path: root/documentation/dev-manual/dev-manual-model.xml

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<chapter id='dev-manual-model'>

<title>Common Development Models</title>

<para>
    Many development models exist for which you can use the Yocto Project.
    This chapter overviews simple methods that use tools provided by the
    Yocto Project:
    <itemizedlist>
        <listitem><para><emphasis>System Development:</emphasis>
             System Development covers Board Support Package (BSP) development
             and kernel modification or configuration.
             For an example on how to create a BSP, see the
             "<ulink url='&YOCTO_DOCS_BSP_URL;#creating-a-new-bsp-layer-using-the-yocto-bsp-script'>Creating a New BSP Layer Using the yocto-bsp Script</ulink>"
             section in the Yocto Project Board Support Package (BSP)
             Developer's Guide.
             For more complete information on how to work with the kernel,
             see the
             <ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;'>Yocto Project Linux Kernel Development Manual</ulink>.
             </para></listitem>
         <listitem><para><emphasis>Temporary Source Code Modification:</emphasis>
             Direct modification of temporary source code is a convenient
             development model to quickly iterate and develop towards a
             solution.
             Once you implement the solution, you should of course take
             steps to get the changes upstream and applied in the affected
             recipes.
             </para></listitem>
         <listitem><para><emphasis>Using a Development Shell:</emphasis>
             You can use a
             <link linkend='platdev-appdev-devshell'><filename>devshell</filename></link>
             to efficiently debug
             commands or simply edit packages.
             Working inside a development shell is a quick way to set up the
             OpenEmbedded build environment to work on parts of a project.
             </para></listitem>
     </itemizedlist>
</para>

<section id="dev-modifying-source-code">
    <title>Modifying Source Code</title>

    <para>
        A common development workflow consists of modifying project source
        files that are external to the Yocto Project and then integrating
        that project's build output into an image built using the
        OpenEmbedded build system.
        Given this scenario, development engineers typically want to stick
        to their familiar project development tools and methods, which allows
        them to just focus on the project.
    </para>

    <para>
        Several workflows exist that allow you to develop, build, and test
        code that is going to be integrated into an image built using the
        OpenEmbedded build system.
        This section describes two:
        <itemizedlist>
            <listitem><para><emphasis><filename>devtool</filename>:</emphasis>
                A set of tools to aid in working on the source code built by
                the OpenEmbedded build system.
                Section
                "<link linkend='using-devtool-in-your-workflow'>Using <filename>devtool</filename> in Your Workflow</link>"
                describes this workflow.
                If you want more information that showcases the workflow, click
                <ulink url='https://drive.google.com/a/linaro.org/file/d/0B3KGzY5fW7laTDVxUXo3UDRvd2s/view'>here</ulink>
                for a presentation by Trevor Woerner that, while somewhat dated,
                provides detailed background information and a complete
                working tutorial.
                </para></listitem>
            <listitem><para><emphasis><ulink url='http://savannah.nongnu.org/projects/quilt'>Quilt</ulink>:</emphasis>
                A powerful tool that allows you to capture source
                code changes without having a clean source tree.
                While Quilt is not the preferred workflow of the two, this
                section includes it for users that are committed to using
                the tool.
                See the
                "<link linkend='using-a-quilt-workflow'>Using Quilt in Your Workflow</link>"
                section for more information.
                </para></listitem>
        </itemizedlist>
    </para>

    <section id='using-devtool-in-your-workflow'>
        <title>Using <filename>devtool</filename> in Your Workflow</title>

        <para>
            As mentioned earlier, <filename>devtool</filename> helps
            you easily develop projects whose build output must be part of
            an image built using the OpenEmbedded build system.
        </para>

        <para>
            Three entry points exist that allow you to develop using
            <filename>devtool</filename>:
            <itemizedlist>
                <listitem><para><emphasis><filename>devtool add</filename></emphasis>
                    </para></listitem>
                <listitem><para><emphasis><filename>devtool modify</filename></emphasis>
                    </para></listitem>
                <listitem><para><emphasis><filename>devtool upgrade</filename></emphasis>
                    </para></listitem>
            </itemizedlist>
        </para>

        <para>
            The remainder of this section presents these workflows.
            See the
            "<ulink url='&YOCTO_DOCS_REF_URL;#ref-devtool-reference'><filename>devtool</filename>&nbsp;Quick Reference</ulink>"
            in the Yocto Project Reference Manual for a
            <filename>devtool</filename> quick reference.
        </para>

