generic-poky/documentation/yocto-project-qs/yocto-project-qs.xml

<!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; ] >

<article id='intro'>
   <imagedata fileref="figures/yocto-project-trans.png" width="6in" depth="1in" align="right" scale="25" />

<section id='fake-title'>
    <title>The Yocto Project Quick Start</title>
    <para>Copyright &copy; &COPYRIGHT_YEAR; Linux Foundation</para>
</section>

<section id='welcome'>
    <title>Welcome!</title>
    <para>
        Welcome to the Yocto Project!  
        The Yocto Project is an open-source collaboration project focused on embedded Linux
        developers.
        Among other things, the Yocto Project uses a build system based on the Poky project
        to construct complete Linux images.
        The Poky project, in turn, draws from and contributes back to the OpenEmbedded project.
    </para>

    <para>
        If you don't have a system that runs Linux and you want to give the Yocto Project a test run, 
        you might consider using the Yocto Project Build Appliance.
        The Build Appliance allows you to build and boot a custom embedded Linux image with the Yocto 
        Project using a non-Linux development system.  
        See the <ulink url='http://www.yoctoproject.org/documentation/build-appliance'>Yocto 
        Project Build Appliance</ulink> for more information.
    </para>

    <para>
        On the other hand, if you know all about open-source development, Linux development environments, 
        Git source repositories and the like and you just want some quick information that lets you try out
        the Yocto Project on your Linux system, skip right to the 
        "<link linkend='super-user'>Super User</link>" section at the end of this quick start.
    </para>

    <para>
        For the rest of you, this short document will give you some basic information about the environment and 
        let you experience it in its simplest form.  
        After reading this document, you will have a basic understanding of what the Yocto Project is
        and how to use some of its core components.  
        This document steps you through a simple example showing you how to build a small image 
        and run it using the Quick EMUlator (QEMU emulator).
    </para>

    <para>
        For more detailed information on the Yocto Project, you should check out these resources:
        <itemizedlist>
            <listitem><para><emphasis>Website:</emphasis> The <ulink url='&YOCTO_HOME_URL;'>Yocto Project Website</ulink>
                provides the latest builds, breaking news, full development documentation, and a rich Yocto 
                Project Development Community into which you can tap.
                </para></listitem>
            <listitem><para><emphasis>FAQs:</emphasis> Lists commonly asked Yocto Project questions and answers.
                You can find two FAQs: <ulink url='&YOCTO_WIKI_URL;/wiki/FAQ'>Yocto Project FAQ</ulink> on 
                a wiki, and the 
                <ulink url='&YOCTO_DOCS_REF_URL;#faq'>FAQ</ulink> chapter in  
                the Yocto Project Reference Manual.
                </para></listitem>
            <listitem><para><emphasis>Developer Screencast:</emphasis> The 
                <ulink url='http://vimeo.com/36450321'>Getting Started with the Yocto Project - New
                Developer Screencast Tutorial</ulink> provides a 30-minute video for the user 
                new to the Yocto Project but familiar with Linux build systems.</para></listitem>
        </itemizedlist>
    </para>
    <note>
        Due to production processes, there could be differences between the Yocto Project
        documentation bundled in a released tarball and the 
        <ulink url='&YOCTO_DOCS_QS_URL;'>Yocto Project Quick Start</ulink> on
        the <ulink url='&YOCTO_HOME_URL;'>Yocto Project</ulink> website.
        For the latest version of this manual, see the manual on the website.
    </note>
</section>

<section id='yp-intro'>
    <title>Introducing the Yocto Project Development Environment</title>
    <para>
        The Yocto Project through the OpenEmbedded build system provides an open source development 
        environment targeting the ARM, MIPS, PowerPC and x86 architectures for a variety of 
        platforms including x86-64 and emulated ones.
        You can use components from the Yocto Project to design, develop, build, debug, simulate,
        and test the complete software stack using Linux, the X Window System, GNOME Mobile-based
        application frameworks, and Qt frameworks.
    </para>

    <mediaobject>
        <imageobject>
            <imagedata fileref="figures/yocto-environment.png" 
                format="PNG" align='center' scalefit='1' width="100%"/>
        </imageobject>
        <caption>
            <para>The Yocto Project Development Environment</para>
        </caption>
     </mediaobject>

