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diff --git a/documentation/overview-manual/overview-manual-concepts.xml b/documentation/overview-manual/overview-manual-concepts.xml
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@@ -0,0 +1,3612 @@
+<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
+[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >
+
+<chapter id=' overview-manual-concepts'>
+<title>Yocto Project Concepts</title>
+
+    <section id='yocto-project-components'>
+        <title>Yocto Project Components</title>
+
+        <para>
+            The
+            <ulink url='&YOCTO_DOCS_REF_URL;#bitbake-term'>BitBake</ulink>
+            task executor together with various types of configuration files
+            form the OpenEmbedded-Core.
+            This section overviews these components by describing their use and
+            how they interact.
+        </para>
+
+        <para>
+            BitBake handles the parsing and execution of the data files.
+            The data itself is of various types:
+            <itemizedlist>
+                <listitem><para>
+                    <emphasis>Recipes:</emphasis>
+                    Provides details about particular pieces of software.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Class Data:</emphasis>
+                    Abstracts common build information (e.g. how to build a
+                    Linux kernel).
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Configuration Data:</emphasis>
+                    Defines machine-specific settings, policy decisions, and
+                    so forth.
+                    Configuration data acts as the glue to bind everything
+                    together.
+                    </para></listitem>
+            </itemizedlist>
+        </para>
+
+        <para>
+            BitBake knows how to combine multiple data sources together and
+            refers to each data source as a layer.
+            For information on layers, see the
+            "<ulink url='&YOCTO_DOCS_DEV_URL;#understanding-and-creating-layers'>Understanding and Creating Layers</ulink>"
+            section of the Yocto Project Development Tasks Manual.
+        </para>
+
+        <para>
+            Following are some brief details on these core components.
+            For additional information on how these components interact during
+            a build, see the
+            "<link linkend='development-concepts'>Development Concepts</link>"
+            section.
+        </para>
+
+        <section id='usingpoky-components-bitbake'>
+            <title>BitBake</title>
+
+            <para>
+                BitBake is the tool at the heart of the
+                <ulink url='&YOCTO_DOCS_REF_URL;#build-system-term'>OpenEmbedded build system</ulink>
+                and is responsible for parsing the
+                <ulink url='&YOCTO_DOCS_REF_URL;#metadata'>Metadata</ulink>,
+                generating a list of tasks from it, and then executing those
+                tasks.
+            </para>
+
+            <para>
+                This section briefly introduces BitBake.
+                If you want more information on BitBake, see the
+                <ulink url='&YOCTO_DOCS_BB_URL;#bitbake-user-manual'>BitBake User Manual</ulink>.
+            </para>
+
+            <para>
+                To see a list of the options BitBake supports, use either of
+                the following commands:
+                <literallayout class='monospaced'>
+     $ bitbake -h
+     $ bitbake --help
+                </literallayout>
+            </para>
+
+            <para>
+                The most common usage for BitBake is
+                <filename>bitbake <replaceable>packagename</replaceable></filename>,
+                where <filename>packagename</filename> is the name of the
+                package you want to build (referred to as the "target").
+                The target often equates to the first part of a recipe's
+                filename (e.g. "foo" for a recipe named
+                <filename>foo_1.3.0-r0.bb</filename>).
+                So, to process the
+                <filename>matchbox-desktop_1.2.3.bb</filename> recipe file, you
+                might type the following:
+                <literallayout class='monospaced'>
+     $ bitbake matchbox-desktop
+                </literallayout>
+                Several different versions of
+                <filename>matchbox-desktop</filename> might exist.
+                BitBake chooses the one selected by the distribution
+                configuration.
+                You can get more details about how BitBake chooses between
+                different target versions and providers in the
+                "<ulink url='&YOCTO_DOCS_BB_URL;#bb-bitbake-preferences'>Preferences</ulink>"
+                section of the BitBake User Manual.
+            </para>
+
+            <para>
+                BitBake also tries to execute any dependent tasks first.
+                So for example, before building
+                <filename>matchbox-desktop</filename>, BitBake would build a
+                cross compiler and <filename>glibc</filename> if they had not
+                already been built.
+            </para>
+
+            <para>
+                A useful BitBake option to consider is the
+                <filename>-k</filename> or <filename>--continue</filename>
+                option.
+                This option instructs BitBake to try and continue processing
+                the job as long as possible even after encountering an error.
+                When an error occurs, the target that failed and those that
+                depend on it cannot be remade.
+                However, when you use this option other dependencies can
+                still be processed.
+            </para>
+        </section>
+
+        <section id='concepts-components-metadata'>
+            <title>Metadata (Recipes)</title>
+
+            <para>
+                Files that have the <filename>.bb</filename> suffix are
+                "recipes" files.
+                In general, a recipe contains information about a single piece
+                of software.
+                This information includes the location from which to download
+                the unaltered source, any source patches to be applied to that
+                source (if needed), which special configuration options to
+                apply, how to compile the source files, and how to package the
+                compiled output.
+            </para>
+
+            <para>
+                The term "package" is sometimes used to refer to recipes.
+                However, since the word "package" is used for the packaged
+                output from the OpenEmbedded build system (i.e.
+                <filename>.ipk</filename> or <filename>.deb</filename> files),
+                this document avoids using the term "package" when referring
+                to recipes.
+            </para>
+        </section>
+
+        <section id='concepts-components-classes'>
+            <title>Classes</title>
+
+            <para>
+                Class files (<filename>.bbclass</filename>) contain information
+                that is useful to share between Metadata files.
+                An example is the
+                <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-autotools'><filename>autotools</filename></ulink>
+                class, which contains common settings for any application that
+                Autotools uses.
+                The
+                "<ulink url='&YOCTO_DOCS_REF_URL;#ref-classes'>Classes</ulink>"
+                chapter in the Yocto Project Reference Manual provides
+                details about classes and how to use them.
+            </para>
+        </section>
+
+        <section id='concepts-components-configuration'>
+            <title>Configuration</title>
+
+            <para>
+                The configuration files (<filename>.conf</filename>) define
+                various configuration variables that govern the OpenEmbedded
+                build process.
+                These files fall into several areas that define machine
+                configuration options, distribution configuration options,
+                compiler tuning options, general common configuration options,
+                and user configuration options in
+                <filename>local.conf</filename>, which is found in the
+                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>.
+            </para>
+        </section>
+    </section>
+
+    <section id='cm-layers'>
+        <title>Layers</title>
+
+        <para>
+            Layers are repositories that contain related sets of instructions
+            that tell the OpenEmbedded build system what to do.
+            You use different layers to logically separate information in your
+            build.
+            You can collaborate, share, and reuse layers.
+            The Layer Model simultaneously supports collaboration and
+            customization.
+        </para>
+
+        <para>
+            For more introductory information on the Yocto Project's layer
+            model, see the
+            "<ulink url='&YOCTO_DOCS_GS_URL;#the-yocto-project-layer-model'>The Yocto Project Layer Model</ulink>"
+            section in the Yocto Project Overview and Concepts Manual.
+            For procedures on how to create layers, see the
+            "<ulink url='&YOCTO_DOCS_DEV_URL;#understanding-and-creating-layers'>Understanding and Creating Layers</ulink>"
+            section in the Yocto Project Development Tasks Manual.
+        </para>
+    </section>
+
+    <section id="development-concepts">
+        <title>Development Concepts</title>
+
+        <para>
+            This section takes a more detailed look inside the build
+            process used by the OpenEmbedded build system.
+            The following diagram represents the build at a high level.
+            The remainder of this section expands on the fundamental input,
+            output, process, and
+            <ulink url='&YOCTO_DOCS_REF_URL;#metadata'>Metadata</ulink>
+            blocks that make up the build process.
+        </para>
+
+        <para id='general-yocto-environment-figure'>
+            <imagedata fileref="figures/yocto-environment-ref.png" align="center" width="8in" depth="4.25in" />
+        </para>
+
+        <para>
+            In general, the build process consists of several functional areas:
+            <itemizedlist>
+                <listitem><para>
+                    <emphasis>User Configuration:</emphasis>
+                    Metadata you can use to control the build process.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Metadata Layers:</emphasis>
+                    Various layers that provide software, machine, and
+                    distro Metadata.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Source Files:</emphasis>
+                    Upstream releases, local projects, and SCMs.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Build System:</emphasis>
+                    Processes under the control of
+                    <ulink url='&YOCTO_DOCS_REF_URL;#bitbake-term'>BitBake</ulink>.
+                    This block expands on how BitBake fetches source, applies
+                    patches, completes compilation, analyzes output for package
+                    generation, creates and tests packages, generates images,
+                    and generates cross-development tools.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Package Feeds:</emphasis>
+                    Directories containing output packages (RPM, DEB or IPK),
+                    which are subsequently used in the construction of an
+                    image or SDK, produced by the build system.
+                    These feeds can also be copied and shared using a web
+                    server or other means to facilitate extending or updating
+                    existing images on devices at runtime if runtime package
+                    management is enabled.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Images:</emphasis>
+                    Images produced by the development process.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Application Development SDK:</emphasis>
+                    Cross-development tools that are produced along with
+                    an image or separately with BitBake.
+                    </para></listitem>
+            </itemizedlist>
+        </para>
+
+        <section id="user-configuration">
+            <title>User Configuration</title>
+
+            <para>
+                User configuration helps define the build.
+                Through user configuration, you can tell BitBake the
+                target architecture for which you are building the image,
+                where to store downloaded source, and other build properties.
+            </para>
+
+            <para>
+                The following figure shows an expanded representation of the
+                "User Configuration" box of the
+                <link linkend='general-yocto-environment-figure'>general Build Process figure</link>:
+            </para>
+
+            <para>
+                <imagedata fileref="figures/user-configuration.png" align="center" width="8in" depth="4.5in" />
+            </para>
+
+            <para>
+                BitBake needs some basic configuration files in order to
+                complete a build.
+                These files are <filename>*.conf</filename> files.
+                The minimally necessary ones reside as example files in the
+                <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>.
+                For simplicity, this section refers to the Source Directory as
+                the "Poky Directory."
+            </para>
+
+            <para>
+                When you clone the <filename>poky</filename> Git repository
+                or you download and unpack a Yocto Project release, you
+                can set up the Source Directory to be named anything you want.
+                For this discussion, the cloned repository uses the default
+                name <filename>poky</filename>.
+                <note>
+                    The
+                    <ulink url='&YOCTO_DOCS_REF_URL;#poky'>Poky</ulink>
+                    repository is primarily an aggregation of existing
+                    repositories.
+                    It is not a canonical upstream source.
+                </note>
+            </para>
+
+            <para>
+                The <filename>meta-poky</filename> layer inside Poky contains
+                a <filename>conf</filename> directory that has example
+                configuration files.
+                These example files are used as a basis for creating actual
+                configuration files when you source the build environment
+                script
+                (i.e.
+                <ulink url='&YOCTO_DOCS_REF_URL;#structure-core-script'><filename>&OE_INIT_FILE;</filename></ulink>).
+            </para>
+
+            <para>
+                Sourcing the build environment script creates a
+                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
+                if one does not already exist.
+                BitBake uses the Build Directory for all its work during
+                builds.
+                The Build Directory has a <filename>conf</filename> directory
+                that contains default versions of your
+                <filename>local.conf</filename> and
+                <filename>bblayers.conf</filename> configuration files.
+                These default configuration files are created only if versions
+                do not already exist in the Build Directory at the time you
+                source the build environment setup script.
+            </para>
+
+            <para>
+                Because the Poky repository is fundamentally an aggregation of
+                existing repositories, some users might be familiar with
+                running the <filename>&OE_INIT_FILE;</filename> script
+                in the context of separate
+                <ulink url='&YOCTO_DOCS_REF_URL;#oe-core'>OpenEmbedded-Core</ulink>
+                and BitBake repositories rather than a single Poky repository.
+                This discussion assumes the script is executed from
+                within a cloned or unpacked version of Poky.
+            </para>
+
+            <para>
+                Depending on where the script is sourced, different
+                sub-scripts are called to set up the Build Directory
+                (Yocto or OpenEmbedded).
+                Specifically, the script
+                <filename>scripts/oe-setup-builddir</filename> inside the
+                poky directory sets up the Build Directory and seeds the
+                directory (if necessary) with configuration files appropriate
+                for the Yocto Project development environment.
+                <note>
+                    The <filename>scripts/oe-setup-builddir</filename> script
+                    uses the <filename>$TEMPLATECONF</filename> variable to
+                    determine which sample configuration files to locate.
+                </note>
+            </para>
+
+            <para>
+                The <filename>local.conf</filename> file provides many
+                basic variables that define a build environment.
+                Here is a list of a few.
+                To see the default configurations in a
+                <filename>local.conf</filename> file created by the build
+                environment script, see the
+                <filename>local.conf.sample</filename> in the
+                <filename>meta-poky</filename> layer:
+                <itemizedlist>
+                    <listitem><para>
+                        <emphasis>Parallelism Options:</emphasis>
+                        Controlled by the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename></ulink>,
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></ulink>,
+                        and
+                        <ulink url='&YOCTO_DOCS_BB_URL;#var-BB_NUMBER_PARSE_THREADS'><filename>BB_NUMBER_PARSE_THREADS</filename></ulink>
+                        variables.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Target Machine Selection:</emphasis>
+                        Controlled by the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>
+                        variable.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Download Directory:</emphasis>
+                        Controlled by the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-DL_DIR'><filename>DL_DIR</filename></ulink>
+                        variable.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Shared State Directory:</emphasis>
+                        Controlled by the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-SSTATE_DIR'><filename>SSTATE_DIR</filename></ulink>
+                        variable.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Build Output:</emphasis>
+                        Controlled by the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink>
+                        variable.
+                        </para></listitem>
+                </itemizedlist>
+                <note>
+                    Configurations set in the
+                    <filename>conf/local.conf</filename> file can also be set
+                    in the <filename>conf/site.conf</filename> and
+                    <filename>conf/auto.conf</filename> configuration files.
+                </note>
+            </para>
+
+            <para>
+                The <filename>bblayers.conf</filename> file tells BitBake what
+                layers you want considered during the build.
+                By default, the layers listed in this file include layers
+                minimally needed by the build system.
+                However, you must manually add any custom layers you have
+                created.
+                You can find more information on working with the
+                <filename>bblayers.conf</filename> file in the
+                "<ulink url='&YOCTO_DOCS_DEV_URL;#enabling-your-layer'>Enabling Your Layer</ulink>"
+                section in the Yocto Project Development Tasks Manual.
+            </para>
+
+            <para>
+                The files <filename>site.conf</filename> and
+                <filename>auto.conf</filename> are not created by the
+                environment initialization script.
+                If you want the <filename>site.conf</filename> file, you
+                need to create that yourself.
+                The <filename>auto.conf</filename> file is typically created by
+                an autobuilder:
+                <itemizedlist>
+                    <listitem><para>
+                        <emphasis><filename>site.conf</filename>:</emphasis>
+                        You can use the <filename>conf/site.conf</filename>
+                        configuration file to configure multiple
+                        build directories.
+                        For example, suppose you had several build environments
+                        and they shared some common features.
+                        You can set these default build properties here.
+                        A good example is perhaps the packaging format to use
+                        through the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_CLASSES'><filename>PACKAGE_CLASSES</filename></ulink>
+                        variable.</para>
+
+                        <para>One useful scenario for using the
+                        <filename>conf/site.conf</filename> file is to extend
+                        your
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-BBPATH'><filename>BBPATH</filename></ulink>
+                        variable to include the path to a
+                        <filename>conf/site.conf</filename>.
+                        Then, when BitBake looks for Metadata using
+                        <filename>BBPATH</filename>, it finds the
+                        <filename>conf/site.conf</filename> file and applies
+                        your common configurations found in the file.
+                        To override configurations in a particular build
+                        directory, alter the similar configurations within
+                        that build directory's
+                        <filename>conf/local.conf</filename> file.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis><filename>auto.conf</filename>:</emphasis>
+                        The file is usually created and written to by
+                        an autobuilder.
+                        The settings put into the file are typically the
+                        same as you would find in the
+                        <filename>conf/local.conf</filename> or the
+                        <filename>conf/site.conf</filename> files.
+                        </para></listitem>
+                </itemizedlist>
+            </para>
+
+            <para>
+                You can edit all configuration files to further define
+                any particular build environment.
+                This process is represented by the "User Configuration Edits"
+                box in the figure.
+            </para>
+
+            <para>
+                When you launch your build with the
+                <filename>bitbake <replaceable>target</replaceable></filename>
+                command, BitBake sorts out the configurations to ultimately
+                define your build environment.
+                It is important to understand that the
+                <ulink url='&YOCTO_DOCS_REF_URL;#build-system-term'>OpenEmbedded build system</ulink>
+                reads the configuration files in a specific order:
+                <filename>site.conf</filename>, <filename>auto.conf</filename>,
+                and <filename>local.conf</filename>.
+                And, the build system applies the normal assignment statement
+                rules.
+                Because the files are parsed in a specific order, variable
+                assignments for the same variable could be affected.
+                For example, if the <filename>auto.conf</filename> file and
+                the <filename>local.conf</filename> set
+                <replaceable>variable1</replaceable> to different values,
+                because the build system parses <filename>local.conf</filename>
+                after <filename>auto.conf</filename>,
+                <replaceable>variable1</replaceable> is assigned the value from
+                the <filename>local.conf</filename> file.
+            </para>
+        </section>
+
+        <section id="metadata-machine-configuration-and-policy-configuration">
+            <title>Metadata, Machine Configuration, and Policy Configuration</title>
+
+            <para>
+                The previous section described the user configurations that
+                define BitBake's global behavior.
+                This section takes a closer look at the layers the build system
+                uses to further control the build.
+                These layers provide Metadata for the software, machine, and
+                policy.
+            </para>
+
+            <para>
+                In general, three types of layer input exist:
+                <itemizedlist>
+                    <listitem><para>
+                        <emphasis>Policy Configuration:</emphasis>
+                        Distribution Layers provide top-level or general
+                        policies for the image or SDK being built.
+                        For example, this layer would dictate whether BitBake
+                        produces RPM or IPK packages.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Machine Configuration:</emphasis>
+                        Board Support Package (BSP) layers provide machine
+                        configurations.
+                        This type of information is specific to a particular
+                        target architecture.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Metadata:</emphasis>
+                        Software layers contain user-supplied recipe files,
+                        patches, and append files.
+                        </para></listitem>
+                </itemizedlist>
+            </para>
+
+            <para>
+                The following figure shows an expanded representation of the
+                Metadata, Machine Configuration, and Policy Configuration input
+                (layers) boxes of the
+                <link linkend='general-yocto-environment-figure'>general Build Process figure</link>:
+            </para>
+
+            <para>
+                <imagedata fileref="figures/layer-input.png" align="center" width="8in" depth="7.5in" />
+            </para>
+
+            <para>
+                In general, all layers have a similar structure.
+                They all contain a licensing file
+                (e.g. <filename>COPYING</filename>) if the layer is to be
+                distributed, a <filename>README</filename> file as good
+                practice and especially if the layer is to be distributed, a
+                configuration directory, and recipe directories.
+            </para>
+
+            <para>
+                The Yocto Project has many layers that can be used.
+                You can see a web-interface listing of them on the
+                <ulink url="http://git.yoctoproject.org/">Source Repositories</ulink>
+                page.
+                The layers appear at the bottom categorized under
+                "Yocto Metadata Layers."
+                These layers are fundamentally a subset of the
+                <ulink url="http://layers.openembedded.org/layerindex/layers/">OpenEmbedded Metadata Index</ulink>,
+                which lists all layers provided by the OpenEmbedded community.
+                <note>
+                    Layers exist in the Yocto Project Source Repositories that
+                    cannot be found in the OpenEmbedded Metadata Index.
+                    These layers are either deprecated or experimental
+                    in nature.
+                </note>
+            </para>
+
+            <para>
+                BitBake uses the <filename>conf/bblayers.conf</filename> file,
+                which is part of the user configuration, to find what layers it
+                should be using as part of the build.
+            </para>
+
+            <para>
+                For more information on layers, see the
+                "<ulink url='&YOCTO_DOCS_DEV_URL;#understanding-and-creating-layers'>Understanding and Creating Layers</ulink>"
+                section in the Yocto Project Development Tasks Manual.
+            </para>
+
+            <section id="distro-layer">
+                <title>Distro Layer</title>
+
+                <para>
+                    The distribution layer provides policy configurations for
+                    your distribution.
+                    Best practices dictate that you isolate these types of
+                    configurations into their own layer.
+                    Settings you provide in
+                    <filename>conf/distro/<replaceable>distro</replaceable>.conf</filename> override
+                    similar settings that BitBake finds in your
+                    <filename>conf/local.conf</filename> file in the Build
+                    Directory.
+                </para>
+
+                <para>
+                    The following list provides some explanation and references
+                    for what you typically find in the distribution layer:
+                    <itemizedlist>
+                        <listitem><para>
+                            <emphasis>classes:</emphasis>
+                            Class files (<filename>.bbclass</filename>) hold
+                            common functionality that can be shared among
+                            recipes in the distribution.
+                            When your recipes inherit a class, they take on the
+                            settings and functions for that class.
+                            You can read more about class files in the
+                            "<ulink url='&YOCTO_DOCS_REF_URL;#ref-classes'>Classes</ulink>"
+                            chapter of the Yocto Reference Manual.
+                            </para></listitem>
+                        <listitem><para>
+                            <emphasis>conf:</emphasis>
+                            This area holds configuration files for the
+                            layer (<filename>conf/layer.conf</filename>),
+                            the distribution
+                            (<filename>conf/distro/<replaceable>distro</replaceable>.conf</filename>),
+                            and any distribution-wide include files.
+                            </para></listitem>
+                        <listitem><para>
+                            <emphasis>recipes-*:</emphasis>
+                            Recipes and append files that affect common
+                            functionality across the distribution.
+                            This area could include recipes and append files
+                            to add distribution-specific configuration,
+                            initialization scripts, custom image recipes,
+                            and so forth.
+                            </para></listitem>
+                    </itemizedlist>
+                </para>
+            </section>
+
+            <section id="bsp-layer">
+                <title>BSP Layer</title>
+
+                <para>
+                    The BSP Layer provides machine configurations.
+                    Everything in this layer is specific to the machine for
+                    which you are building the image or the SDK.
+                    A common structure or form is defined for BSP layers.
+                    You can learn more about this structure in the
+                    <ulink url='&YOCTO_DOCS_BSP_URL;'>Yocto Project Board Support Package (BSP) Developer's Guide</ulink>.
+                    <note>
+                        In order for a BSP layer to be considered compliant
+                        with the Yocto Project, it must meet some structural
+                        requirements.
+                    </note>
+                </para>
+
+                <para>
+                    The BSP Layer's configuration directory contains
+                    configuration files for the machine
+                    (<filename>conf/machine/<replaceable>machine</replaceable>.conf</filename>)
+                    and, of course, the layer
+                    (<filename>conf/layer.conf</filename>).
+                </para>
+
+                <para>
+                    The remainder of the layer is dedicated to specific recipes
+                    by function: <filename>recipes-bsp</filename>,
+                    <filename>recipes-core</filename>,
+                    <filename>recipes-graphics</filename>, and
+                    <filename>recipes-kernel</filename>.
+                    Metadata can exist for multiple formfactors, graphics
+                    support systems, and so forth.
+                    <note>
+                        While the figure shows several
+                        <filename>recipes-*</filename> directories, not all
+                        these directories appear in all BSP layers.
+                    </note>
+                </para>
+            </section>
+
+            <section id="software-layer">
+                <title>Software Layer</title>
+
+                <para>
+                    The software layer provides the Metadata for additional
+                    software packages used during the build.
+                    This layer does not include Metadata that is specific to
+                    the distribution or the machine, which are found in their
+                    respective layers.
+                </para>
+
+                <para>
+                    This layer contains any new recipes that your project
+                    needs in the form of recipe files.
+                </para>
+            </section>
+        </section>
+
+        <section id="sources-dev-environment">
+            <title>Sources</title>
+
+            <para>
+                In order for the OpenEmbedded build system to create an
+                image or any target, it must be able to access source files.
+                The
+                <link linkend='general-yocto-environment-figure'>general Build Process figure</link>
+                represents source files using the "Upstream Project Releases",
+                "Local Projects", and "SCMs (optional)" boxes.
+                The figure represents mirrors, which also play a role in
+                locating source files, with the "Source Mirror(s)" box.
+            </para>
+
+            <para>
+                The method by which source files are ultimately organized is
+                a function of the project.
+                For example, for released software, projects tend to use
+                tarballs or other archived files that can capture the
+                state of a release guaranteeing that it is statically
+                represented.
+                On the other hand, for a project that is more dynamic or
+                experimental in nature, a project might keep source files in a
+                repository controlled by a Source Control Manager (SCM) such as
+                Git.
+                Pulling source from a repository allows you to control
+                the point in the repository (the revision) from which you
+                want to build software.
+                Finally, a combination of the two might exist, which would
+                give the consumer a choice when deciding where to get
+                source files.
+            </para>
+
+            <para>
+                BitBake uses the
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
+                variable to point to source files regardless of their location.
+                Each recipe must have a <filename>SRC_URI</filename> variable
+                that points to the source.
+            </para>
+
+            <para>
+                Another area that plays a significant role in where source
+                files come from is pointed to by the
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-DL_DIR'><filename>DL_DIR</filename></ulink>
+                variable.
+                This area is a cache that can hold previously downloaded
+                source.
+                You can also instruct the OpenEmbedded build system to create
+                tarballs from Git repositories, which is not the default
+                behavior, and store them in the <filename>DL_DIR</filename>
+                by using the
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-BB_GENERATE_MIRROR_TARBALLS'><filename>BB_GENERATE_MIRROR_TARBALLS</filename></ulink>
+                variable.
+            </para>
+
+            <para>
+                Judicious use of a <filename>DL_DIR</filename> directory can
+                save the build system a trip across the Internet when looking
+                for files.
+                A good method for using a download directory is to have
+                <filename>DL_DIR</filename> point to an area outside of your
+                Build Directory.
+                Doing so allows you to safely delete the Build Directory
+                if needed without fear of removing any downloaded source file.
+            </para>
+
+            <para>
+                The remainder of this section provides a deeper look into the
+                source files and the mirrors.
+                Here is a more detailed look at the source file area of the
+                <link linkend='general-yocto-environment-figure'>general Build Process figure</link>:
+                <imagedata fileref="figures/source-input.png" align="center" width="7in" depth="7.5in" />
+            </para>
+
+            <section id='upstream-project-releases'>
+                <title>Upstream Project Releases</title>
+
+                <para>
+                    Upstream project releases exist anywhere in the form of an
+                    archived file (e.g. tarball or zip file).
+                    These files correspond to individual recipes.
+                    For example, the figure uses specific releases each for
+                    BusyBox, Qt, and Dbus.
+                    An archive file can be for any released product that can be
+                    built using a recipe.
+                </para>
+            </section>
+
+            <section id='local-projects'>
+                <title>Local Projects</title>
+
+                <para>
+                    Local projects are custom bits of software the user
+                    provides.
+                    These bits reside somewhere local to a project - perhaps
+                    a directory into which the user checks in items (e.g.
+                    a local directory containing a development source tree
+                    used by the group).
+                </para>
+
+                <para>
+                    The canonical method through which to include a local
+                    project is to use the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-externalsrc'><filename>externalsrc</filename></ulink>
+                    class to include that local project.
+                    You use either the <filename>local.conf</filename> or a
+                    recipe's append file to override or set the
+                    recipe to point to the local directory on your disk to pull
+                    in the whole source tree.
+                </para>
+
+                <para>
+                    For information on how to use the
+                    <filename>externalsrc</filename> class, see the
+                    "<ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-externalsrc'><filename>externalsrc.bbclass</filename></ulink>"
+                    section.
+                </para>
+            </section>
+
+            <section id='scms'>
+                <title>Source Control Managers (Optional)</title>
+
+                <para>
+                    Another place the build system can get source files from is
+                    through an SCM such as Git or Subversion.
+                    In this case, a repository is cloned or checked out.
+                    The
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-fetch'><filename>do_fetch</filename></ulink>
+                    task inside BitBake uses
+                    the <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
+                    variable and the argument's prefix to determine the correct
+                    fetcher module.
+                    <note>
+                        For information on how to have the OpenEmbedded build
+                        system generate tarballs for Git repositories and place
+                        them in the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-DL_DIR'><filename>DL_DIR</filename></ulink>
+                        directory, see the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-BB_GENERATE_MIRROR_TARBALLS'><filename>BB_GENERATE_MIRROR_TARBALLS</filename></ulink>
+                        variable.
+                    </note>
+                </para>
+
+                <para>
+                    When fetching a repository, BitBake uses the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-SRCREV'><filename>SRCREV</filename></ulink>
+                    variable to determine the specific revision from which to
+                    build.
+                </para>
+            </section>
+
+            <section id='source-mirrors'>
+                <title>Source Mirror(s)</title>
+
+                <para>
+                    Two kinds of mirrors exist: pre-mirrors and regular
+                    mirrors.
+                    The
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PREMIRRORS'><filename>PREMIRRORS</filename></ulink>
+                    and
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-MIRRORS'><filename>MIRRORS</filename></ulink>
+                    variables point to these, respectively.
