find more information on BitBake 
                <ulink url='http://bitbake.berlios.de/manual/'>here</ulink>.  
            </para>

            <para>
                The build process supports several types of images to satisfy different needs.  
                When you issue the BitBake command you provide a “top-level” recipe that essentially 
                starts the process off of building the type of image you want.  
            </para>

            <para>
                [WRITER'S NOTE: Consider moving this to the Poky Reference Manual.]
            </para>

            <para>
                You can find these recipes in the <filename>meta/recipes-core/images</filename> and 
                <filename>meta/recipes-sato/images</filename> directories of your local Yocto Project 
                file structure (Git repository or extracted release tarball).  
                Although the recipe names are somewhat explanatory, here is a list that describes them:
                <itemizedlist>
                    <listitem><para><emphasis>Base</emphasis> – A foundational basic image without support 
                        for X that can be reasonably used for customization.</para></listitem>
                    <listitem><para><emphasis>Core</emphasis> – A foundational basic image with support for 
                        X that can be reasonably used for customization.</para></listitem>
                    <listitem><para><emphasis>Direct Disk</emphasis> – An image that you can copy directory to 
                        the disk of the target device.</para></listitem>
                    <listitem><para><emphasis>Live</emphasis> – An image you can run from a USB device or from 
                        a CD without having to first install something.</para></listitem>
                    <listitem><para><emphasis>Minimal</emphasis> – A small image without a GUI.  
                        This image is not much more than a kernel with a shell.</para></listitem>
                    <listitem><para><emphasis>Minimal Development</emphasis> – A Minimal image suitable for 
                        development work.</para></listitem>
                    <listitem><para><emphasis>Minimal Direct Disk</emphasis> – A Minimal Direct Disk image.</para></listitem>
                    <listitem><para><emphasis>Minimal RAM-based Initial Root Filesystem</emphasis> – A minimal image 
                        that has the <filename>initramfs</filename> as part of the kernel, which allows the 
                        system to find the first “init” program more efficiently.</para></listitem>
                    <listitem><para><emphasis>Minimal Live</emphasis> – A Minimal Live image.</para></listitem>
                    <listitem><para><emphasis>Minimal MTD Utilities</emphasis> – A minimal image that has support 
                        for the MTD utilities, which let the user interact with the MTD subsystem in 
                        the kernel to perform operations on flash devices.</para></listitem>
                    <listitem><para><emphasis>Sato</emphasis> – An image with Sato support, a mobile environment 
                        and visual style that works well with mobile devices.</para></listitem>
                    <listitem><para><emphasis>Sato Development</emphasis> – A Sato image suitable for 
                        development work.</para></listitem>
                    <listitem><para><emphasis>Sato Direct Disk</emphasis> – A Sato Direct Disk image.</para></listitem>
                    <listitem><para><emphasis>Sato Live</emphasis> – A Sato Live image.</para></listitem>
                    <listitem><para><emphasis>Sato SDK</emphasis> – A Sato image that includes the Yocto Project 
                        toolchain and development libraries.</para></listitem>
                    <listitem><para><emphasis>Sato SDK Direct Disk</emphasis> – A Sato SDK Direct 
                        Disk image.</para></listitem>
                    <listitem><para><emphasis>Sato SDK Live</emphasis> – A Sato SDK Live image.</para></listitem>
                </itemizedlist>
            </para>

            <para>
                The remainder of this section applies to our example of the <filename>meta-mymachine</filename> layer.
            </para>

            <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-live
                </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>
        </section>
    </section>

    <section id='modifying-a-kernel-kernel-example-app'>
        <title>Modifying a Kernel</title>

        <para>
            Kernel modification involves changing or adding configurations to an existing kernel, or 
            adding recipes to the kernel that are needed to support specific hardware features.  
            The process is similar to creating a Board Support Package (BSP) except that it does not
            involve a BSP layer.
        </para>

        <para>
            This section presents a brief overview of the kernel structure and then provides a simple 
            example that shows how to modify the kernel.
        </para>

        <section id='yocto-project-kernel-app'>
            <title>Yocto Project Kernel Overview</title>

            <para>
                When one thinks of the source files for a kernel they usually think of a fixed structure 
                of files that contain kernel patches.
                The Yocto Project, however, employs mechanisims that in a sense result in a kernel source
                generator.
            </para>

