import-layers/yocto-poky/documentation/dev-manual/dev-manual-newbie.xml

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[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >

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

<title>The Yocto Project Open Source Development Environment</title>

<section id="usingpoky-changes-collaborate">
    <title>Setting Up a Team Yocto Project Development Environment</title>

    <para>
        It might not be immediately clear how you can use the Yocto
        Project in a team development environment, or scale it for a large
        team of developers.
        One of the strengths of the Yocto Project is that it is extremely
        flexible.
        Thus, you can adapt it to many different use cases and scenarios.
        However, these characteristics can cause a struggle if you are trying
        to create a working setup that scales across a large team.
    </para>

    <para>
        To help you understand how to set up this type of environment,
        this section presents a procedure that gives you the information
        to learn how to get the results you want.
        The procedure is high-level and presents some of the project's most
        successful experiences, practices, solutions, and available
        technologies that work well.
        Keep in mind, the procedure here is a starting point.
        You can build off it and customize it to fit any
        particular working environment and set of practices.
        <orderedlist>
            <listitem><para>
                <emphasis>Determine Who is Going to be Developing:</emphasis>
                You need to understand who is going to be doing anything
                related to the Yocto Project and what their roles would be.
                Making this determination is essential to completing the
                steps two and three, which are to get your equipment together
                and set up your development environment's hardware topology.
                </para>

                <para>The following roles exist:
                <itemizedlist>
                    <listitem><para>
                        <emphasis>Application Development:</emphasis>
                        These types of developers do application level work
                        on top of an existing software stack.
                        </para></listitem>
                    <listitem><para>
                        <emphasis>Core System Development:</emphasis>
                        These types of developers work on the contents of the
                        operating system image itself.
                        </para></listitem>
                    <listitem><para>
                        <emphasis>Build Engineer:</emphasis>
                        This type of developer manages Autobuilders and
                        releases.
                        Not all environments need a Build Engineer.
                        </para></listitem>
                    <listitem><para>
                        <emphasis>Test Engineer:</emphasis>
                        This type of developer creates and manages automated
                        tests needed to ensure all application and core
                        system development meets desired quality standards.
                        </para></listitem>
                </itemizedlist>
                </para></listitem>
            <listitem><para>
                <emphasis>Gather the Hardware:</emphasis>
                Based on the size and make-up of the team, get the hardware
                together.
                Any development, build, or test engineer should be using
                a system that is running a supported Linux distribution.
                Systems, in general, should be high performance (e.g. dual,
                six-core Xeons with 24 Gbytes of RAM and plenty of disk space).
                You can help ensure efficiency by having any machines used
                for testing or that run Autobuilders be as high performance
                as possible.
                </para></listitem>
            <listitem><para>
                <emphasis>Understand the Hardware Topology of the Environment:</emphasis>
                Now that you know how many developers and support engineers
                are required, you can understand the topology of the
                hardware environment.
                The following figure shows a moderately sized Yocto Project
                development environment.

                <para role="writernotes">
                Need figure.</para>

                </para></listitem>
            <listitem><para>
                <emphasis>Use Git as Your Source Control Manager (SCM):</emphasis>
                Keeping your
                <ulink url='&YOCTO_DOCS_REF_URL;#metadata'>Metadata</ulink>
                and any software you are developing under the
                control of an SCM system that is compatible
                with the OpenEmbedded build system is advisable.
                Of the SCMs BitBake supports, the
                Yocto Project team strongly recommends using
                <ulink url='&YOCTO_DOCS_REF_URL;#git'>Git</ulink>.
                Git is a distributed system that is easy to backup,
                allows you to work remotely, and then connects back to the
                infrastructure.
                <note>
                    For information about BitBake, see the
                    <ulink url='&YOCTO_DOCS_BB_URL;'>BitBake User Manual</ulink>.
                </note></para>

                <para>It is relatively easy to set up Git services and create
                infrastructure like
                <ulink url='&YOCTO_GIT_URL;'>http://git.yoctoproject.org</ulink>,
                which is based on server software called
                <filename>gitolite</filename> with <filename>cgit</filename>
                being used to generate the web interface that lets you view the
                repositories.
                The <filename>gitolite</filename> software identifies users
                using SSH keys and allows branch-based
                access controls to repositories that you can control as little
                or as much as necessary.