+                    BitBake checks pre-mirrors before looking upstream for any
+                    source files.
+                    Pre-mirrors are appropriate when you have a shared
+                    directory that is not a directory defined by the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-DL_DIR'><filename>DL_DIR</filename></ulink>
+                    variable.
+                    A Pre-mirror typically points to a shared directory that is
+                    local to your organization.
+                </para>
+
+                <para>
+                    Regular mirrors can be any site across the Internet
+                    that is used as an alternative location for source
+                    code should the primary site not be functioning for
+                    some reason or another.
+                </para>
+            </section>
+        </section>
+
+        <section id="package-feeds-dev-environment">
+            <title>Package Feeds</title>
+
+            <para>
+                When the OpenEmbedded build system generates an image or an
+                SDK, it gets the packages from a package feed area located
+                in the
+                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>.
+                The
+                <link linkend='general-yocto-environment-figure'>general Build Process figure</link>
+                shows this package feeds area in the upper-right corner.
+            </para>
+
+            <para>
+                This section looks a little closer into the package feeds
+                area used by the build system.
+                Here is a more detailed look at the area:
+                <imagedata fileref="figures/package-feeds.png" align="center" width="7in" depth="6in" />
+            </para>
+
+            <para>
+                Package feeds are an intermediary step in the build process.
+                The OpenEmbedded build system provides classes to generate
+                different package types, and you specify which classes to
+                enable through the
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_CLASSES'><filename>PACKAGE_CLASSES</filename></ulink>
+                variable.
+                Before placing the packages into package feeds,
+                the build process validates them with generated output quality
+                assurance checks through the
+                <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-insane'><filename>insane</filename></ulink>
+                class.
+            </para>
+
+            <para>
+                The package feed area resides in the Build Directory.
+                The directory the build system uses to temporarily store
+                packages is determined by a combination of variables and the
+                particular package manager in use.
+                See the "Package Feeds" box in the illustration and note the
+                information to the right of that area.
+                In particular, the following defines where package files are
+                kept:
+                <itemizedlist>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPLOY_DIR'><filename>DEPLOY_DIR</filename></ulink>:
+                        Defined as <filename>tmp/deploy</filename> in the Build
+                        Directory.
+                        </para></listitem>
+                    <listitem><para>
+                        <filename>DEPLOY_DIR_*</filename>:
+                        Depending on the package manager used, the package type
+                        sub-folder.
+                        Given RPM, IPK, or DEB packaging and tarball creation,
+                        the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPLOY_DIR_RPM'><filename>DEPLOY_DIR_RPM</filename></ulink>,
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPLOY_DIR_IPK'><filename>DEPLOY_DIR_IPK</filename></ulink>,
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPLOY_DIR_DEB'><filename>DEPLOY_DIR_DEB</filename></ulink>,
+                        or
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPLOY_DIR_TAR'><filename>DEPLOY_DIR_TAR</filename></ulink>,
+                        variables are used, respectively.
+                        </para></listitem>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_ARCH'><filename>PACKAGE_ARCH</filename></ulink>:
+                        Defines architecture-specific sub-folders.
+                        For example, packages could exist for the i586 or
+                        qemux86 architectures.
+                        </para></listitem>
+                </itemizedlist>
+            </para>
+
+            <para>
+                BitBake uses the
+                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package_write_deb'><filename>do_package_write_*</filename></ulink>
+                tasks to generate packages and place them into the package
+                holding area (e.g. <filename>do_package_write_ipk</filename>
+                for IPK packages).
+                See the
+                "<ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package_write_deb'><filename>do_package_write_deb</filename></ulink>",
+                "<ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package_write_ipk'><filename>do_package_write_ipk</filename></ulink>",
+                "<ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package_write_rpm'><filename>do_package_write_rpm</filename></ulink>",
+                and
+                "<ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package_write_tar'><filename>do_package_write_tar</filename></ulink>"
+                sections in the Yocto Project Reference Manual
+                for additional information.
+                As an example, consider a scenario where an IPK packaging
+                manager is being used and package architecture support for
+                both i586 and qemux86 exist.
+                Packages for the i586 architecture are placed in
+                <filename>build/tmp/deploy/ipk/i586</filename>, while packages
+                for the qemux86 architecture are placed in
+                <filename>build/tmp/deploy/ipk/qemux86</filename>.
+            </para>
+        </section>
+
+        <section id='bitbake-dev-environment'>
+            <title>BitBake</title>
+
+            <para>
+                The OpenEmbedded build system uses
+                <ulink url='&YOCTO_DOCS_REF_URL;#bitbake-term'>BitBake</ulink>
+                to produce images.
+                You can see from the
+                <link linkend='general-yocto-environment-figure'>general Build Process figure</link>,
+                the BitBake area consists of several functional areas.
+                This section takes a closer look at each of those areas.
+            </para>
+
+            <para>
+                Separate documentation exists for the BitBake tool.
+                See the
+                <ulink url='&YOCTO_DOCS_BB_URL;#bitbake-user-manual'>BitBake User Manual</ulink>
+                for reference material on BitBake.
+            </para>
+
+            <section id='source-fetching-dev-environment'>
+                <title>Source Fetching</title>
+
+                <para>
+                    The first stages of building a recipe are to fetch and
+                    unpack the source code:
+                    <imagedata fileref="figures/source-fetching.png" align="center" width="6.5in" depth="5in" />
+                </para>
+
+                <para>
+                    The
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-fetch'><filename>do_fetch</filename></ulink>
+                    and
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-unpack'><filename>do_unpack</filename></ulink>
+                    tasks fetch the source files and unpack them into the work
+                    directory.
+                    <note>
+                        For every local file (e.g. <filename>file://</filename>)
+                        that is part of a recipe's
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
+                        statement, the OpenEmbedded build system takes a
+                        checksum of the file for the recipe and inserts the
+                        checksum into the signature for the
+                        <filename>do_fetch</filename>.
+                        If any local file has been modified, the
+                        <filename>do_fetch</filename> task and all tasks that
+                        depend on it are re-executed.
+                    </note>
+                    By default, everything is accomplished in the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>,
+                    which has a defined structure.
+                    For additional general information on the Build Directory,
+                    see the
+                    "<ulink url='&YOCTO_DOCS_REF_URL;#structure-core-build'><filename>build/</filename></ulink>"
+                    section in the Yocto Project Reference Manual.
+                </para>
+
+                <para>
+                    Unpacked source files are pointed to by the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink>
+                    variable.
+                    Each recipe has an area in the Build Directory where the
+                    unpacked source code resides.
+                    The name of that directory for any given recipe is defined
+                    from several different variables.
+                    You can see the variables that define these directories
+                    by looking at the figure:
+                    <itemizedlist>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink>:
+                            The base directory where the OpenEmbedded build
+                            system performs all its work during the build.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_ARCH'><filename>PACKAGE_ARCH</filename></ulink>:
+                            The architecture of the built package or packages.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-TARGET_OS'><filename>TARGET_OS</filename></ulink>:
+                            The operating system of the target device.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PN'><filename>PN</filename></ulink>:
+                            The name of the built package.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink>:
+                            The version of the recipe used to build the
+                            package.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink>:
+                            The revision of the recipe used to build the
+                            package.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink>:
+                            The location within <filename>TMPDIR</filename>
+                            where a specific package is built.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink>:
+                            Contains the unpacked source files for a given
+                            recipe.
+                            </para></listitem>
+                    </itemizedlist>
+                </para>
+            </section>
+
+            <section id='patching-dev-environment'>
+                <title>Patching</title>
+
+                <para>
+                    Once source code is fetched and unpacked, BitBake locates
+                    patch files and applies them to the source files:
+                    <imagedata fileref="figures/patching.png" align="center" width="6in" depth="5in" />
+                </para>
+
+                <para>
+                    The
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-patch'><filename>do_patch</filename></ulink>
+                    task processes recipes by using the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-SRC_URI'><filename>SRC_URI</filename></ulink>
+                    variable to locate applicable patch files, which by default
+                    are <filename>*.patch</filename> or
+                    <filename>*.diff</filename> files, or any file if
+                    "apply=yes" is specified for the file in
+                    <filename>SRC_URI</filename>.
+                </para>
+
+                <para>
+                    BitBake finds and applies multiple patches for a single
+                    recipe in the order in which it finds the patches.
+                    Patches are applied to the recipe's source files located
+                    in the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink>
+                    directory.
+                </para>
+
+                <para>
+                    For more information on how the source directories are
+                    created, see the
+                    "<link linkend='source-fetching-dev-environment'>Source Fetching</link>"
+                    section.
+                </para>
+            </section>
+
+            <section id='configuration-and-compilation-dev-environment'>
+                <title>Configuration and Compilation</title>
+
+                <para>
+                    After source code is patched, BitBake executes tasks that
+                    configure and compile the source code:
+                    <imagedata fileref="figures/configuration-compile-autoreconf.png" align="center" width="7in" depth="5in" />
+                </para>
+
+                <para>
+                    This step in the build process consists of three tasks:
+                    <itemizedlist>
+                        <listitem><para>
+                            <emphasis><ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-prepare_recipe_sysroot'><filename>do_prepare_recipe_sysroot</filename></ulink></emphasis>:
+                            This task sets up the two sysroots in
+                            <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink><filename>}</filename>
+                            (i.e. <filename>recipe-sysroot</filename> and
+                            <filename>recipe-sysroot-native</filename>) so that
+                            the sysroots contain the contents of the
+                            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-populate_sysroot'><filename>do_populate_sysroot</filename></ulink>
+                            tasks of the recipes on which the recipe
+                            containing the tasks depends.
+                            A sysroot exists for both the target and for the
+                            native binaries, which run on the host system.
+                            </para></listitem>
+                        <listitem><para>
+                            <emphasis><filename>do_configure</filename></emphasis>:
+                            This task configures the source by enabling and
+                            disabling any build-time and configuration options
+                            for the software being built.
+                            Configurations can come from the recipe itself as
+                            well as from an inherited class.
+                            Additionally, the software itself might configure
+                            itself depending on the target for which it is
+                            being built.</para>
+
+                            <para>The configurations handled by the
+                            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-configure'><filename>do_configure</filename></ulink>
+                            task are specific to source code configuration for
+                            the source code being built by the recipe.</para>
+
+                            <para>If you are using the
+                            <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-autotools'><filename>autotools</filename></ulink>
+                            class, you can add additional configuration options
+                            by using the
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-EXTRA_OECONF'><filename>EXTRA_OECONF</filename></ulink>
+                            or
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGECONFIG_CONFARGS'><filename>PACKAGECONFIG_CONFARGS</filename></ulink>
+                            variables.
+                            For information on how this variable works within
+                            that class, see the
+                            <filename>meta/classes/autotools.bbclass</filename>
+                            file.
+                            </para></listitem>
+                        <listitem><para>
+                            <emphasis><filename>do_compile</filename></emphasis>:
+                            Once a configuration task has been satisfied, BitBake
+                            compiles the source using the
+                            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-compile'><filename>do_compile</filename></ulink>
+                            task.
+                            Compilation occurs in the directory pointed to by
+                            the
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-B'><filename>B</filename></ulink>
+                            variable.
+                            Realize that the <filename>B</filename> directory
+                            is, by default, the same as the
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink>
+                            directory.
+                            </para></listitem>
+                        <listitem><para>
+                            <emphasis><filename>do_install</filename></emphasis>:
+                            Once compilation is done, BitBake executes the
+                            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-install'><filename>do_install</filename></ulink>
+                            task.
+                            This task copies files from the
+                            <filename>B</filename> directory and places them
+                            in a holding area pointed to by the
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-D'><filename>D</filename></ulink>
+                            variable.
+                            </para></listitem>
+                    </itemizedlist>
+                </para>
+            </section>
+
+            <section id='package-splitting-dev-environment'>
+                <title>Package Splitting</title>
+
+                <para>
+                    After source code is configured and compiled, the
+                    OpenEmbedded build system analyzes
+                    the results and splits the output into packages:
+                    <imagedata fileref="figures/analysis-for-package-splitting.png" align="center" width="7in" depth="7in" />
+                </para>
+
+                <para>
+                    The
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package'><filename>do_package</filename></ulink>
+                    and
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-packagedata'><filename>do_packagedata</filename></ulink>
+                    tasks combine to analyze the files found in the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-D'><filename>D</filename></ulink>
+                    directory and split them into subsets based on available
+                    packages and files.
+                    The analyzing process involves the following as well as
+                    other items: splitting out debugging symbols, looking at
+                    shared library dependencies between packages, and looking
+                    at package relationships.
+                    The <filename>do_packagedata</filename> task creates
+                    package metadata based on the analysis such that the
+                    OpenEmbedded build system can generate the final packages.
+                    Working, staged, and intermediate results of the analysis
+                    and package splitting process use these areas:
+                    <itemizedlist>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PKGD'><filename>PKGD</filename></ulink>:
+                            The destination directory for packages before they
+                            are split.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PKGDATA_DIR'><filename>PKGDATA_DIR</filename></ulink>:
+                            A shared, global-state directory that holds data
+                            generated during the packaging process.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PKGDESTWORK'><filename>PKGDESTWORK</filename></ulink>:
+                            A temporary work area used by the
+                            <filename>do_package</filename> task.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PKGDEST'><filename>PKGDEST</filename></ulink>:
+                            The parent directory for packages after they have
+                            been split.
+                            </para></listitem>
+                    </itemizedlist>
+                    The
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-FILES'><filename>FILES</filename></ulink>
+                    variable defines the files that go into each package in
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGES'><filename>PACKAGES</filename></ulink>.
+                    If you want details on how this is accomplished, you can
+                    look at the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-package'><filename>package</filename></ulink>
+                    class.
+                </para>
+
+                <para>
+                    Depending on the type of packages being created (RPM, DEB,
+                    or IPK), the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package_write_deb'><filename>do_package_write_*</filename></ulink>
+                    task creates the actual packages and places them in the
+                    Package Feed area, which is
+                    <filename>${TMPDIR}/deploy</filename>.
+                    You can see the
+                    "<link linkend='package-feeds-dev-environment'>Package Feeds</link>"
+                    section for more detail on that part of the build process.
+                    <note>
+                        Support for creating feeds directly from the
+                        <filename>deploy/*</filename> directories does not
+                        exist.
+                        Creating such feeds usually requires some kind of feed
+                        maintenance mechanism that would upload the new
+                        packages into an official package feed (e.g. the
+                        Ångström distribution).
+                        This functionality is highly distribution-specific
+                        and thus is not provided out of the box.
+                    </note>
+                </para>
+            </section>
+
+            <section id='image-generation-dev-environment'>
+                <title>Image Generation</title>
+
+                <para>
+                    Once packages are split and stored in the Package Feeds
+                    area, the OpenEmbedded build system uses BitBake to
+                    generate the root filesystem image:
+                    <imagedata fileref="figures/image-generation.png" align="center" width="6in" depth="7in" />
+                </para>
+
+                <para>
+                    The image generation process consists of several stages and
+                    depends on several tasks and variables.
+                    The
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-rootfs'><filename>do_rootfs</filename></ulink>
+                    task creates the root filesystem (file and directory
+                    structure) for an image.
+                    This task uses several key variables to help create the
+                    list of packages to actually install:
+                    <itemizedlist>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_INSTALL'><filename>IMAGE_INSTALL</filename></ulink>:
+                            Lists out the base set of packages to install from
+                            the Package Feeds area.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_EXCLUDE'><filename>PACKAGE_EXCLUDE</filename></ulink>:
+                            Specifies packages that should not be installed.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_FEATURES'><filename>IMAGE_FEATURES</filename></ulink>:
+                            Specifies features to include in the image.
+                            Most of these features map to additional packages
+                            for installation.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_CLASSES'><filename>PACKAGE_CLASSES</filename></ulink>:
+                            Specifies the package backend to use and
+                            consequently helps determine where to locate
+                            packages within the Package Feeds area.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_LINGUAS'><filename>IMAGE_LINGUAS</filename></ulink>:
+                            Determines the language(s) for which additional
+                            language support packages are installed.
+                            </para></listitem>
+                        <listitem><para>
+                            <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_INSTALL'><filename>PACKAGE_INSTALL</filename></ulink>:
+                            The final list of packages passed to the package manager
+                            for installation into the image.
+                            </para></listitem>
+                    </itemizedlist>
+                </para>
+
+                <para>
+                    With
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_ROOTFS'><filename>IMAGE_ROOTFS</filename></ulink>
+                    pointing to the location of the filesystem under
+                    construction and the <filename>PACKAGE_INSTALL</filename>
+                    variable providing the final list of packages to install,
+                    the root file system is created.
+                </para>
+
+                <para>
+                    Package installation is under control of the package
+                    manager (e.g. dnf/rpm, opkg, or apt/dpkg) regardless of
+                    whether or not package management is enabled for the
+                    target.
+                    At the end of the process, if package management is not
+                    enabled for the target, the package manager's data files
+                    are deleted from the root filesystem.
+                    As part of the final stage of package installation,
+                    postinstall scripts that are part of the packages are run.
+                    Any scripts that fail to run
+                    on the build host are run on the target when the target
+                    system is first booted.
+                    If you are using a
+                    <ulink url='&YOCTO_DOCS_DEV_URL;#creating-a-read-only-root-filesystem'>read-only root filesystem</ulink>,
+                    all the post installation scripts must succeed during the
+                    package installation phase since the root filesystem is
+                    read-only.
+                </para>
+
+                <para>
+                    The final stages of the <filename>do_rootfs</filename> task
+                    handle post processing.
+                    Post processing includes creation of a manifest file and
+                    optimizations.
+                </para>
+
+                <para>
+                    The manifest file (<filename>.manifest</filename>) resides
+                    in the same directory as the root filesystem image.
+                    This file lists out, line-by-line, the installed packages.
+                    The manifest file is useful for the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-testimage*'><filename>testimage</filename></ulink>
+                    class, for example, to determine whether or not to run
+                    specific tests.
+                    See the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_MANIFEST'><filename>IMAGE_MANIFEST</filename></ulink>
+                    variable for additional information.
+                </para>
+
+                <para>
+                    Optimizing processes run across the image include
+                    <filename>mklibs</filename>, <filename>prelink</filename>,
+                    and any other post-processing commands as defined by the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-ROOTFS_POSTPROCESS_COMMAND'><filename>ROOTFS_POSTPROCESS_COMMAND</filename></ulink>
+                    variable.
+                    The <filename>mklibs</filename> process optimizes the size
+                    of the libraries, while the <filename>prelink</filename>
+                    process optimizes the dynamic linking of shared libraries
+                    to reduce start up time of executables.
+                </para>
+
+                <para>
+                    After the root filesystem is built, processing begins on
+                    the image through the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-image'><filename>do_image</filename></ulink>
+                    task.
+                    The build system runs any pre-processing commands as
+                    defined by the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_PREPROCESS_COMMAND'><filename>IMAGE_PREPROCESS_COMMAND</filename></ulink>
+                    variable.
+                    This variable specifies a list of functions to call before
+                    the OpenEmbedded build system creates the final image
+                    output files.
+                </para>
+
+                <para>
+                    The OpenEmbedded build system dynamically creates
+                    <filename>do_image_*</filename> tasks as needed, based
+                    on the image types specified in the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></ulink>
+                    variable.
+                    The process turns everything into an image file or a set of
+                    image files and can compress the root filesystem image to
+                    reduce the overall size of the image.
+                    The formats used for the root filesystem depend on the
+                    <filename>IMAGE_FSTYPES</filename> variable.
+                    Compression depends on whether the formats support
+                    compression.
+                </para>
+
+                <para>
+                    As an example, a dynamically created task when creating a
+                    particular image <replaceable>type</replaceable> would
+                    take the following form:
+                    <literallayout class='monospaced'>
+     do_image_<replaceable>type</replaceable>
+                    </literallayout>
+                    So, if the <replaceable>type</replaceable> as specified by
+                    the <filename>IMAGE_FSTYPES</filename> were
+                    <filename>ext4</filename>, the dynamically generated task
+                    would be as follows:
+                    <literallayout class='monospaced'>
+     do_image_ext4
+                    </literallayout>
+                </para>
+
+                <para>
+                    The final task involved in image creation is the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-image-complete'><filename>do_image_complete</filename></ulink>
+                    task.
+                    This task completes the image by applying any image
+                    post processing as defined through the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_POSTPROCESS_COMMAND'><filename>IMAGE_POSTPROCESS_COMMAND</filename></ulink>
+                    variable.
+                    The variable specifies a list of functions to call once the
+                    OpenEmbedded build system has created the final image
+                    output files.
+                    <note>
+                        The entire image generation process is run under
+                        Pseudo.
+                        Running under Pseudo ensures that the files in the
+                        root filesystem have correct ownership.
+                    </note>
+                </para>
+            </section>
+
+            <section id='sdk-generation-dev-environment'>
+                <title>SDK Generation</title>
+
+                <para>
+                    The OpenEmbedded build system uses BitBake to generate the
+                    Software Development Kit (SDK) installer script for both
+                    the standard and extensible SDKs:
+                    <imagedata fileref="figures/sdk-generation.png" align="center" />
+                    <note>
+                        For more information on the cross-development toolchain
+                        generation, see the
+                        "<link linkend='cross-development-toolchain-generation'>Cross-Development Toolchain Generation</link>"
+                        section.
+                        For information on advantages gained when building a
+                        cross-development toolchain using the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-populate_sdk'><filename>do_populate_sdk</filename></ulink>
+                        task, see the
+                        "<ulink url='&YOCTO_DOCS_SDK_URL;#sdk-building-an-sdk-installer'>Building an SDK Installer</ulink>"
+                        section in the Yocto Project Application Development
+                        and the Extensible Software Development Kit (SDK)
+                        manual.
+                    </note>
+                </para>
+
+                <para>
+                    Like image generation, the SDK script process consists of
+                    several stages and depends on many variables.
+                    The <filename>do_populate_sdk</filename> and
+                    <filename>do_populate_sdk_ext</filename> tasks use these
+                    key variables to help create the list of packages to
+                    actually install.
+                    For information on the variables listed in the figure,
+                    see the
+                    "<link linkend='sdk-dev-environment'>Application Development SDK</link>"
+                    section.
+                </para>
+
+                <para>
+                    The <filename>do_populate_sdk</filename> task helps create
+                    the standard SDK and handles two parts: a target part and a
+                    host part.
+                    The target part is the part built for the target hardware
+                    and includes libraries and headers.
+                    The host part is the part of the SDK that runs on the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-SDKMACHINE'><filename>SDKMACHINE</filename></ulink>.
+                </para>
+
+                <para>
+                    The <filename>do_populate_sdk_ext</filename> task helps
+                    create the extensible SDK and handles host and target parts
+                    differently than its counter part does for the standard SDK.
+                    For the extensible SDK, the task encapsulates the build
+                    system, which includes everything needed (host and target)
+                    for the SDK.
+                </para>
+
+                <para>
+                    Regardless of the type of SDK being constructed, the
+                    tasks perform some cleanup after which a cross-development
+                    environment setup script and any needed configuration files
+                    are created.
+                    The final output is the Cross-development
+                    toolchain installation script (<filename>.sh</filename>
+                    file), which includes the environment setup script.
+                </para>
+            </section>
+
+            <section id='stamp-files-and-the-rerunning-of-tasks'>
+                <title>Stamp Files and the Rerunning of Tasks</title>
+
+                <para>
+                    For each task that completes successfully, BitBake writes a
+                    stamp file into the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-STAMPS_DIR'><filename>STAMPS_DIR</filename></ulink>
+                    directory.
+                    The beginning of the stamp file's filename is determined
+                    by the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-STAMP'><filename>STAMP</filename></ulink>
+                    variable, and the end of the name consists of the task's
+                    name and current
+                    <ulink url='&YOCTO_DOCS_GS_URL;#overview-checksums'>input checksum</ulink>.
+                    <note>
+                        This naming scheme assumes that
+                        <ulink url='&YOCTO_DOCS_BB_URL;#var-BB_SIGNATURE_HANDLER'><filename>BB_SIGNATURE_HANDLER</filename></ulink>
+                        is "OEBasicHash", which is almost always the case in
+                        current OpenEmbedded.
+                    </note>
+                    To determine if a task needs to be rerun, BitBake checks
+                    if a stamp file with a matching input checksum exists
+                    for the task.
+                    If such a stamp file exists, the task's output is
+                    assumed to exist and still be valid.
+                    If the file does not exist, the task is rerun.
+                    <note>
+                        <para>The stamp mechanism is more general than the
+                        shared state (sstate) cache mechanism described in the
+                        "<link linkend='setscene-tasks-and-shared-state'>Setscene Tasks and Shared State</link>"
+                        section.
+                        BitBake avoids rerunning any task that has a valid
+                        stamp file, not just tasks that can be accelerated
+                        through the sstate cache.</para>
+
+                        <para>However, you should realize that stamp files only
+                        serve as a marker that some work has been done and that
+                        these files do not record task output.
+                        The actual task output would usually be somewhere in
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink>
+                        (e.g. in some recipe's
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink>.)
+                        What the sstate cache mechanism adds is a way to cache
+                        task output that can then be shared between build
+                        machines.</para>
+                    </note>
+                    Since <filename>STAMPS_DIR</filename> is usually a
+                    subdirectory of <filename>TMPDIR</filename>, removing
+                    <filename>TMPDIR</filename> will also remove
+                    <filename>STAMPS_DIR</filename>, which means tasks will
+                    properly be rerun to repopulate
+                    <filename>TMPDIR</filename>.
+                </para>
+
+                <para>
+                    If you want some task to always be considered "out of
+                    date", you can mark it with the
+                    <ulink url='&YOCTO_DOCS_BB_URL;#variable-flags'><filename>nostamp</filename></ulink>
+                    varflag.
+                    If some other task depends on such a task, then that
+                    task will also always be considered out of date, which
+                    might not be what you want.
+                </para>
+
+                <para>
+                    For details on how to view information about a task's
+                    signature, see the
+                    "<ulink url='&YOCTO_DOCS_DEV_URL;#dev-viewing-task-variable-dependencies'>Viewing Task Variable Dependencies</ulink>"
+                    section in the Yocto Project Development Tasks Manual.
+                </para>
+            </section>
+
+            <section id='setscene-tasks-and-shared-state'>
+                <title>Setscene Tasks and Shared State</title>
+
+                <para>
+                    The description of tasks so far assumes that BitBake needs
+                    to build everything and there are no prebuilt objects
+                    available.
+                    BitBake does support skipping tasks if prebuilt objects are
+                    available.
+                    These objects are usually made available in the form of a
+                    shared state (sstate) cache.
+                    <note>
+                        For information on variables affecting sstate, see the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-SSTATE_DIR'><filename>SSTATE_DIR</filename></ulink>
+                        and
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-SSTATE_MIRRORS'><filename>SSTATE_MIRRORS</filename></ulink>
+                        variables.
+                    </note>
+                </para>
+
+                <para>
+                    The idea of a setscene task (i.e
+                    <filename>do_</filename><replaceable>taskname</replaceable><filename>_setscene</filename>)
+                    is a version of the task where
+                    instead of building something, BitBake can skip to the end
+                    result and simply place a set of files into specific
+                    locations as needed.
+                    In some cases, it makes sense to have a setscene task
+                    variant (e.g. generating package files in the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package_write_deb'><filename>do_package_write_*</filename></ulink>
+                    task).
+                    In other cases, it does not make sense, (e.g. a
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-patch'><filename>do_patch</filename></ulink>
+                    task or
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-unpack'><filename>do_unpack</filename></ulink>
+                    task) since the work involved would be equal to or greater
+                    than the underlying task.
+                </para>
+
+                <para>
+                    In the OpenEmbedded build system, the common tasks that
+                    have setscene variants are
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package'><filename>do_package</filename></ulink>,
+                    <filename>do_package_write_*</filename>,
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-deploy'><filename>do_deploy</filename></ulink>,
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-packagedata'><filename>do_packagedata</filename></ulink>,
+                    and
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-populate_sysroot'><filename>do_populate_sysroot</filename></ulink>.
+                    Notice that these are most of the tasks whose output is an
+                    end result.
+                </para>
+
+                <para>
+                    The OpenEmbedded build system has knowledge of the
+                    relationship between these tasks and other tasks that
+                    precede them.
+                    For example, if BitBake runs
+                    <filename>do_populate_sysroot_setscene</filename> for
+                    something, there is little point in running any of the
+                    <filename>do_fetch</filename>,
+                    <filename>do_unpack</filename>,
+                    <filename>do_patch</filename>,
+                    <filename>do_configure</filename>,
+                    <filename>do_compile</filename>, and
+                    <filename>do_install</filename> tasks.
+                    However, if <filename>do_package</filename> needs to be
+                    run, BitBake would need to run those other tasks.
+                </para>
+
+                <para>
+                    It becomes more complicated if everything can come
+                    from an sstate cache because some objects are simply
+                    not required at all.
+                    For example, you do not need a compiler or native tools,
+                    such as quilt, if there is nothing to compile or patch.
+                    If the <filename>do_package_write_*</filename> packages
+                    are available from sstate, BitBake does not need the
+                    <filename>do_package</filename> task data.
+                </para>
+
+                <para>
+                    To handle all these complexities, BitBake runs in two
+                    phases.
+                    The first is the "setscene" stage.