        <section id='use-devtool-to-integrate-new-code'>
            <title>Use <filename>devtool add</filename> to Add an Application</title>

            <para>
                The <filename>devtool add</filename> command generates
                a new recipe based on existing source code.
                This command takes advantage of the
                <ulink url='&YOCTO_DOCS_DEV_URL;#devtool-the-workspace-layer-structure'>workspace</ulink>
                layer that many <filename>devtool</filename> commands
                use.
                The command is flexible enough to allow you to extract source
                code into both the workspace or a separate local Git repository
                and to use existing code that does not need to be extracted.
            </para>

            <para>
                Depending on your particular scenario, the arguments and options
                you use with <filename>devtool add</filename> form different
                combinations.
                The following diagram shows common development flows
                you would use with the <filename>devtool add</filename>
                command:
            </para>

            <para>
                <imagedata fileref="figures/devtool-add-flow.png" align="center" />
            </para>

            <para>
                <orderedlist>
                    <listitem><para><emphasis>Generating the New Recipe</emphasis>:
                        The top part of the flow shows three scenarios by which
                        you could use <filename>devtool add</filename> to
                        generate a recipe based on existing source code.</para>

                        <para>In a shared development environment, it is
                        typical where other developers are responsible for
                        various areas of source code.
                        As a developer, you are probably interested in using
                        that source code as part of your development using
                        the Yocto Project.
                        All you need is access to the code, a recipe, and a
                        controlled area in which to do your work.</para>

                        <para>Within the diagram, three possible scenarios
                        feed into the <filename>devtool add</filename> workflow:
                        <itemizedlist>
                            <listitem><para><emphasis>Left</emphasis>:
                                The left scenario represents a common situation
                                where the source code does not exist locally
                                and needs to be extracted.
                                In this situation, you just let it get
                                extracted to the default workspace - you do not
                                want it in some specific location outside of the
                                workspace.
                                Thus, everything you need will be located in the
                                workspace:
                                <literallayout class='monospaced'>
     $ devtool add <replaceable>recipe fetchuri</replaceable>
                                </literallayout>
                                With this command, <filename>devtool</filename>
                                creates a recipe and an append file in the
                                workspace as well as extracts the upstream
                                source files into a local Git repository also
                                within the <filename>sources</filename> folder.
                                </para></listitem>
                            <listitem><para><emphasis>Middle</emphasis>:
                                The middle scenario also represents a situation where
                                the source code does not exist locally.
                                In this case, the code is again upstream
                                and needs to be extracted to some
                                local area - this time outside of the default
                                workspace.
                                If required, <filename>devtool</filename>
                                always creates
                                a Git repository locally during the extraction.
                                Furthermore, the first positional argument
                                <replaceable>srctree</replaceable> in this case
                                identifies where the
                                <filename>devtool add</filename> command
                                will locate the extracted code outside of the
                                workspace:
                                <literallayout class='monospaced'>
     $ devtool add <replaceable>recipe srctree fetchuri</replaceable>
                                </literallayout>
                                In summary, the source code is pulled from
                                <replaceable>fetchuri</replaceable> and extracted
                                into the location defined by
                                <replaceable>srctree</replaceable> as a local
                                Git repository.</para>

                                <para>Within workspace, <filename>devtool</filename>
                                creates both the recipe and an append file
                                for the recipe.
                                </para></listitem>
                            <listitem><para><emphasis>Right</emphasis>:
                                The right scenario represents a situation
                                where the source tree (srctree) has been
                                previously prepared outside of the
                                <filename>devtool</filename> workspace.
                                </para>

                                <para>The following command names the recipe
                                and identifies where the existing source tree
                                is located:
                                <literallayout class='monospaced'>
     $ devtool add <replaceable>recipe srctree</replaceable>
                                </literallayout>
                                The command examines the source code and creates
                                a recipe for it placing the recipe into the
                                workspace.</para>

                                <para>Because the extracted source code already exists,
                                <filename>devtool</filename> does not try to
                                relocate it into the workspace - just the new
                                the recipe is placed in the workspace.</para>