                <note>
                   The setup of these services is beyond the scope of this
                   manual.
                   However, sites such as these exist that describe how to
                   perform setup:
                   <itemizedlist>
                       <listitem><para>
                           <ulink url='http://git-scm.com/book/ch4-8.html'>Git documentation</ulink>:
                           Describes how to install <filename>gitolite</filename>
                           on the server.
                           </para></listitem>
                       <listitem><para>
                           <ulink url='http://sitaramc.github.com/gitolite/master-toc.html'>The <filename>gitolite</filename> master index</ulink>:
                            All topics for <filename>gitolite</filename>.
                            </para></listitem>
                        <listitem><para>
                            <ulink url='https://git.wiki.kernel.org/index.php/Interfaces,_frontends,_and_tools'>Interfaces, frontends, and tools</ulink>:
                            Documentation on how to create interfaces and frontends
                            for Git.
                            </para></listitem>
                    </itemizedlist>
                </note>
                </para></listitem>
            <listitem><para>
                <emphasis>Set up the Application Development Machines:</emphasis>
                As mentioned earlier, application developers are creating
                applications on top of existing software stacks.
                Following are some best practices for setting up machines
                that do application development:
                <itemizedlist>
                    <listitem><para>
                        Use a pre-built toolchain that
                        contains the software stack itself.
                        Then, develop the application code on top of the
                        stack.
                        This method works well for small numbers of relatively
                        isolated applications.
                        </para></listitem>
                    <listitem><para>
                        When possible, use the Yocto Project
                        plug-in for the
                        <trademark class='trade'>Eclipse</trademark> IDE
                        and SDK development practices.
                        For more information, see the
                        "<ulink url='&YOCTO_DOCS_SDK_URL;'>Yocto Project Application Development and the Extensible Software Development Kit (eSDK)</ulink>"
                        manual.
                        </para></listitem>
                    <listitem><para>
                        Keep your cross-development toolchains updated.
                        You can do this through provisioning either as new
                        toolchain downloads or as updates through a package
                        update mechanism using <filename>opkg</filename>
                        to provide updates to an existing toolchain.
                        The exact mechanics of how and when to do this are a
                        question for local policy.
                        </para></listitem>
                    <listitem><para>
                        Use multiple toolchains installed locally
                        into different locations to allow development across
                        versions.
                        </para></listitem>
                </itemizedlist>
                </para></listitem>
            <listitem><para>
                <emphasis>Set up the Core Development Machines:</emphasis>
                As mentioned earlier, these types of developers work on the
                contents of the operating system itself.
                Following are some best practices for setting up machines
                used for developing images:
                <itemizedlist>
                    <listitem><para>
                        Have the Yocto Project build system itself available on
                        the developer workstations so developers can run their own
                        builds and directly rebuild the software stack.
                        </para></listitem>
                    <listitem><para>
                        Keep the core system unchanged as much as
                        possible and do your work in layers on top of the
                        core system.
                        Doing so gives you a greater level of portability when
                        upgrading to new versions of the core system or Board
                        Support Packages (BSPs).
                        </para></listitem>
                    <listitem><para>
                        Share layers amongst the developers of a
                        particular project and contain the policy configuration
                        that defines the project.
                        </para></listitem>
                </itemizedlist>
                </para></listitem>
            <listitem><para>
                <emphasis>Set up an Autobuilder:</emphasis>
                Autobuilders are often the core of the development
                environment.
                It is here that changes from individual developers are brought
                together and centrally tested and subsequent decisions about
                releases can be made.
                Autobuilders also allow for "continuous integration" style
                testing of software components and regression identification
                and tracking.</para>

                <para>See "<ulink url='http://autobuilder.yoctoproject.org'>Yocto Project Autobuilder</ulink>"
                for more information and links to buildbot.
                The Yocto Project team has found this implementation
                works well in this role.
                A public example of this is the Yocto Project
                Autobuilders, which we use to test the overall health of the
                project.</para>