    <para>
        Here are some highlights for the Yocto Project:
    </para>

    <itemizedlist>
        <listitem>
            <para>Provides a recent Linux kernel along with a set of system commands and libraries suitable for the embedded environment.</para>
        </listitem>
        <listitem>
            <para>Makes available system components such as X11, Matchbox, GTK+, Pimlico, Clutter,
            GuPNP and Qt (among others) so you can create a richer user interface experience on 
            devices that use displays or have a GUI.
            For devices that don't have a GUI or display, you simply would not employ these 
            components.</para>
        </listitem>
        <listitem>
            <para>Creates a focused and stable core compatible with the OpenEmbedded 
            project with which you can easily and reliably build and develop.</para>
        </listitem>
        <listitem>
            <para>Fully supports a wide range of hardware and device emulation through the QEMU
            Emulator.</para>
        </listitem>
    </itemizedlist>

    <para>
        The Yocto Project can generate images for many kinds of devices.  
        However, the standard example machines target QEMU full-system emulation for x86, x86-64, ARM, MIPS,
        and PPC-based architectures as well as specific hardware such as the 
        <trademark class='registered'>Intel</trademark> Desktop Board DH55TC.  
        Because an image developed with the Yocto Project can boot inside a QEMU emulator, the 
        development environment works nicely as a test platform for developing embedded software.
    </para>

    <para>
        Another important Yocto Project feature is the Sato reference User Interface. 
        This optional GNOME mobile-based UI, which is intended for devices with
        restricted screen sizes, sits neatly on top of a device using the 
        GNOME Mobile Stack and provides a well-defined user experience. 
        Implemented in its own layer, it makes it clear to developers how they can implement 
        their own user interface on top of a Linux image created with the Yocto Project.
    </para>
</section>

<section id='resources'>
    <title>What You Need and How You Get It</title>

    <para>
        You need these things to develop in the Yocto Project environment:
    </para>

    <itemizedlist>
        <listitem>
            <para>A host system running a supported Linux distribution (i.e. recent releases of
                Fedora, openSUSE, CentOS, and Ubuntu).
                If the host system supports multiple cores and threads, you can configure the 
                Yocto Project build system to decrease the time needed to build images
                significantly.
            </para>
        </listitem>
        <listitem>
            <para>The right packages.</para>
        </listitem>
        <listitem>
            <para>A release of the Yocto Project.</para>
        </listitem>
    </itemizedlist>

    <section id='the-linux-distro'>
        <title>The Linux Distribution</title>

        <para>
            The Yocto Project team is continually verifying more and more Linux 
            distributions with each release.
            In general, if you have the current release minus one of the following 
            distributions you should have no problems.
            <itemizedlist>
                <listitem><para>Ubuntu</para></listitem>
                <listitem><para>Fedora</para></listitem>
                <listitem><para>openSUSE</para></listitem>
                <listitem><para>CentOS</para></listitem>
            </itemizedlist>
            For a list of the distributions under validation and their status, see the
            <ulink url='&YOCTO_WIKI_URL;/wiki/Distribution_Support'>Distribution
            Support</ulink> wiki page.
            <note>
                For notes about using the Yocto Project on a RHEL 4-based host, see the
                <ulink url='&YOCTO_WIKI_URL;/wiki/BuildingOnRHEL4'>BuildingOnRHEL4</ulink>
                wiki page.
            </note>
            </para>
        <para>
            The OpenEmbedded build system should be able to run on any modern distribution with Python 2.6 or 2.7.
            Earlier releases of Python are known to not work and the system does not support Python 3 at this time.
            This document assumes you are running one of the previously noted distributions on your Linux-based 
            host systems.
        </para>
        <note><para>
            If you attempt to use a distribution not in the above list, you may or may not have success - you 
            are venturing into untested territory.
            Refer to  
            <ulink url='&OE_HOME_URL;/index.php?title=OEandYourDistro&amp;action=historysubmit&amp;diff=4309&amp;okdid=4225'>OE and Your Distro</ulink> and 
            <ulink url='&OE_HOME_URL;/index.php?title=Required_software&amp;action=historysubmit&amp;diff=4311&amp;oldid=4251'>Required Software</ulink> 
            for information for other distributions used with the OpenEmbedded project, which might be
            a starting point for exploration.
            If you go down this path, you should expect problems.
            When you do, please go to <ulink url='&YOCTO_BUGZILLA_URL;'>Yocto Project Bugzilla</ulink>
            and submit a bug.
            We are interested in hearing about your experience.
        </para></note>
    </section>