                                <para>Aside from a recipe folder, the command
                                also creates an append folder and places an initial
                                <filename>*.bbappend</filename> within.
                                </para></listitem>
                        </itemizedlist>
                        </para></listitem>
                    <listitem><para><emphasis>Edit the Recipe</emphasis>:
                        At this point, you can use <filename>devtool edit-recipe</filename>
                        to open up the editor as defined by the
                        <filename>$EDITOR</filename> environment variable
                        and modify the file:
                        <literallayout class='monospaced'>
     $ devtool edit-recipe <replaceable>recipe</replaceable>
                        </literallayout>
                        From within the editor, you can make modifications to the
                        recipe that take affect when you build it later.
                        </para></listitem>
                    <listitem><para><emphasis>Build the Recipe or Rebuild the Image</emphasis>:
                        At this point in the flow, the next step you
                        take depends on what you are going to do with
                        the new code.</para>
                        <para>If you need to take the build output and eventually
                        move it to the target hardware, you would use
                        <filename>devtool build</filename>:
                        <literallayout class='monospaced'>
     $ devtool build <replaceable>recipe</replaceable>
                        </literallayout></para>
                        <para>On the other hand, if you want an image to
                        contain the recipe's packages for immediate deployment
                        onto a device (e.g. for testing purposes), you can use
                        the <filename>devtool build-image</filename> command:
                        <literallayout class='monospaced'>
     $ devtool build-image <replaceable>image</replaceable>
                        </literallayout>
                        </para></listitem>
                    <listitem><para><emphasis>Deploy the Build Output</emphasis>:
                        When you use the <filename>devtool build</filename>
                        command to build out your recipe, you probably want to
                        see if the resulting build output works as expected on target
                        hardware.
                        <note>
                            This step assumes you have a previously built
                            image that is already either running in QEMU or
                            running on actual hardware.
                            Also, it is assumed that for deployment of the image
                            to the target, SSH is installed in the image and if
                            the image is running on real hardware that you have
                            network access to and from your development machine.
                        </note>
                        You can deploy your build output to that target hardware by
                        using the <filename>devtool deploy-target</filename> command:
                        <literallayout class='monospaced'>
     $ devtool deploy-target <replaceable>recipe target</replaceable>
                        </literallayout>
                        The <replaceable>target</replaceable> is a live target machine
                        running as an SSH server.</para>

                        <para>You can, of course, also deploy the image you build
                        using the <filename>devtool build-image</filename> command
                        to actual hardware.
                        However, <filename>devtool</filename> does not provide a
                        specific command that allows you to do this.
                        </para></listitem>
                    <listitem><para>
                        <emphasis>Finish Your Work With the Recipe</emphasis>:
                        The <filename>devtool finish</filename> command creates
                        any patches corresponding to commits in the local
                        Git repository, moves the new recipe to a more permanent
                        layer, and then resets the recipe so that the recipe is
                        built normally rather than from the workspace.
                        <literallayout class='monospaced'>
     $ devtool finish <replaceable>recipe layer</replaceable>
                        </literallayout>
                        <note>
                            Any changes you want to turn into patches must be
                            committed to the Git repository in the source tree.
                        </note></para>

                        <para>As mentioned, the <filename>devtool finish</filename>
                        command moves the final recipe to its permanent layer.
                        </para>

                        <para>As a final process of the
                        <filename>devtool finish</filename> command, the state
                        of the standard layers and the upstream source is
                        restored so that you can build the recipe from those
                        areas rather than the workspace.
                        <note>
                            You can use the <filename>devtool reset</filename>
                            command to put things back should you decide you
                            do not want to proceed with your work.
                            If you do use this command, realize that the source
                            tree is preserved.
                        </note>
                        </para></listitem>
                </orderedlist>
            </para>
        </section>

        <section id='devtool-use-devtool-modify-to-enable-work-on-code-associated-with-an-existing-recipe'>
            <title>Use <filename>devtool modify</filename> to Modify the Source of an Existing Component</title>

            <para>
                The <filename>devtool modify</filename> command prepares the
                way to work on existing code that already has a recipe in
                place.
                The command is flexible enough to allow you to extract code,
                specify the existing recipe, and keep track of and gather any
                patch files from other developers that are
                associated with the code.
            </para>

            <para>
                Depending on your particular scenario, the arguments and options
                you use with <filename>devtool modify</filename> form different
                combinations.
                The following diagram shows common development flows
                you would use with the <filename>devtool modify</filename>
                command:
            </para>

            <para>
                <imagedata fileref="figures/devtool-modify-flow.png" align="center" />
            </para>