                <para>The features of this system are:
                <itemizedlist>
                    <listitem><para>
                         Highlights when commits break the build.
                         </para></listitem>
                    <listitem><para>
                        Populates an sstate cache from which
                        developers can pull rather than requiring local
                        builds.
                        </para></listitem>
                    <listitem><para>
                        Allows commit hook triggers,
                        which trigger builds when commits are made.
                        </para></listitem>
                    <listitem><para>
                        Allows triggering of automated image booting
                        and testing under the QuickEMUlator (QEMU).
                        </para></listitem>
                    <listitem><para>
                        Supports incremental build testing and
                        from-scratch builds.
                        </para></listitem>
                    <listitem><para>
                        Shares output that allows developer
                        testing and historical regression investigation.
                        </para></listitem>
                    <listitem><para>
                        Creates output that can be used for releases.
                        </para></listitem>
                    <listitem><para>
                        Allows scheduling of builds so that resources
                        can be used efficiently.
                        </para></listitem>
               </itemizedlist>
               </para></listitem>
           <listitem><para>
               <emphasis>Set up Test Machines:</emphasis>
               Use a small number of shared, high performance systems
               for testing purposes.
               Developers can use these systems for wider, more
               extensive testing while they continue to develop
               locally using their primary development system.
               </para></listitem>
           <listitem><para>
               <emphasis>Document Policies and Change Flow:</emphasis>
               The Yocto Project itself uses a hierarchical structure and a
                pull model.
                Scripts exist to create and send pull requests
                (i.e. <filename>create-pull-request</filename> and
                <filename>send-pull-request</filename>).
                This model is in line with other open source projects where
                maintainers are responsible for specific areas of the project
                and a single maintainer handles the final "top-of-tree" merges.
                <note>
                    You can also use a more collective push model.
                    The <filename>gitolite</filename> software supports both the
                    push and pull models quite easily.
                </note></para>

                <para>As with any development environment, it is important
                to document the policy used as well as any main project
                guidelines so they are understood by everyone.
                It is also a good idea to have well structured
                commit messages, which are usually a part of a project's
                guidelines.
                Good commit messages are essential when looking back in time and
                trying to understand why changes were made.</para>

                <para>If you discover that changes are needed to the core
                layer of the project, it is worth sharing those with the
                community as soon as possible.
                Chances are if you have discovered the need for changes,
                someone else in the community needs them also.
                </para></listitem>
            <listitem><para>
                <emphasis>Development Environment Summary:</emphasis>
                Aside from the previous steps, some best practices exist
                within the Yocto Project development environment.
                Consider the following:
                <itemizedlist>
                    <listitem><para>
                        Use <ulink url='&YOCTO_DOCS_REF_URL;#git'>Git</ulink>
                        as the source control system.
                        </para></listitem>
                    <listitem><para>
                        Maintain your Metadata in layers that make sense
                        for your situation.
                        See the "<link linkend='understanding-and-creating-layers'>Understanding
                        and Creating Layers</link>" section for more information on
                        layers.
                        </para></listitem>
                    <listitem><para>
                        Separate the project's Metadata and code by using
                        separate Git repositories.
                        See the
                        "<ulink url='&YOCTO_DOCS_REF_URL;#yocto-project-repositories'>Yocto Project Source Repositories</ulink>"
                        section for information on these repositories.
                        See the
                        "<link linkend='working-with-yocto-project-source-files'>Working With Yocto Project Source Files</link>"
                        section for information on how to set up local Git
                        repositories for related upstream Yocto Project
                        Git repositories.
                        </para></listitem>
                    <listitem><para>
                        Set up the directory for the shared state cache
                        (<ulink url='&YOCTO_DOCS_REF_URL;#var-SSTATE_DIR'><filename>SSTATE_DIR</filename></ulink>)
                        where it makes sense.
                        For example, set up the sstate cache on a system used
                        by developers in the same organization and share the
                        same source directories on their machines.
                        </para></listitem>
                    <listitem><para>
                        Set up an Autobuilder and have it populate the
                        sstate cache and source directories.
                        </para></listitem>
                    <listitem><para>
                        The Yocto Project community encourages you
                        to send patches to the project to fix bugs or add features.
                        If you do submit patches, follow the project commit
                        guidelines for writing good commit messages.
                        See the "<link linkend='how-to-submit-a-change'>Submitting a Change to the Yocto Project</link>"
                        section.
                        </para></listitem>
                    <listitem><para>
                        Send changes to the core sooner than later
                        as others are likely to run into the same issues.
                        For some guidance on mailing lists to use, see the list in the
                        "<link linkend='how-to-submit-a-change'>Submitting a Change to the Yocto Project</link>"
                        section.
                        For a description of the available mailing lists, see the
                        "<ulink url='&YOCTO_DOCS_REF_URL;#resources-mailinglist'>Mailing Lists</ulink>"
                        section in the Yocto Project Reference Manual.
                        </para></listitem>
                </itemizedlist>
                </para></listitem>
        </orderedlist>
    </para>
</section>

<section id='submitting-a-defect-against-the-yocto-project'>
    <title>Submitting a Defect Against the Yocto Project</title>