    <section id='packages'>
        <title>The Packages</title>

        <para>
            Packages and package installation vary depending on your development system.  
            In general, you need to have root access and then install the required packages.
            The next few sections show you how to get set up with the right packages for
            Ubuntu, Fedora, openSUSE, and CentOS.
        </para>
  
        <section id='ubuntu'>
            <title>Ubuntu</title>

            <para>
                The packages you need for a supported Ubuntu distribution are shown in the following command:
            </para>

                <literallayout class='monospaced'>
     $ sudo apt-get install sed wget subversion git-core coreutils \
     unzip texi2html texinfo libsdl1.2-dev docbook-utils fop gawk \
     python-pysqlite2 diffstat make gcc build-essential xsltproc \
     g++ desktop-file-utils chrpath libgl1-mesa-dev libglu1-mesa-dev \
     autoconf automake groff libtool xterm libxml-parser-perl dblatex
                </literallayout>
        </section>

        <section id='fedora'>
            <title>Fedora</title>

            <para>
                The packages you need for a supported Fedora distribution are shown in the following
                commands:
            </para>

                <literallayout class='monospaced'>
     $ sudo yum groupinstall "development tools"
     $ sudo yum install python m4 make wget curl ftp tar bzip2 gzip \
     unzip perl texinfo texi2html diffstat openjade \
     docbook-style-dsssl sed docbook-style-xsl docbook-dtds fop libxslt \
     docbook-utils sed bc eglibc-devel ccache pcre pcre-devel quilt \
     groff linuxdoc-tools patch cmake \
     perl-ExtUtils-MakeMaker tcl-devel gettext chrpath ncurses apr \
     SDL-devel mesa-libGL-devel mesa-libGLU-devel gnome-doc-utils \
     autoconf automake libtool xterm dblatex
                </literallayout>

        </section>

        <section id='opensuse'>
            <title>openSUSE</title>

            <para>
                The packages you need for a supported openSUSE distribution are shown in the following 
                command:
            </para>

                <literallayout class='monospaced'>
     $ sudo zypper install python gcc gcc-c++ libtool fop \
     subversion git chrpath automake make wget xsltproc \
     diffstat texinfo freeglut-devel libSDL-devel dblatex
                </literallayout>
        </section>

        <section id='centos'>
            <title>CentOS</title>

            <para>
                The packages you need for a supported CentOS distribution are shown in the following 
                commands:
            </para>

                <literallayout class='monospaced'>
     $ sudo yum -y groupinstall "development tools"
     $ sudo yum -y install tetex gawk sqlite-devel vim-common redhat-lsb xz \
       m4 make wget curl ftp tar bzip2 gzip python-devel \
       unzip perl texinfo texi2html diffstat openjade zlib-devel \
       docbook-style-dsssl sed docbook-style-xsl docbook-dtds \
       docbook-utils bc glibc-devel pcre pcre-devel \
       groff linuxdoc-tools patch cmake \
       tcl-devel gettext ncurses apr \
       SDL-devel mesa-libGL-devel mesa-libGLU-devel gnome-doc-utils \
       autoconf automake libtool xterm dblatex
                </literallayout>
            <note><para>
                Depending on the CentOS version you are using, other requirements and dependencies
                might exist. 
                For details, you should look at the CentOS sections on the 
                <ulink url='&YOCTO_WIKI_URL;/wiki/Poky/GettingStarted/Dependencies'>Poky/GettingStarted/Dependencies</ulink>
                wiki page.
            </para></note>

        </section>
    </section>

    <section id='releases'>
        <title>Yocto Project Release</title>
            
        <para>
            You can download the latest Yocto Project release by going to the 
            <ulink url="&YOCTO_HOME_URL;/download">Yocto Project Download page</ulink>.
            Just go to the page and click the "Yocto Downloads" link found in the "Download"
            navigation pane to the right to view all available Yocto Project releases. 
            Then, click the "Yocto Release" link for the release you want from the list to 
            begin the download. 
            Nightly and developmental builds are also maintained at
            <ulink url="&YOCTO_AB_NIGHTLY_URL;"></ulink>.  
            However, for this document a released version of Yocto Project is used.
        </para>