            <para>
                <orderedlist>
                    <listitem><para><emphasis>Preparing to Modify the Code</emphasis>:
                        The top part of the flow shows three scenarios by which
                        you could use <filename>devtool modify</filename> to
                        prepare to work on source files.
                        Each scenario assumes the following:
                        <itemizedlist>
                            <listitem><para>The recipe exists in some layer external
                                to the <filename>devtool</filename> workspace.
                                </para></listitem>
                            <listitem><para>The source files exist upstream in an
                                un-extracted state or locally in a previously
                                extracted state.
                                </para></listitem>
                        </itemizedlist>
                        The typical situation is where another developer has
                        created some layer for use with the Yocto Project and
                        their recipe already resides in that layer.
                        Furthermore, their source code is readily available
                        either upstream or locally.
                        <itemizedlist>
                            <listitem><para><emphasis>Left</emphasis>:
                                The left scenario represents a common situation
                                where the source code does not exist locally
                                and needs to be extracted.
                                In this situation, the source is extracted
                                into the default workspace location.
                                The recipe, in this scenario, is in its own
                                layer outside the workspace
                                (i.e.
                                <filename>meta-</filename><replaceable>layername</replaceable>).
                                </para>

                                <para>The following command identifies the recipe
                                and by default extracts the source files:
                                <literallayout class='monospaced'>
     $ devtool modify <replaceable>recipe</replaceable>
                                </literallayout>
                                Once <filename>devtool</filename>locates the recipe,
                                it uses the
                                <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
                                variable to locate the source code and
                                any local patch files from other developers are
                                located.
                                <note>
                                    You cannot provide an URL for
                                    <replaceable>srctree</replaceable> when using the
                                    <filename>devtool modify</filename> command.
                                </note>
                                With this scenario, however, since no
                                <replaceable>srctree</replaceable> argument exists, the
                                <filename>devtool modify</filename> command by default
                                extracts the source files to a Git structure.
                                Furthermore, the location for the extracted source is the
                                default area within the workspace.
                                The result is that the command sets up both the source
                                code and an append file within the workspace with the
                                recipe remaining in its original location.
                                </para></listitem>
                            <listitem><para><emphasis>Middle</emphasis>:
                                The middle scenario represents a situation where
                                the source code also does not exist locally.
                                In this case, the code is again upstream
                                and needs to be extracted to some
                                local area as a Git repository.
                                The recipe, in this scenario, is again in its own
                                layer outside the workspace.</para>

                                <para>The following command tells
                                <filename>devtool</filename> what recipe with
                                which to work and, in this case, identifies a local
                                area for the extracted source files that is outside
                                of the default workspace:
                                <literallayout class='monospaced'>
     $ devtool modify <replaceable>recipe srctree</replaceable>
                                </literallayout>
                                As with all extractions, the command uses
                                the recipe's <filename>SRC_URI</filename> to locate the
                                source files.
                                Once the files are located, the command by default
                                extracts them.
                                Providing the <replaceable>srctree</replaceable>
                                argument instructs <filename>devtool</filename> where
                                to place the extracted source.</para>

                                <para>Within workspace, <filename>devtool</filename>
                                creates an append file for the recipe.
                                The recipe remains in its original location but
                                the source files are extracted to the location you
                                provided with <replaceable>srctree</replaceable>.
                                </para></listitem>
                            <listitem><para><emphasis>Right</emphasis>:
                                The right scenario represents a situation
                                where the source tree
                                (<replaceable>srctree</replaceable>) exists as a
                                previously extracted Git structure outside of
                                the <filename>devtool</filename> workspace.
                                In this example, the recipe also exists
                                elsewhere in its own layer.
                                </para>

                                <para>The following command tells
                                <filename>devtool</filename> the recipe
                                with which to work, uses the "-n" option to indicate
                                source does not need to be extracted, and uses
                                <replaceable>srctree</replaceable> to point to the
                                previously extracted source files:
                                <literallayout class='monospaced'>
     $ devtool modify -n <replaceable>recipe srctree</replaceable>
                                </literallayout>
                                </para>