    <para>
        Use the Yocto Project implementation of
        <ulink url='http://www.bugzilla.org/about/'>Bugzilla</ulink>
        to submit a defect (bug) against the Yocto Project.
        For additional information on this implementation of Bugzilla see the
        "<ulink url='&YOCTO_DOCS_REF_URL;#resources-bugtracker'>Yocto Project Bugzilla</ulink>"
        section in the Yocto Project Reference Manual.
        For more detail on any of the following steps, see the Yocto Project
        <ulink url='&YOCTO_WIKI_URL;/wiki/Bugzilla_Configuration_and_Bug_Tracking'>Bugzilla wiki page</ulink>.
    </para>

    <para>
        Use the following general steps to submit a bug"

        <orderedlist>
            <listitem><para>
                Open the Yocto Project implementation of
                <ulink url='&YOCTO_BUGZILLA_URL;'>Bugzilla</ulink>.
                </para></listitem>
            <listitem><para>
                Click "File a Bug" to enter a new bug.
                </para></listitem>
            <listitem><para>
                Choose the appropriate "Classification", "Product", and
                "Component" for which the bug was found.
                Bugs for the Yocto Project fall into one of several
                classifications, which in turn break down into several
                products and components.
                For example, for a bug against the
                <filename>meta-intel</filename> layer, you would choose
                "Build System, Metadata &amp; Runtime", "BSPs", and
                "bsps-meta-intel", respectively.
                </para></listitem>
            <listitem><para>
                Choose the "Version" of the Yocto Project for which you found
                the bug (e.g. &DISTRO;).
                </para></listitem>
            <listitem><para>
                Determine and select the "Severity" of the bug.
                The severity indicates how the bug impacted your work.
                </para></listitem>
            <listitem><para>
                Choose the "Hardware" that the bug impacts.
                </para></listitem>
            <listitem><para>
                Choose the "Architecture" that the bug impacts.
                </para></listitem>
            <listitem><para>
                Choose a "Documentation change" item for the bug.
                Fixing a bug might or might not affect the Yocto Project
                documentation.
                If you are unsure of the impact to the documentation, select
                "Don't Know".
                </para></listitem>
            <listitem><para>
                Provide a brief "Summary" of the bug.
                Try to limit your summary to just a line or two and be sure
                to capture the essence of the bug.
                </para></listitem>
            <listitem><para>
                Provide a detailed "Description" of the bug.
                You should provide as much detail as you can about the context,
                behavior, output, and so forth that surrounds the bug.
                You can even attach supporting files for output from logs by
                using the "Add an attachment" button.
                </para></listitem>
            <listitem><para>
                Click the "Submit Bug" button submit the bug.
                A new Bugzilla number is assigned to the bug and the defect
                is logged in the bug tracking system.
                </para></listitem>
        </orderedlist>
        Once you file a bug, the bug is processed by the Yocto Project Bug
        Triage Team and further details concerning the bug are assigned
        (e.g. priority and owner).
        You are the "Submitter" of the bug and any further categorization,
        progress, or comments on the bug result in Bugzilla sending you an
        automated email concerning the particular change or progress to the
        bug.
    </para>
</section>

<section id='how-to-submit-a-change'>
    <title>Submitting a Change to the Yocto Project</title>

    <para>
        Contributions to the Yocto Project and OpenEmbedded are very welcome.
        Because the system is extremely configurable and flexible, we recognize
        that developers will want to extend, configure or optimize it for
        their specific uses.
    </para>

    <para>
        The Yocto Project uses a mailing list and a patch-based workflow
        that is similar to the Linux kernel but contains important
        differences.
        In general, a mailing list exists through which you can submit
        patches.
        You should send patches to the appropriate mailing list so that they
        can be reviewed and merged by the appropriate maintainer.
        The specific mailing list you need to use depends on the
        location of the code you are changing.
        Each component (e.g. layer) should have a
        <filename>README</filename> file that indicates where to send
        the changes and which process to follow.
    </para>

    <para>
        You can send the patch to the mailing list using whichever approach
        you feel comfortable with to generate the patch.
        Once sent, the patch is usually reviewed by the community at large.
        If somebody has concerns with the patch, they will usually voice
        their concern over the mailing list.
        If a patch does not receive any negative reviews, the maintainer of
        the affected layer typically takes the patch, tests it, and then
        based on successful testing, merges the patch.
    </para>