            <para>
                The Yocto Project uses the source code management (SCM) tool Git to manage and track Yocto 
                Project files.
                Git employs branching strategies that effectively produce a tree-like structure whose 
                branches represent diversions from more general code. 
                For example, suppose two kernels are basically identical with the exception of a couple
                different features in each.
                In the Yocto Project source repositories managed by Git a main branch can contain the 
                common or shared
                parts of the kernel source and two branches that diverge from that common branch can 
                each contain the features specific to the respective kernel.
                The result is a managed tree whose "leaves" represent the end of a specific path that yields
                a set of kernel source files necessary for a specific piece of hardware and its features.
            </para>
         
            <para>
                A big advantage to this scheme is the sharing of common features by keeping them in 
                "larger" branches that are further up the tree.  
                This practice eliminates redundant storage of similar features shared among kernels.
            </para>

            <para>
                When you build the kernel on your development system all files needed for the build
                are taken from the Yocto Project source repositories pointed to by the 
                <filename>SRC_URI</filename> variable and gathered in a temporary work area
                where they are subsequently used to create the unique kernel.
                Thus, in a sense, the process constructs a local source tree specific to your 
                kernel to generate the new kernel image - a source generator if you will.
            </para>

            <para>
                For a complete discussion of the Yocto Project kernel's architcture and its branching strategy,
                see the <ulink url='http://www.yoctoproject.org/docs/1.1/kernel-manual/kernel-manual.html'>
                The Yocto Project Kernel Architecture and Use Manual</ulink>.
            </para>

            <para>  
                You can find a web interface to the Yocto Project source repository at 
                <ulink url='http://git.yoctoproject.org/'></ulink>.  
                Within the interface you will see groups of related source code, each of which can 
                be cloned using Git to result in a working Git repository on your local system 
                (referred to as the "local Yocto Project files" in this manual).
                The Yocto Project supports four types of kernels in its source repositories at 
                <ulink url='http://git.yoctoproject.org/'></ulink>:
                <itemizedlist>
                    <listitem><para><emphasis><filename>linux-yocto-2.6.34</filename></emphasis> - The 
                    stable Linux Yocto kernel that is based on the Linux 2.6.34 release.</para></listitem>
                    <listitem><para><emphasis><filename>linux-yocto-2.6.37</filename></emphasis> - The current
                    Linux Yocto kernel that is based on the Linux 2.6.37 release.</para></listitem>
                    <listitem><para><emphasis><filename>linux-yocto-dev</filename></emphasis> - A development
                    kernel based on the Linux 2.6.39-rc1 release.</para></listitem>
                    <listitem><para><emphasis><filename>linux-2.6</filename></emphasis> - A kernel based on 
                    minimal Linux mainline tracking.
                    [WRITER'S NOTE: I don't know which Git repository the user needs to clone to get this
                    repository on their development system.]</para></listitem>
                </itemizedlist>
            </para>
        </section>

        <section id='modifying-a-kernel-example-app'>
            <title>Modifying a Kernel Example</title>

            <para>
                This section presents a simple example that illustrates kernel modification
                based on the <filename>linux-yocto-2.6.37</filename> kernel.
                The example uses the audio and mixer capabilities supported by the 
                <ulink url='http://www.alsa-project.org/main/index.php/Main_Page'>Advanced Linux 
                Sound Architecture (ALSA) Project</ulink>.
                As the example progresses you will see how to do the following:
                <itemizedlist>
                    <listitem><para>Iteratively modify a base kernel locally.</para></listitem>      
                    <listitem><para>Provide a recipe-based solution for your modified kernel.
                    </para></listitem>
                    <listitem><para>Proved an "in-tree" solution for your modified kernel
                    (i.e. make the modifcations part of the Yocto Project).</para></listitem>
                </itemizedlist>
            </para>

            <para>
                The example flows as follows:
            </para>

            <para>
                <itemizedlist>
                    <listitem><para>Be sure your host development system is set up to support 
                    development using the Yocto Project. 
                    See  
                    <ulink url='http://www.yoctoproject.org/docs/1.1/yocto-project-qs/yocto-project-qs.html#the-linux-distro'>
                    The Linux Distributions</ulink> section and  
                    <ulink url='http://www.yoctoproject.org/docs/1.1/yocto-project-qs/yocto-project-qs.html#packages'>
                    The Packages</ulink> section both
                    in the Yocto Project Quick Start for requirements.
                    You will also need a release of Yocto Project installed on the host.</para></listitem>
                    <listitem><para>Set up your environment for optimal local kernel development.
                    </para></listitem>
                    <listitem><para>Create a layer to isolate your kernel work.</para></listitem>
                    <listitem><para>Next item.</para></listitem>
                    <listitem><para>Next item.</para></listitem>
                    <listitem><para>Next item.</para></listitem>
                    <listitem><para>Next item.</para></listitem>
                </itemizedlist>        
            </para>