        <para>
            You can also get the Yocto Project files you need by setting up (cloning in Git terms)
            a local copy of the <filename>poky</filename> Git repository on your host development 
            system. 
            Doing so allows you to contribute back to the Yocto Project project.
            For information on how to get set up using this method, see the 
            "<ulink url='&YOCTO_DOCS_DEV_URL;#local-yp-release'>Yocto 
            Project Release</ulink>" item in the Yocto Project Development Manual.
        </para>
    </section>
</section>

<section id='test-run'>
    <title>A Quick Test Run</title>

    <para>
        Now that you have your system requirements in order, you can give the Yocto Project a try.  
        This section presents some steps that let you do the following:
    </para>

    <itemizedlist>
        <listitem>
            <para>Build an image and run it in the QEMU emulator</para>
        </listitem>
        <listitem>
            <para>Use a pre-built image and run it in the QEMU emulator</para>
        </listitem>
    </itemizedlist>

    <section id='building-image'>
        <title>Building an Image</title>
 
        <para>
            In the development environment you will need to build an image whenever you change hardware 
            support, add or change system libraries, or add or change services that have dependencies.
        </para>

        <mediaobject>
            <imageobject>
                <imagedata fileref="figures/building-an-image.png" format="PNG" align='center' scalefit='1'/>
            </imageobject>
            <caption>
                <para>Building an Image</para>
            </caption>
         </mediaobject>

         <para>
             Use the following commands to build your image.  
             The OpenEmbedded build process creates an entire Linux distribution, including the toolchain, 
             from source.
         </para>

         <note><para>
             The build process using Sato currently consumes about 50GB of disk space.
             To allow for variations in the build process and for future package expansion, we 
             recommend having at least 100GB of free disk space.
         </para></note>

         <note><para>
             By default, the build process searches for source code using a pre-determined order
             through a set of locations.
             If you encounter problems with the build process finding and downloading source code, see the 
             "<ulink url='&YOCTO_DOCS_REF_URL;#how-does-the-yocto-project-obtain-source-code-and-will-it-work-behind-my-firewall-or-proxy-server'>How does the OpenEmbedded build system obtain source code and will it work behind my
             firewall or proxy server?</ulink>" in the Yocto Project Reference Manual.
         </para></note>

         <para>
             <literallayout class='monospaced'>
     $ wget &YOCTO_POKY_DL_URL;
     $ tar xjf &YOCTO_POKY;.tar.bz2
     $ source &OE_INIT_PATH; &YOCTO_POKY;-build
             </literallayout>
         </para>

         <tip><para>
             To help conserve disk space during builds, you can add the following statement
             to your project's configuration file, which for this example
             is <filename>&YOCTO_POKY;-build/conf/local.conf</filename>.
             Adding this statement deletes the work directory used for building a package
             once the package is built.
             <literallayout class='monospaced'>
     INHERIT += "rm_work"
             </literallayout>
         </para></tip>

         <itemizedlist>
             <listitem><para>In the previous example, the first command retrieves the Yocto Project
                 release tarball from the source repositories using the
                 <filename>wget</filename> command.
                 Alternatively, you can go to the 
                 <ulink url='&YOCTO_HOME_URL;/download'>Yocto Project website's Downloads page</ulink>
                 to retrieve the tarball.</para></listitem>
             <listitem><para>The second command extracts the files from the tarball and places 
                 them into a directory named <filename>&YOCTO_POKY;</filename> in the current 
                 directory.</para></listitem>
             <listitem><para>The third command runs the Yocto Project environment setup script.
                 Running this script defines OpenEmbedded build environment settings needed to 
                 complete the build.
                 The script also creates the 
                 <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>build directory</ulink>,
                 which is <filename>&YOCTO_POKY;-build</filename> in this case.
                 After the script runs, your current working directory is set 
                 to the build directory.
                 Later, when the build completes, the build directory contains all the files 
                 created during the build.
                 </para></listitem>
         </itemizedlist>
         <para>
             Take some time to examine your <filename>local.conf</filename> file 
             in your project's configuration directory.
             The defaults in that file should work fine.
             However, there are some variables of interest at which you might look.
         </para>

         <para>  
             By default, the target architecture for the build is <filename>qemux86</filename>, 
             which produces an image that can be used in the QEMU emulator and is targeted at an
             <trademark class='registered'>Intel</trademark> 32-bit based architecture.
             To change this default, edit the value of the <filename>MACHINE</filename> variable 
             in the configuration file before launching the build.
         </para>