    <para id='figuring-out-the-mailing-list-to-use'>
        The "poky" repository, which is the Yocto Project's reference build
        environment, is a hybrid repository that contains several
        individual pieces (e.g. BitBake, Metadata, documentation,
        and so forth) built using the combo-layer tool.
        The upstream location used for submitting changes varies by
        component:
        <itemizedlist>
            <listitem><para>
                <emphasis>Core Metadata:</emphasis>
                Send your patch to the
                <ulink url='http://lists.openembedded.org/mailman/listinfo/openembedded-core'>openembedded-core</ulink>
                mailing list.  For example, a change to anything under
                the <filename>meta</filename> or
                <filename>scripts</filename> directories should be sent
                to this mailing list.
                </para></listitem>
            <listitem><para>
                <emphasis>BitBake:</emphasis>
                For changes to BitBake (i.e. anything under the
                <filename>bitbake</filename> directory), send your patch
                to the
                <ulink url='http://lists.openembedded.org/mailman/listinfo/bitbake-devel'>bitbake-devel</ulink>
                mailing list.
                </para></listitem>
            <listitem><para>
                <emphasis>"meta-*" trees:</emphasis>
                These trees contain Metadata.
                Use the
                <ulink url='https://lists.yoctoproject.org/listinfo/poky'>poky</ulink>
                mailing list.
                </para></listitem>
        </itemizedlist>
    </para>

    <para>
        For changes to other layers hosted in the Yocto Project source
        repositories (i.e. <filename>yoctoproject.org</filename>), tools,
        and the Yocto Project documentation, use the
        <ulink url='https://lists.yoctoproject.org/listinfo/yocto'>Yocto Project</ulink>
        general mailing list.
        <note>
            Sometimes a layer's documentation specifies to use a
            particular mailing list.
            If so, use that list.
        </note>
        For additional recipes that do not fit into the core Metadata, you
        should determine which layer the recipe should go into and submit
        the change in the manner recommended by the documentation (e.g.
        the <filename>README</filename> file) supplied with the layer.
        If in doubt, please ask on the Yocto general mailing list or on
        the openembedded-devel mailing list.
    </para>

    <para>
        You can also push a change upstream and request a maintainer to
        pull the change into the component's upstream repository.
        You do this by pushing to a contribution repository that is upstream.
        See the
        "<ulink url='&YOCTO_DOCS_REF_URL;#workflows'>Workflows</ulink>"
        section in the Yocto Project Reference Manual for additional
        concepts on working in the Yocto Project development environment.
    </para>

    <para>
        Two commonly used testing repositories exist for
        OpenEmbedded-Core:
        <itemizedlist>
            <listitem><para>
                <emphasis>"ross/mut" branch:</emphasis>
                The "mut" (master-under-test) tree
                exists in the <filename>poky-contrib</filename> repository
                in the
                <ulink url='&YOCTO_GIT_URL;'>Yocto Project source repositories</ulink>.
                </para></listitem>
            <listitem><para>
                <emphasis>"master-next" branch:</emphasis>
                This branch is part of the main
                "poky" repository in the Yocto Project source repositories.
                </para></listitem>
        </itemizedlist>
        Maintainers use these branches to test submissions prior to merging
        patches.
        Thus, you can get an idea of the status of a patch based on
        whether the patch has been merged into one of these branches.
        <note>
            This system is imperfect and changes can sometimes get lost in the
            flow.
            Asking about the status of a patch or change is reasonable if the
            change has been idle for a while with no feedback.
            The Yocto Project does have plans to use
            <ulink url='https://en.wikipedia.org/wiki/Patchwork_(software)'>Patchwork</ulink>
            to track the status of patches and also to automatically preview
            patches.
        </note>
    </para>

    <para>
        The following sections provide procedures for submitting a change.
    </para>

    <section id='pushing-a-change-upstream'>
        <title>Using Scripts to Push a Change Upstream and Request a Pull</title>