+                    During this stage, BitBake first checks the sstate cache
+                    for any targets it is planning to build.
+                    BitBake does a fast check to see if the object exists
+                    rather than a complete download.
+                    If nothing exists, the second phase, which is the setscene
+                    stage, completes and the main build proceeds.
+                </para>
+
+                <para>
+                    If objects are found in the sstate cache, the OpenEmbedded
+                    build system works backwards from the end targets specified
+                    by the user.
+                    For example, if an image is being built, the OpenEmbedded
+                    build system first looks for the packages needed for
+                    that image and the tools needed to construct an image.
+                    If those are available, the compiler is not needed.
+                    Thus, the compiler is not even downloaded.
+                    If something was found to be unavailable, or the
+                    download or setscene task fails, the OpenEmbedded build
+                    system then tries to install dependencies, such as the
+                    compiler, from the cache.
+                </para>
+
+                <para>
+                    The availability of objects in the sstate cache is
+                    handled by the function specified by the
+                    <ulink url='&YOCTO_DOCS_BB_URL;#var-BB_HASHCHECK_FUNCTION'><filename>BB_HASHCHECK_FUNCTION</filename></ulink>
+                    variable and returns a list of the objects that are
+                    available.
+                    The function specified by the
+                    <ulink url='&YOCTO_DOCS_BB_URL;#var-BB_SETSCENE_DEPVALID'><filename>BB_SETSCENE_DEPVALID</filename></ulink>
+                    variable is the function that determines whether a given
+                    dependency needs to be followed, and whether for any given
+                    relationship the function needs to be passed.
+                    The function returns a True or False value.
+                </para>
+            </section>
+        </section>
+
+        <section id='images-dev-environment'>
+            <title>Images</title>
+
+            <para>
+                The images produced by the OpenEmbedded build system
+                are compressed forms of the
+                root filesystem that are ready to boot on a target device.
+                You can see from the
+                <link linkend='general-yocto-environment-figure'>general Build Process figure</link>
+                that BitBake output, in part, consists of images.
+                This section is going to look more closely at this output:
+                <imagedata fileref="figures/images.png" align="center" width="5.5in" depth="5.5in" />
+            </para>
+
+            <para>
+                For a list of example images that the Yocto Project provides,
+                see the
+                "<ulink url='&YOCTO_DOCS_REF_URL;#ref-images'>Images</ulink>"
+                chapter in the Yocto Project Reference Manual.
+            </para>
+
+            <para>
+                Images are written out to the
+                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
+                inside the
+                <filename>tmp/deploy/images/<replaceable>machine</replaceable>/</filename>
+                folder as shown in the figure.
+                This folder contains any files expected to be loaded on the
+                target device.
+                The
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPLOY_DIR'><filename>DEPLOY_DIR</filename></ulink>
+                variable points to the <filename>deploy</filename> directory,
+                while the
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPLOY_DIR_IMAGE'><filename>DEPLOY_DIR_IMAGE</filename></ulink>
+                variable points to the appropriate directory containing images
+                for the current configuration.
+                <itemizedlist>
+                    <listitem><para>
+                        <filename><replaceable>kernel-image</replaceable></filename>:
+                        A kernel binary file.
+                        The
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-KERNEL_IMAGETYPE'><filename>KERNEL_IMAGETYPE</filename></ulink>
+                        variable setting determines the naming scheme for the
+                        kernel image file.
+                        Depending on that variable, the file could begin with
+                        a variety of naming strings.
+                        The
+                        <filename>deploy/images/<replaceable>machine</replaceable></filename>
+                        directory can contain multiple image files for the
+                        machine.
+                        </para></listitem>
+                    <listitem><para>
+                        <filename><replaceable>root-filesystem-image</replaceable></filename>:
+                        Root filesystems for the target device (e.g.
+                        <filename>*.ext3</filename> or
+                        <filename>*.bz2</filename> files).
+                        The
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-IMAGE_FSTYPES'><filename>IMAGE_FSTYPES</filename></ulink>
+                        variable setting determines the root filesystem image
+                        type.
+                        The
+                        <filename>deploy/images/<replaceable>machine</replaceable></filename>
+                        directory can contain multiple root filesystems for the
+                        machine.
+                        </para></listitem>
+                    <listitem><para>
+                        <filename><replaceable>kernel-modules</replaceable></filename>:
+                        Tarballs that contain all the modules built for the
+                        kernel.
+                        Kernel module tarballs exist for legacy purposes and
+                        can be suppressed by setting the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-MODULE_TARBALL_DEPLOY'><filename>MODULE_TARBALL_DEPLOY</filename></ulink>
+                        variable to "0".
+                        The
+                        <filename>deploy/images/<replaceable>machine</replaceable></filename>
+                        directory can contain multiple kernel module tarballs
+                        for the machine.
+                        </para></listitem>
+                    <listitem><para>
+                        <filename><replaceable>bootloaders</replaceable></filename>:
+                        Bootloaders supporting the image, if applicable to the
+                        target machine.
+                        The <filename>deploy/images/<replaceable>machine</replaceable></filename>
+                        directory can contain multiple bootloaders for the
+                        machine.
+                        </para></listitem>
+                    <listitem><para>
+                        <filename><replaceable>symlinks</replaceable></filename>:
+                        The
+                        <filename>deploy/images/<replaceable>machine</replaceable></filename>
+                        folder contains a symbolic link that points to the
+                        most recently built file for each machine.
+                        These links might be useful for external scripts that
+                        need to obtain the latest version of each file.
+                        </para></listitem>
+                </itemizedlist>
+            </para>
+        </section>
+
+        <section id='sdk-dev-environment'>
+            <title>Application Development SDK</title>
+
+            <para>
+                In the
+                <link linkend='general-yocto-environment-figure'>general Yocto Project Development Environment figure</link>,
+                the output labeled "Application Development SDK" represents an
+                SDK.
+                The SDK generation process differs depending on whether you
+                build a standard SDK (e.g.
+                <filename>bitbake -c populate_sdk</filename> <replaceable>imagename</replaceable>)
+                or an extensible SDK (e.g.
+                <filename>bitbake -c populate_sdk_ext</filename> <replaceable>imagename</replaceable>).
+                This section is going to take a closer look at this output:
+                <imagedata fileref="figures/sdk.png" align="center" width="9in" depth="7.25in" />
+            </para>
+
+            <para>
+                The specific form of this output is a self-extracting
+                SDK installer (<filename>*.sh</filename>) that, when run,
+                installs the SDK, which consists of a cross-development
+                toolchain, a set of libraries and headers, and an SDK
+                environment setup script.
+                Running this installer essentially sets up your
+                cross-development environment.
+                You can think of the cross-toolchain as the "host"
+                part because it runs on the SDK machine.
+                You can think of the libraries and headers as the "target"
+                part because they are built for the target hardware.
+                The environment setup script is added so that you can
+                initialize the environment before using the tools.
+            </para>
+
+            <note><title>Notes</title>
+                <itemizedlist>
+                    <listitem><para>
+                        The Yocto Project supports several methods by which
+                        you can set up this cross-development environment.
+                        These methods include downloading pre-built SDK
+                        installers or building and installing your own SDK
+                        installer.
+                        </para></listitem>
+                    <listitem><para>
+                        For background information on cross-development
+                        toolchains in the Yocto Project development
+                        environment, see the
+                        "<link linkend='cross-development-toolchain-generation'>Cross-Development Toolchain Generation</link>"
+                        section.
+                        </para></listitem>
+                    <listitem><para>
+                        For information on setting up a cross-development
+                        environment, see the
+                        <ulink url='&YOCTO_DOCS_SDK_URL;'>Yocto Project Application Development and the Extensible Software Development Kit (eSDK)</ulink>
+                        manual.
+                        </para></listitem>
+                </itemizedlist>
+            </note>
+
+            <para>
+                Once built, the SDK installers are written out to the
+                <filename>deploy/sdk</filename> folder inside the
+                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
+                as shown in the figure at the beginning of this section.
+                Depending on the type of SDK, several variables exist that help
+                configure these files.
+                The following list shows the variables associated with
+                a standard SDK:
+                <itemizedlist>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPLOY_DIR'><filename>DEPLOY_DIR</filename></ulink>:
+                        Points to the <filename>deploy</filename>
+                        directory.
+                        </para></listitem>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-SDKMACHINE'><filename>SDKMACHINE</filename></ulink>:
+                        Specifies the architecture of the machine
+                        on which the cross-development tools are run to
+                        create packages for the target hardware.
+                        </para></listitem>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-SDKIMAGE_FEATURES'><filename>SDKIMAGE_FEATURES</filename></ulink>:
+                        Lists the features to include in the "target" part
+                        of the SDK.
+                        </para></listitem>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-TOOLCHAIN_HOST_TASK'><filename>TOOLCHAIN_HOST_TASK</filename></ulink>:
+                        Lists packages that make up the host
+                        part of the SDK (i.e. the part that runs on
+                        the <filename>SDKMACHINE</filename>).
+                        When you use
+                        <filename>bitbake -c populate_sdk <replaceable>imagename</replaceable></filename>
+                        to create the SDK, a set of default packages
+                        apply.
+                        This variable allows you to add more packages.
+                        </para></listitem>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-TOOLCHAIN_TARGET_TASK'><filename>TOOLCHAIN_TARGET_TASK</filename></ulink>:
+                        Lists packages that make up the target part
+                        of the SDK (i.e. the part built for the
+                        target hardware).
+                        </para></listitem>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-SDKPATH'><filename>SDKPATH</filename></ulink>:
+                        Defines the default SDK installation path offered
+                        by the installation script.
+                        </para></listitem>
+                </itemizedlist>
+                This next list, shows the variables associated with an
+                extensible SDK:
+                <itemizedlist>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPLOY_DIR'><filename>DEPLOY_DIR</filename></ulink>:
+                        Points to the <filename>deploy</filename> directory.
+                        </para></listitem>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-SDK_EXT_TYPE'><filename>SDK_EXT_TYPE</filename></ulink>:
+                        Controls whether or not shared state artifacts are
+                        copied into the extensible SDK.
+                        By default, all required shared state artifacts are
+                        copied into the SDK.
+                        </para></listitem>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-SDK_INCLUDE_PKGDATA'><filename>SDK_INCLUDE_PKGDATA</filename></ulink>:
+                        Specifies whether or not packagedata will be
+                        included in the extensible SDK for all recipes in
+                        the "world" target.
+                        </para></listitem>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-SDK_INCLUDE_TOOLCHAIN'><filename>SDK_INCLUDE_TOOLCHAIN</filename></ulink>:
+                        Specifies whether or not the toolchain will be included
+                        when building the extensible SDK.
+                        </para></listitem>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-SDK_LOCAL_CONF_WHITELIST'><filename>SDK_LOCAL_CONF_WHITELIST</filename></ulink>:
+                        A list of variables allowed through from the build
+                        system configuration into the extensible SDK
+                        configuration.
+                        </para></listitem>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-SDK_LOCAL_CONF_BLACKLIST'><filename>SDK_LOCAL_CONF_BLACKLIST</filename></ulink>:
+                        A list of variables not allowed through from the build
+                        system configuration into the extensible SDK
+                        configuration.
+                        </para></listitem>
+                    <listitem><para>
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-SDK_INHERIT_BLACKLIST'><filename>SDK_INHERIT_BLACKLIST</filename></ulink>:
+                        A list of classes to remove from the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#var-INHERIT'><filename>INHERIT</filename></ulink>
+                        value globally within the extensible SDK configuration.
+                        </para></listitem>
+                </itemizedlist>
+            </para>
+        </section>
+    </section>
+
+    <section id="cross-development-toolchain-generation">
+        <title>Cross-Development Toolchain Generation</title>
+
+        <para>
+            The Yocto Project does most of the work for you when it comes to
+            creating
+            <ulink url='&YOCTO_DOCS_REF_URL;#cross-development-toolchain'>cross-development toolchains</ulink>.
+            This section provides some technical background on how
+            cross-development toolchains are created and used.
+            For more information on toolchains, you can also see the
+            <ulink url='&YOCTO_DOCS_SDK_URL;'>Yocto Project Application Development and the Extensible Software Development Kit (eSDK)</ulink>
+            manual.
+        </para>
+
+        <para>
+            In the Yocto Project development environment, cross-development
+            toolchains are used to build the image and applications that run
+            on the target hardware.
+            With just a few commands, the OpenEmbedded build system creates
+            these necessary toolchains for you.
+        </para>
+
+        <para>
+            The following figure shows a high-level build environment regarding
+            toolchain construction and use.
+        </para>
+
+        <para>
+            <imagedata fileref="figures/cross-development-toolchains.png" width="8in" depth="6in" align="center" />
+        </para>
+
+        <para>
+            Most of the work occurs on the Build Host.
+            This is the machine used to build images and generally work within
+            the the Yocto Project environment.
+            When you run
+            <ulink url='&YOCTO_DOCS_REF_URL;#bitbake-term'>BitBake</ulink>
+            to create an image, the OpenEmbedded build system
+            uses the host <filename>gcc</filename> compiler to bootstrap a
+            cross-compiler named <filename>gcc-cross</filename>.
+            The <filename>gcc-cross</filename> compiler is what BitBake uses to
+            compile source files when creating the target image.
+            You can think of <filename>gcc-cross</filename> simply as an
+            automatically generated cross-compiler that is used internally
+            within BitBake only.
+            <note>
+                The extensible SDK does not use
+                <filename>gcc-cross-canadian</filename> since this SDK
+                ships a copy of the OpenEmbedded build system and the sysroot
+                within it contains <filename>gcc-cross</filename>.
+            </note>
+        </para>
+
+        <para>
+            The chain of events that occurs when <filename>gcc-cross</filename> is
+            bootstrapped is as follows:
+            <literallayout class='monospaced'>
+     gcc -> binutils-cross -> gcc-cross-initial -> linux-libc-headers -> glibc-initial -> glibc -> gcc-cross -> gcc-runtime
+            </literallayout>
+            <itemizedlist>
+                <listitem><para>
+                    <filename>gcc</filename>:
+                    The build host's GNU Compiler Collection (GCC).
+                    </para></listitem>
+                <listitem><para>
+                    <filename>binutils-cross</filename>:
+                    The bare minimum binary utilities needed in order to run
+                    the <filename>gcc-cross-initial</filename> phase of the
+                    bootstrap operation.
+                    </para></listitem>
+                <listitem><para>
+                    <filename>gcc-cross-initial</filename>:
+                    An early stage of the bootstrap process for creating
+                    the cross-compiler.
+                    This stage builds enough of the <filename>gcc-cross</filename>,
+                    the C library, and other pieces needed to finish building the
+                    final cross-compiler in later stages.
+                    This tool is a "native" package (i.e. it is designed to run on
+                    the build host).
+                    </para></listitem>
+                <listitem><para>
+                    <filename>linux-libc-headers</filename>:
+                    Headers needed for the cross-compiler.
+                    </para></listitem>
+                <listitem><para>
+                    <filename>glibc-initial</filename>:
+                    An initial version of the Embedded GLIBC needed to bootstrap
+                    <filename>glibc</filename>.
+                    </para></listitem>
+                <listitem><para>
+                    <filename>gcc-cross</filename>:
+                    The final stage of the bootstrap process for the
+                    cross-compiler.
+                    This stage results in the actual cross-compiler that
+                    BitBake uses when it builds an image for a targeted
+                    device.
+                    <note>
+                        If you are replacing this cross compiler toolchain
+                        with a custom version, you must replace
+                        <filename>gcc-cross</filename>.
+                    </note>
+                    This tool is also a "native" package (i.e. it is
+                    designed to run on the build host).
+                    </para></listitem>
+                <listitem><para>
+                    <filename>gcc-runtime</filename>:
+                    Runtime libraries resulting from the toolchain bootstrapping
+                    process.
+                    This tool produces a binary that consists of the
+                    runtime libraries need for the targeted device.
+                    </para></listitem>
+            </itemizedlist>
+        </para>
+
+        <para>
+            You can use the OpenEmbedded build system to build an installer for
+            the relocatable SDK used to develop applications.
+            When you run the installer, it installs the toolchain, which
+            contains the development tools (e.g.,
+            <filename>gcc-cross-canadian</filename>,
+            <filename>binutils-cross-canadian</filename>, and other
+            <filename>nativesdk-*</filename> tools),
+            which are tools native to the SDK (i.e. native to
+            <ulink url='&YOCTO_DOCS_REF_URL;#var-SDK_ARCH'><filename>SDK_ARCH</filename></ulink>),
+            you need to cross-compile and test your software.
+            The figure shows the commands you use to easily build out this
+            toolchain.
+            This cross-development toolchain is built to execute on the
+            <ulink url='&YOCTO_DOCS_REF_URL;#var-SDKMACHINE'><filename>SDKMACHINE</filename></ulink>,
+            which might or might not be the same
+            machine as the Build Host.
+            <note>
+                If your target architecture is supported by the Yocto Project,
+                you can take advantage of pre-built images that ship with the
+                Yocto Project and already contain cross-development toolchain
+                installers.
+            </note>
+        </para>
+
+        <para>
+            Here is the bootstrap process for the relocatable toolchain:
+            <literallayout class='monospaced'>
+     gcc -> binutils-crosssdk -> gcc-crosssdk-initial -> linux-libc-headers ->
+        glibc-initial -> nativesdk-glibc -> gcc-crosssdk -> gcc-cross-canadian
+            </literallayout>
+            <itemizedlist>
+                <listitem><para>
+                    <filename>gcc</filename>:
+                    The build host's GNU Compiler Collection (GCC).
+                    </para></listitem>
+                <listitem><para>
+                    <filename>binutils-crosssdk</filename>:
+                    The bare minimum binary utilities needed in order to run
+                    the <filename>gcc-crosssdk-initial</filename> phase of the
+                    bootstrap operation.
+                    </para></listitem>
+                <listitem><para>
+                    <filename>gcc-crosssdk-initial</filename>:
+                    An early stage of the bootstrap process for creating
+                    the cross-compiler.
+                    This stage builds enough of the
+                    <filename>gcc-crosssdk</filename> and supporting pieces so that
+                    the final stage of the bootstrap process can produce the
+                    finished cross-compiler.
+                    This tool is a "native" binary that runs on the build host.
+                    </para></listitem>
+                <listitem><para>
+                    <filename>linux-libc-headers</filename>:
+                    Headers needed for the cross-compiler.
+                    </para></listitem>
+                <listitem><para>
+                    <filename>glibc-initial</filename>:
+                    An initial version of the Embedded GLIBC needed to bootstrap
+                    <filename>nativesdk-glibc</filename>.
+                    </para></listitem>
+                <listitem><para>
+                    <filename>nativesdk-glibc</filename>:
+                    The Embedded GLIBC needed to bootstrap the
+                    <filename>gcc-crosssdk</filename>.
+                    </para></listitem>
+                <listitem><para>
+                    <filename>gcc-crosssdk</filename>:
+                    The final stage of the bootstrap process for the
+                    relocatable cross-compiler.
+                    The <filename>gcc-crosssdk</filename> is a transitory compiler
+                    and never leaves the build host.
+                    Its purpose is to help in the bootstrap process to create the
+                    eventual relocatable <filename>gcc-cross-canadian</filename>
+                    compiler, which is relocatable.
+                    This tool is also a "native" package (i.e. it is
+                    designed to run on the build host).
+                    </para></listitem>
+                <listitem><para>
+                    <filename>gcc-cross-canadian</filename>:
+                    The final relocatable cross-compiler.
+                    When run on the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-SDKMACHINE'><filename>SDKMACHINE</filename></ulink>,
+                    this tool
+                    produces executable code that runs on the target device.
+                    Only one cross-canadian compiler is produced per architecture
+                    since they can be targeted at different processor optimizations
+                    using configurations passed to the compiler through the
+                    compile commands.
+                    This circumvents the need for multiple compilers and thus
+                    reduces the size of the toolchains.
+                    </para></listitem>
+            </itemizedlist>
+        </para>
+
+        <note>
+            For information on advantages gained when building a
+            cross-development toolchain installer, see the
+            "<ulink url='&YOCTO_DOCS_SDK_URL;#sdk-building-an-sdk-installer'>Building an SDK Installer</ulink>"
+            section in the Yocto Project Application Development and the
+            Extensible Software Development Kit (eSDK) manual.
+        </note>
+    </section>
+
+    <section id="shared-state-cache">
+        <title>Shared State Cache</title>
+
+        <para>
+            By design, the OpenEmbedded build system builds everything from
+            scratch unless
+            <ulink url='&YOCTO_DOCS_REF_URL;#bitbake-term'>BitBake</ulink>
+            can determine that parts do not need to be rebuilt.
+            Fundamentally, building from scratch is attractive as it means all
+            parts are built fresh and there is no possibility of stale data
+            causing problems.
+            When developers hit problems, they typically default back to
+            building from scratch so they know the state of things from the
+            start.
+        </para>
+
+        <para>
+            Building an image from scratch is both an advantage and a
+            disadvantage to the process.
+            As mentioned in the previous paragraph, building from scratch
+            ensures that everything is current and starts from a known state.
+            However, building from scratch also takes much longer as it
+            generally means rebuilding things that do not necessarily need
+            to be rebuilt.
+        </para>
+
+        <para>
+            The Yocto Project implements shared state code that supports
+            incremental builds.
+            The implementation of the shared state code answers the following
+            questions that were fundamental roadblocks within the OpenEmbedded
+            incremental build support system:
+            <itemizedlist>
+                <listitem><para>
+                    What pieces of the system have changed and what pieces have
+                    not changed?
+                    </para></listitem>
+                <listitem><para>
+                    How are changed pieces of software removed and replaced?
+                    </para></listitem>
+                <listitem><para>
+                    How are pre-built components that do not need to be rebuilt
+                    from scratch used when they are available?
+                    </para></listitem>
+            </itemizedlist>
+        </para>
+
+        <para>
+            For the first question, the
+            <ulink url='&YOCTO_DOCS_REF_URL;#build-system-term'>OpenEmbedded build system</ulink>
+            detects changes in the "inputs" to a given task by creating a
+            checksum (or signature) of the task's inputs.
+            If the checksum changes, the system assumes the inputs have changed
+            and the task needs to be rerun.
+            For the second question, the shared state (sstate) code tracks
+            which tasks add which output to the build process.
+            This means the output from a given task can be removed, upgraded
+            or otherwise manipulated.
+            The third question is partly addressed by the solution for the
+            second question assuming the build system can fetch the sstate
+            objects from remote locations and install them if they are deemed
+            to be valid.
+            <note>
+                The OpenEmbedded build system does not maintain
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink>
+                information as part of the shared state packages.
+                Consequently, considerations exist that affect maintaining
+                shared state feeds.
+                For information on how the OpenEmbedded build system
+                works with packages and can track incrementing
+                <filename>PR</filename> information, see the
+                "<ulink url='&YOCTO_DOCS_DEV_URL;#automatically-incrementing-a-binary-package-revision-number'>Automatically Incrementing a Binary Package Revision Number</ulink>"
+                section in the Yocto Project Development Tasks Manual.
+            </note>
+        </para>
+
+        <para>
+            The rest of this section goes into detail about the overall
+            incremental build architecture, the checksums (signatures), shared
+            state, and some tips and tricks.
+        </para>
+
+        <section id='concepts-overall-architecture'>
+            <title>Overall Architecture</title>
+
+            <para>
+                When determining what parts of the system need to be built,
+                BitBake works on a per-task basis rather than a per-recipe
+                basis.
+                You might wonder why using a per-task basis is preferred over
+                a per-recipe basis.
+                To help explain, consider having the IPK packaging backend
+                enabled and then switching to DEB.
+                In this case, the
+                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-install'><filename>do_install</filename></ulink>
+                and
+                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package'><filename>do_package</filename></ulink>
+                task outputs are still valid.
+                However, with a per-recipe approach, the build would not
+                include the <filename>.deb</filename> files.
+                Consequently, you would have to invalidate the whole build and
+                rerun it.
+                Rerunning everything is not the best solution.
+                Also, in this case, the core must be "taught" much about
+                specific tasks.
+                This methodology does not scale well and does not allow users
+                to easily add new tasks in layers or as external recipes
+                without touching the packaged-staging core.
+            </para>
+        </section>
+
+        <section id='overview-checksums'>
+            <title>Checksums (Signatures)</title>
+
+            <para>
+                The shared state code uses a checksum, which is a unique
+                signature of a task's inputs, to determine if a task needs to
+                be run again.
+                Because it is a change in a task's inputs that triggers a
+                rerun, the process needs to detect all the inputs to a given
+                task.
+                For shell tasks, this turns out to be fairly easy because
+                the build process generates a "run" shell script for each task
+                and it is possible to create a checksum that gives you a good
+                idea of when the task's data changes.
+            </para>
+
+            <para>
+                To complicate the problem, there are things that should not be
+                included in the checksum.
+                First, there is the actual specific build path of a given
+                task - the
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink>.
+                It does not matter if the work directory changes because it
+                should not affect the output for target packages.
+                Also, the build process has the objective of making native
+                or cross packages relocatable.
+                <note>
+                    Both native and cross packages run on the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#hardware-build-system-term'>build host</ulink>.
+                    However, cross packages generate output for the target
+                    architecture.
+                </note>
+                The checksum therefore needs to exclude
+                <filename>WORKDIR</filename>.
+                The simplistic approach for excluding the work directory is to
+                set <filename>WORKDIR</filename> to some fixed value and
+                create the checksum for the "run" script.
+            </para>
+
+            <para>
+                Another problem results from the "run" scripts containing
+                functions that might or might not get called.
+                The incremental build solution contains code that figures out
+                dependencies between shell functions.
+                This code is used to prune the "run" scripts down to the
+                minimum set, thereby alleviating this problem and making the
+                "run" scripts much more readable as a bonus.
+            </para>
+
+            <para>
+                So far, solutions for shell scripts exist.
+                What about Python tasks?
+                The same approach applies even though these tasks are more
+                difficult.
+                The process needs to figure out what variables a Python
+                function accesses and what functions it calls.
+                Again, the incremental build solution contains code that first
+                figures out the variable and function dependencies, and then
+                creates a checksum for the data used as the input to the task.
+            </para>
+
+            <para>
+                Like the <filename>WORKDIR</filename> case, situations exist
+                where dependencies should be ignored.
+                For these situations, you can instruct the build process to
+                ignore a dependency by using a line like the following:
+                <literallayout class='monospaced'>
+     PACKAGE_ARCHS[vardepsexclude] = "MACHINE"
+                </literallayout>
+                This example ensures that the
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_ARCHS'><filename>PACKAGE_ARCHS</filename></ulink>
+                variable does not depend on the value of
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-MACHINE'><filename>MACHINE</filename></ulink>,
+                even if it does reference it.
+            </para>
+
+            <para>
+                Equally, there are cases where you need to add dependencies
+                BitBake is not able to find.
+                You can accomplish this by using a line like the following:
+                <literallayout class='monospaced'>
+      PACKAGE_ARCHS[vardeps] = "MACHINE"
+                </literallayout>
+                This example explicitly adds the <filename>MACHINE</filename>
+                variable as a dependency for
+                <filename>PACKAGE_ARCHS</filename>.
+            </para>
+
+            <para>
+                As an example, consider a case with in-line Python where
+                BitBake is not able to figure out dependencies.
+                When running in debug mode (i.e. using
+                <filename>-DDD</filename>), BitBake produces output when it
+                discovers something for which it cannot figure out dependencies.
+                The Yocto Project team has currently not managed to cover
+                those dependencies in detail and is aware of the need to fix
+                this situation.
+            </para>
+
+            <para>
+                Thus far, this section has limited discussion to the direct
+                inputs into a task.
+                Information based on direct inputs is referred to as the
+                "basehash" in the code.
+                However, there is still the question of a task's indirect
+                inputs - the things that were already built and present in the
+                <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>.
+                The checksum (or signature) for a particular task needs to add
+                the hashes of all the tasks on which the particular task
+                depends.
+                Choosing which dependencies to add is a policy decision.
+                However, the effect is to generate a master checksum that
+                combines the basehash and the hashes of the task's
+                dependencies.
+            </para>
+
+            <para>
+                At the code level, a variety of ways exist by which both the
+                basehash and the dependent task hashes can be influenced.
+                Within the BitBake configuration file, you can give BitBake
+                some extra information to help it construct the basehash.
+                The following statement effectively results in a list of
+                global variable dependency excludes - variables never
+                included in any checksum:
+                <literallayout class='monospaced'>
+     BB_HASHBASE_WHITELIST ?= "TMPDIR FILE PATH PWD BB_TASKHASH BBPATH DL_DIR \
+         SSTATE_DIR THISDIR FILESEXTRAPATHS FILE_DIRNAME HOME LOGNAME SHELL TERM \
+         USER FILESPATH STAGING_DIR_HOST STAGING_DIR_TARGET COREBASE PRSERV_HOST \
+         PRSERV_DUMPDIR PRSERV_DUMPFILE PRSERV_LOCKDOWN PARALLEL_MAKE \
+         CCACHE_DIR EXTERNAL_TOOLCHAIN CCACHE CCACHE_DISABLE LICENSE_PATH SDKPKGSUFFIX"
+                </literallayout>
+                The previous example excludes
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink>
+                since that variable is actually constructed as a path within
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-TMPDIR'><filename>TMPDIR</filename></ulink>,
+                which is on the whitelist.