            <section id='setting-up-yocto-project-kernel-example-app'>
                <title>Setting Up Yocto Project</title>

                <para>
                    You need to have the Yocto Project files available on your host system.  
                    The process is identical to that described in getting the files in section
                    <xref linkend='setting-up-yocto-project-app'>"Setting Up Yocto Project"</xref> for
                    the BSP development case.
                    Be sure to either set up a local Git repository for <filename>poky</filename>
                    or download and unpack the Yocto Project release tarball.  
                </para>
            </section>

            <section id='create-a-git-repository-of-poky-extras-app'>
                <title>Create a Git Repository of <filename>poky-extras</filename></title>

                <para>
                    Everytime you change a configuration or add a recipe to the kernel you need to 
                    do a fetch from the Linux Yocto kernel source repositories.
                    This can get tedious and time consuming if you need to fetch the entire 
                    Linux Yocto 2.6.37 Git repository down from the Internet everytime you make a change
                    to the kernel.  
                </para>

                <para>
                    You can get around this by setting up a <filename>meta-kernel-dev</filename>
                    area on your local system.  
                    This area contains "append" files for every kernel recipe, which also include
                    a <filename>KSRC</filename> statement that points to the kernel source files.
                    You can set up the environment so that the <filename>KSRC</filename> points to the
                    <filename>meta-kernel-dev</filename>, thus pulling source from a local area.
                    This setup can speed up development time. 
                 </para>

                 <para>
                    To get set up you need to do two things: create a local Git repository 
                    of the <filename>poky-extras</filename> repository, and create a bare clone of the 
                    Linux Yocto 2.6.37 kernel Git repository.
                 </para>

                 <para>
                    The following transcript shows how to clone the <filename>poky-extras</filename> 
                    Git repository into the current working directory, which is <filename>poky</filename>
                    in this example.  
                    The command creates the repository in a directory named <filename>poky-extras</filename>:
                    <literallayout class='monospaced'>
     $ git clone git://git.yoctoproject.org/poky-extras
     Initialized empty Git repository in /home/scottrif/poky/poky-extras/.git/
     remote: Counting objects: 532, done.
     remote: Compressing objects: 100% (472/472), done.
     remote: Total 532 (delta 138), reused 307 (delta 39)
     Receiving objects: 100% (532/532), 534.28 KiB | 362 KiB/s, done.
     Resolving deltas: 100% (138/138), done.
                    </literallayout>
                </para>

                <para>
                    This transcript shows how to clone a bare Git repository of the Linux Yocto 
                    2.6.37 kernel:
                    <literallayout class='monospaced'>
     $ git clone --bare git://git.yoctoproject.org/linux-yocto-2.6.37
     Initialized empty Git repository in /home/scottrif/linux-yocto-2.6.37.git/
     remote: Counting objects: 1886034, done.
     remote: Compressing objects: 100% (314326/314326), done.
     remote: Total 1886034 (delta 1570202), reused 1870335 (delta 1554798)
     Receiving objects: 100% (1886034/1886034), 401.51 MiB | 714 KiB/s, done.
     Resolving deltas: 100% (1570202/1570202), done.
                    </literallayout>
                </para>

                <para>
                    The bare clone of the Linux Yocto 2.6.37 kernel on your local system mirrors
                    the upstream repository of the kernel.
                    You can effectively point to this local clone now during development to avoid 
                    having to fetch the entire Linux Yocto 2.6.37 kernel every time you make a 
                    kernel change.
                </para>
            </section>

            <section id='create-a-layer-for-your-kernel-work-app'>
                <title>Create a Layer for Your Kernel Work</title>

                <para>
                    It is always good to isolate your work using your own layer.
                    Doing so allows you to experiment and easily start over should things go wrong. 
                    This example uses a layer named <filename>meta-amixer</filename>.
                </para>