        <para>
            Follow this procedure to push a change to an upstream "contrib"
            Git repository:
            <note>
                You can find general Git information on how to push a change
                upstream in the
                <ulink url='http://git-scm.com/book/en/v2/Distributed-Git-Distributed-Workflows'>Git Community Book</ulink>.
            </note>
            <orderedlist>
                <listitem><para>
                    <emphasis>Make Your Changes Locally:</emphasis>
                    Make your changes in your local Git repository.
                    You should make small, controlled, isolated changes.
                    Keeping changes small and isolated aids review,
                    makes merging/rebasing easier and keeps the change
                    history clean should anyone need to refer to it in
                    future.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Stage Your Changes:</emphasis>
                    Stage your changes by using the <filename>git add</filename>
                    command on each file you changed.
                    </para></listitem>
                <listitem><para id='making-sure-you-have-correct-commit-information'>
                    <emphasis>Commit Your Changes:</emphasis>
                    Commit the change by using the
                    <filename>git commit</filename> command.
                    Make sure your commit information follows standards by
                    following these accepted conventions:
                    <itemizedlist>
                        <listitem><para>
                            Be sure to include a "Signed-off-by:" line in the
                            same style as required by the Linux kernel.
                            Adding this line signifies that you, the submitter,
                            have agreed to the Developer's Certificate of
                            Origin 1.1 as follows:
                            <literallayout class='monospaced'>
     Developer's Certificate of Origin 1.1

     By making a contribution to this project, I certify that:

     (a) The contribution was created in whole or in part by me and I
         have the right to submit it under the open source license
         indicated in the file; or

     (b) The contribution is based upon previous work that, to the best
         of my knowledge, is covered under an appropriate open source
         license and I have the right under that license to submit that
         work with modifications, whether created in whole or in part
         by me, under the same open source license (unless I am
         permitted to submit under a different license), as indicated
         in the file; or

     (c) The contribution was provided directly to me by some other
         person who certified (a), (b) or (c) and I have not modified
         it.

     (d) I understand and agree that this project and the contribution
         are public and that a record of the contribution (including all
         personal information I submit with it, including my sign-off) is
         maintained indefinitely and may be redistributed consistent with
         this project or the open source license(s) involved.
                            </literallayout>
                            </para></listitem>
                        <listitem><para>
                            Provide a single-line summary of the change.
                            and,
                            if more explanation is needed, provide more
                            detail in the body of the commit.
                            This summary is typically viewable in the
                            "shortlist" of changes.
                            Thus, providing something short and descriptive
                            that gives the reader a summary of the change is
                            useful when viewing a list of many commits.
                            You should prefix this short description with the
                            recipe name (if changing a recipe), or else with
                            the short form path to the file being changed.
                            </para></listitem>
                        <listitem><para>
                            For the body of the commit message, provide
                            detailed information that describes what you
                            changed, why you made the change, and the approach
                            you used.
                            It might also be helpful if you mention how you
                            tested the change.
                            Provide as much detail as you can in the body of
                            the commit message.
                            <note>
                                You do not need to provide a more detailed
                                explanation of a change if the change is
                                minor to the point of the single line
                                summary providing all the information.
                            </note>
                            </para></listitem>
                        <listitem><para>
                            If the change addresses a specific bug or issue
                            that is associated with a bug-tracking ID,
                            include a reference to that ID in your detailed
                            description.
                            For example, the Yocto Project uses a specific
                            convention for bug references - any commit that
                            addresses a specific bug should use the following
                            form for the detailed description.
                            Be sure to use the actual bug-tracking ID from
                            Bugzilla for
                            <replaceable>bug-id</replaceable>:
                            <literallayout class='monospaced'>
     Fixes [YOCTO #<replaceable>bug-id</replaceable>]

     <replaceable>detailed description of change</replaceable>
                            </literallayout>
                            </para></listitem>
                    </itemizedlist>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Push Your Commits to a "Contrib" Upstream:</emphasis>
                    If you have arranged for permissions to push to an
                    upstream contrib repository, push the change to that
                    repository:
                    <literallayout class='monospaced'>
     $ git push <replaceable>upstream_remote_repo</replaceable> <replaceable>local_branch_name</replaceable>
                    </literallayout>
                    For example, suppose you have permissions to push into the
                    upstream <filename>meta-intel-contrib</filename>
                    repository and you are working in a local branch named
                    <replaceable>your_name</replaceable><filename>/README</filename>.
                    The following command pushes your local commits to the
                    <filename>meta-intel-contrib</filename> upstream
                    repository and puts the commit in a branch named
                    <replaceable>your_name</replaceable><filename>/README</filename>:
                    <literallayout class='monospaced'>
     $ git push meta-intel-contrib <replaceable>your_name</replaceable>/README
                    </literallayout>
                    </para></listitem>
                <listitem><para id='push-determine-who-to-notify'>
                    <emphasis>Determine Who to Notify:</emphasis>
                    Determine the maintainer or the mailing list
                    that you need to notify for the change.</para>