         <para>
             Another couple of variables of interest are the 
             <ulink url='&YOCTO_DOCS_REF_URL;#var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename></ulink> and the 
             <ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></ulink> variables.
             By default, these variables are commented out. 
             However, if you have a multi-core CPU you might want to uncomment
             the lines and set both variables equal to twice the number of your 
             host's processor cores.
             Setting these variables can significantly shorten your build time.
         </para>

        <para>
            Another consideration before you build is the package manager used when creating 
            the image. 
            By default, the OpenEmbedded build system uses the RPM package manager.
            You can control this configuration by using the 
            <filename><ulink url='&YOCTO_DOCS_REF_URL;#var-PACKAGE_CLASSES'><filename>PACKAGE_CLASSES</filename></ulink></filename> variable.  
             For additional package manager selection information, see 
             "<ulink url='&YOCTO_DOCS_REF_URL;#ref-classes-package'>Packaging - <filename>package*.bbclass</filename></ulink>" 
             in the Yocto Project Reference Manual.
        </para>

         <para>
             Continue with the following command to build an OS image for the target, which is 
             <filename>core-image-sato</filename> in this example.
             For information on the <filename>-k</filename> option use the 
             <filename>bitbake --help</filename> command or see the
             "<ulink url='&YOCTO_DOCS_REF_URL;#usingpoky-components-bitbake'>BitBake</ulink>" section in 
             the Yocto Project Reference Manual.
             <literallayout class='monospaced'>
     $ bitbake -k core-image-sato
             </literallayout>
             <note><para>
                 BitBake requires Python 2.6 or 2.7.  For more information on this requirement, 
                 see the 
                 <ulink url='&YOCTO_DOCS_REF_URL;#faq'>FAQ</ulink> in the Yocto Project Reference 
                 Manual.
             </para></note>
             The final command runs the image:
             <literallayout class='monospaced'>
     $ runqemu qemux86
             </literallayout>
             <note><para>
                 Depending on the number of processors and cores, the amount or RAM, the speed of your
                 Internet connection and other factors, the build process could take several hours the first
                 time you run it.
                 Subsequent builds run much faster since parts of the build are cached.
             </para></note>
         </para>
    </section>

    <section id='using-pre-built'>
        <title>Using Pre-Built Binaries and QEMU</title>
 
        <para>
            If hardware, libraries and services are stable, you can get started by using a pre-built binary 
            of the filesystem image, kernel, and toolchain and run it using the QEMU emulator.  
            This scenario is useful for developing application software.
        </para>

        <mediaobject>
            <imageobject>
            <imagedata fileref="figures/using-a-pre-built-image.png" format="PNG" align='center' scalefit='1'/>
            </imageobject>
            <caption>
                <para>Using a Pre-Built Image</para>
            </caption>
        </mediaobject>

        <para>
            For this scenario, you need to do several things:
        </para>

        <itemizedlist>
            <listitem><para>Install the appropriate stand-alone toolchain tarball.</para></listitem>
            <listitem><para>Download the pre-built image that will boot with QEMU.  
                You need to be sure to get the QEMU image that matches your target machine’s 
                architecture (e.g. x86, ARM, etc.).</para></listitem>
            <listitem><para>Download the filesystem image for your target machine's architecture.
                </para></listitem>
            <listitem><para>Set up the environment to emulate the hardware and then start the QEMU emulator.
                </para></listitem>
        </itemizedlist>

        <section id='installing-the-toolchain'>
            <title>Installing the Toolchain</title>
            <para>
                You can download a tarball with the pre-built toolchain, which includes the 
                <filename>runqemu</filename> 
                script and support files, from the appropriate directory under
                <ulink url='&YOCTO_TOOLCHAIN_DL_URL;'></ulink>.  
                Toolchains are available for 32-bit and 64-bit development systems from the 
                <filename>i686</filename> and <filename>x86-64</filename> directories, respectively. 
                Each type of development system supports five target architectures.
                The names of the tarballs are such that a string representing the host system appears 
                first in the filename and then is immediately followed by a string representing
                the target architecture.
            </para>

            <literallayout class='monospaced'>
     poky-eglibc-&lt;<emphasis>host_system</emphasis>&gt;-&lt;<emphasis>arch</emphasis>&gt;-toolchain-gmae-&lt;<emphasis>release</emphasis>&gt;.tar.bz2

     Where:
         &lt;<emphasis>host_system</emphasis>&gt; is a string representing your development system: 
                i686 or x86_64.
       