                <para>
                    When you set up a layer for kernel work you should follow the general layout
                    guidelines as described for BSP layers. 
                    This layout is described in the
                    <ulink url='http://www.yoctoproject.org/docs/1.1/bsp-guide/bsp-guide.html#bsp-filelayout'>
                    Example Filesystem Layout</ulink> section of the Board Support Package (BSP) Development
                    Guide.  
                    In the standard layout you will notice a suggested structure for recipes and  
                    configuration information.  
                    [WRITER'S NOTE: The <filename>meta-elc</filename> example uses an 
                    <filename>images</filename> directory.
                    Currently, <filename>images</filename> is not part of the standard BSP layout.
                    I need to find out from Darren if this directory is required for kernel work.]
                </para>

                <para>
                    [WRITER'S NOTE:  I need a paragraph here describing how to set up the layer. 
                    I am not sure if you should copy an existing BSP layer and modify from there.
                    Or, if you should just look at a BSP layer and then create your own files.
                    Email to Darren on this but no answer yet.]
                </para>
            </section>

            <section id='making-changes-to-your-kernel-layer-app'>
                <title>Making Changes to Your Kernel Layer</title>
            
                <para>
                    In the standard layer structure you have several areas that you need to examine or 
                    modify.
                    For this example the layer contains four areas:
                    <itemizedlist>
                        <listitem><para><emphasis><filename>conf</filename></emphasis> - Contains the 
                        <filename>layer.conf</filename> that identifies the location of the recipe files. 
                        </para></listitem>
                        <listitem><para><emphasis><filename>images</filename></emphasis> - Contains the 
                        image recipe file. 
                        This recipe includes the base image you will be using and specifies other 
                        packages the image might need.</para></listitem>
                        <listitem><para><emphasis><filename>recipes-bsp</filename></emphasis> - Contains 
                        recipes specific to the hardware for which you are developing the kernel.
                        </para></listitem>
                        <listitem><para><emphasis><filename>recipes-kernel</filename></emphasis> - Contains the 
                        "append" files that add information to the main recipe kernel.  
                        </para></listitem>
                    </itemizedlist>
                </para>

                <para>
                    Let's take a look at the <filename>layer.conf</filename> in the 
                    <filename>conf</filename> directory first.
                    This configuration file enables the Yocto Project build system to locate and 
                    use the information in your new layer.
                </para>

                <para>
                    The variable <filename>BBPATH</filename> needs to include the path to your layer
                    as follows:
                    <literallayout class='monospaced'>
     BBPATH := "${BBPATH}:${LAYERDIR}"
                    </literallayout>
                    And, the variable <filename>BBFILES</filename> needs to be modified to include your 
                    recipe and append files:
                    <literallayout class='monospaced'>
     BBFILES := "${BBFILES} ${LAYERDIR}/images/*.bb \ 
        ${LAYERDIR}/images/*.bbappend \
        ${LAYERDIR}/recipes-*/*/*.bb \
        ${LAYERDIR}/recipes-*/*/*.bbappend"
                    </literallayout>
                    Finally, you need to be sure to use your layer name in these variables at the 
                    end of the file:
                    <literallayout class='monospaced'>
     BBFILE_COLLECTIONS += "elc"
     BBFILE_PATTERN_elc := "^${LAYERDIR}/"
     BBFILE_PRIORITY_elc = "9"
                   </literallayout>
                </para>

                <para>
                    The <filename>images</filename> directory contains an append file that helps 
                    further define the image.
                    In our example, the base image is <filename>core-image-minimal</filename>.  
                    The image does, however, need some additional modules that we are using
                    for this example.
                    These modules support the amixer functionality.
                    Here is the append file:
                    <literallayout class='monospaced'>
     require recipes-core/images/poky-image-minimal.bb

     IMAGE_INSTALL += "dropbear alsa-utils-aplay alsa-utils-alsamixer"
     IMAGE_INSTALL_append_qemux86 += " kernel-module-snd-ens1370 \
        kernel-module-snd-rawmidi kernel-module-loop kernel-module-nls-cp437 \
        kernel-module-nls-iso8859-1 qemux86-audio alsa-utils-amixer"

     LICENSE = "MIT"
                   </literallayout>
               </para>

               <para>
                   While the focus of this example is not on the BSP, it is worth mentioning that the
                   <filename>recipes-bsp</filename> directory has the recipes and append files for 
                   features that the hardware requires. 
                   In this example, there is a script and a recipe to support the 
                   <filename>amixer</filename> functionality in QEMU.
                   It is beyond the scope of this manual to go too deeply into the script.
                   Suffice it to say that the script tests for the presence of the mixer, sets up 
                   default mixer values, enables the mixer, unmutes master and then 
                   sets the volume to 100.
               </para>