                    <para>Before submitting any change, you need to be sure
                    who the maintainer is or what mailing list that you need
                    to notify.
                    Use either these methods to find out:
                    <itemizedlist>
                        <listitem><para>
                            <emphasis>Maintenance File:</emphasis>
                            Examine the <filename>maintainers.inc</filename>
                            file, which is located in the
                            <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
                            at
                            <filename>meta/conf/distro/include</filename>,
                            to see who is responsible for code.
                            </para></listitem>
                        <listitem><para>
                            <emphasis>Search by File:</emphasis>
                            Using <ulink url='&YOCTO_DOCS_REF_URL;#git'>Git</ulink>,
                            you can enter the following command to bring up a
                            short list of all commits against a specific file:
                            <literallayout class='monospaced'>
     git shortlog -- <replaceable>filename</replaceable>
                            </literallayout>
                            Just provide the name of the file for which you
                            are interested.
                            The information returned is not ordered by history
                            but does include a list of everyone who has
                            committed grouped by name.
                            From the list, you can see who is responsible for
                            the bulk of the changes against the file.
                            </para></listitem>
                        <listitem><para>
                            <emphasis>Examine the List of Mailing Lists:</emphasis>
                            For a list of the Yocto Project and related mailing
                            lists, see the
                            "<ulink url='&YOCTO_DOCS_REF_URL;#resources-mailinglist'>Mailing lists</ulink>"
                            section in the Yocto Project Reference Manual.
                            </para></listitem>
                    </itemizedlist>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Make a Pull Request:</emphasis>
                    Notify the maintainer or the mailing list that you have
                    pushed a change by making a pull request.</para>

                    <para>The Yocto Project provides two scripts that
                    conveniently let you generate and send pull requests to the
                    Yocto Project.
                    These scripts are <filename>create-pull-request</filename>
                    and <filename>send-pull-request</filename>.
                    You can find these scripts in the
                    <filename>scripts</filename> directory within the
                    <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
                    (e.g. <filename>~/poky/scripts</filename>).
                    </para>

                    <para>Using these scripts correctly formats the requests
                    without introducing any whitespace or HTML formatting.
                    The maintainer that receives your patches either directly
                    or through the mailing list needs to be able to save and
                    apply them directly from your emails.
                    Using these scripts is the preferred method for sending
                    patches.</para>

                    <para>First, create the pull request.
                    For example, the following command runs the script,
                    specifies the upstream repository in the contrib directory
                    into which you pushed the change, and provides a subject
                    line in the created patch files:
                    <literallayout class='monospaced'>
     $ ~/poky/scripts/create-pull-request -u meta-intel-contrib -s "Updated Manual Section Reference in README"
                    </literallayout>
                    Running this script forms
                    <filename>*.patch</filename> files in a folder named
                    <filename>pull-</filename><replaceable>PID</replaceable>
                    in the current directory.
                    One of the patch files is a cover letter.</para>

                    <para>Before running the
                    <filename>send-pull-request</filename> script, you must
                    edit the cover letter patch to insert information about
                    your change.
                    After editing the cover letter, send the pull request.
                    For example, the following command runs the script and
                    specifies the patch directory and email address.
                    In this example, the email address is a mailing list:
                    <literallayout class='monospaced'>
     $ ~/poky/scripts/send-pull-request -p ~/meta-intel/pull-10565 -t meta-intel@yoctoproject.org
                    </literallayout>
                    You need to follow the prompts as the script is
                    interactive.
                    <note>
                        For help on using these scripts, simply provide the
                        <filename>-h</filename> argument as follows:
                        <literallayout class='monospaced'>
     $ poky/scripts/create-pull-request -h
     $ poky/scripts/send-pull-request -h
                        </literallayout>
                    </note>
                    </para></listitem>
            </orderedlist>
        </para>
    </section>

    <section id='submitting-a-patch'>
        <title>Using Email to Submit a Patch</title>

        <para>
            You can submit patches without using the
            <filename>create-pull-request</filename> and
            <filename>send-pull-request</filename> scripts described in the
            previous section.
            However, keep in mind, the preferred method is to use the scripts.
        </para>

        <para>
            Depending on the components changed, you need to submit the email
            to a specific mailing list.
            For some guidance on which mailing list to use, see the
            <link linkend='figuring-out-the-mailing-list-to-use'>beginning</link>
            of this section.
            For a description of all the available mailing lists, see the
            "<ulink url='&YOCTO_DOCS_REF_URL;#resources-mailinglist'>Mailing Lists</ulink>"
            section in the Yocto Project Reference Manual.
        </para>

