path: root/docs/usermanual/chapters/getting_oe.xml

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<chapter id="chapter_getting_oe">
  <title>Getting Started</title>

  <section id="gettingoe_directory_setup">
    <title>OpenEmbedded Directory Structure</title>

    <para>Before you begin downloading OpenEmbedded, you need to setup your
    working environment.</para>

	<para>The first step is to decide where on your system you wish to
    work. This document will use the <varname>$OEBASE</varname> variable to
    denote the base directory of the OpenEmbedded environment. For
    example, <varname>$OEBASE</varname> could
    be <literal>/home/joe/work/oe</literal>.</para>

    <para>The base directory of your OpenEmbedded environment
    (<varname>$OEBASE</varname>) is the location where sources will be checked
    out (or unpacked). You must choose a location with <emphasis>no symlinks
    above it</emphasis>.</para>

	<para>To create the directory structure:

    <screen>
$ <command>mkdir</command> -p $OEBASE/build/conf
$ <command>cd</command> $OEBASE</screen>

	The <literal>$OEBASE/build</literal> directory will contain your
	local configurations and extensions to the OpenEmbedded system which allow
	you to build your applications and images.
    </para>

	<para>The <varname>$OEBASE</varname> will also contain both of the
	<literal>bitbake/</literal> and <literal>openembedded/</literal> directories.
	These will be discussed in <xref linkend="gettingoe_getting_bitbake"/> and
	<xref linkend="gettingoe_getting_oe"/>.
	</para>
  </section>

  <section id="gettingoe_getting_bitbake">
    <title>Getting <application>BitBake</application></title>

    <para>Before using OE, you must first obtain the build tool it needs:
    bitbake.</para>

    <para>It is recommended to run bitbake without installing it, as a sibling
    directory of <literal>openembedded/</literal>
    and <literal>build/</literal> directories. Indeed, as bitbake is written
    in python it does not need compilation for being used. You'll just have to
    set the <varname>PATH</varname> variable so that the BitBake tools are
    accessible (see <xref linkend="gettingoe_configuring_oe"/>).</para>

	<section><title>Downloading a <application>BitBake</application> release</title>
	  <para>Releases are available from the berlios project website. The current
          release series is <application>BitBake</application> <emphasis>1.8</emphasis>
          and the current release is <emphasis>1.8.18</emphasis>. To download execute
	  the following commands:
		<screen>
$ <command>cd</command> $OEBASE
$ <command>wget</command> http://download.berlios.de/bitbake/bitbake-1.8.18.tar.gz
$ <command>tar</command> -xvzf bitbake-1.8.18.tar.gz
$ <command>mv</command> bitbake-1.8.18 bitbake
</screen>
	  </para>

	  <para><application>BitBake</application> is now downloaded and
		the <varname>$OEBASE</varname> directory will contain
		a <literal>bitbake/</literal> subdirectory.</para>
	</section>
  </section>


  <section id="gettingoe_getting_oe">
    <title>Getting OpenEmbedded</title>

    <para><emphasis>Note:</emphasis> Once upon a time OpenEmbedded used
      Monotone for version control. If you have an OE Monotone repository on
      your computer, you should replace it with the Git repository.</para>

    <para>The OpenEmbedded metadata has a high rate of development, so it's a
      good idea to stay up to date. You'll need Git to get the metadata and
      stay up to date. Git is available in most distributions and has binaries
      at <ulink url="http://git-scm.com/">Git homepage</ulink>.</para>

    <section><title>Checking Out OpenEmbedded With Git</title>
      <para>Once you have installed Git, checkout the OpenEmbedded repository:
        <screen>
$ <command>cd</command> $OEBASE
$ <command>git</command> clone git://git.openembedded.org/openembedded</screen>
        The <literal>$OEBASE/openembedded/</literal> directory should now
        exist.</para>
    </section>

    <section><title>Updating OpenEmbedded</title>
      <para>The <literal>org.openembedded.dev</literal> branch of OpenEmbedded
        is updated very frequently (as much as several times an hour). The
        distro branches are not updated as much but still fairly often. It
        seems good practice to update your OpenEmbedded tree at least
        daily. To do this, run:
        <screen>
$ <command>cd</command> $OEBASE
$ <command>git</command> pull</screen>
      </para>
    </section>
    <section><title>Changing Branches</title>
      <para>Working with multiple branches is very easy to do with Git. The
        OpenEmbedded repository holds many branches. To list all branches, use this command:
        <screen>$ <command>git</command> branch -a</screen>
        Branch names that begin with <literal>origin/</literal> denote
        branches that exist on the remote server. The name with a * in front
        of it is the branch currently checked out. If you want to work with a
        remote branch, you must first create a local copy of it. The following
        command will create a local copy of a remote branch:
        <screen>$ <command>git</command> branch &lt;local_name&gt; &lt;remote_name&gt;</screen>
        To change branches, use this command:
        <screen>$ <command>git</command> checkout &lt;branch_name&gt;</screen>
        There are more complicated branch operations that can be done with git,
        but those are beyond the scope of this document.</para>
    </section>
  </section>