         &lt;<emphasis>arch</emphasis>&gt; is a string representing the target architecture: 
                i586, x86_64, powerpc, mips, or arm.
       
         &lt;<emphasis>release</emphasis>&gt; is the version of Yocto Project.
            </literallayout>

            <para>       
                For example, the following toolchain tarball is for a 64-bit development 
                host system and a 32-bit target architecture:
            </para>

            <literallayout class='monospaced'>
     poky-eglibc-x86_64-i586-toolchain-gmae-&DISTRO;.tar.bz2
            </literallayout>

            <para>
                The toolchain tarballs are self-contained and must be installed into <filename>/opt/poky</filename>.
                The following commands show how you install the toolchain tarball given a 64-bit development 
                host system and a 32-bit target architecture.
                The example assumes the toolchain tarball is located in <filename>~/toolchains/</filename>.
                You must have your working directory set to root before unpacking the tarball:
            </para>

            <para>
                <literallayout class='monospaced'>
     $ cd /
     $ sudo tar -xvjf ~/toolchains/poky-eglibc-x86_64-i586-toolchain-gmae-&DISTRO;.tar.bz2
                </literallayout>
            </para>

            <para>
                For more information on how to install tarballs, see the 
                "<ulink url='&YOCTO_DOCS_ADT_URL;#using-an-existing-toolchain-tarball'>Using a Cross-Toolchain Tarball</ulink>" and 
                "<ulink url='&YOCTO_DOCS_ADT_URL;#using-the-toolchain-from-within-the-build-tree'>Using BitBake and the Build Directory</ulink>" sections in the Yocto Project Application Development Toolkit (ADT) 
                User's Guide.
            </para>
        </section>

        <section id='downloading-the-pre-built-linux-kernel'>
            <title>Downloading the Pre-Built Linux Kernel</title>
      
            <para>
                You can download the pre-built Linux kernel suitable for running in the QEMU emulator from 
                <ulink url='&YOCTO_QEMU_DL_URL;'></ulink>.
                Be sure to use the kernel that matches the architecture you want to simulate.
                Download areas exist for the five supported machine architectures:
                <filename>qemuarm</filename>, <filename>qemumips</filename>, <filename>qemuppc</filename>,
                <filename>qemux86</filename>, and <filename>qemux86-64</filename>.
            </para>
         
            <para>  
                Most kernel files have one of the following forms:
                <literallayout class='monospaced'>
     *zImage-qemu&lt;<emphasis>arch</emphasis>&gt;.bin
     vmlinux-qemu&lt;<emphasis>arch</emphasis>&gt;.bin

     Where:
         &lt;<emphasis>arch</emphasis>&gt; is a string representing the target architecture: 
                x86, x86-64, ppc, mips, or arm.
                </literallayout>
            </para>

            <para>
                You can learn more about downloading a Yocto Project kernel in the 
                "<ulink url='&YOCTO_DOCS_DEV_URL;#local-kernel-files'>Yocto Project Kernel</ulink>" 
                bulleted item in the Yocto Project Development Manual.
            </para>
        </section>

        <section id='downloading-the-filesystem'>
            <title>Downloading the Filesystem</title>

            <para>
                You can also download the filesystem image suitable for your target architecture from
                <ulink url='&YOCTO_QEMU_DL_URL;'></ulink>.
                Again, be sure to use the filesystem that matches the architecture you want 
                to simulate.
            </para>

            <para>
                The filesystem image has two tarball forms: <filename>ext3</filename> and 
                <filename>tar</filename>.
                You must use the <filename>ext3</filename> form when booting an image using the 
                QEMU emulator.
                The <filename>tar</filename> form can be flattened out in your host development system
                and used for build purposes with the Yocto Project.
                <literallayout class='monospaced'>
     core-image-&lt;<emphasis>profile</emphasis>&gt;-qemu&lt;<emphasis>arch</emphasis>&gt;.ext3
     core-image-&lt;<emphasis>profile</emphasis>&gt;-qemu&lt;<emphasis>arch</emphasis>&gt;.tar.bz2

     Where:
         &lt;<emphasis>profile</emphasis>&gt; is the filesystem image's profile:
                   lsb, lsb-dev, lsb-sdk, lsb-qt3, minimal, minimal-dev, sato, sato-dev, or sato-sdk.
                   For information on these types of image profiles, see the
                   "<ulink url='&YOCTO_DOCS_REF_URL;#ref-images'>Images</ulink>" chapter
                   in the Yocto Project Reference Manual.