+            </para>
+
+            <para>
+                The rules for deciding which hashes of dependent tasks to
+                include through dependency chains are more complex and are
+                generally accomplished with a Python function.
+                The code in <filename>meta/lib/oe/sstatesig.py</filename> shows
+                two examples of this and also illustrates how you can insert
+                your own policy into the system if so desired.
+                This file defines the two basic signature generators
+                <ulink url='&YOCTO_DOCS_REF_URL;#oe-core'>OE-Core</ulink>
+                uses:  "OEBasic" and "OEBasicHash".
+                By default, there is a dummy "noop" signature handler enabled
+                in BitBake.
+                This means that behavior is unchanged from previous versions.
+                OE-Core uses the "OEBasicHash" signature handler by default
+                through this setting in the <filename>bitbake.conf</filename>
+                file:
+                <literallayout class='monospaced'>
+     BB_SIGNATURE_HANDLER ?= "OEBasicHash"
+                </literallayout>
+                The "OEBasicHash" <filename>BB_SIGNATURE_HANDLER</filename>
+                is the same as the "OEBasic" version but adds the task hash to
+                the stamp files.
+                This results in any
+                <ulink url='&YOCTO_DOCS_REF_URL;#metadata'>Metadata</ulink>
+                change that changes the task hash, automatically
+                causing the task to be run again.
+                This removes the need to bump
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink>
+                values, and changes to Metadata automatically ripple across
+                the build.
+            </para>
+
+            <para>
+                It is also worth noting that the end result of these
+                signature generators is to make some dependency and hash
+                information available to the build.
+                This information includes:
+                <itemizedlist>
+                    <listitem><para>
+                        <filename>BB_BASEHASH_task-</filename><replaceable>taskname</replaceable>:
+                        The base hashes for each task in the recipe.
+                        </para></listitem>
+                    <listitem><para>
+                        <filename>BB_BASEHASH_</filename><replaceable>filename</replaceable><filename>:</filename><replaceable>taskname</replaceable>:
+                        The base hashes for each dependent task.
+                        </para></listitem>
+                    <listitem><para>
+                        <filename>BBHASHDEPS_</filename><replaceable>filename</replaceable><filename>:</filename><replaceable>taskname</replaceable>:
+                        The task dependencies for each task.
+                        </para></listitem>
+                    <listitem><para>
+                        <filename>BB_TASKHASH</filename>:
+                        The hash of the currently running task.
+                        </para></listitem>
+                </itemizedlist>
+            </para>
+        </section>
+
+        <section id='shared-state'>
+            <title>Shared State</title>
+
+            <para>
+                Checksums and dependencies, as discussed in the previous
+                section, solve half the problem of supporting a shared state.
+                The other part of the problem is being able to use checksum
+                information during the build and being able to reuse or rebuild
+                specific components.
+            </para>
+
+            <para>
+                The
+                <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-sstate'><filename>sstate</filename></ulink>
+                class is a relatively generic implementation of how to
+                "capture" a snapshot of a given task.
+                The idea is that the build process does not care about the
+                source of a task's output.
+                Output could be freshly built or it could be downloaded and
+                unpacked from somewhere - the build process does not need to
+                worry about its origin.
+            </para>
+
+            <para>
+                Two types of output exist.
+                One type is just about creating a directory in
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink>.
+                A good example is the output of either
+                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-install'><filename>do_install</filename></ulink>
+                or
+                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package'><filename>do_package</filename></ulink>.
+                The other type of output occurs when a set of data is merged
+                into a shared directory tree such as the sysroot.
+            </para>
+
+            <para>
+                The Yocto Project team has tried to keep the details of the
+                implementation hidden in <filename>sstate</filename> class.
+                From a user's perspective, adding shared state wrapping to a task
+                is as simple as this
+                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-deploy'><filename>do_deploy</filename></ulink>
+                example taken from the
+                <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-deploy'><filename>deploy</filename></ulink>
+                class:
+                <literallayout class='monospaced'>
+     DEPLOYDIR = "${WORKDIR}/deploy-${PN}"
+     SSTATETASKS += "do_deploy"
+     do_deploy[sstate-inputdirs] = "${DEPLOYDIR}"
+     do_deploy[sstate-outputdirs] = "${DEPLOY_DIR_IMAGE}"
+
+     python do_deploy_setscene () {
+         sstate_setscene(d)
+     }
+     addtask do_deploy_setscene
+     do_deploy[dirs] = "${DEPLOYDIR} ${B}"
+                </literallayout>
+                The following list explains the previous example:
+                <itemizedlist>
+                    <listitem><para>
+                        Adding "do_deploy" to <filename>SSTATETASKS</filename>
+                        adds some required sstate-related processing, which is
+                        implemented in the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-sstate'><filename>sstate</filename></ulink>
+                        class, to before and after the
+                        <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-deploy'><filename>do_deploy</filename></ulink>
+                        task.
+                        </para></listitem>
+                    <listitem><para>
+                        The
+                        <filename>do_deploy[sstate-inputdirs] = "${DEPLOYDIR}"</filename>
+                        declares that <filename>do_deploy</filename> places its
+                        output in <filename>${DEPLOYDIR}</filename> when run
+                        normally (i.e. when not using the sstate cache).
+                        This output becomes the input to the shared state cache.
+                        </para></listitem>
+                    <listitem><para>
+                        The
+                        <filename>do_deploy[sstate-outputdirs] = "${DEPLOY_DIR_IMAGE}"</filename>
+                        line causes the contents of the shared state cache to be
+                        copied to <filename>${DEPLOY_DIR_IMAGE}</filename>.
+                        <note>
+                            If <filename>do_deploy</filename> is not already in
+                            the shared state cache or if its input checksum
+                            (signature) has changed from when the output was
+                            cached, the task will be run to populate the shared
+                            state cache, after which the contents of the shared
+                            state cache is copied to
+                            <filename>${DEPLOY_DIR_IMAGE}</filename>.
+                            If <filename>do_deploy</filename> is in the shared
+                            state cache and its signature indicates that the
+                            cached output is still valid (i.e. if no
+                            relevant task inputs have changed), then the
+                            contents of the shared state cache will be copied
+                            directly to
+                            <filename>${DEPLOY_DIR_IMAGE}</filename> by the
+                            <filename>do_deploy_setscene</filename> task
+                            instead, skipping the
+                            <filename>do_deploy</filename> task.
+                        </note>
+                        </para></listitem>
+                    <listitem><para>
+                        The following task definition is glue logic needed to
+                        make the previous settings effective:
+                        <literallayout class='monospaced'>
+     python do_deploy_setscene () {
+         sstate_setscene(d)
+     }
+     addtask do_deploy_setscene
+                        </literallayout>
+                        <filename>sstate_setscene()</filename> takes the flags
+                        above as input and accelerates the
+                        <filename>do_deploy</filename> task through the
+                        shared state cache if possible.
+                        If the task was accelerated,
+                        <filename>sstate_setscene()</filename> returns True.
+                        Otherwise, it returns False, and the normal
+                        <filename>do_deploy</filename> task runs.
+                        For more information, see the
+                        "<ulink url='&YOCTO_DOCS_BB_URL;#setscene'>setscene</ulink>"
+                        section in the BitBake User Manual.
+                        </para></listitem>
+                    <listitem><para>
+                        The <filename>do_deploy[dirs] = "${DEPLOYDIR} ${B}"</filename>
+                        line creates <filename>${DEPLOYDIR}</filename> and
+                        <filename>${B}</filename> before the
+                        <filename>do_deploy</filename> task runs, and also sets
+                        the current working directory of
+                        <filename>do_deploy</filename> to
+                        <filename>${B}</filename>.
+                        For more information, see the
+                        "<ulink url='&YOCTO_DOCS_BB_URL;#variable-flags'>Variable Flags</ulink>"
+                        section in the BitBake User Manual.
+                        <note>
+                            In cases where
+                            <filename>sstate-inputdirs</filename> and
+                            <filename>sstate-outputdirs</filename> would be the
+                            same, you can use
+                            <filename>sstate-plaindirs</filename>.
+                            For example, to preserve the
+                            <filename>${PKGD}</filename> and
+                            <filename>${PKGDEST}</filename> output from the
+                            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package'><filename>do_package</filename></ulink>
+                            task, use the following:
+                            <literallayout class='monospaced'>
+     do_package[sstate-plaindirs] = "${PKGD} ${PKGDEST}"
+                            </literallayout>
+                        </note>
+                        </para></listitem>
+                    <listitem><para>
+                        <filename>sstate-inputdirs</filename> and
+                        <filename>sstate-outputdirs</filename> can also be used
+                        with multiple directories.
+                        For example, the following declares
+                        <filename>PKGDESTWORK</filename> and
+                        <filename>SHLIBWORK</filename> as shared state
+                        input directories, which populates the shared state
+                        cache, and <filename>PKGDATA_DIR</filename> and
+                        <filename>SHLIBSDIR</filename> as the corresponding
+                        shared state output directories:
+                        <literallayout class='monospaced'>
+     do_package[sstate-inputdirs] = "${PKGDESTWORK} ${SHLIBSWORKDIR}"
+     do_package[sstate-outputdirs] = "${PKGDATA_DIR} ${SHLIBSDIR}"
+                        </literallayout>
+                        </para></listitem>
+                    <listitem><para>
+                        These methods also include the ability to take a
+                        lockfile when manipulating shared state directory
+                        structures, for cases where file additions or removals
+                        are sensitive:
+                        <literallayout class='monospaced'>
+     do_package[sstate-lockfile] = "${PACKAGELOCK}"
+                        </literallayout>
+                        </para></listitem>
+                </itemizedlist>
+            </para>
+
+            <para>
+                Behind the scenes, the shared state code works by looking in
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-SSTATE_DIR'><filename>SSTATE_DIR</filename></ulink>
+                and
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-SSTATE_MIRRORS'><filename>SSTATE_MIRRORS</filename></ulink>
+                for shared state files.
+                Here is an example:
+                <literallayout class='monospaced'>
+     SSTATE_MIRRORS ?= "\
+     file://.* http://someserver.tld/share/sstate/PATH;downloadfilename=PATH \n \
+     file://.* file:///some/local/dir/sstate/PATH"
+                </literallayout>
+                <note>
+                    The shared state directory
+                    (<filename>SSTATE_DIR</filename>) is organized into
+                    two-character subdirectories, where the subdirectory
+                    names are based on the first two characters of the hash.
+                    If the shared state directory structure for a mirror has the
+                    same structure as <filename>SSTATE_DIR</filename>, you must
+                    specify "PATH" as part of the URI to enable the build system
+                    to map to the appropriate subdirectory.
+                </note>
+            </para>
+
+            <para>
+                The shared state package validity can be detected just by
+                looking at the filename since the filename contains the task
+                checksum (or signature) as described earlier in this section.
+                If a valid shared state package is found, the build process
+                downloads it and uses it to accelerate the task.
+            </para>
+
+            <para>
+                The build processes use the <filename>*_setscene</filename>
+                tasks for the task acceleration phase.
+                BitBake goes through this phase before the main execution
+                code and tries to accelerate any tasks for which it can find
+                shared state packages.
+                If a shared state package for a task is available, the
+                shared state package is used.
+                This means the task and any tasks on which it is dependent
+                are not executed.
+            </para>
+
+            <para>
+                As a real world example, the aim is when building an IPK-based
+                image, only the
+                <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package_write_ipk'><filename>do_package_write_ipk</filename></ulink>
+                tasks would have their shared state packages fetched and
+                extracted.
+                Since the sysroot is not used, it would never get extracted.
+                This is another reason why a task-based approach is preferred
+                over a recipe-based approach, which would have to install the
+                output from every task.n
+            </para>
+        </section>
+
+        <section id='concepts-tips-and-tricks'>
+            <title>Tips and Tricks</title>
+
+            <para>
+                The code in the build system that supports incremental builds
+                is not simple code.
+                This section presents some tips and tricks that help you work
+                around issues related to shared state code.
+            </para>
+
+            <section id='concepts-overview-debugging'>
+                <title>Debugging</title>
+
+                <para>
+                    Seeing what metadata went into creating the input signature
+                    of a shared state (sstate) task can be a useful debugging
+                    aid.
+                    This information is available in signature information
+                    (<filename>siginfo</filename>) files in
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-SSTATE_DIR'><filename>SSTATE_DIR</filename></ulink>.
+                    For information on how to view and interpret information in
+                    <filename>siginfo</filename> files, see the
+                    "<ulink url='&YOCTO_DOCS_DEV_URL;#dev-viewing-task-variable-dependencies'>Viewing Task Variable Dependencies</ulink>"
+                    section in the Yocto Project Development Tasks Manual.
+                </para>
+            </section>
+
+            <section id='concepts-invalidating-shared-state'>
+                <title>Invalidating Shared State</title>
+
+                <para>
+                    The OpenEmbedded build system uses checksums and shared
+                    state cache to avoid unnecessarily rebuilding tasks.
+                    Collectively, this scheme is known as "shared state code."
+                </para>
+
+                <para>
+                    As with all schemes, this one has some drawbacks.
+                    It is possible that you could make implicit changes to your
+                    code that the checksum calculations do not take into
+                    account.
+                    These implicit changes affect a task's output but do not
+                    trigger the shared state code into rebuilding a recipe.
+                    Consider an example during which a tool changes its output.
+                    Assume that the output of <filename>rpmdeps</filename>
+                    changes.
+                    The result of the change should be that all the
+                    <filename>package</filename> and
+                    <filename>package_write_rpm</filename> shared state cache
+                    items become invalid.
+                    However, because the change to the output is
+                    external to the code and therefore implicit,
+                    the associated shared state cache items do not become
+                    invalidated.
+                    In this case, the build process uses the cached items
+                    rather than running the task again.
+                    Obviously, these types of implicit changes can cause
+                    problems.
+                </para>
+
+                <para>
+                    To avoid these problems during the build, you need to
+                    understand the effects of any changes you make.
+                    Realize that changes you make directly to a function
+                    are automatically factored into the checksum calculation.
+                    Thus, these explicit changes invalidate the associated
+                    area of shared state cache.
+                    However, you need to be aware of any implicit changes that
+                    are not obvious changes to the code and could affect
+                    the output of a given task.
+                </para>
+
+                <para>
+                    When you identify an implicit change, you can easily
+                    take steps to invalidate the cache and force the tasks
+                    to run.
+                    The steps you can take are as simple as changing a
+                    function's comments in the source code.
+                    For example, to invalidate package shared state files,
+                    change the comment statements of
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package'><filename>do_package</filename></ulink>
+                    or the comments of one of the functions it calls.
+                    Even though the change is purely cosmetic, it causes the
+                    checksum to be recalculated and forces the OpenEmbedded
+                    build system to run the task again.
+                    <note>
+                        For an example of a commit that makes a cosmetic
+                        change to invalidate shared state, see this
+                        <ulink url='&YOCTO_GIT_URL;/cgit.cgi/poky/commit/meta/classes/package.bbclass?id=737f8bbb4f27b4837047cb9b4fbfe01dfde36d54'>commit</ulink>.
+                    </note>
+                </para>
+            </section>
+        </section>
+    </section>
+
+    <section id='automatically-added-runtime-dependencies'>
+        <title>Automatically Added Runtime Dependencies</title>
+
+        <para>
+            The OpenEmbedded build system automatically adds common types of
+            runtime dependencies between packages, which means that you do not
+            need to explicitly declare the packages using
+            <ulink url='&YOCTO_DOCS_REF_URL;#var-RDEPENDS'><filename>RDEPENDS</filename></ulink>.
+            Three automatic mechanisms exist (<filename>shlibdeps</filename>,
+            <filename>pcdeps</filename>, and <filename>depchains</filename>)
+            that handle shared libraries, package configuration (pkg-config)
+            modules, and <filename>-dev</filename> and
+            <filename>-dbg</filename> packages, respectively.
+            For other types of runtime dependencies, you must manually declare
+            the dependencies.
+            <itemizedlist>
+                <listitem><para>
+                    <filename>shlibdeps</filename>:
+                    During the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package'><filename>do_package</filename></ulink>
+                    task of each recipe, all shared libraries installed by the
+                    recipe are located.
+                    For each shared library, the package that contains the
+                    shared library is registered as providing the shared
+                    library.
+                    More specifically, the package is registered as providing
+                    the
+                    <ulink url='https://en.wikipedia.org/wiki/Soname'>soname</ulink>
+                    of the library.
+                    The resulting shared-library-to-package mapping
+                    is saved globally in
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PKGDATA_DIR'><filename>PKGDATA_DIR</filename></ulink>
+                    by the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-packagedata'><filename>do_packagedata</filename></ulink>
+                    task.</para>
+
+                    <para>Simultaneously, all executables and shared libraries
+                    installed by the recipe are inspected to see what shared
+                    libraries they link against.
+                    For each shared library dependency that is found,
+                    <filename>PKGDATA_DIR</filename> is queried to
+                    see if some package (likely from a different recipe)
+                    contains the shared library.
+                    If such a package is found, a runtime dependency is added
+                    from the package that depends on the shared library to the
+                    package that contains the library.</para>
+
+                    <para>The automatically added runtime dependency also
+                    includes a version restriction.
+                    This version restriction specifies that at least the
+                    current version of the package that provides the shared
+                    library must be used, as if
+                    "<replaceable>package</replaceable> (>= <replaceable>version</replaceable>)"
+                    had been added to <filename>RDEPENDS</filename>.
+                    This forces an upgrade of the package containing the shared
+                    library when installing the package that depends on the
+                    library, if needed.</para>
+
+                    <para>If you want to avoid a package being registered as
+                    providing a particular shared library (e.g. because the library
+                    is for internal use only), then add the library to
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PRIVATE_LIBS'><filename>PRIVATE_LIBS</filename></ulink>
+                    inside the package's recipe.
+                    </para></listitem>
+                <listitem><para>
+                    <filename>pcdeps</filename>:
+                    During the <filename>do_package</filename> task of each
+                    recipe, all pkg-config modules
+                    (<filename>*.pc</filename> files) installed by the recipe
+                    are located.
+                    For each module, the package that contains the module is
+                    registered as providing the module.
+                    The resulting module-to-package mapping is saved globally in
+                    <filename>PKGDATA_DIR</filename> by the
+                    <filename>do_packagedata</filename> task.</para>
+
+                    <para>Simultaneously, all pkg-config modules installed by
+                    the recipe are inspected to see what other pkg-config
+                    modules they depend on.
+                    A module is seen as depending on another module if it
+                    contains a "Requires:" line that specifies the other module.
+                    For each module dependency,
+                    <filename>PKGDATA_DIR</filename> is queried to see if some
+                    package contains the module.
+                    If such a package is found, a runtime dependency is added
+                    from the package that depends on the module to the package
+                    that contains the module.
+                    <note>
+                        The <filename>pcdeps</filename> mechanism most often
+                        infers dependencies between <filename>-dev</filename>
+                        packages.
+                    </note>
+                    </para></listitem>
+                <listitem><para>
+                    <filename>depchains</filename>:
+                    If a package <filename>foo</filename> depends on a package
+                    <filename>bar</filename>, then <filename>foo-dev</filename>
+                    and <filename>foo-dbg</filename> are also made to depend on
+                    <filename>bar-dev</filename> and
+                    <filename>bar-dbg</filename>, respectively.
+                    Taking the <filename>-dev</filename> packages as an
+                    example, the <filename>bar-dev</filename> package might
+                    provide headers and shared library symlinks needed by
+                    <filename>foo-dev</filename>, which shows the need
+                    for a dependency between the packages.</para>
+
+                    <para>The dependencies added by
+                    <filename>depchains</filename> are in the form of
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-RRECOMMENDS'><filename>RRECOMMENDS</filename></ulink>.
+                    <note>
+                        By default, <filename>foo-dev</filename> also has an
+                        <filename>RDEPENDS</filename>-style dependency on
+                        <filename>foo</filename>, because the default value of
+                        <filename>RDEPENDS_${PN}-dev</filename> (set in
+                        <filename>bitbake.conf</filename>) includes
+                        "${PN}".
+                    </note></para>
+
+                    <para>To ensure that the dependency chain is never broken,
+                    <filename>-dev</filename> and <filename>-dbg</filename>
+                    packages are always generated by default, even if the
+                    packages turn out to be empty.
+                    See the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-ALLOW_EMPTY'><filename>ALLOW_EMPTY</filename></ulink>
+                    variable for more information.
+                    </para></listitem>
+            </itemizedlist>
+        </para>
+
+        <para>
+            The <filename>do_package</filename> task depends on the
+            <filename>do_packagedata</filename> task of each recipe in
+            <ulink url='&YOCTO_DOCS_REF_URL;#var-DEPENDS'><filename>DEPENDS</filename></ulink>
+            through use of a
+            <filename>[</filename><ulink url='&YOCTO_DOCS_BB_URL;#variable-flags'><filename>deptask</filename></ulink><filename>]</filename>
+            declaration, which guarantees that the required
+            shared-library/module-to-package mapping information will be available
+            when needed as long as <filename>DEPENDS</filename> has been
+            correctly set.
+        </para>
+    </section>
+
+    <section id='fakeroot-and-pseudo'>
+        <title>Fakeroot and Pseudo</title>
+
+        <para>
+            Some tasks are easier to implement when allowed to perform certain
+            operations that are normally reserved for the root user (e.g.
+            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-install'><filename>do_install</filename></ulink>,
+            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-package_write_deb'><filename>do_package_write*</filename></ulink>,
+            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-rootfs'><filename>do_rootfs</filename></ulink>,
+            and
+            <ulink url='&YOCTO_DOCS_REF_URL;#ref-tasks-image'><filename>do_image*</filename></ulink>).
+            For example, the <filename>do_install</filename> task benefits
+            from being able to set the UID and GID of installed files to
+            arbitrary values.
+        </para>
+
+        <para>
+            One approach to allowing tasks to perform root-only operations
+            would be to require
+            <ulink url='&YOCTO_DOCS_REF_URL;#bitbake-term'>BitBake</ulink>
+            to run as root.
+            However, this method is cumbersome and has security issues.
+            The approach that is actually used is to run tasks that benefit
+            from root privileges in a "fake" root environment.
+            Within this environment, the task and its child processes believe
+            that they are running as the root user, and see an internally
+            consistent view of the filesystem.
+            As long as generating the final output (e.g. a package or an image)
+            does not require root privileges, the fact that some earlier
+            steps ran in a fake root environment does not cause problems.
+        </para>
+
+        <para>
+            The capability to run tasks in a fake root environment is known as
+            "<ulink url='http://man.he.net/man1/fakeroot'>fakeroot</ulink>",
+            which is derived from the BitBake keyword/variable
+            flag that requests a fake root environment for a task.
+        </para>
+
+        <para>
+            In the
+            <ulink url='&YOCTO_DOCS_REF_URL;#build-system-term'>OpenEmbedded build system</ulink>,
+            the program that implements fakeroot is known as Pseudo.
+            Pseudo overrides system calls by using the environment variable
+            <filename>LD_PRELOAD</filename>, which results in the illusion
+            of running as root.
+            To keep track of "fake" file ownership and permissions resulting
+            from operations that require root permissions, Pseudo uses
+            an SQLite 3 database.
+            This database is stored in
+            <filename>${</filename><ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink><filename>}/pseudo/files.db</filename>
+            for individual recipes.
+            Storing the database in a file as opposed to in memory
+            gives persistence between tasks and builds, which is not
+            accomplished using fakeroot.
+            <note><title>Caution</title>
+                If you add your own task that manipulates the same files or
+                directories as a fakeroot task, then that task also needs to
+                run under fakeroot.
+                Otherwise, the task cannot run root-only operations, and
+                cannot see the fake file ownership and permissions set by the
+                other task.
+                You need to also add a dependency on
+                <filename>virtual/fakeroot-native:do_populate_sysroot</filename>,
+                giving the following:
+                <literallayout class='monospaced'>
+       fakeroot do_mytask () {
+           ...
+       }
+       do_mytask[depends] += "virtual/fakeroot-native:do_populate_sysroot"
+                </literallayout>
+            </note>
+            For more information, see the
+            <ulink url='&YOCTO_DOCS_BB_URL;#var-FAKEROOT'><filename>FAKEROOT*</filename></ulink>
+            variables in the BitBake User Manual.
+            You can also reference the
+            "<ulink url='http://www.ibm.com/developerworks/opensource/library/os-aapseudo1/index.html'>Pseudo</ulink>"
+            and
+            "<ulink url='https://github.com/wrpseudo/pseudo/wiki/WhyNotFakeroot'>Why Not Fakeroot?</ulink>"
+            articles for background information on Pseudo.
+        </para>
+    </section>
+
+    <section id="wayland">
+        <title>Wayland</title>
+
+        <para>
+            <ulink url='http://en.wikipedia.org/wiki/Wayland_(display_server_protocol)'>Wayland</ulink>
+            is a computer display server protocol that
+            provides a method for compositing window managers to communicate
+            directly with applications and video hardware and expects them to
+            communicate with input hardware using other libraries.
+            Using Wayland with supporting targets can result in better control
+            over graphics frame rendering than an application might otherwise
+            achieve.
+        </para>
+
+        <para>
+            The Yocto Project provides the Wayland protocol libraries and the
+            reference
+            <ulink url='http://en.wikipedia.org/wiki/Wayland_(display_server_protocol)#Weston'>Weston</ulink>
+            compositor as part of its release.
+            This section describes what you need to do to implement Wayland and
+            use the compositor when building an image for a supporting target.
+        </para>
+
+        <section id="wayland-support">
+            <title>Support</title>
+
+            <para>
+                The Wayland protocol libraries and the reference Weston
+                compositor ship as integrated packages in the
+                <filename>meta</filename> layer of the
+                <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>.
+                Specifically, you can find the recipes that build both Wayland
+                and Weston at
+                <filename>meta/recipes-graphics/wayland</filename>.
+            </para>
+
+            <para>
+                You can build both the Wayland and Weston packages for use only
+                with targets that accept the
+                <ulink url='https://en.wikipedia.org/wiki/Mesa_(computer_graphics)'>Mesa 3D and Direct Rendering Infrastructure</ulink>,
+                which is also known as Mesa DRI.
+                This implies that you cannot build and use the packages if your
+                target uses, for example, the
+                <trademark class='registered'>Intel</trademark> Embedded Media
+                and Graphics Driver
+                (<trademark class='registered'>Intel</trademark> EMGD) that
+                overrides Mesa DRI.
+                <note>
+                    Due to lack of EGL support, Weston 1.0.3 will not run
+                    directly on the emulated QEMU hardware.
+                    However, this version of Weston will run under X emulation
+                    without issues.
+                </note>
+            </para>
+        </section>
+
+        <section id="enabling-wayland-in-an-image">
+            <title>Enabling Wayland in an Image</title>
+
+            <para>
+                To enable Wayland, you need to enable it to be built and enable
+                it to be included in the image.
+            </para>
+
+            <section id="enable-building">
+                <title>Building</title>
+
+                <para>
+                    To cause Mesa to build the <filename>wayland-egl</filename>
+                    platform and Weston to build Wayland with Kernel Mode
+                    Setting
+                    (<ulink url='https://wiki.archlinux.org/index.php/Kernel_Mode_Setting'>KMS</ulink>)
+                    support, include the "wayland" flag in the
+                    <ulink url="&YOCTO_DOCS_REF_URL;#var-DISTRO_FEATURES"><filename>DISTRO_FEATURES</filename></ulink>
+                    statement in your <filename>local.conf</filename> file:
+                    <literallayout class='monospaced'>
+     DISTRO_FEATURES_append = " wayland"
+                    </literallayout>
+                    <note>
+                        If X11 has been enabled elsewhere, Weston will build
+                        Wayland with X11 support
+                    </note>
+                </para>
+            </section>
+
+            <section id="enable-installation-in-an-image">
+                <title>Installing</title>
+
+                <para>
+                    To install the Wayland feature into an image, you must
+                    include the following
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-CORE_IMAGE_EXTRA_INSTALL'><filename>CORE_IMAGE_EXTRA_INSTALL</filename></ulink>
+                    statement in your <filename>local.conf</filename> file:
+                    <literallayout class='monospaced'>
+     CORE_IMAGE_EXTRA_INSTALL += "wayland weston"
+                    </literallayout>
+                </para>
+            </section>
+        </section>
+
+        <section id="running-weston">
+            <title>Running Weston</title>
+
+            <para>
+                To run Weston inside X11, enabling it as described earlier and
+                building a Sato image is sufficient.
+                If you are running your image under Sato, a Weston Launcher
+                appears in the "Utility" category.
+            </para>
+
+            <para>
+                Alternatively, you can run Weston through the command-line
+                interpretor (CLI), which is better suited for development work.
+                To run Weston under the CLI, you need to do the following after
+                your image is built:
+                <orderedlist>
+                    <listitem><para>
+                        Run these commands to export
+                        <filename>XDG_RUNTIME_DIR</filename>:
+                        <literallayout class='monospaced'>
+     mkdir -p /tmp/$USER-weston
+     chmod 0700 /tmp/$USER-weston
+     export XDG_RUNTIME_DIR=/tmp/$USER-weston
+                        </literallayout>
+                        </para></listitem>
+                    <listitem><para>
+                        Launch Weston in the shell:
+                        <literallayout class='monospaced'>
+     weston
+                        </literallayout></para></listitem>
+                </orderedlist>
+            </para>
+        </section>
+    </section>
+
+    <section id="overview-licenses">
+        <title>Licenses</title>
+
+        <para>
+            This section describes the mechanism by which the
+            <ulink url='&YOCTO_DOCS_REF_URL;#build-system-term'>OpenEmbedded build system</ulink>
+            tracks changes to licensing text.