               <para>
                   The recipe <filename>qemu86-audio.bb</filename> installs and runs the 
                   <filename>amixer</filename> when the system boots.
                   Here is the recipe:
                   <literallayout class='monospaced'>
     SUMMARY = "Provide a basic init script to enable audio"
     DESCRIPTION = "Set the volume and unmute the Front mixer setting during boot."
     SECTION = "base"
     LICENSE = "MIT"
     LIC_FILES_CHKSUM = "file://${POKYBASE}/LICENSE;md5=3f40d7994397109285ec7b81fdeb3b58"

     PR = "r4"

     inherit update-rc.d

     RDEPENDS = "alsa-utils-amixer"

     SRC_URI = "file://qemux86-audio"

     INITSCRIPT_NAME = "qemux86-audio"
     INITSCRIPT_PARAMS = "defaults 90"

     do_install() {
	     install -d ${D}${sysconfdir} \
     	           ${D}${sysconfdir}/init.d
     	install -m 0755 ${WORKDIR}/qemux86-audio ${D}${sysconfdir}/init.d
             cat ${WORKDIR}/${INITSCRIPT_NAME} | \
                 sed -e 's,/etc,${sysconfdir},g' \
                     -e 's,/usr/sbin,${sbindir},g' \
                     -e 's,/var,${localstatedir},g' \
                     -e 's,/usr/bin,${bindir},g' \
                     -e 's,/usr,${prefix},g' > ${D}${sysconfdir}/init.d/${INITSCRIPT_NAME}
             chmod 755 ${D}${sysconfdir}/init.d/${INITSCRIPT_NAME}
     }
                </literallayout>
                </para>

                <para>
                    The last area to look at is <filename>recipes-kernel</filename>.
                    This area holds configuration fragments and kernel append files.
                    The append file must have the same name as the kernel recipe, which is 
                    <filename>linux-yocto-2.6.37</filename> in this example.
                    The file can <filename>SRC_URI</filename> statements to point to configuration 
                    fragments you might have in the layer. 
                    The file can also contain <filename>KERNEL_FEATURES</filename> statements that specify
                    included kernel configurations that ship with the Yocto Project.
                </para>
            </section>
        </section>
    </section>
</section>

</appendix>


                
            

<!--


            <para>
                [WRITER'S NOTE:  This section is a second example that focuses on just modifying the kernel.
                I don't have any information on this yet.
            </para>

            <para>
                Here are some points to consider though:
                <itemizedlist>
                    <listitem><para>Reference Darren's presentation 
                        <ulink url='http://events.linuxfoundation.org/events/embedded-linux-conference/hart'>
                        here</ulink></para></listitem>
                    <listitem><para>Reference <xref linkend='dev-manual-start'>Getting Started with the Yocto Project</xref>
                        section to get set up at minimum.</para></listitem>
                    <listitem><para>Are there extra steps I need specific to kernel development to get started?</para></listitem>
                    <listitem><para>What do I do to get set up?  
                        Is it a matter of just installing YP and having some pieces together?  
                        What are the pieces?</para></listitem>
                    <listitem><para>Where do I get the base kernel to start with?</para></listitem>
                    <listitem><para>Do I install the appropriate toolchain?</para></listitem>
                    <listitem><para>What kernel git repository do I use?</para></listitem>
                    <listitem><para>What is the conversion script?  
                        What does it do?</para></listitem>
                    <listitem><para>What do I have to do to integrate the kernel layer?</para></listitem>
                    <listitem><para>What do I use to integrate the kernel layer?  
                        HOB? 
                        Do I just Bitbake it?</para></listitem>
                    <listitem><para>Using the System Image Creator.]</para></listitem>
                </itemizedlist>
            </para>
        </section>
    </section>
</section>

<section id='user-application-development'>
    <title>User Application Development</title>

    <para>
        [WRITER'S NOTE:  This section is the second major development case - developing an application.
        Here are points to consider:
        <itemizedlist>
            <listitem><para>User-space Application Development scenario overview.</para></listitem>
            <listitem><para>Using the Yocto Eclipse Plug-in.</para></listitem>
            <listitem><para>Back-door support.</para></listitem>
            <listitem><para>I feel there is more to this area than we have captured during our two 
                review meetings.]</para></listitem>
        </itemizedlist>
    </para>
</section>
</chapter>
-->

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