         &lt;<emphasis>arch</emphasis>&gt; is a string representing the target architecture: 
                x86, x86-64, ppc, mips, or arm.
                </literallayout>
            </para>
        </section>

        <section id='setting-up-the-environment-and-starting-the-qemu-emulator'>
            <title>Setting Up the Environment and Starting the QEMU Emulator</title>
           
            <para>
                Before you start the QEMU emulator, you need to set up the emulation environment.
                The following command form sets up the emulation environment.
                <literallayout class='monospaced'>
     $ source &YOCTO_ADTPATH_DIR;/environment-setup-&lt;<emphasis>arch</emphasis>&gt;-poky-linux-&lt;<emphasis>if</emphasis>&gt; 

     Where:
         &lt;<emphasis>arch</emphasis>&gt; is a string representing the target architecture: 
                i586, x86_64, ppc603e, mips, or armv5te.

         &lt;<emphasis>if</emphasis>&gt; is a string representing an embedded application binary interface.
              Not all setup scripts include this string.
                </literallayout>
            </para>

            <para>
                Finally, this command form invokes the QEMU emulator 
                <literallayout class='monospaced'>
     $ runqemu &lt;<emphasis>qemuarch</emphasis>&gt; &lt;<emphasis>kernel-image</emphasis>&gt; &lt;<emphasis>filesystem-image</emphasis>&gt;

     Where:
         &lt;<emphasis>qemuarch</emphasis>&gt; is a string representing the target architecture: qemux86, qemux86-64, 
                    qemuppc, qemumips, or qemuarm.

         &lt;<emphasis>kernel-image</emphasis>&gt; is the architecture-specific kernel image.

         &lt;<emphasis>filesystem-image</emphasis>&gt; is the .ext3 filesystem image.

                </literallayout>
            </para>

            <para>
                Continuing with the example, the following two commands setup the emulation 
                environment and launch QEMU.
                This example assumes the root filesystem (<filename>.ext3</filename> file) and 
                the pre-built kernel image file both reside in your home directory. 
                The kernel and filesystem are for a 32-bit target architecture.
                <literallayout class='monospaced'>
     $ cd $HOME
     $ source &YOCTO_ADTPATH_DIR;/environment-setup-i586-poky-linux 
     $ runqemu qemux86 bzImage-qemux86.bin \
     core-image-sato-qemux86.ext3
                </literallayout>
            </para>

            <para>
                The environment in which QEMU launches varies depending on the filesystem image and on the 
                target architecture.  
                For example, if you source the environment for the ARM target 
                architecture and then boot the minimal QEMU image, the emulator comes up in a new 
                shell in command-line mode.  
                However, if you boot the SDK image, QEMU comes up with a GUI.
                <note>Booting the PPC image results in QEMU launching in the same shell in 
                command-line mode.</note>
            </para>
        </section>     
    </section>
</section>

<section id='super-user'>
    <title>Super User 
</title>

    <para>
        This section 
        <footnote>
            <para>
                Kudos and thanks to Robert P. J. Day of 
                <ulink url='http://www.crashcourse.ca'>CrashCourse</ulink> for providing the basis
                for this "expert" section with information from one of his
                <ulink url='http://www.crashcourse.ca/wiki/index.php/Yocto_Project_Quick_Start'>wiki</ulink>
                pages.
            </para>
        </footnote>
        gives you a very fast description of how to use the Yocto Project to build images 
        for a BeagleBoard xM starting from scratch. 
        The steps were performed on a 64-bit Ubuntu 10.04 system.
    </para>

    <section id='getting-yocto'>
        <title>Getting the Yocto Project</title>

        <para>
            Set up your <ulink url='&YOCTO_DOCS_DEV_URL;#source-directory'>source directory</ulink>
            one of two ways:
            <itemizedlist>
                <listitem><para><emphasis>Tarball:</emphasis> 
                    Use if you want the latest stable release:
                    <literallayout class='monospaced'>
     $ wget &YOCTO_RELEASE_DL_URL;/&YOCTO_POKY_TARBALL;
     $ tar xvjf &YOCTO_POKY_TARBALL;
                    </literallayout></para></listitem>
                <listitem><para><emphasis>Git Repository:</emphasis>
                    Use if you want to work with cutting edge development content:
                    <literallayout class='monospaced'>
     $ git clone git://git.yoctoproject.org/poky
                    </literallayout></para></listitem>
            </itemizedlist>
            The remainder of the section assumes the Git repository method.
        </para>
    </section>