+            The section also describes how to enable commercially licensed
+            recipes, which by default are disabled.
+        </para>
+
+        <para>
+            For information that can help you maintain compliance with
+            various open source licensing during the lifecycle of the product,
+            see the
+            "<ulink url='&YOCTO_DOCS_DEV_URL;#maintaining-open-source-license-compliance-during-your-products-lifecycle'>Maintaining Open Source License Compliance During Your Project's Lifecycle</ulink>"
+            section in the Yocto Project Development Tasks Manual.
+        </para>
+
+        <section id="usingpoky-configuring-LIC_FILES_CHKSUM">
+            <title>Tracking License Changes</title>
+
+            <para>
+                The license of an upstream project might change in the future.
+                In order to prevent these changes going unnoticed, the
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-LIC_FILES_CHKSUM'><filename>LIC_FILES_CHKSUM</filename></ulink>
+                variable tracks changes to the license text. The checksums are
+                validated at the end of the configure step, and if the
+                checksums do not match, the build will fail.
+            </para>
+
+            <section id="usingpoky-specifying-LIC_FILES_CHKSUM">
+                <title>Specifying the <filename>LIC_FILES_CHKSUM</filename> Variable</title>
+
+                <para>
+                    The <filename>LIC_FILES_CHKSUM</filename>
+                    variable contains checksums of the license text in the
+                    source code for the recipe.
+                    Following is an example of how to specify
+                    <filename>LIC_FILES_CHKSUM</filename>:
+                    <literallayout class='monospaced'>
+     LIC_FILES_CHKSUM = "file://COPYING;md5=xxxx \
+                         file://licfile1.txt;beginline=5;endline=29;md5=yyyy \
+                         file://licfile2.txt;endline=50;md5=zzzz \
+                         ..."
+                    </literallayout>
+                    <note><title>Notes</title>
+                        <itemizedlist>
+                            <listitem><para>
+                                When using "beginline" and "endline", realize
+                                that line numbering begins with one and not
+                                zero.
+                                Also, the included lines are inclusive (i.e.
+                                lines five through and including 29 in the
+                                previous example for
+                                <filename>licfile1.txt</filename>).
+                                </para></listitem>
+                            <listitem><para>
+                                When a license check fails, the selected license
+                                text is included as part of the QA message.
+                                Using this output, you can determine the exact
+                                start and finish for the needed license text.
+                                </para></listitem>
+                        </itemizedlist>
+                    </note>
+                </para>
+
+                <para>
+                    The build system uses the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-S'><filename>S</filename></ulink>
+                    variable as the default directory when searching files
+                    listed in <filename>LIC_FILES_CHKSUM</filename>.
+                    The previous example employs the default directory.
+                </para>
+
+                <para>
+                    Consider this next example:
+                    <literallayout class='monospaced'>
+     LIC_FILES_CHKSUM = "file://src/ls.c;beginline=5;endline=16;\
+                                         md5=bb14ed3c4cda583abc85401304b5cd4e"
+     LIC_FILES_CHKSUM = "file://${WORKDIR}/license.html;md5=5c94767cedb5d6987c902ac850ded2c6"
+                    </literallayout>
+                </para>
+
+                <para>
+                    The first line locates a file in
+                    <filename>${S}/src/ls.c</filename> and isolates lines five
+                    through 16 as license text.
+                    The second line refers to a file in
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-WORKDIR'><filename>WORKDIR</filename></ulink>.
+                </para>
+
+                <para>
+                    Note that <filename>LIC_FILES_CHKSUM</filename> variable is
+                    mandatory for all recipes, unless the
+                    <filename>LICENSE</filename> variable is set to "CLOSED".
+                </para>
+            </section>
+
+            <section id="usingpoky-LIC_FILES_CHKSUM-explanation-of-syntax">
+                <title>Explanation of Syntax</title>
+
+                <para>
+                    As mentioned in the previous section, the
+                    <filename>LIC_FILES_CHKSUM</filename> variable lists all
+                    the important files that contain the license text for the
+                    source code.
+                    It is possible to specify a checksum for an entire file,
+                    or a specific section of a file (specified by beginning and
+                    ending line numbers with the "beginline" and "endline"
+                    parameters, respectively).
+                    The latter is useful for source files with a license
+                    notice header, README documents, and so forth.
+                    If you do not use the "beginline" parameter, then it is
+                    assumed that the text begins on the first line of the file.
+                    Similarly, if you do not use the "endline" parameter,
+                    it is assumed that the license text ends with the last
+                    line of the file.
+                </para>
+
+                <para>
+                    The "md5" parameter stores the md5 checksum of the license
+                    text.
+                    If the license text changes in any way as compared to
+                    this parameter then a mismatch occurs.
+                    This mismatch triggers a build failure and notifies
+                    the developer.
+                    Notification allows the developer to review and address
+                    the license text changes.
+                    Also note that if a mismatch occurs during the build,
+                    the correct md5 checksum is placed in the build log and
+                    can be easily copied to the recipe.
+                </para>
+
+                <para>
+                    There is no limit to how many files you can specify using
+                    the <filename>LIC_FILES_CHKSUM</filename> variable.
+                    Generally, however, every project requires a few
+                    specifications for license tracking.
+                    Many projects have a "COPYING" file that stores the
+                    license information for all the source code files.
+                    This practice allows you to just track the "COPYING"
+                    file as long as it is kept up to date.
+                    <note><title>Tips</title>
+                        <itemizedlist>
+                            <listitem><para>
+                                If you specify an empty or invalid "md5"
+                                parameter,
+                                <ulink url='&YOCTO_DOCS_REF_URL;#bitbake-term'>BitBake</ulink>
+                                returns an md5 mis-match
+                                error and displays the correct "md5" parameter
+                                value during the build.
+                                The correct parameter is also captured in
+                                the build log.
+                                </para></listitem>
+                            <listitem><para>
+                                If the whole file contains only license text,
+                                you do not need to use the "beginline" and
+                               "endline" parameters.
+                               </para></listitem>
+                        </itemizedlist>
+                    </note>
+                </para>
+            </section>
+        </section>
+
+        <section id="enabling-commercially-licensed-recipes">
+            <title>Enabling Commercially Licensed Recipes</title>
+
+            <para>
+                By default, the OpenEmbedded build system disables
+                components that have commercial or other special licensing
+                requirements.
+                Such requirements are defined on a
+                recipe-by-recipe basis through the
+                <ulink url='&YOCTO_DOCS_REF_URL;#var-LICENSE_FLAGS'><filename>LICENSE_FLAGS</filename></ulink>
+                variable definition in the affected recipe.
+                For instance, the
+                <filename>poky/meta/recipes-multimedia/gstreamer/gst-plugins-ugly</filename>
+                recipe contains the following statement:
+                <literallayout class='monospaced'>
+     LICENSE_FLAGS = "commercial"
+                </literallayout>
+                Here is a slightly more complicated example that contains both
+                an explicit recipe name and version (after variable expansion):
+                <literallayout class='monospaced'>
+     LICENSE_FLAGS = "license_${PN}_${PV}"
+                </literallayout>
+                    In order for a component restricted by a
+                <filename>LICENSE_FLAGS</filename> definition to be enabled and
+                included in an image, it needs to have a matching entry in the
+                global
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-LICENSE_FLAGS_WHITELIST'><filename>LICENSE_FLAGS_WHITELIST</filename></ulink>
+                variable, which is a variable typically defined in your
+                <filename>local.conf</filename> file.
+                For example, to enable the
+                <filename>poky/meta/recipes-multimedia/gstreamer/gst-plugins-ugly</filename>
+                    package, you could add either the string
+                    "commercial_gst-plugins-ugly" or the more general string
+                    "commercial" to <filename>LICENSE_FLAGS_WHITELIST</filename>.
+                See the
+                "<link linkend='license-flag-matching'>License Flag Matching</link>"
+                section for a full
+                explanation of how <filename>LICENSE_FLAGS</filename> matching
+                works.
+                Here is the example:
+                <literallayout class='monospaced'>
+     LICENSE_FLAGS_WHITELIST = "commercial_gst-plugins-ugly"
+                </literallayout>
+                    Likewise, to additionally enable the package built from the
+                recipe containing
+                    <filename>LICENSE_FLAGS = "license_${PN}_${PV}"</filename>,
+                and assuming that the actual recipe name was
+                <filename>emgd_1.10.bb</filename>, the following string would
+                enable that package as well as the original
+                <filename>gst-plugins-ugly</filename> package:
+                <literallayout class='monospaced'>
+     LICENSE_FLAGS_WHITELIST = "commercial_gst-plugins-ugly license_emgd_1.10"
+                </literallayout>
+                    As a convenience, you do not need to specify the complete
+                license string in the whitelist for every package.
+                You can use an abbreviated form, which consists
+                of just the first portion or portions of the license
+                string before the initial underscore character or characters.
+                A partial string will match any license that contains the
+                given string as the first portion of its license.
+                For example, the following whitelist string will also match
+                both of the packages previously mentioned as well as any other
+                packages that have licenses starting with "commercial" or
+                "license".
+                <literallayout class='monospaced'>
+     LICENSE_FLAGS_WHITELIST = "commercial license"
+                </literallayout>
+            </para>
+
+            <section id="license-flag-matching">
+                <title>License Flag Matching</title>
+
+                <para>
+                            License flag matching allows you to control what recipes
+                    the OpenEmbedded build system includes in the build.
+                    Fundamentally, the build system attempts to match
+                    <filename>LICENSE_FLAGS</filename> strings found in recipes
+                    against <filename>LICENSE_FLAGS_WHITELIST</filename>
+                    strings found in the whitelist.
+                    A match causes the build system to include a recipe in the
+                    build, while failure to find a match causes the build
+                    system to exclude a recipe.
+                </para>
+
+                <para>
+                    In general, license flag matching is simple.
+                    However, understanding some concepts will help you
+                    correctly and effectively use matching.
+                </para>
+
+                <para>
+                    Before a flag
+                    defined by a particular recipe is tested against the
+                    contents of the whitelist, the expanded string
+                    <filename>_${PN}</filename> is appended to the flag.
+                    This expansion makes each
+                    <filename>LICENSE_FLAGS</filename> value recipe-specific.
+                    After expansion, the string is then matched against the
+                    whitelist.
+                    Thus, specifying
+                    <filename>LICENSE_FLAGS = "commercial"</filename>
+                    in recipe "foo", for example, results in the string
+                    <filename>"commercial_foo"</filename>.
+                    And, to create a match, that string must appear in the
+                    whitelist.
+                </para>
+
+                <para>
+                    Judicious use of the <filename>LICENSE_FLAGS</filename>
+                    strings and the contents of the
+                    <filename>LICENSE_FLAGS_WHITELIST</filename> variable
+                    allows you a lot of flexibility for including or excluding
+                    recipes based on licensing.
+                    For example, you can broaden the matching capabilities by
+                    using license flags string subsets in the whitelist.
+                    <note>
+                        When using a string subset, be sure to use the part of
+                        the expanded string that precedes the appended
+                        underscore character (e.g.
+                        <filename>usethispart_1.3</filename>,
+                        <filename>usethispart_1.4</filename>, and so forth).
+                    </note>
+                    For example, simply specifying the string "commercial" in
+                    the whitelist matches any expanded
+                    <filename>LICENSE_FLAGS</filename> definition that starts
+                    with the string "commercial" such as "commercial_foo" and
+                    "commercial_bar", which are the strings the build system
+                    automatically generates for hypothetical recipes named
+                    "foo" and "bar" assuming those recipes simply specify the
+                    following:
+                    <literallayout class='monospaced'>
+     LICENSE_FLAGS = "commercial"
+                    </literallayout>
+                    Thus, you can choose to exhaustively
+                    enumerate each license flag in the whitelist and
+                    allow only specific recipes into the image, or
+                    you can use a string subset that causes a broader range of
+                    matches to allow a range of recipes into the image.
+                </para>
+
+                <para>
+                    This scheme works even if the
+                    <filename>LICENSE_FLAGS</filename> string already
+                    has <filename>_${PN}</filename> appended.
+                    For example, the build system turns the license flag
+                    "commercial_1.2_foo" into "commercial_1.2_foo_foo" and
+                    would match both the general "commercial" and the specific
+                    "commercial_1.2_foo" strings found in the whitelist, as
+                    expected.
+                </para>
+
+                <para>
+                    Here are some other scenarios:
+                    <itemizedlist>
+                        <listitem><para>
+                            You can specify a versioned string in the recipe
+                            such as "commercial_foo_1.2" in a "foo" recipe.
+                            The build system expands this string to
+                            "commercial_foo_1.2_foo".
+                            Combine this license flag with a whitelist that has
+                            the string "commercial" and you match the flag
+                            along with any other flag that starts with the
+                            string "commercial".
+                            </para></listitem>
+                        <listitem><para>
+                            Under the same circumstances, you can use
+                            "commercial_foo" in the whitelist and the build
+                            system not only matches "commercial_foo_1.2" but
+                            also matches any license flag with the string
+                            "commercial_foo", regardless of the version.
+                            </para></listitem>
+                        <listitem><para>
+                            You can be very specific and use both the
+                            package and version parts in the whitelist (e.g.
+                            "commercial_foo_1.2") to specifically match a
+                            versioned recipe.
+                            </para></listitem>
+                    </itemizedlist>
+                </para>
+            </section>
+
+            <section id="other-variables-related-to-commercial-licenses">
+                <title>Other Variables Related to Commercial Licenses</title>
+
+                <para>
+                    Other helpful variables related to commercial
+                    license handling exist and are defined in the
+                    <filename>poky/meta/conf/distro/include/default-distrovars.inc</filename> file:
+                    <literallayout class='monospaced'>
+     COMMERCIAL_AUDIO_PLUGINS ?= ""
+     COMMERCIAL_VIDEO_PLUGINS ?= ""
+                    </literallayout>
+                    If you want to enable these components, you can do so by
+                    making sure you have statements similar to the following
+                    in your <filename>local.conf</filename> configuration file:
+                    <literallayout class='monospaced'>
+     COMMERCIAL_AUDIO_PLUGINS = "gst-plugins-ugly-mad \
+        gst-plugins-ugly-mpegaudioparse"
+     COMMERCIAL_VIDEO_PLUGINS = "gst-plugins-ugly-mpeg2dec \
+        gst-plugins-ugly-mpegstream gst-plugins-bad-mpegvideoparse"
+     LICENSE_FLAGS_WHITELIST = "commercial_gst-plugins-ugly commercial_gst-plugins-bad commercial_qmmp"
+                    </literallayout>
+                    Of course, you could also create a matching whitelist
+                    for those components using the more general "commercial"
+                    in the whitelist, but that would also enable all the
+                    other packages with <filename>LICENSE_FLAGS</filename>
+                    containing "commercial", which you may or may not want:
+                    <literallayout class='monospaced'>
+     LICENSE_FLAGS_WHITELIST = "commercial"
+                    </literallayout>
+                </para>
+
+                <para>
+                    Specifying audio and video plug-ins as part of the
+                    <filename>COMMERCIAL_AUDIO_PLUGINS</filename> and
+                    <filename>COMMERCIAL_VIDEO_PLUGINS</filename> statements
+                    (along with the enabling
+                    <filename>LICENSE_FLAGS_WHITELIST</filename>) includes the
+                    plug-ins or components into built images, thus adding
+                    support for media formats or components.
+                </para>
+            </section>
+        </section>
+    </section>
+</chapter>
+<!--
+vim: expandtab tw=80 ts=4
+-->
diff --git a/documentation/overview-manual/overview-manual-customization.xsl b/documentation/overview-manual/overview-manual-customization.xsl
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@@ -0,0 +1,27 @@
+<?xml version='1.0'?>
+<xsl:stylesheet xmlns:xsl="http://www.w3.org/1999/XSL/Transform" xmlns="http://www.w3.org/1999/xhtml" xmlns:fo="http://www.w3.org/1999/XSL/Format" version="1.0">
+
+  <xsl:import href="http://downloads.yoctoproject.org/mirror/docbook-mirror/docbook-xsl-1.76.1/xhtml/docbook.xsl" />
+
+<!--
+
+  <xsl:import href="../template/1.76.1/docbook-xsl-1.76.1/xhtml/docbook.xsl" />
+
+  <xsl:import href="http://docbook.sourceforge.net/release/xsl/1.76.1/xhtml/docbook.xsl" />
+
+-->
+
+  <xsl:include href="../template/permalinks.xsl"/>
+  <xsl:include href="../template/section.title.xsl"/>
+  <xsl:include href="../template/component.title.xsl"/>
+  <xsl:include href="../template/division.title.xsl"/>
+  <xsl:include href="../template/formal.object.heading.xsl"/>
+
+  <xsl:param name="html.stylesheet" select="'overview-manual-style.css'" />
+  <xsl:param name="chapter.autolabel" select="1" />
+  <xsl:param name="appendix.autolabel" select="A" />
+  <xsl:param name="section.autolabel" select="1" />
+  <xsl:param name="section.label.includes.component.label" select="1" />
+  <xsl:param name="generate.id.attributes" select="1" />
+
+</xsl:stylesheet>
diff --git a/documentation/overview-manual/overview-manual-development-environment.xml b/documentation/overview-manual/overview-manual-development-environment.xml
new file mode 100644
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@@ -0,0 +1,972 @@
+<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
+[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >
+
+<chapter id='overview-development-environment'>
+<title>The Yocto Project Development Environment</title>
+
+<para>
+    This chapter takes a look at the Yocto Project development
+    environment.
+    The chapter provides Yocto Project Development environment concepts that
+    help you understand how work is accomplished in an open source environment,
+    which is very different as compared to work accomplished in a closed,
+    proprietary environment.
+</para>
+
+<para>
+    Specifically, this chapter addresses open source philosophy, source
+    repositories, workflows, Git, and licensing.
+</para>
+
+<section id='open-source-philosophy'>
+    <title>Open Source Philosophy</title>
+
+    <para>
+        Open source philosophy is characterized by software development
+        directed by peer production and collaboration through an active
+        community of developers.
+        Contrast this to the more standard centralized development models
+        used by commercial software companies where a finite set of developers
+        produces a product for sale using a defined set of procedures that
+        ultimately result in an end product whose architecture and source
+        material are closed to the public.
+    </para>
+
+    <para>
+        Open source projects conceptually have differing concurrent agendas,
+        approaches, and production.
+        These facets of the development process can come from anyone in the
+        public (community) who has a stake in the software project.
+        The open source environment contains new copyright, licensing, domain,
+        and consumer issues that differ from the more traditional development
+        environment.
+        In an open source environment, the end product, source material,
+        and documentation are all available to the public at no cost.
+    </para>
+
+    <para>
+        A benchmark example of an open source project is the Linux kernel,
+        which was initially conceived and created by Finnish computer science
+        student Linus Torvalds in 1991.
+        Conversely, a good example of a non-open source project is the
+        <trademark class='registered'>Windows</trademark> family of operating
+        systems developed by
+        <trademark class='registered'>Microsoft</trademark> Corporation.
+    </para>
+
+    <para>
+        Wikipedia has a good historical description of the Open Source
+        Philosophy
+        <ulink url='http://en.wikipedia.org/wiki/Open_source'>here</ulink>.
+        You can also find helpful information on how to participate in the
+        Linux Community
+        <ulink url='http://ldn.linuxfoundation.org/book/how-participate-linux-community'>here</ulink>.
+    </para>
+</section>
+
+<section id='gs-the-development-host'>
+    <title>The Development Host</title>
+
+    <para>
+        A development host or build host is key to using the Yocto Project.
+        Because the goal of the Yocto Project is to develop images or
+        applications that run on embedded hardware, development of those
+        images and applications generally takes place on a system not
+        intended to run the software - the development host.
+    </para>
+
+    <para>
+        You need to set up a development host in order to use it with the
+        Yocto Project.
+        Most find that it is best to have a native Linux machine function as
+        the development host.
+        However, it is possible to use a system that does not run Linux
+        as its operating system as your development host.
+        When you have a Mac or Windows-based system, you can set it up
+        as the development host by using
+        <ulink url='https://git.yoctoproject.org/cgit/cgit.cgi/crops/about/'>CROPS</ulink>,
+        which leverages
+        <ulink url='https://www.docker.com/'>Docker Containers</ulink>.
+        Once you take the steps to set up a CROPS machine, you effectively
+        have access to a shell environment that is similar to what you see
+        when using a Linux-based development host.
+        For the steps needed to set up a system using CROPS, see the
+        "<ulink url='&YOCTO_DOCS_DEV_URL;#setting-up-to-use-crops'>Setting Up to Use CROss PlatformS (CROPS)</ulink>"
+        section in the Yocto Project Development Tasks Manual.
+    </para>
+
+    <para>
+        If your development host is going to be a system that runs a Linux
+        distribution, steps still exist that you must take to prepare the
+        system for use with the Yocto Project.
+        You need to be sure that the Linux distribution on the system is
+        one that supports the Yocto Project.
+        You also need to be sure that the correct set of host packages are
+        installed that allow development using the Yocto Project.
+        For the steps needed to set up a development host that runs Linux,
+        see the
+        "<ulink url='&YOCTO_DOCS_DEV_URL;#setting-up-a-native-linux-host'>Setting Up a Native Linux Host</ulink>"
+        section in the Yocto Project Development Tasks Manual.
+    </para>
+
+    <para>
+        Once your development host is set up to use the Yocto Project,
+        several methods exist for you to do work in the Yocto Project
+        environment:
+        <itemizedlist>
+            <listitem><para>
+                <emphasis>Command Lines, BitBake, and Shells:</emphasis>
+                Traditional development in the Yocto Project involves using
+                OpenEmbedded build system, which uses BitBake, in a
+                command-line environment from a shell on your development
+                host.
+                You can accomplish this from a host that is a native Linux
+                machine or from a host that has been set up with CROPS.
+                Either way, you create, modify, and build images and
+                applications all within a shell-based environment using
+                components and tools available through your Linux distribution
+                and the Yocto Project.</para>
+
+                <para>For a general flow of the build procedures, see the
+                "<ulink url='&YOCTO_DOCS_DEV_URL;#dev-building-an-image'>Building an Image</ulink>"
+                section in the Yocto Project Development Tasks Manual.
+                </para></listitem>
+            <listitem><para>
+                <emphasis>Board Support Package (BSP) Development:</emphasis>
+                Development of BSPs involves using the Yocto Project to
+                create and test layers that allow easy development of
+                images and applications targeted for specific hardware.
+                To development BSPs, you need to take some additional steps
+                beyond what was described in setting up a development host.
+                </para>
+
+                <para>The
+                <ulink url='&YOCTO_DOCS_BSP_URL;'>Yocto Project Board Support Package (BSP) Developer's Guide'</ulink>
+                provides BSP-related development information.
+                For specifics on development host preparation, see the
+                "<ulink url='&YOCTO_DOCS_BSP_URL;#preparing-your-build-host-to-work-with-bsp-layers'>Preparing Your Build Host to Work With BSP Layers</ulink>"
+                section in the Yocto Project Board Support Package (BSP)
+                Developer's Guide.
+                </para></listitem>
+            <listitem><para>
+                <emphasis>Kernel Development:</emphasis>
+                If you are going to be developing kernels using the Yocto
+                Project you likely will be using <filename>devtool</filename>.
+                A workflow using <filename>devtool</filename> makes kernel
+                development quicker by reducing iteration cycle times.</para>
+
+                <para>The
+                <ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;'>Yocto Project Linux Kernel Development Manual</ulink>
+                provides kernel-related development information.
+                For specifics on development host preparation, see the
+                "<ulink url='&YOCTO_DOCS_KERNEL_DEV_URL;#preparing-the-build-host-to-work-on-the-kernel'>Preparing the Build Host to Work on the Kernel</ulink>"
+                section in the Yocto Project Linux Kernel Development Manual.
+                </para></listitem>
+            <listitem><para>
+                <emphasis>Using the <trademark class='trade'>Eclipse</trademark> IDE:</emphasis>
+                One of two Yocto Project development methods that involves an
+                interface that effectively puts the Yocto Project into the
+                background is the popular Eclipse IDE.
+                This method of development is advantageous if you are already
+                familiar with working within Eclipse.
+                Development is supported through a plugin that you install
+                onto your development host.</para>
+
+                <para>For steps that show you how to set up your development
+                host to use the Eclipse Yocto Project plugin, see the
+                "<ulink url='&YOCTO_DOCS_SDK_URL;#sdk-eclipse-project'>Developing Applications Using <trademark class='trade'>Eclipse</trademark></ulink>"
+                Chapter in the Yocto Project Application Development and the
+                Extensible Software Development Kit (eSDK) manual.
+                </para></listitem>
+            <listitem><para>
+                <emphasis>Using the Toaster:</emphasis>
+                The other Yocto Project development method that involves an
+                interface that effectively puts the Yocto Project into the
+                background is Toaster.
+                Toaster provides an interface to the OpenEmbedded build system.
+                The interface enables you to configure and run your builds.
+                Information about builds is collected and stored in a database.
+                You can use Toaster to configure and start builds on multiple
+                remote build servers.</para>
+
+                <para>For steps that show you how to set up your development
+                host to use Toaster and on how to use Toaster in general,
+                see the
+                <ulink url='&YOCTO_DOCS_TOAST_URL;'>Toaster User Manual</ulink>.
+                </para></listitem>
+        </itemizedlist>
+    </para>
+</section>
+
+<section id='yocto-project-repositories'>
+    <title>Yocto Project Source Repositories</title>
+
+    <para>
+        The Yocto Project team maintains complete source repositories for all
+        Yocto Project files at
+        <ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi'></ulink>.
+        This web-based source code browser is organized into categories by
+        function such as IDE Plugins, Matchbox, Poky, Yocto Linux Kernel, and
+        so forth.
+        From the interface, you can click on any particular item in the "Name"
+        column and see the URL at the bottom of the page that you need to clone
+        a Git repository for that particular item.
+        Having a local Git repository of the
+        <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>,
+        which is usually named "poky", allows
+        you to make changes, contribute to the history, and ultimately enhance
+        the Yocto Project's tools, Board Support Packages, and so forth.
+    </para>
+
+    <para>
+        For any supported release of Yocto Project, you can also go to the
+        <ulink url='&YOCTO_HOME_URL;'>Yocto Project Website</ulink> and
+        select the "Downloads" tab and get a released tarball of the
+        <filename>poky</filename> repository or any supported BSP tarballs.
+        Unpacking these tarballs gives you a snapshot of the released
+        files.
+        <note><title>Notes</title>
+            <itemizedlist>
+                <listitem><para>
+                    The recommended method for setting up the Yocto Project
+                    <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
+                    and the files for supported BSPs
+                    (e.g., <filename>meta-intel</filename>) is to use
+                    <link linkend='git'>Git</link> to create a local copy of
+                    the upstream repositories.
+                    </para></listitem>
+                <listitem><para>
+                    Be sure to always work in matching branches for both
+                    the selected BSP repository and the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
+                    (i.e. <filename>poky</filename>) repository.
+                    For example, if you have checked out the "master" branch
+                    of <filename>poky</filename> and you are going to use
+                    <filename>meta-intel</filename>, be sure to checkout the
+                    "master" branch of <filename>meta-intel</filename>.
+                    </para></listitem>
+            </itemizedlist>
+        </note>
+    </para>
+
+    <para>
+        In summary, here is where you can get the project files needed for
+        development:
+        <itemizedlist>
+            <listitem><para id='source-repositories'>
+                <emphasis>
+                <ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi'>Source Repositories:</ulink>
+                </emphasis>
+                This area contains IDE Plugins, Matchbox, Poky, Poky Support,
+                Tools, Yocto Linux Kernel, and Yocto Metadata Layers.
+                You can create local copies of Git repositories for each of
+                these areas.</para>
+
+                <para>
+                <imagedata fileref="figures/source-repos.png" align="center" width="6in" depth="4in" />
+                For steps on how to view and access these upstream Git
+                repositories, see the
+                "<ulink url='&YOCTO_DOCS_DEV_URL;#accessing-source-repositories'>Accessing Source Repositories</ulink>"
+                Section in the Yocto Project Development Tasks Manual.
+                </para></listitem>
+            <listitem><para><anchor id='index-downloads' />
+                <emphasis>
+                <ulink url='&YOCTO_DL_URL;/releases/'>Index of /releases:</ulink>
+                </emphasis>
+                This is an index of releases such as
+                the <trademark class='trade'>Eclipse</trademark>
+                Yocto Plug-in, miscellaneous support, Poky, Pseudo, installers
+                for cross-development toolchains, and all released versions of
+                Yocto Project in the form of images or tarballs.