  <section id="gettingoe_configuring_oe">
    <title>Configuring OpenEmbedded</title>

    <para>At this point, your <literal>$OEBASE/</literal> directory should
      contain at least the following subdirectories:
      <itemizedlist>
        <listitem><simpara><literal>build/</literal></simpara></listitem>
        <listitem><simpara><literal>bitbake/</literal></simpara></listitem>
        <listitem><simpara><literal>openembedded/</literal></simpara></listitem>
      </itemizedlist>
    </para>

    <section><title>Environment Setup</title>
      <para>There are a few environment variables that you will need to set
        before you can build software for OpenEmbedded using BitBake. You will
        need to set these variables every time you open a terminal for
        development. You can automate this in
        <filename>~/.profile</filename>, <filename>/etc/profile</filename>, or
        perhaps use a script to set the necessary variables for using BitBake.
      </para>

      <para>Since the path to your OpenEmbedded installation will be used in
        many places, setting it in your environment will allow you to use
        the <varname>$OEBASE</varname> variable in all pathes and make it
        easier to change in the future should the need arise. To
        set <varname>$OEBASE</varname> if you use a Bourne like shell
        <footnote>
          <para>If you use a CSH like shell (e.g. on a FreeBSD system), you
            will set environment variables like this:
            <screen>
$ <command>setenv</command> VAR_NAME "VAR_VALUE"</screen>
          </para>
        </footnote>, do this:

        <screen>
$ <command>export</command> OEBASE=/path/to/your/oe/installation</screen>

      </para>

      <para>If you followed the recommendation to use BitBake from svn, you
        will need to add the path to the BitBake executable to
        your <varname>PATH</varname> environment variable like this:

        <screen>
$ <command>export</command> PATH=$OEBASE/bitbake/bin:$PATH</screen>
      </para>

      <para>In order for bitbake to find the configuration files for
        OpenEmbedded, you will need to set the <varname>BBPATH</varname>
        variable.

        <screen>
$ <command>export</command> BBPATH=$OEBASE/build:$OEBASE/openembedded</screen>
      </para>

      <para>Finally, if you wish to allow BitBake to inherit
        the <varname>$OEBASE</varname> variable from the environment, you will
        need to set the <varname>BB_ENV_EXTRAWHITE</varname> variable:

        <screen>
$ <command>export</command> BB_ENV_EXTRAWHITE="OEBASE"</screen>

        Note the absence of the "$" character which implies that you are
        setting <varname>BB_ENV_EXTRAWHITE</varname> to the variable name, not
        the variable value.
      </para>
    </section>

    <section><title>Local Configuration</title>
      <para>It is now time to create your local configuration. While you could
        copy the default <filename>local.conf.sample</filename> like this:

        <screen>
$ <command>cd</command> $OEBASE
$ <command>cp</command> openembedded/conf/local.conf.sample build/conf/local.conf
$ <command>vi</command> build/conf/local.conf</screen>

        It is actually recommended to start smaller and
        keep <filename>local.conf.sample</filename> in the background. Add
        entries from there step-by-step as you understand and need
        them. Please, do not just edit
        <filename>build/conf/local.conf.sample</filename> but
        actually <emphasis>READ</emphasis> it (read it and then edit it).
      </para>

      <para>For building an <literal>org.openembedded.dev</literal> branch, in
        your <filename>local.conf</filename> file, you should have at least
        the following three
        entries: <varname>BBFILES</varname>, <varname>DISTRO</varname>
        and <varname>MACHINE</varname>. For example, consider the following
        minimal <literal>local.conf</literal> file for the &Aring;ngstr&ouml;m
        distribution and the Openmoko gta01 machine:

        <screen>
BBFILES = "${OEBASE}/openembedded/recipes/*/*.bb"
DISTRO = "angstrom-2008.1"
MACHINE = "om-gta01"</screen>
      </para>
    </section>
  </section>

  <section id="gettingoe_building_software">
    <title>Building Software</title>

    <para>The primary interface to the build system is
      the <command>bitbake</command> command (see
      the <ulink url="http://bitbake.berlios.de/manual/">BitBake
      users manual</ulink>). BitBake will download and patch files from the
      internet, so it helps if you are on a well connected machine.
    </para>

    <para>Note that you should issue all BitBake commands from inside of the
      <filename>build/</filename> directory, or you should
      override <varname>TMPDIR</varname> in
      your <filename>$OEBASE/build/conf/local.conf</filename> to point
      elsewhere (by default it goes to <filename>tmp/</filename> relative to
      the directory you run <command>bitbake</command> commands in).
    </para>