                                <para>Once the command finishes, it creates only
                                an append file for the recipe in the workspace.
                                The recipe and the source code remain in their
                                original locations.
                                </para></listitem>
                            </itemizedlist>
                        </para></listitem>
                    <listitem><para><emphasis>Edit the Source</emphasis>:
                        Once you have used the <filename>devtool modify</filename>
                        command, you are free to make changes to the source
                        files.
                        You can use any editor you like to make and save
                        your source code modifications.
                        </para></listitem>
                    <listitem><para><emphasis>Build the Recipe</emphasis>:
                        Once you have updated the source files, you can build
                        the recipe.
                        </para></listitem>
                    <listitem><para><emphasis>Deploy the Build Output</emphasis>:
                        When you use the <filename>devtool build</filename>
                        command to build out your recipe, you probably want to see
                        if the resulting build output works as expected on target
                        hardware.
                        <note>
                            This step assumes you have a previously built
                            image that is already either running in QEMU or
                            running on actual hardware.
                            Also, it is assumed that for deployment of the image
                            to the target, SSH is installed in the image and if
                            the image is running on real hardware that you have
                            network access to and from your development machine.
                        </note>
                        You can deploy your build output to that target hardware by
                        using the <filename>devtool deploy-target</filename> command:
                        <literallayout class='monospaced'>
     $ devtool deploy-target <replaceable>recipe target</replaceable>
                        </literallayout>
                        The <replaceable>target</replaceable> is a live target machine
                        running as an SSH server.</para>

                        <para>You can, of course, also deploy the image you build
                        using the <filename>devtool build-image</filename> command
                        to actual hardware.
                        However, <filename>devtool</filename> does not provide a
                        specific command that allows you to do this.
                        </para></listitem>
                    <listitem><para>
                        <emphasis>Finish Your Work With the Recipe</emphasis>:
                        The <filename>devtool finish</filename> command creates
                        any patches corresponding to commits in the local
                        Git repository, updates the recipe to point to them
                        (or creates a <filename>.bbappend</filename> file to do
                        so, depending on the specified destination layer), and
                        then resets the recipe so that the recipe is built normally
                        rather than from the workspace.
                        <literallayout class='monospaced'>
     $ devtool finish <replaceable>recipe layer</replaceable>
                        </literallayout>
                        <note>
                            Any changes you want to turn into patches must be
                            committed to the Git repository in the source tree.
                        </note></para>

                        <para>Because there is no need to move the recipe,
                        <filename>devtool finish</filename> either updates the
                        original recipe in the original layer or the command
                        creates a <filename>.bbappend</filename> in a different
                        layer as provided by <replaceable>layer</replaceable>.
                        </para>

                        <para>As a final process of the
                        <filename>devtool finish</filename> command, the state
                        of the standard layers and the upstream source is
                        restored so that you can build the recipe from those
                        areas rather than the workspace.
                        <note>
                            You can use the <filename>devtool reset</filename>
                            command to put things back should you decide you
                            do not want to proceed with your work.
                            If you do use this command, realize that the source
                            tree is preserved.
                        </note>
                        </para></listitem>
                </orderedlist>
            </para>
        </section>

        <section id='devtool-use-devtool-upgrade-to-create-a-version-of-the-recipe-that-supports-a-newer-version-of-the-software'>
            <title>Use <filename>devtool upgrade</filename> to Create a Version of the Recipe that Supports a Newer Version of the Software</title>

            <para>
                The <filename>devtool upgrade</filename> command updates
                an existing recipe so that you can build it for an updated
                set of source files.
                The command is flexible enough to allow you to specify
                source code revision and versioning schemes, extract code into
                or out of the <filename>devtool</filename> workspace, and
                work with any source file forms that the fetchers support.
            </para>

            <para>
                The following diagram shows the common development flow
                you would use with the <filename>devtool upgrade</filename>
                command:
            </para>

            <para>
                <imagedata fileref="figures/devtool-upgrade-flow.png" align="center" />
            </para>

            <para>
                <orderedlist>
                    <listitem><para><emphasis>Initiate the Upgrade</emphasis>:
                        The top part of the flow shows a typical scenario by which
                        you could use <filename>devtool upgrade</filename>.
                        The following conditions exist:
                        <itemizedlist>
                            <listitem><para>The recipe exists in some layer external
                                to the <filename>devtool</filename> workspace.
                                </para></listitem>
                            <listitem><para>The source files for the new release
                                exist adjacent to the same location pointed to by
                                <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
                                in the recipe (e.g. a tarball with the new version
                                number in the name, or as a different revision in
                                the upstream Git repository).
                                </para></listitem>
                        </itemizedlist>
                        A common situation is where third-party software has
                        undergone a revision so that it has been upgraded.
                        The recipe you have access to is likely in your own layer.
                        Thus, you need to upgrade the recipe to use the
                        newer version of the software:
                        <literallayout class='monospaced'>
     $ devtool upgrade -V <replaceable>version recipe</replaceable>
                        </literallayout>
                        By default, the <filename>devtool upgrade</filename> command
                        extracts source code into the <filename>sources</filename>
                        directory in the workspace.
                        If you want the code extracted to any other location, you
                        need to provide the <replaceable>srctree</replaceable>
                        positional argument with the command as follows:
                        <literallayout class='monospaced'>
     $ devtool upgrade -V <replaceable>version recipe srctree</replaceable>
                        </literallayout>
                        Also, in this example, the "-V" option is used to specify
                        the new version.
                        If the source files pointed to by the
                        <filename>SRC_URI</filename> statement in the recipe are
                        in a Git repository, you must provide the "-S" option and
                        specify a revision for the software.</para>