+                Downloading and extracting these files does not produce a local
+                copy of the Git repository but rather a snapshot of a
+                particular release or image.</para>
+
+                <para>
+                <imagedata fileref="figures/index-downloads.png" align="center" width="6in" depth="3.5in" />
+                For steps on how to view and access these files, see the
+                "<ulink url='&YOCTO_DOCS_DEV_URL;#accessing-index-of-releases'>Accessing Index of Releases</ulink>"
+                section in the Yocto Project Development Tasks Manual.
+                </para></listitem>
+            <listitem><para id='downloads-page'>
+                <emphasis>"Downloads" page for the
+                <ulink url='&YOCTO_HOME_URL;'>Yocto Project Website</ulink>:
+                </emphasis></para>
+
+                <para>The Yocto Project website includes a "DOWNLOADS" page
+                accessible through the "SOFTWARE" tab
+                that allows you to download any Yocto Project
+                release, tool, and Board Support Package (BSP) in tarball form.
+                The tarballs are similar to those found in the
+                <ulink url='&YOCTO_DL_URL;/releases/'>Index of /releases:</ulink> area.</para>
+
+                <para>
+                <imagedata fileref="figures/yp-download.png" align="center" width="6in" depth="4in" />
+                For steps on how to use the "DOWNLOADS" page, see the
+                "<ulink url='&YOCTO_DOCS_DEV_URL;#using-the-downloads-page'>Using the Downloads Page</ulink>"
+                section in the Yocto Project Development Tasks Manual.
+                </para></listitem>
+        </itemizedlist>
+    </para>
+</section>
+
+<section id='gs-git-workflows-and-the-yocto-project'>
+    <title>Git Workflows and the Yocto Project</title>
+
+    <para>
+        Developing using the Yocto Project likely requires the use of
+        <link linkend='git'>Git</link>.
+        Git is a free, open source distributed version control system
+        used as part of many collaborative design environments.
+        This section provides workflow concepts using the Yocto Project and
+        Git.
+        In particular, the information covers basic practices that describe
+        roles and actions in a collaborative development environment.
+        <note>
+            If you are familiar with this type of development environment, you
+            might not want to read this section.
+        </note>
+    </para>
+
+    <para>
+        The Yocto Project files are maintained using Git in "branches"
+        whose Git histories track every change and whose structures
+        provide branches for all diverging functionality.
+        Although there is no need to use Git, many open source projects do so.
+    <para>
+
+    </para>
+        For the Yocto Project, a key individual called the "maintainer" is
+        responsible for the integrity of the "master" branch of a given Git
+        repository.
+        The "master" branch is the “upstream” repository from which final or
+        most recent builds of a project occur.
+        The maintainer is responsible for accepting changes from other
+        developers and for organizing the underlying branch structure to
+        reflect release strategies and so forth.
+        <note>
+            For information on finding out who is responsible for (maintains)
+            a particular area of code in the Yocto Project, see the
+            "<ulink url='&YOCTO_DOCS_DEV_URL;#how-to-submit-a-change'>Submitting a Change to the Yocto Project</ulink>"
+            section of the Yocto Project Development Tasks Manual.
+        </note>
+    </para>
+
+    <para>
+        The Yocto Project <filename>poky</filename> Git repository also has an
+        upstream contribution Git repository named
+        <filename>poky-contrib</filename>.
+        You can see all the branches in this repository using the web interface
+        of the
+        <ulink url='&YOCTO_GIT_URL;'>Source Repositories</ulink> organized
+        within the "Poky Support" area.
+        These branches hold changes (commits) to the project that have been
+        submitted or committed by the Yocto Project development team and by
+        community members who contribute to the project.
+        The maintainer determines if the changes are qualified to be moved
+        from the "contrib" branches into the "master" branch of the Git
+        repository.
+    </para>
+
+    <para>
+        Developers (including contributing community members) create and
+        maintain cloned repositories of upstream branches.
+        The cloned repositories are local to their development platforms and
+        are used to develop changes.
+        When a developer is satisfied with a particular feature or change,
+        they "push" the change to the appropriate "contrib" repository.
+    </para>
+
+    <para>
+        Developers are responsible for keeping their local repository
+        up-to-date with whatever upstream branch they are working against.
+        They are also responsible for straightening out any conflicts that
+        might arise within files that are being worked on simultaneously by
+        more than one person.
+        All this work is done locally on the development host before
+        anything is pushed to a "contrib" area and examined at the maintainer’s
+        level.
+    </para>
+
+    <para>
+        A somewhat formal method exists by which developers commit changes
+        and push them into the "contrib" area and subsequently request that
+        the maintainer include them into an upstream branch.
+        This process is called “submitting a patch” or "submitting a change."
+        For information on submitting patches and changes, see the
+        "<ulink url='&YOCTO_DOCS_DEV_URL;#how-to-submit-a-change'>Submitting a Change to the Yocto Project</ulink>"
+        section in the Yocto Project Development Tasks Manual.
+    </para>
+
+    <para>
+        To summarize the development workflow:  a single point of entry
+        exists for changes into a "master" or development branch of the
+        Git repository, which is controlled by the project’s maintainer.
+        And, a set of developers exist who independently develop, test, and
+        submit changes to "contrib" areas for the maintainer to examine.
+        The maintainer then chooses which changes are going to become a
+        permanent part of the project.
+    </para>
+
+    <para>
+        <imagedata fileref="figures/git-workflow.png" width="6in" depth="3in" align="left" scalefit="1" />
+    </para>
+
+    <para>
+        While each development environment is unique, there are some best
+        practices or methods that help development run smoothly.
+        The following list describes some of these practices.
+        For more information about Git workflows, see the workflow topics in
+        the
+        <ulink url='http://book.git-scm.com'>Git Community Book</ulink>.
+        <itemizedlist>
+            <listitem><para>
+                <emphasis>Make Small Changes:</emphasis>
+                It is best to keep the changes you commit small as compared to
+                bundling many disparate changes into a single commit.
+                This practice not only keeps things manageable but also allows
+                the maintainer to more easily include or refuse changes.
+                </para></listitem>
+            <listitem><para>
+                <emphasis>Make Complete Changes:</emphasis>
+                It is also good practice to leave the repository in a
+                state that allows you to still successfully build your project.
+                In other words, do not commit half of a feature,
+                then add the other half as a separate, later commit.
+                Each commit should take you from one buildable project state
+                to another buildable state.
+                </para></listitem>
+            <listitem><para>
+                <emphasis>Use Branches Liberally:</emphasis>
+                It is very easy to create, use, and delete local branches in
+                your working Git repository on the development host.
+                You can name these branches anything you like.
+                It is helpful to give them names associated with the particular
+                feature or change on which you are working.
+                Once you are done with a feature or change and have merged it
+                into your local master branch, simply discard the temporary
+                branch.
+                </para></listitem>
+            <listitem><para>
+                <emphasis>Merge Changes:</emphasis>
+                The <filename>git merge</filename> command allows you to take
+                the changes from one branch and fold them into another branch.
+                This process is especially helpful when more than a single
+                developer might be working on different parts of the same
+                feature.
+                Merging changes also automatically identifies any collisions
+                or "conflicts" that might happen as a result of the same lines
+                of code being altered by two different developers.
+                </para></listitem>
+            <listitem><para>
+                <emphasis>Manage Branches:</emphasis>
+                Because branches are easy to use, you should use a system
+                where branches indicate varying levels of code readiness.
+                For example, you can have a "work" branch to develop in, a
+                "test" branch where the code or change is tested, a "stage"
+                branch where changes are ready to be committed, and so forth.
+                As your project develops, you can merge code across the
+                branches to reflect ever-increasing stable states of the
+                development.
+                </para></listitem>
+            <listitem><para>
+                <emphasis>Use Push and Pull:</emphasis>
+                The push-pull workflow is based on the concept of developers
+                "pushing" local commits to a remote repository, which is
+                usually a contribution repository.
+                This workflow is also based on developers "pulling" known
+                states of the project down into their local development
+                repositories.
+                The workflow easily allows you to pull changes submitted by
+                other developers from the upstream repository into your
+                work area ensuring that you have the most recent software
+                on which to develop.
+                The Yocto Project has two scripts named
+                <filename>create-pull-request</filename> and
+                <filename>send-pull-request</filename> that ship with the
+                release to facilitate this workflow.
+                You can find these scripts in the <filename>scripts</filename>
+                folder of the
+                <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>.
+                For information on how to use these scripts, see the
+                "<ulink url='&YOCTO_DOCS_DEV_URL;#pushing-a-change-upstream'>Using Scripts to Push a Change Upstream and Request a Pull</ulink>"
+                section in the Yocto Project Development Tasks Manual.
+                </para></listitem>
+            <listitem><para>
+                <emphasis>Patch Workflow:</emphasis>
+                This workflow allows you to notify the maintainer through an
+                email that you have a change (or patch) you would like
+                considered for the "master" branch of the Git repository.
+                To send this type of change, you format the patch and then
+                send the email using the Git commands
+                <filename>git format-patch</filename> and
+                <filename>git send-email</filename>.
+                For information on how to use these scripts, see the
+                "<ulink url='&YOCTO_DOCS_DEV_URL;#how-to-submit-a-change'>Submitting a Change to the Yocto Project</ulink>"
+                section in the Yocto Project Development Tasks Manual.
+                </para></listitem>
+        </itemizedlist>
+    </para>
+</section>
+
+<section id='git'>
+    <title>Git</title>
+
+    <para>
+        The Yocto Project makes extensive use of Git, which is a
+        free, open source distributed version control system.
+        Git supports distributed development, non-linear development,
+        and can handle large projects.
+        It is best that you have some fundamental understanding
+        of how Git tracks projects and how to work with Git if
+        you are going to use the Yocto Project for development.
+        This section provides a quick overview of how Git works and
+        provides you with a summary of some essential Git commands.
+        <note><title>Notes</title>
+            <itemizedlist>
+                <listitem><para>
+                    For more information on Git, see
+                    <ulink url='http://git-scm.com/documentation'></ulink>.
+                    </para></listitem>
+                <listitem><para>
+                    If you need to download Git, it is recommended that you add
+                    Git to your system through your distribution's "software
+                    store" (e.g. for Ubuntu, use the Ubuntu Software feature).
+                    For the Git download page, see
+                    <ulink url='http://git-scm.com/download'></ulink>.
+                    </para></listitem>
+                <listitem><para>
+                    For information beyond the introductory nature in this
+                    section, see the
+                    "<ulink url='&YOCTO_DOCS_DEV_URL;#working-with-yocto-project-source-files'>Working With Yocto Project Source Files</ulink>"
+                    section in the Yocto Project Development Tasks Manual.
+                    </para></listitem>
+            </itemizedlist>
+        </note>
+    </para>
+
+    <section id='repositories-tags-and-branches'>
+        <title>Repositories, Tags, and Branches</title>
+
+        <para>
+            As mentioned briefly in the previous section and also in the
+            "<link linkend='gs-git-workflows-and-the-yocto-project'>Git Workflows and the Yocto Project</link>"
+            section, the Yocto Project maintains source repositories at
+            <ulink url='&YOCTO_GIT_URL;/cgit.cgi'></ulink>.
+            If you look at this web-interface of the repositories, each item
+            is a separate Git repository.
+        </para>
+
+        <para>
+            Git repositories use branching techniques that track content
+            change (not files) within a project (e.g. a new feature or updated
+            documentation).
+            Creating a tree-like structure based on project divergence allows
+            for excellent historical information over the life of a project.
+            This methodology also allows for an environment from which you can
+            do lots of local experimentation on projects as you develop
+            changes or new features.
+        </para>
+
+        <para>
+            A Git repository represents all development efforts for a given
+            project.
+            For example, the Git repository <filename>poky</filename> contains
+            all changes and developments for that repository over the course
+            of its entire life.
+            That means that all changes that make up all releases are captured.
+            The repository maintains a complete history of changes.
+        </para>
+
+        <para>
+            You can create a local copy of any repository by "cloning" it
+            with the <filename>git clone</filename> command.
+            When you clone a Git repository, you end up with an identical
+            copy of the repository on your development system.
+            Once you have a local copy of a repository, you can take steps to
+            develop locally.
+            For examples on how to clone Git repositories, see the
+            "<ulink url='&YOCTO_DOCS_DEV_URL;#working-with-yocto-project-source-files'>Working With Yocto Project Source Files</ulink>"
+            section in the Yocto Project Development Tasks Manual.
+        </para>
+
+        <para>
+            It is important to understand that Git tracks content change and
+            not files.
+            Git uses "branches" to organize different development efforts.
+            For example, the <filename>poky</filename> repository has
+            several branches that include the current "&DISTRO_NAME_NO_CAP;"
+            branch, the "master" branch, and many branches for past
+            Yocto Project releases.
+            You can see all the branches by going to
+            <ulink url='&YOCTO_GIT_URL;/cgit.cgi/poky/'></ulink> and
+            clicking on the
+            <filename><ulink url='&YOCTO_GIT_URL;/cgit.cgi/poky/refs/heads'>[...]</ulink></filename>
+            link beneath the "Branch" heading.
+        </para>
+
+        <para>
+            Each of these branches represents a specific area of development.
+            The "master" branch represents the current or most recent
+            development.
+            All other branches represent offshoots of the "master" branch.
+        </para>
+
+        <para>
+            When you create a local copy of a Git repository, the copy has
+            the same set of branches as the original.
+            This means you can use Git to create a local working area
+            (also called a branch) that tracks a specific development branch
+            from the upstream source Git repository.
+            in other words, you can define your local Git environment to
+            work on any development branch in the repository.
+            To help illustrate, consider the following example Git commands:
+            <literallayout class='monospaced'>
+     $ cd ~
+     $ git clone git://git.yoctoproject.org/poky
+     $ cd poky
+     $ git checkout -b &DISTRO_NAME_NO_CAP; origin/&DISTRO_NAME_NO_CAP;
+            </literallayout>
+            In the previous example after moving to the home directory, the
+            <filename>git clone</filename> command creates a
+            local copy of the upstream <filename>poky</filename> Git repository.
+            By default, Git checks out the "master" branch for your work.
+            After changing the working directory to the new local repository
+            (i.e. <filename>poky</filename>), the
+            <filename>git checkout</filename> command creates
+            and checks out a local branch named "&DISTRO_NAME_NO_CAP;", which
+            tracks the upstream "origin/&DISTRO_NAME_NO_CAP;" branch.
+            Changes you make while in this branch would ultimately affect
+            the upstream "&DISTRO_NAME_NO_CAP;" branch of the
+            <filename>poky</filename> repository.
+        </para>
+
+        <para>
+            It is important to understand that when you create and checkout a
+            local working branch based on a branch name,
+            your local environment matches the "tip" of that particular
+            development branch at the time you created your local branch,
+            which could be different from the files in the "master" branch
+            of the upstream repository.
+            In other words, creating and checking out a local branch based on
+            the "&DISTRO_NAME_NO_CAP;" branch name is not the same as
+            checking out the "master" branch in the repository.
+            Keep reading to see how you create a local snapshot of a Yocto
+            Project Release.
+        </para>
+
+        <para>
+            Git uses "tags" to mark specific changes in a repository branch
+            structure.
+            Typically, a tag is used to mark a special point such as the final
+            change (or commit) before a project is released.
+            You can see the tags used with the <filename>poky</filename> Git
+            repository by going to
+            <ulink url='&YOCTO_GIT_URL;/cgit.cgi/poky/'></ulink> and
+            clicking on the
+            <filename><ulink url='&YOCTO_GIT_URL;/cgit.cgi/poky/refs/tags'>[...]</ulink></filename>
+            link beneath the "Tag" heading.
+        </para>
+
+        <para>
+            Some key tags for the <filename>poky</filename> repository are
+            <filename>jethro-14.0.3</filename>,
+            <filename>morty-16.0.1</filename>,
+            <filename>pyro-17.0.0</filename>, and
+            <filename>&DISTRO_NAME_NO_CAP;-&POKYVERSION;</filename>.
+            These tags represent Yocto Project releases.
+        </para>
+
+        <para>
+            When you create a local copy of the Git repository, you also
+            have access to all the tags in the upstream repository.
+            Similar to branches, you can create and checkout a local working
+            Git branch based on a tag name.
+            When you do this, you get a snapshot of the Git repository that
+            reflects the state of the files when the change was made associated
+            with that tag.
+            The most common use is to checkout a working branch that matches
+            a specific Yocto Project release.
+            Here is an example:
+            <literallayout class='monospaced'>
+     $ cd ~
+     $ git clone git://git.yoctoproject.org/poky
+     $ cd poky
+     $ git fetch --all --tags --prune
+     $ git checkout tags/pyro-17.0.0 -b my-pyro-17.0.0
+            </literallayout>
+            In this example, the name of the top-level directory of your
+            local Yocto Project repository is <filename>poky</filename>.
+            After moving to the <filename>poky</filename> directory, the
+            <filename>git fetch</filename> command makes all the upstream
+            tags available locally in your repository.
+            Finally, the <filename>git checkout</filename> command
+            creates and checks out a branch named "my-pyro-17.0.0" that is
+            based on the upstream branch whose "HEAD" matches the
+            commit in the repository associated with the "pyro-17.0.0" tag.
+            The files in your repository now exactly match that particular
+            Yocto Project release as it is tagged in the upstream Git
+            repository.
+            It is important to understand that when you create and
+            checkout a local working branch based on a tag, your environment
+            matches a specific point in time and not the entire development
+            branch (i.e. from the "tip" of the branch backwards).
+        </para>
+    </section>
+
+    <section id='basic-commands'>
+        <title>Basic Commands</title>
+
+        <para>
+            Git has an extensive set of commands that lets you manage changes
+            and perform collaboration over the life of a project.
+            Conveniently though, you can manage with a small set of basic
+            operations and workflows once you understand the basic
+            philosophy behind Git.
+            You do not have to be an expert in Git to be functional.
+            A good place to look for instruction on a minimal set of Git
+            commands is
+            <ulink url='http://git-scm.com/documentation'>here</ulink>.
+        </para>
+
+        <para>
+            If you do not know much about Git, you should educate
+            yourself by visiting the links previously mentioned.
+        </para>
+
+        <para>
+            The following list of Git commands briefly describes some basic
+            Git operations as a way to get started.
+            As with any set of commands, this list (in most cases) simply shows
+            the base command and omits the many arguments it supports.
+            See the Git documentation for complete descriptions and strategies
+            on how to use these commands:
+            <itemizedlist>
+                <listitem><para>
+                    <emphasis><filename>git init</filename>:</emphasis>
+                    Initializes an empty Git repository.
+                    You cannot use Git commands unless you have a
+                    <filename>.git</filename> repository.
+                    </para></listitem>
+                <listitem><para id='git-commands-clone'>
+                    <emphasis><filename>git clone</filename>:</emphasis>
+                    Creates a local clone of a Git repository that is on
+                    equal footing with a fellow developer’s Git repository
+                    or an upstream repository.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><filename>git add</filename>:</emphasis>
+                    Locally stages updated file contents to the index that
+                    Git uses to track changes.
+                    You must stage all files that have changed before you
+                    can commit them.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><filename>git commit</filename>:</emphasis>
+                    Creates a local "commit" that documents the changes you
+                    made.
+                    Only changes that have been staged can be committed.
+                    Commits are used for historical purposes, for determining
+                    if a maintainer of a project will allow the change,
+                    and for ultimately pushing the change from your local
+                    Git repository into the project’s upstream repository.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><filename>git status</filename>:</emphasis>
+                    Reports any modified files that possibly need to be
+                    staged and gives you a status of where you stand regarding
+                    local commits as compared to the upstream repository.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><filename>git checkout</filename> <replaceable>branch-name</replaceable>:</emphasis>
+                    Changes your local working branch and in this form
+                    assumes the local branch already exists.
+                    This command is analogous to "cd".
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><filename>git checkout –b</filename> <replaceable>working-branch</replaceable> <replaceable>upstream-branch</replaceable>:</emphasis>
+                    Creates and checks out a working branch on your local
+                    machine.
+                    The local branch tracks the upstream branch.
+                    You can use your local branch to isolate your work.
+                    It is a good idea to use local branches when adding
+                    specific features or changes.
+                    Using isolated branches facilitates easy removal of
+                    changes if they do not work out.
+                    </para></listitem>
+                <listitem><para><emphasis><filename>git branch</filename>:</emphasis>
+                    Displays the existing local branches associated with your
+                    local repository.
+                    The branch that you have currently checked out is noted
+                    with an asterisk character.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><filename>git branch -D</filename> <replaceable>branch-name</replaceable>:</emphasis>
+                    Deletes an existing local branch.
+                    You need to be in a local branch other than the one you
+                    are deleting in order to delete
+                    <replaceable>branch-name</replaceable>.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><filename>git pull --rebase</filename>:</emphasis>
+                    Retrieves information from an upstream Git repository
+                    and places it in your local Git repository.
+                    You use this command to make sure you are synchronized with
+                    the repository from which you are basing changes
+                    (.e.g. the "master" branch).
+                    The "--rebase" option ensures that any local commits you
+                    have in your branch are preserved at the top of your
+                    local branch.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><filename>git push</filename> <replaceable>repo-name</replaceable> <replaceable>local-branch</replaceable><filename>:</filename><replaceable>upstream-branch</replaceable>:</emphasis>
+                    Sends all your committed local changes to the upstream Git
+                    repository that your local repository is tracking
+                    (e.g. a contribution repository).
+                    The maintainer of the project draws from these repositories
+                    to merge changes (commits) into the appropriate branch
+                    of project's upstream repository.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><filename>git merge</filename>:</emphasis>
+                    Combines or adds changes from one
+                    local branch of your repository with another branch.
+                    When you create a local Git repository, the default branch
+                    is named "master".
+                    A typical workflow is to create a temporary branch that is
+                    based off "master" that you would use for isolated work.
+                    You would make your changes in that isolated branch,
+                    stage and commit them locally, switch to the "master"
+                    branch, and then use the <filename>git merge</filename>
+                    command to apply the changes from your isolated branch
+                    into the currently checked out branch (e.g. "master").
+                    After the merge is complete and if you are done with
+                    working in that isolated branch, you can safely delete
+                    the isolated branch.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><filename>git cherry-pick</filename> <replaceable>commits</replaceable>:</emphasis>
+                    Choose and apply specific commits from one branch
+                    into another branch.
+                    There are times when you might not be able to merge
+                    all the changes in one branch with
+                    another but need to pick out certain ones.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><filename>gitk</filename>:</emphasis>
+                    Provides a GUI view of the branches and changes in your
+                    local Git repository.
+                    This command is a good way to graphically see where things
+                    have diverged in your local repository.
+                    <note>
+                        You need to install the <filename>gitk</filename>
+                        package on your development system to use this
+                        command.
+                    </note>
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><filename>git log</filename>:</emphasis>
+                    Reports a history of your commits to the repository.
+                    This report lists all commits regardless of whether you
+                    have pushed them upstream or not.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><filename>git diff</filename>:</emphasis>
+                    Displays line-by-line differences between a local
+                    working file and the same file as understood by Git.
+                    This command is useful to see what you have changed
+                    in any given file.
+                    </para></listitem>
+            </itemizedlist>
+        </para>
+    </section>
+</section>
+
+<section id='licensing'>
+    <title>Licensing</title>
+
+    <para>
+        Because open source projects are open to the public, they have
+        different licensing structures in place.
+        License evolution for both Open Source and Free Software has an
+        interesting history.
+        If you are interested in this history, you can find basic information
+        here:
+        <itemizedlist>
+            <listitem><para>
+                <ulink url='http://en.wikipedia.org/wiki/Open-source_license'>Open source license history</ulink>
+                </para></listitem>
+            <listitem><para>
+                <ulink url='http://en.wikipedia.org/wiki/Free_software_license'>Free software license history</ulink>
+                </para></listitem>
+        </itemizedlist>
+    </para>
+
+    <para>
+        In general, the Yocto Project is broadly licensed under the
+        Massachusetts Institute of Technology (MIT) License.
+        MIT licensing permits the reuse of software within proprietary
+        software as long as the license is distributed with that software.
+        MIT is also compatible with the GNU General Public License (GPL).
+        Patches to the Yocto Project follow the upstream licensing scheme.
+        You can find information on the MIT license
+        <ulink url='http://www.opensource.org/licenses/mit-license.php'>here</ulink>.
+        You can find information on the GNU GPL
+        <ulink url='http://www.opensource.org/licenses/LGPL-3.0'>here</ulink>.
+    </para>
+
+    <para>
+        When you build an image using the Yocto Project, the build process
+        uses a known list of licenses to ensure compliance.
+        You can find this list in the
+        <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
+        at <filename>meta/files/common-licenses</filename>.
+        Once the build completes, the list of all licenses found and used
+        during that build are kept in the
+        <ulink url='&YOCTO_DOCS_REF_URL;#build-directory'>Build Directory</ulink>
+        at <filename>tmp/deploy/licenses</filename>.
+    </para>
+
+    <para>
+        If a module requires a license that is not in the base list, the
+        build process generates a warning during the build.
+        These tools make it easier for a developer to be certain of the
+        licenses with which their shipped products must comply.
+        However, even with these tools it is still up to the developer to
+        resolve potential licensing issues.
+    </para>
+
+    <para>
+        The base list of licenses used by the build process is a combination
+        of the Software Package Data Exchange (SPDX) list and the Open
+        Source Initiative (OSI) projects.
+        <ulink url='http://spdx.org'>SPDX Group</ulink> is a working group of
+        the Linux Foundation that maintains a specification for a standard
+        format for communicating the components, licenses, and copyrights
+        associated with a software package.
+        <ulink url='http://opensource.org'>OSI</ulink> is a corporation
+        dedicated to the Open Source Definition and the effort for reviewing
+        and approving licenses that conform to the Open Source Definition
+        (OSD).
+    </para>
+
+    <para>
+        You can find a list of the combined SPDX and OSI licenses that the
+        Yocto Project uses in the
+        <filename>meta/files/common-licenses</filename> directory in your
+        <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>.
+    </para>
+
+    <para>
+        For information that can help you maintain compliance with various
+        open source licensing during the lifecycle of a product created using
+        the Yocto Project, see the
+        "<ulink url='&YOCTO_DOCS_DEV_URL;#maintaining-open-source-license-compliance-during-your-products-lifecycle'>Maintaining Open Source License Compliance During Your Product's Lifecycle</ulink>"
+        section in the Yocto Project Development Tasks Manual.
+    </para>
+</section>
+</chapter>
+<!--
+vim: expandtab tw=80 ts=4
+-->
diff --git a/documentation/overview-manual/overview-manual-eclipse-customization.xsl b/documentation/overview-manual/overview-manual-eclipse-customization.xsl
new file mode 100644
index 0000000000..aaf99ea1ba
--- /dev/null
+++ b/documentation/overview-manual/overview-manual-eclipse-customization.xsl
@@ -0,0 +1,35 @@
+<?xml version='1.0'?>
+<xsl:stylesheet
+        xmlns:xsl="http://www.w3.org/1999/XSL/Transform"
+        xmlns="http://www.w3.org/1999/xhtml"
+        xmlns:fo="http://www.w3.org/1999/XSL/Format"
+        version="1.0">
+
+  <xsl:import href="http://downloads.yoctoproject.org/mirror/docbook-mirror/docbook-xsl-1.76.1/eclipse/eclipse3.xsl" />
+
+<!--
+
+  <xsl:import href="../template/1.76.1/docbook-xsl-1.76.1/eclipse/eclipse3.xsl" />
+
+  <xsl:import
+          href="http://docbook.sourceforge.net/release/xsl/1.76.1/eclipse/eclipse3.xsl" />
+
+-->
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+  <xsl:param name="chunker.output.indent" select="'yes'"/>
+  <xsl:param name="chunk.quietly" select="1"/>
+  <xsl:param name="chunk.first.sections" select="1"/>
+  <xsl:param name="chunk.section.depth" select="10"/>
+  <xsl:param name="use.id.as.filename" select="1"/>
+  <xsl:param name="ulink.target" select="'_self'" />
+  <xsl:param name="base.dir" select="'html/overview-manual/'"/>
+  <xsl:param name="html.stylesheet" select="'../book.css'"/>
+  <xsl:param name="eclipse.manifest" select="0"/>
+  <xsl:param name="create.plugin.xml" select="0"/>
+  <xsl:param name="suppress.navigation" select="1"/>
+  <xsl:param name="generate.index" select="0"/>
+  <xsl:param name="chapter.autolabel" select="1" />
+  <xsl:param name="appendix.autolabel" select="1" />
+  <xsl:param name="section.autolabel" select="1" />
+  <xsl:param name="section.label.includes.component.label" select="1" />
+</xsl:stylesheet>
diff --git a/documentation/overview-manual/overview-manual-intro.xml b/documentation/overview-manual/overview-manual-intro.xml
new file mode 100644
index 0000000000..2976f7c1b6
--- /dev/null
+++ b/documentation/overview-manual/overview-manual-intro.xml
@@ -0,0 +1,111 @@
+<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
+[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >
+
+<chapter id='overview-manual-intro'>
+
+<title>The Yocto Project Overview and Concepts Manual</title>
+    <section id='overview-manual-welcome'>
+        <title>Welcome</title>
+
+        <para>
+            Welcome to the Yocto Project Overview and Concepts Manual!
+            This manual introduces the Yocto Project by providing concepts,
+            software overviews, best-known-methods (BKMs), and any other
+            high-level introductory information suitable for a new Yocto
+            Project user.