    <section id='setting-up-your-host'>
        <title>Setting Up Your Host</title>

        <para>
            You need some packages for everything to work. 
            Rather than duplicate them here, look at the "<link linkend='packages'>The Packages</link>"
            section earlier in this quick start.
        </para>
    </section>

    <section id='initializing-the-build-environment'>
        <title>Initializing the Build Environment</title>

        <para>
            From the parent directory of local source directory, initialize your environment 
            and provide a meaningful 
            <ulink url='&YOCTO_DOCS_DEV_URL;#build-directory'>build directory</ulink>
            name:
            <literallayout class='monospaced'>
     $ source poky/oe-init-build-env mybuilds
            </literallayout>
            At this point, the <filename>mybuilds</filename> directory has been created for you 
            and it is now your current working directory.
            If you don't provide your own directory name it defaults to <filename>build</filename>.
        </para>
    </section>

    <section id='configuring-the-local.conf-file'>
        <title>Configuring the local.conf File</title>

        <para>
            Initializing the build environment creates a <filename>conf/local.conf</filename> configuration file
            in the build directory.
            You need to manually edit this file to specify the machine you are building and to optimize
            your build time.
            Here are the minimal changes to make:
            <literallayout class='monospaced'>
     BB_NUMBER_THREADS = "8"
     PARALLEL_MAKE = "-j 8"
     MACHINE ?= "beagleboard"
            </literallayout>
            Briefly, set <ulink url='&YOCTO_DOCS_REF_URL;#var-BB_NUMBER_THREADS'><filename>BB_NUMBER_THREADS</filename></ulink> 
            and <ulink url='&YOCTO_DOCS_REF_URL;#var-PARALLEL_MAKE'><filename>PARALLEL_MAKE</filename></ulink> to
            twice your host processor's number of cores.
        </para>

        <para>
            A good deal that goes into a Yocto Project build is simply downloading all of the source 
            tarballs. 
            Maybe you have been working with another build system (OpenEmbedded, Angstrom, etc) for which 
            you've built up a sizable directory of source tarballs.
            Or perhaps someone else has such a directory for which you have read access. 
            If so, you can save time by adding the <filename>PREMIRRORS</filename>
            statement to your configuration file so that local directories are first checked for existing 
            tarballs before running out to the net:
            <literallayout class='monospaced'>
     PREMIRRORS_prepend = "\
     git://.*/.* file:///home/you/dl/ \n \
     svn://.*/.* file:///home/you/dl/ \n \
     cvs://.*/.* file:///home/you/dl/ \n \
     ftp://.*/.* file:///home/you/dl/ \n \
     http://.*/.* file:///home/you/dl/ \n \
     https://.*/.* file:///home/you/dl/ \n"
            </literallayout>
        </para>
    </section>

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

        <para>
            At this point, you need to select an image to build for the BeagleBoard xM.
            If this is your first build using the Yocto Project, you should try the smallest and simplest
            image:
            <literallayout class='monospaced'>
     $ bitbake core-image-minimal
            </literallayout>
            Now you just wait for the build to finish.
        </para>

        <para>
            Here are some variations on the build process that could be helpful:
            <itemizedlist>
                <listitem><para>Fetch all the necessary sources without starting the build:
                    <literallayout class='monospaced'>
     $ bitbake -c fetchall core-image-minimal
                    </literallayout>
                    This variation guarantees that you have all the sources for that BitBake target 
                    should you to disconnect from the net and want to do the build later offline.
                    </para></listitem>
                <listitem><para>Specify to continue the build even if BitBake encounters an error.
                    By default, BitBake aborts the build when it encounters an error.
                    This command keeps a faulty build going:
                    <literallayout class='monospaced'>
     $ bitbake -k core-image-minimal
                    </literallayout></para></listitem>
            </itemizedlist>
        </para>

        <para>
            Once you have your image, you can take steps to load and boot it on the target hardware.
        </para>
    </section>
</section>

</article>
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