                        <para>Once <filename>devtool</filename> locates the recipe,
                        it uses the <filename>SRC_URI</filename> variable to locate
                        the source code and any local patch files from other
                        developers are located.
                        The result is that the command sets up the source
                        code, the new version of the recipe, and an append file
                        all within the workspace.
                        </para></listitem>
                    <listitem><para><emphasis>Resolve any Conflicts created by the Upgrade</emphasis>:
                        At this point, there could be some conflicts due to the
                        software being upgraded to a new version.
                        This would occur if your recipe specifies some patch files in
                        <filename>SRC_URI</filename> that conflict with changes
                        made in the new version of the software.
                        If this is the case, you need to resolve the conflicts
                        by editing the source and following the normal
                        <filename>git rebase</filename> conflict resolution
                        process.</para>

                        <para>Before moving onto the next step, be sure to resolve any
                        such conflicts created through use of a newer or different
                        version of the software.
                        </para></listitem>
                    <listitem><para><emphasis>Build the Recipe</emphasis>:
                        Once you have your recipe in order, you can build it.
                        You can either use <filename>devtool build</filename> or
                        <filename>bitbake</filename>.
                        Either method produces build output that is stored
                        in
                        <ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink>.
                        </para></listitem>
                    <listitem><para><emphasis>Deploy the Build Output</emphasis>:
                        When you use the <filename>devtool build</filename>
                        command or <filename>bitbake</filename> to build out your
                        recipe, you probably want to see if the resulting build
                        output works as expected on target hardware.
                        <note>
                            This step assumes you have a previously built
                            image that is already either running in QEMU or
                            running on actual hardware.
                            Also, it is assumed that for deployment of the image
                            to the target, SSH is installed in the image and if
                            the image is running on real hardware that you have
                            network access to and from your development machine.
                        </note>
                        You can deploy your build output to that target hardware by
                        using the <filename>devtool deploy-target</filename> command:
                        <literallayout class='monospaced'>
     $ devtool deploy-target <replaceable>recipe target</replaceable>
                        </literallayout>
                        The <replaceable>target</replaceable> is a live target machine
                        running as an SSH server.</para>

                        <para>You can, of course, also deploy the image you build
                        using the <filename>devtool build-image</filename> command
                        to actual hardware.
                        However, <filename>devtool</filename> does not provide a
                        specific command that allows you to do this.
                        </para></listitem>
                    <listitem><para>
                        <emphasis>Finish Your Work With the Recipe</emphasis>:
                        The <filename>devtool finish</filename> command creates
                        any patches corresponding to commits in the local
                        Git repository, moves the new recipe to a more permanent
                        layer, and then resets the recipe so that the recipe is
                        built normally rather than from the workspace.
                        If you specify a destination layer that is the same as
                        the original source, then the old version of the
                        recipe and associated files will be removed prior to
                        adding the new version.
                        <literallayout class='monospaced'>
     $ devtool finish <replaceable>recipe layer</replaceable>
                        </literallayout>
                        <note>
                            Any changes you want to turn into patches must be
                            committed to the Git repository in the source tree.
                        </note></para>
                        <para>As a final process of the
                        <filename>devtool finish</filename> command, the state
                        of the standard layers and the upstream source is
                        restored so that you can build the recipe from those
                        areas rather than the workspace.
                        <note>
                            You can use the <filename>devtool reset</filename>
                            command to put things back should you decide you
                            do not want to proceed with your work.
                            If you do use this command, realize that the source
                            tree is preserved.
                        </note>
                        </para></listitem>
                </orderedlist>
            </para>
        </section>
    </section>
</section>

</chapter>