+        </para>
+
+        <para>
+            The following list describes what you can get from this manual:
+            <itemizedlist>
+                <listitem><para>
+                    <emphasis><link linkend='overview-yp'>Introducing the Yocto Project</link>:</emphasis>
+                    This chapter provides an introduction to the Yocto
+                    Project.
+                    You will learn about features and challenges of the
+                    Yocto Project, the layer model, components and tools,
+                    development methods, the Poky reference distribution,
+                    the OpenEmbedded build system workflow, and some basic
+                    Yocto terms.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><link linkend='overview-development-environment'>The Yocto Project Development Environment</link>:</emphasis>
+                    This chapter helps you get started understanding the
+                    Yocto Project development environment.
+                    You will learn about open source, development hosts,
+                    Yocto Project source repositories, workflows using Git
+                    and the Yocto Project, a Git primer, and information
+                    about licensing.
+                    </para></listitem>
+            </itemizedlist>
+        </para>
+
+        <para>
+            This manual does not give you the following:
+            <itemizedlist>
+                <listitem><para>
+                    <emphasis>Step-by-step Instructions for Development Tasks:</emphasis>
+                    Instructional procedures reside in other manuals within
+                    the Yocto Project documentation set.
+                    For example, the
+                    <ulink url='&YOCTO_DOCS_DEV_URL;'>Yocto Project Development Tasks Manual</ulink>
+                    provides examples on how to perform various development
+                    tasks.
+                    As another example, the
+                    <ulink url='&YOCTO_DOCS_SDK_URL;'>Yocto Project Application Development and the Extensible Software Development Kit (eSDK)</ulink>
+                    manual contains detailed instructions on how to install an
+                    SDK, which is used to develop applications for target
+                    hardware.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Reference Material:</emphasis>
+                    This type of material resides in an appropriate reference
+                    manual.
+                    For example, system variables are documented in the
+                    <ulink url='&YOCTO_DOCS_REF_URL;'>Yocto Project Reference Manual</ulink>.
+                    As another example, the
+                    <ulink url='&YOCTO_DOCS_BSP_URL;'>Yocto Project Board Support Package (BSP) Developer's Guide</ulink>
+                    contains reference information on BSPs.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Detailed Public Information Not Specific to the
+                    Yocto Project:</emphasis>
+                    For example, exhaustive information on how to use the
+                    Source Control Manager Git is better covered with Internet
+                    searches and official Git Documentation than through the
+                    Yocto Project documentation.
+                    </para></listitem>
+            </itemizedlist>
+        </para>
+    </section>
+
+    <section id='overview-manual-other-information'>
+        <title>Other Information</title>
+
+        <para>
+            Because this manual presents information for many different
+            topics, supplemental information is recommended for full
+            comprehension.
+            For additional introductory information on the Yocto Project, see
+            the <ulink url='&YOCTO_HOME_URL;'>Yocto Project Website</ulink>.
+            If you want to build an image with no knowledge of Yocto Project
+            as a way of quickly testing it out, see the
+            <ulink url='&YOCTO_DOCS_BRIEF_URL;'>Yocto Project Quick Build</ulink>
+            document.
+        </para>
+
+        <para>
+            For a comprehensive list of links and other documentation, see the
+            "<ulink url='&YOCTO_DOCS_REF_URL;#resources-links-and-related-documentation'>Links and Related Documentation</ulink>"
+            section in the Yocto Project Reference Manual.
+            For a paper showing how to set up and run a quick build using the
+            Yocto Project, see the
+            "<ulink url='&YOCTO_DOCS_BRIEF_URL;'>My First Yocto Project Build</ulink>"
+            paper.
+        </para>
+    </section>
+</chapter>
+<!--
+vim: expandtab tw=80 ts=4
+-->
diff --git a/documentation/overview-manual/overview-manual-style.css b/documentation/overview-manual/overview-manual-style.css
new file mode 100644
index 0000000000..97a364b125
--- /dev/null
+++ b/documentation/overview-manual/overview-manual-style.css
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+
+   Browser wrangling and typographic design by
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+
+   Customised for Poky by
+      Matthew Allum / mallum@o-hand.com
+
+   Thanks to:
+     Liam R. E. Quin
+     William Skaggs
+     Jakub Steiner
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diff --git a/documentation/overview-manual/overview-manual-yp-intro.xml b/documentation/overview-manual/overview-manual-yp-intro.xml
new file mode 100644
index 0000000000..437635842a
--- /dev/null
+++ b/documentation/overview-manual/overview-manual-yp-intro.xml
@@ -0,0 +1,1335 @@
+<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
+[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >
+
+<chapter id='overview-yp'>
+    <title>Introducing the Yocto Project</title>
+
+    <section id='what-is-the-yocto-project'>
+        <title>What is the Yocto Project?</title>
+
+        <para>
+            The Yocto Project is an open source collaboration project
+            that helps developers create custom Linux-based systems that are
+            designed for embedded products regardless of the product's hardware
+            architecture.
+            Yocto Project provides a flexible toolset and a development
+            environment that allows embedded device developers across the
+            world to collaborate through shared technologies, software stacks,
+            configurations, and best practices used to create these tailored
+            Linux images.
+        </para>
+
+        <para>
+            Thousands of developers worldwide have discovered that Yocto
+            Project provides advantages in both systems and applications
+            development, archival and management benefits, and customizations
+            used for speed, footprint, and memory utilization.
+            The project is a standard when it comes to delivering hardware
+            support and software stacks, allowing software configuration
+            and build interchange, and build and support customizations for
+            multiple hardware platforms and software stacks that can be
+            maintained and scaled.
+        </para>
+
+        <para id='yp-key-dev-elements'>
+                <imagedata fileref="figures/key-dev-elements.png" format="PNG" align='center' width="8in"/>
+        </para>
+
+        <para>
+            For further introductory information on the Yocto Project, you
+            might be interested in this
+            <ulink url='https://www.embedded.com/electronics-blogs/say-what-/4458600/Why-the-Yocto-Project-for-my-IoT-Project-'>article</ulink>
+            by Drew Moseley and in this short introductory
+            <ulink url='https://www.youtube.com/watch?v=utZpKM7i5Z4'>video</ulink>.
+        </para>
+
+        <para>
+            The remainder of this section overviews advantages and challenges
+            tied to the Yocto Project.
+        </para>
+
+        <section id='gs-features'>
+            <title>Features</title>
+
+            <para>
+                The following list describes features and advantages of the
+                Yocto Project:
+                <itemizedlist>
+                    <listitem><para>
+                        <emphasis>Widely Adopted Across the Industry:</emphasis>
+                        Semiconductor, operating system, software, and
+                        service vendors exist whose products and services
+                        adopt and support the Yocto Project.
+                        For a look at the companies involved with the Yocto
+                        Project, see the membership, associate, and
+                        participant pages on the Yocto Project home page.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Architecture Agnostic:</emphasis>
+                        Yocto Project supports Intel, ARM, MIPS, AMD, PPC
+                        and other architectures.
+                        Most ODMs, OSVs, and chip vendors create and supply
+                        BSPs that support their hardware.
+                        If you have custom silicon, you can create a BSP
+                        that supports that architecture.</para>
+
+                        <para>Aside from lots of architecture support, the
+                        Yocto Project fully supports a wide range of device
+                        emulation through the Quick EMUlator (QEMU).
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Images and Code Transfer Easily:</emphasis>
+                        Yocto Project output can easily move between
+                        architectures without moving to new development
+                        environments.
+                        Additionally, if you have used the Yocto Project to
+                        create an image or application and you find yourself
+                        not able to support it, commercial Linux vendors such
+                        as Wind River, Mentor Graphics, Timesys, and ENEA could
+                        take it and provide ongoing support.
+                        These vendors have offerings that are built using
+                        the Yocto Project.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Flexibility:</emphasis>
+                        Corporations use the Yocto Project many different ways.
+                        One example is to create an internal Linux distribution
+                        as a code base the corporation can use across multiple
+                        product groups.
+                        Through customization and layering, a project group
+                        can leverage the base Linux distribution to create
+                        a distribution that works for their product needs.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Ideal for Constrained Embedded and IoT devices:</emphasis>
+                        Unlike a full Linux distribution, you can use the
+                        Yocto Project to create exactly what you need for
+                        embedded devices.
+                        You only add the feature support or packages that you
+                        absolutely need for the device.
+                        For devices that have display hardware, you can use
+                        available system components such as X11, GTK+, Qt,
+                        Clutter, and SDL (among others) to create a rich user
+                        experience.
+                        For devices that do not have a display or where you
+                        want to use alternative UI frameworks, you can choose
+                        to not install these components.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Comprehensive Toolchain Capabilities:</emphasis>
+                        Toolchains for supported architectures satisfy most
+                        use cases.
+                        However, if your hardware supports features that are
+                        not part of a standard toolchain, you can easily
+                        customize that toolchain through specification of
+                        platform-specific tuning parameters.
+                        And, should you need to use a third-party toolchain,
+                        mechanisms built into the Yocto Project allow for that.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Mechanism Rules Over Policy:</emphasis>
+                        Focusing on mechanism rather than policy ensures that
+                        you are free to set policies based on the needs of your
+                        design instead of adopting decisions enforced by some
+                        system software provider.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Uses a Layer Model:</emphasis>
+                        The Yocto Project layer infrastructure groups related
+                        functionality into separate bundles.
+                        You can incrementally add these grouped functionalities
+                        to your project as needed.
+                        Using layers to isolate and group functionality
+                        reduces project complexity and redundancy, allows you
+                        to easily extend the system, make customizations,
+                        and keep functionality organized.
+                        </para></listitem>
+                     <listitem><para>
+                        <emphasis>Supports Partial Builds:</emphasis>
+                        You can build and rebuild individual packages as
+                        needed.
+                        Yocto Project accomplishes this through its
+                        shared-state cache (sstate) scheme.
+                        Being able to build and debug components individually
+                        eases project development.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Releases According to a Strict Schedule:</emphasis>
+                        Major releases occur on a six-month cycle predictably
+                        in October and April.
+                        The most recent two releases support point releases
+                        to address common vulnerabilities and exposures.
+                        This predictability is crucial for projects based on
+                        the Yocto Project and allows development teams to
+                        plan activities.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Rich Ecosystem of Individuals and Organizations:</emphasis>
+                        For open source projects, the value of community is
+                        very important.
+                        Support forums, expertise, and active developers who
+                        continue to push the Yocto Project forward are readily
+                        available.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Binary Reproducibility:</emphasis>
+                        The Yocto Project allows you to be very specific about
+                        dependencies and achieves very high percentages of
+                        binary reproducibility (e.g. 99.8% for
+                        <filename>core-image-minimal</filename>).
+                        When distributions are not specific about which
+                        packages are pulled in and in what order to support
+                        dependencies, other build systems can arbitrarily
+                        include packages.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>License Manifest:</emphasis>
+                        The Yocto Project provides a license manifest for
+                        review by people who need to track the use of open
+                        source licenses (e.g.legal teams).
+                        </para></listitem>
+                </itemizedlist>
+            </para>
+        </section>
+
+        <section id='gs-challenges'>
+            <title>Challenges</title>
+
+            <para>
+                The following list presents challenges you might encounter
+                when developing using the Yocto Project:
+                <itemizedlist>
+                    <listitem><para>
+                        <emphasis>Steep Learning Curve:</emphasis>
+                        The Yocto Project has a steep learning curve and has
+                        many different ways to accomplish similar tasks.
+                        It can be difficult to choose how to proceed when
+                        varying methods exist by which to accomplish a given
+                        task.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Understanding What Changes You Need to Make
+                        For Your Design Requires Some Research:</emphasis>
+                        Beyond the simple tutorial stage, understanding what
+                        changes need to be made for your particular design
+                        can require a significant amount of research and
+                        investigation.
+                        For information that helps you transition from
+                        trying out the Yocto Project to using it for your
+                        project, see the "What I wish I'd Known" and
+                        "Transitioning to a Custom Environment for Systems
+                        Development" documents on the Yocto Project website.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Project Workflow Could Be Confusing:</emphasis>
+                        The Yocto Project workflow could be confusing if you
+                        are used to traditional desktop and server software
+                        development.
+                        In a desktop development environment, mechanisms exist
+                        to easily pull and install new packages, which are
+                        typically pre-compiled binaries from servers accessible
+                        over the Internet.
+                        Using the Yocto Project, you must modify your
+                        configuration and rebuild to add additional packages.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Working in a Cross-Build Environment Can
+                        Feel Unfamiliar:</emphasis>
+                        When developing code to run on a target, compilation,
+                        execution, and testing done on the actual target
+                        can be faster than running a BitBake build on a
+                        development host and then deploying binaries to the
+                        target for test.
+                        While the Yocto Project does support development tools
+                        on the target, the additional step of integrating your
+                        changes back into the Yocto Project build environment
+                        would be required.
+                        Yocto Project supports an intermediate approach that
+                        involves making changes on the development system
+                        within the BitBake environment and then deploying only
+                        the updated packages to the target.</para>
+
+                        <para>The Yocto Project OpenEmbedded build system
+                        produces packages in standard formats (i.e. RPM,
+                        DEB, IPK, and TAR).
+                        You can deploy these packages into the running system
+                        on the target by using utilities on the target such
+                        as <filename>rpm</filename> or
+                        <filename>ipk</filename>.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Initial Build Times Can be Significant:</emphasis>
+                        Long initial build times are unfortunately unavoidable
+                        due to the large number of packages initially built
+                        from scratch for a fully functioning Linux system.
+                        Once that initial build is completed, however, the
+                        shared-state (sstate) cache mechanism Yocto Project
+                        uses keeps the system from rebuilding packages that
+                        have not been "touched" since the last build.
+                        The sstate mechanism significantly reduces times
+                        for successive builds.
+                        </para></listitem>
+                </itemizedlist>
+            </para>
+        </section>
+    </section>
+
+    <section id='the-yocto-project-layer-model'>
+        <title>The Yocto Project Layer Model</title>
+
+        <para>
+            The Yocto Project's "Layer Model" is a development model for
+            embedded and IoT Linux creation that distinguishes the
+            Yocto Project from other simple build systems.
+            The Layer Model simultaneously supports collaboration and
+            customization.
+            Layers are repositories that contain related sets of instructions
+            that tell the OpenEmbedded build system what to do.
+            You can collaborate, share, and reuse layers.
+        </para>
+
+        <para>
+            Layers can contain changes to previous instructions or settings
+            at any time.
+            This powerful override capability is what allows you to customize
+            previously supplied collaborative or community layers to suit your
+            product requirements.
+        </para>
+
+        <para>
+            You use different layers to logically separate information in your
+            build.
+            As an example, you could have BSP, GUI, distro configuration,
+            middleware, or application layers.
+            Putting your entire build into one layer limits and complicates
+            future customization and reuse.
+            Isolating information into layers, on the other hand, helps
+            simplify future customizations and reuse.
+            You might find it tempting to keep everything in one layer when
+            working on a single project.
+            However, the more modular your Metadata, the easier
+            it is to cope with future changes.
+            <note><title>Notes</title>
+                <itemizedlist>
+                    <listitem><para>
+                        Use Board Support Package (BSP) layers from silicon
+                        vendors when possible.
+                        </para></listitem>
+                    <listitem><para>
+                        Familiarize yourself with the
+                        <ulink url='https://caffelli-staging.yoctoproject.org/software-overview/layers/'>Yocto Project curated layer index</ulink>
+                        or the
+                        <ulink url='http://layers.openembedded.org/layerindex/branch/master/layers/'>OpenEmbedded layer index</ulink>.
+                        The latter contains more layers but they are less
+                        universally validated.
+                        </para></listitem>
+                    <listitem><para>
+                        Layers support the inclusion of technologies, hardware
+                        components, and software components.
+                        The Yocto Project Compatible designation provides a
+                        minimum level of standardization that contributes to a
+                        strong ecosystem.
+                        "YP Compatible" is applied to appropriate products and
+                        software components such as BSPs, other OE-compatible
+                        layers, and related open-source projects, allowing the
+                        producer to use Yocto Project badges and branding
+                        assets.
+                        </para></listitem>
+                </itemizedlist>
+            </note>
+        </para>
+
+        <para>
+            To illustrate how layers are used to keep things modular, consider
+            machine customizations.
+            These types of customizations typically reside in a special layer,
+            rather than a general layer, called a BSP Layer.
+            Furthermore, the machine customizations should be isolated from
+            recipes and Metadata that support a new GUI environment,
+            for example.
+            This situation gives you a couple of layers: one for the machine
+            configurations, and one for the GUI environment.
+            It is important to understand, however, that the BSP layer can
+            still make machine-specific additions to recipes within the GUI
+            environment layer without polluting the GUI layer itself
+            with those machine-specific changes.
+            You can accomplish this through a recipe that is a BitBake append
+            (<filename>.bbappend</filename>) file, which is described later
+            in this section.
+            <note>
+                For general information on BSP layer structure, see the
+                <ulink url='&YOCTO_DOCS_BSP_URL;#bsp'>Board Support Packages (BSP) - Developer's Guide</ulink>.
+            </note>
+        </para>
+
+        <para>
+            The
+            <ulink url='&YOCTO_DOCS_REF_URL;#source-directory'>Source Directory</ulink>
+            contains both general layers and BSP layers right out of the box.
+            You can easily identify layers that ship with a Yocto Project
+            release in the Source Directory by their names.
+            Layers typically have names that begin with the string
+            <filename>meta-</filename>.
+            <note>
+                It is not a requirement that a layer name begin with the
+                prefix <filename>meta-</filename>, but it is a commonly
+                accepted standard in the Yocto Project community.
+            </note>
+            For example, if you were to examine the
+            <ulink url='https://git.yoctoproject.org/cgit/cgit.cgi/poky/tree/'>tree view</ulink>
+            of the <filename>poky</filename> repository, you will see several
+            layers: <filename>meta</filename>,
+            <filename>meta-skeleton</filename>,
+            <filename>meta-selftest</filename>,
+            <filename>meta-poky</filename>, and
+            <filename>meta-yocto-bsp</filename>.
+            Each of these repositories represents a distinct layer.
+        </para>
+
+        <para>
+            For procedures on how to create layers, see the
+            "<ulink url='&YOCTO_DOCS_DEV_URL;#understanding-and-creating-layers'>Understanding and Creating Layers</ulink>"
+            section in the Yocto Project Development Tasks Manual.
+        </para>
+    </section>
+
+    <section id='components-and-tools'>
+        <title>Components and Tools</title>
+
+        <para>
+            The Yocto Project employs a collection of components and
+            tools used by the project itself, by project developers,
+            and by those using the Yocto Project.
+            These components and tools are open source projects and
+            metadata that are separate from the reference distribution
+            (Poky) and the OpenEmbedded build system.
+            Most of the components and tools are downloaded separately.
+        </para>
+
+        <para>
+            This section provides brief overviews of the components and
+            tools associated with the Yocto Project.
+        </para>
+
+        <section id='gs-development-tools'>
+            <title>Development Tools</title>
+
+            <para>
+                The following list consists of tools that help you develop
+                images and applications using the Yocto Project:
+                <itemizedlist>
+                    <listitem><para id='gs-crops-overview'>
+                        <emphasis>CROPS:</emphasis>
+                        <ulink url='https://git.yoctoproject.org/cgit/cgit.cgi/crops/about/'>CROPS</ulink>
+                        is an open source, cross-platform development framework
+                        that leverages
+                        <ulink url='https://www.docker.com/'>Docker Containers</ulink>.
+                        CROPS provides an easily managed, extensible environment
+                        that allows you to build binaries for a variety of
+                        architectures on Windows, Linux and Mac OS X hosts.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis><filename>devtool</filename>:</emphasis>
+                        This command-line tool is available as part of the
+                        extensible SDK (eSDK) and is its cornerstone.
+                        You can use <filename>devtool</filename> to help build,
+                        test, and package software within the eSDK.
+                        You can use the tool to optionally integrate what you
+                        build into an image built by the OpenEmbedded build
+                        system.</para>
+
+                        <para>The <filename>devtool</filename> command employs
+                        a number of sub-commands that allow you to add, modify,
+                        and upgrade recipes.
+                        As with the OpenEmbedded build system, “recipes”
+                        represent software packages within
+                        <filename>devtool</filename>.
+                        When you use <filename>devtool add</filename>, a recipe
+                        is automatically created.
+                        When you use <filename>devtool modify</filename>, the
+                        specified existing recipe is used in order to determine
+                        where to get the source code and how to patch it.
+                        In both cases, an environment is set up so that when
+                        you build the recipe a source tree that is under your
+                        control is used in order to allow you to make changes
+                        to the source as desired.
+                        By default, both new recipes and the source go into
+                        a “workspace” directory under the eSDK.
+                        The <filename>devtool upgrade</filename> command
+                        updates an existing recipe so that you can build it
+                        for an updated set of source files.</para>
+
+                        <para>You can read about the
+                        <filename>devtool</filename> workflow in the Yocto
+                        Project Application Development and Extensible
+                        Software Development Kit (eSDK) Manual in the
+                        "<ulink url='&YOCTO_DOCS_SDK_URL;#using-devtool-in-your-sdk-workflow'>Using <filename>devtool</filename> in Your SDK Workflow'</ulink>"
+                        section.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Extensible Software Development Kit (eSDK):</emphasis>
+                        The eSDK provides a cross-development toolchain and
+                        libraries tailored to the contents of a specific image.
+                        The eSDK makes it easy to add new applications and
+                        libraries to an image, modify the source for an
+                        existing component, test changes on the target
+                        hardware, and integrate into the rest of the
+                        OpenEmbedded build system.
+                        The eSDK gives you a toolchain experience supplemented
+                        with the powerful set of <filename>devtool</filename>
+                        commands tailored for the Yocto Project environment.
+                        </para>
+
+                        <para>For information on the eSDK, see the
+                        <ulink url='&YOCTO_DOCS_SDK_URL;'>Yocto Project Application Development and Extensible Software Development Kit (eSDK) Manual</ulink>.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis><trademark class='trade'>Eclipse</trademark> IDE Plug-in:</emphasis>
+                        This plug-in enables you to use the popular Eclipse
+                        Integrated Development Environment (IDE), which allows
+                        for development using the Yocto Project all within the
+                        Eclipse IDE.
+                        You can work within Eclipse to cross-compile, deploy,
+                        and execute your output into a QEMU emulation session
+                        as well as onto actual target hardware.</para>
+
+                        <para>The environment also supports performance
+                        enhancing tools that allow you to perform remote
+                        profiling, tracing, collection of power data,
+                        collection of latency data, and collection of
+                        performance data.</para>
+
+                        <para>Once you enable the plug-in, standard Eclipse
+                        functions automatically use the cross-toolchain
+                        and target system libraries.
+                        You can build applications using any of these
+                        libraries.</para>
+
+                        <para>For more information on the Eclipse plug-in,
+                        see the
+                        "<ulink url='&YOCTO_DOCS_SDK_URL;#adt-eclipse'>Working Within Eclipse</ulink>"
+                        section in the Yocto Project Application Development
+                        and the Extensible Software Development Kit (eSDK)
+                        manual.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Toaster:</emphasis>
+                        Toaster is a web interface to the Yocto Project
+                        OpenEmbedded build system.
+                        Toaster allows you to configure, run, and view
+                        information about builds.
+                        </para></listitem>
+                </itemizedlist>
+            </para>
+        </section>
+
+        <section id='gs-production-tools'>
+            <title>Production Tools</title>
+
+            <para>
+                The following list consists of tools that help production
+                related activities using the Yocto Project:
+                <itemizedlist>
+                    <listitem><para>
+                        <emphasis>Auto Upgrade Helper:</emphasis>
+                        This utility when used in conjunction with the
+                        OpenEmbedded build system (BitBake and OE-Core)
+                        automatically generates upgrades for recipes that
+                        are based on new versions of the recipes published
+                        upstream.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Recipe Reporting System:</emphasis>
+                        The Recipe Reporting System tracks recipe versions
+                        available for Yocto Project.
+                        The main purpose of the system is to help you
+                        manage the recipes you maintain and to offer a dynamic
+                        overview of the project.
+                        The Recipe Reporting System is built on top
+                        the of OpenEmbedded Metadata Index, which is a website
+                        that indexes layers for the OpenEmbedded build system.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Patchwork:</emphasis>
+                        <ulink url='http://jk.ozlabs.org/projects/patchwork/'>Patchwork</ulink>
+                        is a fork of a project originally started by
+                        <ulink url='http://ozlabs.org/'>OzLabs</ulink>.
+                        The project is a web-based tracking system designed
+                        to streamline the process of bringing contributions
+                        into a project.
+                        The Yocto Project uses Patchwork as an organizational
+                        tool to handle patches, which number in the thousands
+                        for every release.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>AutoBuilder:</emphasis>
+                        AutoBuilder is a project that automates build tests
+                        and quality assurance (QA).
+                        By using the public AutoBuilder, anyone can determine
+                        the status of the current "master" branch of Poky.
+                        </para>
+
+                        <para>A goal of the Yocto Project is to lead the
+                        open source industry with a project that automates
+                        testing and QA procedures.
+                        In doing so, the project encourages a development
+                        community that publishes QA and test plans, publicly
+                        demonstrates QA and test plans, and encourages
+                        development of tools that automate and test and QA
+                        procedures for the benefit of the development
+                        community.</para>
+
+                        <para>You can learn more about the AutoBuilder used
+                        by the Yocto Project
+                        <ulink url='&YOCTO_AB_URL;'>here</ulink>.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Cross-Prelink:</emphasis>
+                        Prelinking is the process of pre-computing the load
+                        addresses and link tables generated by the dynamic
+                        linker as compared to doing this at runtime.
+                        Doing this ahead of time results in performance
+                        improvements when the application is launched and
+                        reduced memory usage for libraries shared by many
+                        applications.</para>
+
+                        <para>Historically, cross-prelink is a variant of
+                        prelink, which was conceived by
+                        <ulink url='http://people.redhat.com/jakub/prelink.pdf'>Jakub Jel&iacute;nek</ulink>
+                        a number of years ago.
+                        Both prelink and cross-prelink are maintained in the
+                        same repository albeit on separate branches.
+                        By providing an emulated runtime dynamic linker
+                        (i.e. <filename>glibc</filename>-derived
+                        <filename>ld.so</filename> emulation), the
+                        cross-prelink project extends the prelink software’s
+                        ability to prelink a sysroot environment.
+                        Additionally, the cross-prelink software enables the
+                        ability to work in sysroot style environments.</para>
+
+                        <para>The dynamic linker determines standard load
+                        address calculations based on a variety of factors
+                        such as mapping addresses, library usage, and library
+                        function conflicts.
+                        The prelink tool uses this information, from the
+                        dynamic linker, to determine unique load addresses
+                        for executable and linkable format (ELF) binaries
+                        that are shared libraries and dynamically linked.
+                        The prelink tool modifies these ELF binaries with the
+                        pre-computed information.
+                        The result is faster loading and often lower memory
+                        consumption because more of the library code can
+                        be re-used from shared Copy-On-Write (COW) pages.
+                        </para>
+
+                        <para>The original upstream prelink project only
+                        supports running prelink on the end target device
+                        due to the reliance on the target device’s dynamic
+                        linker.
+                        This restriction causes issues when developing a
+                        cross-compiled system.
+                        The cross-prelink adds a synthesized dynamic loader
+                        that runs on the host, thus permitting cross-prelinking
+                        without ever having to run on a read-write target
+                        filesystem.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Pseudo:</emphasis>
+                        Pseudo is the Yocto Project implementation of
+                        <ulink url='http://man.he.net/man1/fakeroot'>fakeroot</ulink>,
+                        which is used to run commands in an environment
+                        that seemingly has root privileges.</para>
+
+                        <para>During a build, it can be necessary to perform
+                        operations that require system administrator
+                        privileges.
+                        For example, file ownership or permissions might need
+                        definition.
+                        Pseudo is a tool that you can either use directly or
+                        through the environment variable
+                        <filename>LD_PRELOAD</filename>.
+                        Either method allows these operations to succeed as
+                        if system administrator privileges exist even
+                        when they do not.</para>
+
+                        <para>You can read more about Pseudo in the
+                        "<ulink url='&YOCTO_DOCS_GS_URL;#fakeroot-and-pseudo'>Fakeroot and Pseudo</ulink>"
+                        section of the Yocto Project Overview and Concepts
+                        Manual.
+                        </para></listitem>
+                </itemizedlist>
+            </para>
+        </section>
+
+        <section id='gs-openembedded-build-system'>
+            <title>Open-Embedded Build System Components</title>
+
+            <para>
+                The following list consists of components associated with the
+                Open-Embedded build system:
+                <itemizedlist>
+                    <listitem><para>
+                        <emphasis>BitBake:</emphasis>
+                        BitBake is a core component of the Yocto Project and is
+                        used by the OpenEmbedded build system to build images.
+                        While BitBake is key to the build system, BitBake
+                        is maintained separately from the Yocto Project.</para>
+
+                        <para>BitBake is a generic task execution engine that
+                        allows shell and Python tasks to be run efficiently
+                        and in parallel while working within complex inter-task
+                        dependency constraints.