        <para>
            Here is the general procedure on how to submit a patch through
            email without using the scripts:
            <orderedlist>
                <listitem><para>
                    <emphasis>Make Your Changes Locally:</emphasis>
                    Make your changes in your local Git repository.
                    You should make small, controlled, isolated changes.
                    Keeping changes small and isolated aids review,
                    makes merging/rebasing easier and keeps the change
                    history clean should anyone need to refer to it in
                    future.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Stage Your Changes:</emphasis>
                    Stage your changes by using the <filename>git add</filename>
                    command on each file you changed.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Commit Your Changes:</emphasis>
                    Commit the change by using the
                    <filename>git commit --signoff</filename> command.
                    Using the <filename>--signoff</filename> option identifies
                    you as the person making the change and also satisfies
                    the Developer's Certificate of Origin (DCO) shown earlier.
                    </para>

                    <para>When you form a commit, you must follow certain
                    standards established by the Yocto Project development
                    team.
                    See
                    <link linkend='making-sure-you-have-correct-commit-information'>Step 3</link>
                    in the previous section for information on how to
                    provide commit information that meets Yocto Project
                    commit message standards.
                    </para></listitem>
                <listitem><para>
                    <emphasis>Format the Commit:</emphasis>
                    Format the commit into an email message.
                    To format commits, use the
                    <filename>git format-patch</filename> command.
                    When you provide the command, you must include a revision
                    list or a number of patches as part of the command.
                    For example, either of these two commands takes your most
                    recent single commit and formats it as an email message in
                    the current directory:
                    <literallayout class='monospaced'>
     $ git format-patch -1
                    </literallayout>
                    or
                    <literallayout class='monospaced'>
     $ git format-patch HEAD~
                    </literallayout></para>

                    <para>After the command is run, the current directory
                    contains a numbered <filename>.patch</filename> file for
                    the commit.</para>

                    <para>If you provide several commits as part of the
                    command, the <filename>git format-patch</filename> command
                    produces a series of numbered files in the current
                    directory – one for each commit.
                    If you have more than one patch, you should also use the
                    <filename>--cover</filename> option with the command,
                    which generates a cover letter as the first "patch" in
                    the series.
                    You can then edit the cover letter to provide a
                    description for the series of patches.
                    For information on the
                    <filename>git format-patch</filename> command,
                    see <filename>GIT_FORMAT_PATCH(1)</filename> displayed
                    using the <filename>man git-format-patch</filename>
                    command.
                    <note>
                        If you are or will be a frequent contributor to the
                        Yocto Project or to OpenEmbedded, you might consider
                        requesting a contrib area and the necessary associated
                        rights.
                    </note>
                    </para></listitem>
                <listitem><para>
                    <emphasis>Import the Files Into Your Mail Client:</emphasis>
                    Import the files into your mail client by using the
                    <filename>git send-email</filename> command.
                    <note>
                        In order to use <filename>git send-email</filename>,
                        you must have the proper Git packages installed on
                        your host.
                        For Ubuntu, Debian, and Fedora the package is
                        <filename>git-email</filename>.
                    </note></para>

                    <para>The <filename>git send-email</filename> command
                    sends email by using a local or remote Mail Transport Agent
                    (MTA) such as <filename>msmtp</filename>,
                    <filename>sendmail</filename>, or through a direct
                    <filename>smtp</filename> configuration in your Git
                    <filename>~/.gitconfig</filename> file.
                    If you are submitting patches through email only, it is
                    very important that you submit them without any whitespace
                    or HTML formatting that either you or your mailer
                    introduces.
                    The maintainer that receives your patches needs to be able
                    to save and apply them directly from your emails.
                    A good way to verify that what you are sending will be
                    applicable by the maintainer is to do a dry run and send
                    them to yourself and then save and apply them as the
                    maintainer would.</para>

                    <para>The <filename>git send-email</filename> command is
                    the preferred method for sending your patches using
                    email since there is no risk of compromising whitespace
                    in the body of the message, which can occur when you use
                    your own mail client.
                    The command also has several options that let you
                    specify recipients and perform further editing of the
                    email message.
                    For information on how to use the
                    <filename>git send-email</filename> command,
                    see <filename>GIT-SEND-EMAIL(1)</filename> displayed using
                    the <filename>man git-send-email</filename> command.
                    </para></listitem>
            </orderedlist>
        </para>
    </section>
</section>
</chapter>
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