+                        In short, BitBake is a build engine that works
+                        through recipes written in a specific format in order
+                        to perform sets of tasks.</para>
+
+                        <para>You can learn more about BitBake in the
+                        <ulink url='&YOCTO_DOCS_BB_URL;'>BitBake User Manual</ulink>.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>OpenEmbedded-Core:</emphasis>
+                        OpenEmbedded-Core (OE-Core) is a common layer of
+                        metadata (i.e. recipes, classes, and associated files)
+                        used by OpenEmbedded-derived systems, which includes
+                        the Yocto Project.
+                        The Yocto Project and the OpenEmbedded Project both
+                        maintain the OpenEmbedded-Core.
+                        You can find the OE-Core metadata in the Yocto
+                        Project
+                        <ulink url='&YOCTO_DOCS_GS_URL;#source-repositories'>Source Repositories</ulink>
+                        <ulink url='https://git.yoctoproject.org/cgit/cgit.cgi/poky/tree/meta'>here</ulink>.
+                        </para>
+
+                        <para>Historically, the Yocto Project integrated the
+                        OE-Core metadata throughout the Yocto Project
+                        source repository reference system (Poky).
+                        After Yocto Project Version 1.0, the Yocto Project
+                        and OpenEmbedded agreed to work together and share a
+                        common core set of metadata (OE-Core), which contained
+                        much of the functionality previously found in Poky.
+                        This collaboration achieved a long-standing
+                        OpenEmbedded objective for having a more tightly
+                        controlled and quality-assured core.
+                        The results also fit well with the Yocto Project
+                        objective of achieving a smaller number of fully
+                        featured tools as compared to many different ones.
+                        </para>
+
+                        <para>Sharing a core set of metadata results in Poky
+                        as an integration layer on top of OE-Core.
+                        You can see that in this
+                        <link linkend='yp-key-dev-elements'>figure</link>.
+                        The Yocto Project combines various components such as
+                        BitBake, OE-Core, script “glue”, and documentation
+                        for its build system.
+                        </para></listitem>
+                </itemizedlist>
+            </para>
+        </section>
+
+        <section id='gs-reference-distribution-poky'>
+            <title>Reference Distribution (Poky)</title>
+
+            <para>
+                Poky is the Yocto Project reference distribution.
+                It contains the OpenEmbedded build system (BitBake and OE-Core)
+                as well as a set of metadata to get you started building your
+                own distribution.
+                See the
+                <link linkend='what-is-the-yocto-project'>figure</link> in
+                "What is the Yocto Project?" section for an illustration
+                that shows Poky and its relationship with other parts of the
+                Yocto Project.</para>
+
+                <para>To use the Yocto Project tools and components, you
+                can download (<filename>clone</filename>) Poky and use it
+                to bootstrap your own distribution.
+                <note>
+                    Poky does not contain binary files.
+                    It is a working example of how to build your own custom
+                    Linux distribution from source.
+                </note>
+                You can read more about Poky in the
+                "<link linkend='reference-embedded-distribution'>Reference Embedded Distribution (Poky)</link>"
+                section.
+            </para>
+        </section>
+
+        <section id='gs-packages-for-finished-targets'>
+            <title>Packages for Finished Targets</title>
+
+            <para>
+                The following lists components associated with packages
+                for finished targets:
+                <itemizedlist>
+                    <listitem><para>
+                        <emphasis>Matchbox:</emphasis>
+                        Matchbox is an Open Source, base environment for the
+                        X Window System running on non-desktop, embedded
+                        platforms such as handhelds, set-top boxes, kiosks,
+                        and anything else for which screen space, input
+                        mechanisms, or system resources are limited.</para>
+
+                        <para>Matchbox consists of a number of interchangeable
+                        and optional applications that you can tailor to a
+                        specific, non-desktop platform to enhance usability
+                        in constrained environments.</para>
+
+                        <para>You can find the Matchbox source in its
+                        <ulink url='http://git.yoctoproject.org/cgit/cgit.cgi'>repository</ulink>
+                        listed in the Yocto Project
+                        <ulink url='&YOCTO_DOCS_GS_URL;#source-repositories'>Source Repositories</ulink>.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Opkg</emphasis>
+                        Open PacKaGe management (opkg) is a lightweight
+                        package management system based on the itsy package
+                        (ipkg) management system.
+                        Opkg is written in C and resembles Advanced Package
+                        Tool (APT) and Debian Package (dpkg) in operation.
+                        </para>
+
+                        <para>Opkg is intended for use on embedded Linux
+                        devices and is used in this capacity in the
+                        <ulink url='http://www.openembedded.org/wiki/Main_Page'>OpenEmbedded</ulink>
+                        and
+                        <ulink url='https://openwrt.org/'>OpenWrt</ulink>
+                        projects, as well as the Yocto Project.
+                        <note>
+                            As best it can, opkg maintains backwards
+                            compatibility with ipkg and conforms to a subset
+                            of Debian’s policy manual regarding control files.
+                        </note>
+                        </para></listitem>
+                </itemizedlist>
+            </para>
+        </section>
+
+        <section id='gs-archived-components'>
+            <title>Archived Components</title>
+
+            <para>
+                The Build Appliance is a virtual machine image that enables
+                you to build and boot a custom embedded Linux image with
+                the Yocto Project using a non-Linux development system.
+            </para>
+
+            <para>
+                Historically, the Build Appliance was the second of three
+                methods by which you could use the Yocto Project on a system
+                that was not native to Linux.
+                <orderedlist>
+                    <listitem><para>
+                        <emphasis>Hob:</emphasis>
+                        Hob, which is now deprecated and is no longer available
+                        since the 2.1 release of the Yocto Project provided
+                        a rudimentary, GUI-based interface to the Yocto
+                        Project.
+                        Toaster has fully replaced Hob.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>Build Appliance:</emphasis>
+                        Post Hob, the Build Appliance became available.
+                        It was never recommended that you use the Build
+                        Appliance as a day-to-day production development
+                        environment with the Yocto Project.
+                        Build Appliance was useful as a way to try out
+                        development in the Yocto Project environment.
+                        </para></listitem>
+                    <listitem><para>
+                        <emphasis>CROPS:</emphasis>
+                        The final and best solution available now for
+                        developing using the Yocto Project on a system
+                        not native to Linux is with
+                        <link linkend='gs-crops-overview'>CROPS</link>.
+                        </para></listitem>
+                </orderedlist>
+            </para>
+        </section>
+    </section>
+
+    <section id='gs-development-methods'>
+        <title>Development Methods</title>
+
+        <para>
+            The Yocto Project development environment usually involves a
+            <ulink url='&YOCTO_DOCS_REF_URL;#hardware-build-system-term'>Build Host</ulink>
+            and target hardware.
+            You use the Build Host to build images and develop applications,
+            while you use the target hardware to test deployed software.
+        </para>
+
+        <para>
+            This section provides an introduction to the choices or
+            development methods you have when setting up your Build Host.
+            Depending on the your particular workflow preference and the
+            type of operating system your Build Host runs, several choices
+            exist that allow you to use the Yocto Project.
+            <note>
+                For additional detail about the Yocto Project development
+                environment, see the
+                "<link linkend='overview-development-environment'>The Yocto Project Development Environment</link>"
+                chapter.
+            </note>
+            <itemizedlist>
+                <listitem><para>
+                    <emphasis>Native Linux Host:</emphasis>
+                    By far the best option for a Build Host.
+                    A system running Linux as its native operating system
+                    allows you to develop software by directly using the
+                    <ulink url='&YOCTO_DOCS_REF_URL;#bitbake-term'>BitBake</ulink>
+                    tool.
+                    You can accomplish all aspects of development from a
+                    familiar shell of a supported Linux distribution.</para>
+
+                    <para>For information on how to set up a Build Host on
+                    a system running Linux as its native operating system,
+                    see the
+                    "<ulink url='&YOCTO_DOCS_DEV_URL;#setting-up-a-native-linux-host'>Setting Up a Native Linux Host</ulink>"
+                    section in the Yocto Project Development Tasks Manual.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>CROss PlatformS (CROPS):</emphasis>
+                    Typically, you use
+                    <ulink url='https://git.yoctoproject.org/cgit/cgit.cgi/crops/about/'>CROPS</ulink>,
+                    which leverages
+                    <ulink url='https://www.docker.com/'>Docker Containers</ulink>,
+                    to set up a Build Host that is not running Linux (e.g.
+                    <trademark class='registered'>Microsoft</trademark>
+                    <trademark class='trademark'>Windows</trademark>
+                    or
+                    <trademark class='registered'>macOS</trademark>).
+                    <note>
+                        You can, however, use CROPS on a Linux-based system.
+                    </note>
+                    CROPS is an open source, cross-platform development
+                    framework that provides an easily managed, extensible
+                    environment for building binaries targeted for a variety
+                    of architectures on Windows, macOS, or Linux hosts.
+                    Once the Build Host is set up using CROPS, you can prepare
+                    a shell environment to mimic that of a shell being used
+                    on a system natively running Linux.</para>
+
+                    <para>For information on how to set up a Build Host with
+                    CROPS, see the
+                    "<ulink url='&YOCTO_DOCS_DEV_URL;#setting-up-to-use-crops'>Setting Up to Use CROss PlatformS (CROPS)</ulink>"
+                    section in the Yocto Project Development Tasks Manual.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Toaster:</emphasis>
+                    Regardless of what your Build Host is running, you can
+                    use Toaster to develop software using the Yocto Project.
+                    Toaster is a web interface to the Yocto Project's
+                    OpenEmbedded build system.
+                    The interface enables you to configure and run your
+                    builds.
+                    Information about builds is collected and stored in a
+                    database.
+                    You can use Toaster to configure and start builds on
+                    multiple remote build servers.</para>
+
+                    <para>For information about and how to use Toaster,
+                    see the
+                    <ulink url='&YOCTO_DOCS_TOAST_URL;'>Toaster User Manual</ulink>.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis><trademark class='trade'>Eclipse</trademark> IDE:</emphasis>
+                    If your Build Host supports and runs the popular
+                    Eclipse IDE, you can install the Yocto Project Eclipse
+                    plug-in and use the Yocto Project to develop software.
+                    The plug-in integrates the Yocto Project functionality
+                    into Eclipse development practices.</para>
+
+                    <para>For information about how to install and use the
+                    Yocto Project Eclipse plug-in, see the
+                    "<ulink url='&YOCTO_DOCS_SDK_URL;#sdk-eclipse-project'>Developing Applications Using Eclipse</ulink>"
+                    section in the Yocto Project Application Development and
+                    the Extensible Software Development Kit (eSDK) Manual.
+                    </para></listitem>
+            </itemizedlist>
+        </para>
+    </section>
+
+    <section id='reference-embedded-distribution'>
+        <title>Reference Embedded Distribution (Poky)</title>
+
+        <para>
+            "Poky", which is pronounced <emphasis>Pock</emphasis>-ee, is the
+            name of the Yocto Project's reference distribution or Reference OS
+            Kit.
+            Poky contains the
+            <ulink url='&YOCTO_DOCS_REF_URL;#build-system-term'>OpenEmbedded Build System</ulink>
+            build system
+            (<ulink url='&YOCTO_DOCS_REF_URL;#bitbake-term'>BitBake</ulink> and
+            <ulink url='&YOCTO_DOCS_REF_URL;#oe-core'>OpenEmbedded-Core</ulink>)
+            as well as a set of
+            <ulink url='&YOCTO_DOCS_REF_URL;#metadata'>metadata</ulink> to get
+            you started building your own distro.
+            In other words, Poky is a base specification of the functionality
+            needed for a typical embedded system as well as the components
+            from the Yocto Project that allow you to build a distribution into
+            a usable binary image.
+        </para>
+
+        <para>
+            Poky is a combined repository of BitBake, OpenEmbedded-Core
+            (which is found in <filename>meta</filename>),
+            <filename>meta-poky</filename>,
+            <filename>meta-yocto-bsp</filename>, and documentation provided
+            all together and known to work well together.
+            You can view these items that make up the Poky repository in the
+            <ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi/poky/tree/'>Source Repositories</ulink>.
+            <note>
+                If you are interested in all the contents of the
+                <filename>poky</filename> Git repository, see the
+                "<ulink url='&YOCTO_DOCS_REF_URL;#structure-core'>Top-Level Core Components</ulink>"
+                section in the Yocto Project Reference Manual.
+            </note>
+        </para>
+
+        <para id='gs-poky-reference-distribution'>
+            The following figure illustrates what generally comprises Poky:
+            <imagedata fileref="figures/poky-reference-distribution.png" format="PNG" align='center' width="8in"/>
+            <itemizedlist>
+                <listitem><para>
+                    BitBake is a task executor and scheduler that is the heart of
+                    the OpenEmbedded build system.
+                    </para></listitem>
+                <listitem><para>
+                    <filename>meta-poky</filename>, which is Poky-specific
+                    metadata.
+                    </para></listitem>
+                <listitem><para>
+                    <filename>meta-yocto-bsp</filename>, which is Yocto
+                    Project-specific Board Support Packages (BSPs).
+                    </para></listitem>
+                <listitem><para>
+                    OpenEmbedded-Core (OE-Core) metadata, which includes
+                    shared configurations, global variable definitions,
+                    shared classes, packaging, and recipes.
+                    Classes define the encapsulation and inheritance of build
+                    logic.
+                    Recipes are the logical units of software and images
+                    to be built.
+                    </para></listitem>
+                <listitem><para>
+                    Documentation, which contains the Yocto Project source
+                    files used to make the set of user manuals.
+                    </para></listitem>
+            </itemizedlist>
+            <note>
+                While Poky is a "complete" distribution specification and is
+                tested and put through QA, you cannot use it as a product
+                "out of the box" in its current form.
+            </note>
+        </para>
+
+        <para>
+            To use the Yocto Project tools, you can use Git to clone (download)
+            the Poky repository then use your local copy of the reference
+            distribution to bootstrap your own distribution.
+            <note>
+                Poky does not contain binary files.
+                It is a working example of how to build your own custom Linux distribution
+                from source.
+            </note>
+        </para>
+
+        <para>
+            Poky has a regular, well established, six-month release cycle
+            under its own version.
+            Major releases occur at the same time major releases (point
+            releases) occur for the Yocto Project, which are typically in the
+            Spring and Fall.
+            For more information on the Yocto Project release schedule and
+            cadence, see the
+            "<ulink url='&YOCTO_DOCS_REF_URL;#ref-release-process'>Yocto Project Releases and the Stable Release Process</ulink>"
+            chapter in the Yocto Project Reference Manual.
+        </para>
+
+        <para>
+            Much has been said about Poky being a "default configuration."
+            A default configuration provides a starting image footprint.
+            You can use Poky out of the box to create an image ranging from a
+            shell-accessible minimal image all the way up to a Linux
+            Standard Base-compliant image that uses a GNOME Mobile and
+            Embedded (GMAE) based reference user interface called Sato.
+        </para>
+
+        <para>
+            One of the most powerful properties of Poky is that every aspect
+            of a build is controlled by the metadata.
+            You can use metadata to augment these base image types by
+            adding metadata layers that extend functionality.
+            These layers can provide, for example, an additional software
+            stack for an image type, add a board support package (BSP) for
+            additional hardware, or even create a new image type.
+        </para>
+
+        <para>
+            Metadata is loosely grouped into configuration files or package
+            recipes.
+            A recipe is a collection of non-executable metadata used by
+            BitBake to set variables or define additional build-time tasks.
+            A recipe contains fields such as the recipe description, the recipe
+            version, the license of the package and the upstream source
+            repository.
+            A recipe might also indicate that the build process uses autotools,
+            make, distutils or any other build process, in which case the basic
+            functionality can be defined by the classes it inherits from
+            the OE-Core layer's class definitions in
+            <filename>./meta/classes</filename>.
+            Within a recipe you can also define additional tasks as well as
+            task prerequisites.
+            Recipe syntax through BitBake also supports both
+            <filename>_prepend</filename> and <filename>_append</filename>
+            operators as a method of extending task functionality.
+            These operators inject code into the beginning or end of a task.
+            For information on these BitBake operators, see the
+            "<ulink url='&YOCTO_DOCS_BB_URL;#appending-and-prepending-override-style-syntax'>Appending and Prepending (Override Style Syntax)</ulink>"
+            section in the BitBake User's Manual.
+        </para>
+    </section>
+
+    <section id='openembedded-build-system-workflow'>
+        <title>The OpenEmbedded Build System Workflow</title>
+
+        <para>
+            The OpenEmbedded build system uses a "workflow" to accomplish
+            image and SDK generation.
+            The following figure overviews that workflow:
+            <imagedata fileref="figures/YP-flow-diagram.png"
+                format="PNG" align='center' width="8in"/>
+            Following is a brief summary of the "workflow":
+            <orderedlist>
+                <listitem><para>
+                    Developers specify architecture, policies, patches and
+                    configuration details.
+                    </para></listitem>
+                <listitem><para>
+                    The build system fetches and downloads the source code
+                    from the specified location.
+                    The build system supports standard methods such as tarballs
+                    or source code repositories systems such as Git.
+                    </para></listitem>
+                <listitem><para>
+                    Once downloaded, the build system extracts the sources
+                    into a local work area where patches are applied and
+                    common steps for configuring and compiling the software
+                    are run.
+                    </para></listitem>
+                <listitem><para>
+                    The build system then installs the software into a
+                    temporary staging area where the binary package format you
+                    select (DEB, RPM, or IPK) is used to roll up the software.
+                    </para></listitem>
+                <listitem><para>
+                    Different QA and sanity checks run throughout entire
+                    build process.
+                    </para></listitem>
+                <listitem><para>
+                    After the binaries are created, the build system
+                    generates a binary package feed that is used to create
+                    the final root file image.
+                    </para></listitem>
+                <listitem><para>
+                    The build system generates the file system image and a
+                    customized Extensible SDK (eSDSK) for application
+                    development in parallel.
+                    </para></listitem>
+            </orderedlist>
+        </para>
+
+        <para>
+            For a very detailed look at this workflow, see the
+            "<ulink url='&YOCTO_DOCS_GS_URL;#development-concepts'>Development Concepts</ulink>"
+            section in the Yocto Project Overview and Concepts Manual.
+        </para>
+    </section>
+
+
+    <section id='some-basic-terms'>
+        <title>Some Basic Terms</title>
+
+        <para>
+            It helps to understand some basic fundamental terms when
+            learning the Yocto Project.
+            Although a list of terms exists in the
+            "<ulink url='&YOCTO_DOCS_REF_URL;#ref-terms'>Yocto Project Terms</ulink>"
+            section of the Yocto Project Reference Manual, this section
+            provides the definitions of some terms helpful for getting started:
+            <itemizedlist>
+                <listitem><para>
+                    <emphasis>Configuration Files:</emphasis>
+                    Files that hold global definitions of variables,
+                    user-defined variables, and hardware configuration
+                    information.
+                    These files tell the OpenEmbedded build system what to
+                    build and what to put into the image to support a
+                    particular platform.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Extensible Software Development Kit (eSDK):</emphasis>
+                    A custom SDK for application developers.
+                    This eSDK allows developers to incorporate their library
+                    and programming changes back into the image to make
+                    their code available to other application developers.
+                    For information on the eSDK, see the
+                    <ulink url='&YOCTO_DOCS_SDK_URL;'>Yocto Project Application Development and Extensible Software Development Kit (eSDK)</ulink>
+                    manual.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Layer:</emphasis>
+                    A collection of related recipes.
+                    Layers allow you to consolidate related metadata to
+                    customize your build.
+                    Layers also isolate information used when building
+                    for multiple architectures.
+                    Layers are hierarchical in their ability to override
+                    previous specifications.
+                    You can include any number of available layers from the
+                    Yocto Project and customize the build by adding your
+                    layers after them.
+                    You can search the Layer Index for layers used within
+                    Yocto Project.</para>
+
+                    <para>For more detailed information on layers, see the
+                    "<ulink url='&YOCTO_DOCS_DEV_URL;#understanding-and-creating-layers'>Understanding and Creating Layers</ulink>"
+                    section in the Yocto Project Development Tasks Manual.
+                    For a discussion specifically on BSP Layers, see the
+                    "<ulink url='&YOCTO_DOCS_BSP_URL;#bsp-layers'>BSP Layers</ulink>"
+                    section in the Yocto Project Board Support Packages (BSP)
+                    Developer's Guide.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Metadata:</emphasis>
+                    A key element of the Yocto Project is the Metadata that
+                    is used to construct a Linux distribution and is contained
+                    in the files that the
+                    <link linkend='gs-term-openembedded-build-system'>OpenEmbedded build system</link> parses
+                    when building an image.
+                    In general, Metadata includes recipes, configuration
+                    files, and other information that refers to the build
+                    instructions themselves, as well as the data used to
+                    control what things get built and the effects of the
+                    build.
+                    Metadata also includes commands and data used to
+                    indicate what versions of software are used, from
+                    where they are obtained, and changes or additions to the
+                    software itself (patches or auxiliary files) that
+                    are used to fix bugs or customize the software for use
+                    in a particular situation.
+                    OpenEmbedded-Core is an important set of validated
+                    metadata.
+                    </para></listitem>
+                <listitem><para id='gs-term-openembedded-build-system'>
+                    <emphasis>OpenEmbedded Build System:</emphasis>
+                    The terms "BitBake" and "build system" are sometimes
+                    used for the OpenEmbedded Build System.</para>
+
+                    <para>BitBake is a task scheduler and execution engine
+                    that parses instructions (i.e. recipes) and configuration
+                    data.
+                    After a parsing phase, BitBake creates a dependency tree
+                    to order the compilation, schedules the compilation of
+                    the included code, and finally executes the building
+                    of the specified custom Linux image (distribution).
+                    BitBake is similar to the <filename>make</filename>
+                    tool.</para>
+
+                    <para>During a build process, the build system tracks
+                    dependencies and performs a native or cross-compilation
+                    of the package.
+                    As a first step in a cross-build setup, the framework
+                    attempts to create a cross-compiler toolchain
+                    (i.e. Extensible SDK) suited for the target platform.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>OpenEmbedded-Core (OE-Core):</emphasis>
+                    OE-Core is metadata comprised of foundation recipes,
+                    classes, and associated files that are meant to be
+                    common among many different OpenEmbedded-derived systems,
+                    including the Yocto Project.
+                    OE-Core is a curated subset of an original repository
+                    developed by the OpenEmbedded community that has been
+                    pared down into a smaller, core set of continuously
+                    validated recipes.
+                    The result is a tightly controlled and quality-assured
+                    core set of recipes.</para>
+
+                    <para>You can see the Metadata in the
+                    <filename>meta</filename> directory of the Yocto Project
+                    <ulink url='http://git.yoctoproject.org/cgit/cgit.cgi'>Source Repositories</ulink>.
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Packages:</emphasis>
+                    In the context of the Yocto Project, this term refers to a
+                    recipe's packaged output produced by BitBake (i.e. a
+                    "baked recipe").
+                    A package is generally the compiled binaries produced from the
+                    recipe's sources.
+                    You "bake" something by running it through BitBake.</para>
+
+                    <para>It is worth noting that the term "package" can,
+                    in general, have subtle meanings.
+                    For example, the packages referred to in the
+                    "<ulink url='&YOCTO_DOCS_REF_URL;#required-packages-for-the-host-development-system'>Required Packages for the Host Development System</ulink>"
+                    section in the Yocto Project Reference Manual are compiled
+                    binaries that, when installed, add functionality to your
+                    Linux distribution.</para>
+
+                    <para>Another point worth noting is that historically within
+                    the Yocto Project, recipes were referred to as packages - thus,
+                    the existence of several BitBake variables that are seemingly
+                    mis-named,
+                    (e.g. <ulink url='&YOCTO_DOCS_REF_URL;#var-PR'><filename>PR</filename></ulink>,
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PV'><filename>PV</filename></ulink>,
+                    and
+                    <ulink url='&YOCTO_DOCS_REF_URL;#var-PE'><filename>PE</filename></ulink>).
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Poky:</emphasis>
+                    Poky is a reference embedded distribution and a reference
+                    test configuration.
+                    Poky provides the following:
+                    <itemizedlist>
+                        <listitem><para>
+                            A base-level functional distro used to illustrate
+                            how to customize a distribution.
+                            </para></listitem>
+                        <listitem><para>
+                            A means by which to test the Yocto Project
+                            components (i.e. Poky is used to validate
+                            the Yocto Project).
+                            </para></listitem>
+                        <listitem><para>
+                            A vehicle through which you can download
+                            the Yocto Project.
+                            </para></listitem>
+                    </itemizedlist>
+                    Poky is not a product level distro.
+                    Rather, it is a good starting point for customization.
+                    <note>
+                        Poky is an integration layer on top of OE-Core.
+                    </note>
+                    </para></listitem>
+                <listitem><para>
+                    <emphasis>Recipe:</emphasis>
+                    The most common form of metadata.
+                    A recipe contains a list of settings and tasks
+                    (i.e. instructions) for building packages that are then
+                    used to build the binary image.
+                    A recipe describes where you get source code and which
+                    patches to apply.
+                    Recipes describe dependencies for libraries or for other
+                    recipes as well as configuration and compilation options.
+                    Related recipes are consolidated into a layer.
+                    </para></listitem>
+            </itemizedlist>
+        </para>
+    </section>
+</chapter>
+<!--
+vim: expandtab tw=80 ts=4
+-->
diff --git a/documentation/overview-manual/overview-manual.xml b/documentation/overview-manual/overview-manual.xml
new file mode 100644
index 0000000000..f04fbaf3bd
--- /dev/null
+++ b/documentation/overview-manual/overview-manual.xml
@@ -0,0 +1,108 @@
+<!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
+"http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd"
+[<!ENTITY % poky SYSTEM "../poky.ent"> %poky; ] >
+
+<book id='overview-manual' lang='en'
+      xmlns:xi="http://www.w3.org/2003/XInclude"
+      xmlns="http://docbook.org/ns/docbook"
+      >
+    <bookinfo>
+
+        <mediaobject>
+            <imageobject>
+                <imagedata fileref='figures/overview-manual-title.png'
+                    format='SVG'
+                    align='left' scalefit='1' width='100%'/>
+            </imageobject>
+        </mediaobject>
+
+        <title>
+            Yocto Project Overview and Concepts Manual
+        </title>
+
+        <authorgroup>
+            <author>
+                <firstname>Scott</firstname> <surname>Rifenbark</surname>
+                <affiliation>
+                    <orgname>Scotty's Documentation Services, INC</orgname>
+                </affiliation>
+                <email>srifenbark@gmail.com</email>
+            </author>
+        </authorgroup>
+
+        <revhistory>
+            <revision>
+                <revnumber>2.5</revnumber>
+                <date>April 2018</date>
+                <revremark>The initial document released with the Yocto Project 2.5 Release.</revremark>
+            </revision>
+        </revhistory>
+
+    <copyright>
+     <year>&COPYRIGHT_YEAR;</year>
+      <holder>Linux Foundation</holder>
+    </copyright>
+
+    <legalnotice>
+      <para>
+          Permission is granted to copy, distribute and/or modify this document under
+          the terms of the <ulink type="http" url="http://creativecommons.org/licenses/by-sa/2.0/uk/">
+          Creative Commons Attribution-Share Alike 2.0 UK: England &amp; Wales</ulink> as published by
+          Creative Commons.
+      </para>
+           <note><title>Manual Notes</title>
+               <itemizedlist>
+                   <listitem><para>
+                       This version of the
+                       <emphasis>Yocto Project Overview and Concepts Manual</emphasis>
+                       is for the &YOCTO_DOC_VERSION; release of the
+                       Yocto Project.
+                       To be sure you have the latest version of the manual
+                       for this release, go to the
+                       <ulink url='&YOCTO_HOME_URL;/documentation'>Yocto Project documentation page</ulink>
+                       and select the manual from that site.
+                       Manuals from the site are more up-to-date than manuals
+                       derived from the Yocto Project released TAR files.
+                       </para></listitem>
+                   <listitem><para>
+                       If you located this manual through a web search, the
+                       version of the manual might not be the one you want
+                       (e.g. the search might have returned a manual much
+                       older than the Yocto Project version with which you
+                       are working).
+                       You can see all Yocto Project major releases by
+                       visiting the
+                       <ulink url='&YOCTO_WIKI_URL;/wiki/Releases'>Releases</ulink>
+                       page.
+                       If you need a version of this manual for a different
+                       Yocto Project release, visit the
+                       <ulink url='&YOCTO_HOME_URL;/documentation'>Yocto Project documentation page</ulink>
+                       and select the manual set by using the
+                       "ACTIVE RELEASES DOCUMENTATION" or "DOCUMENTS ARCHIVE"
+                       pull-down menus.
+                       </para></listitem>
+                   <listitem><para>
+                       To report any inaccuracies or problems with this
+                       manual, send an email to the Yocto Project
+                       discussion group at
+                       <filename>yocto@yoctoproject.com</filename> or log into
+                       the freenode <filename>#yocto</filename> channel.
+                       </para></listitem>
+               </itemizedlist>
+           </note>
+    </legalnotice>
+
+    </bookinfo>
+
+    <xi:include href="overview-manual-intro.xml"/>
+
+    <xi:include href="overview-manual-yp-intro.xml"/>
+
+    <xi:include href="overview-manual-development-environment.xml"/>
+
+    <xi:include href="overview-manual-concepts.xml" />
+
+</book>
+<!--
+vim: expandtab tw=80 ts=4
+-->