    <note>
      <para>BitBake might complain that there is a problem with the setting in
        <filename>/proc/sys/vm/mmap_min_addr</filename>, which needs to be set
        to zero. You can set it by doing the following as root:

        <screen># echo 0 > /proc/sys/vm/mmap_min_addr</screen>

        Note that you can not use a text editor to do this since files
        in <filename>/proc</filename> are not real files. Also note that this
        above change will be lost when you reboot your system. To have the
        change made automatically when the system boots, some systems provide
        a <filename>/etc/sysctl.conf</filename> file. Add the following line
        to that file:

        <screen>vm.mmap_min_addr=0</screen>

        If your system does not provide
        the <filename>/etc/sysctl.conf</filename> mechanism, you can try adding
        the above <command>echo</command> command line to
        your <filename>/etc/rc.local</filename>.  But that's not all.

        On some systems (such as Fedora 11), changing that kernel setting
        will cause an SELinux violation if you're running SELinux in enforcing
        mode. If that's the case, you can either disable SELinux or run:

        <screen>$ setsebool -P allow_unconfirmed_mmap_low 1</screen>
      </para>
    </note>

    <para>Once BitBake and OpenEmbedded are set up and configured, you can build
      software and images like this:

      <screen>$ bitbake &lt;recipe_name&gt;</screen>

      A recipe name corresponds to a BitBake <filename>.bb</filename> file.  A
      BitBake file is a logical unit of tasks to be executed. Normally this is
      a package to be built. Inter-recipe dependencies are obeyed. The recipes
      are located by BitBake via the <varname>BBFILES</varname> variable (set
      in your <filename>$OEBASE/build/conf/local.conf</filename>), which is a
      space separated list of <filename>.bb</filename> files, and does handle
      wildcards.
    </para>

    <para>To build a single package, bypassing the long parse step (and
      therefore its dependencies -- use with care):

      <screen>$ bitbake -b $OEBASE/openembedded/recipes/blah/blah.bb</screen>
    </para>

    <para>There are a few groups of special recipes located in subdirectories
      of the <filename>$OEBASE/openembedded/recipes/</filename>
      directory. These groups are:

      <variablelist>
        <varlistentry>
          <term><filename>tasks/</filename></term>
          <listitem><para>A collection of meta-packages that depend on real
              packages to make managing package sets easier.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><filename>meta/</filename></term>
          <listitem><para>A collection of useful meta tasks and recipes that
              don't fit in a general category.</para></listitem>
        </varlistentry>

        <varlistentry>
          <term><filename>images/</filename></term>
          <listitem><para>A collection of image targets that depend on
              packages that will be installed into an image which can be put
              on the target system.</para></listitem>
        </varlistentry>
      </variablelist>
    </para>

    <section><title>Useful Target Recipes</title>
      <para>Although BitBake can build individual packages, it is often more
        useful to build a set of packages and combine them into an image. The
        following recipe names are commonly used to that effect.
      </para>

      <section><title>Images</title>
        <para>
          <variablelist>
            <varlistentry>
              <term><literal>helloworld-image</literal></term>
              <listitem>
                <para>Builds an image, that if used as a root filesystem, will
                  start a static executable that prints hello world then
                  loops infinitely. Can be used to test the Linux boot
                  procedure into user space (init).
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>bootstrap-image</literal></term>
              <listitem>
                <para>Build image contains task-base packages.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>console-image</literal></term>
              <listitem>
                <para>Build an image without the X11, gtk+, or qt windowing
                  libraries.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>x11-image</literal></term>
              <listitem>
                <para>Builds an image with X11.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>beagleboard-demo-image</literal></term>
              <listitem>
                <para>Builds the &Aring;ngstr&ouml;m distribution like Koen
                proposed.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>opie-image</literal></term>
              <listitem>
                <para>Build image based on the
                  <ulink url="http://opie.handhelds.org/">Open Palmtop
                  Integrated Environment</ulink> (OPIE). OPIE is a completely
                  Open Source based graphical user environment and suite of
                  applications for small form-factor devices, such as PDAs,
                  running Linux.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>opie-kdepim-image</literal></term>
              <listitem>
                <para>Build image based on the OPIE and full featured
                  KDE-based PIM (pi-sync, ko/pi, ka/pi, etc).
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>pivotboot-image</literal></term>
              <listitem>
                <para>Build image that is necessary to flash a Sharp SL C3000,
                  Zaurus. It pivots after booting from the NAND and finalizes
                  the install to the HD during the first boot.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>twin-image</literal></term>
              <listitem>
                <para>A image with task-base plus a couple of editors, nano and
                  vim (why two?), and a mail reader, mutt.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>uml-image</literal></term>
              <listitem>
                <para>A root image for user-mode-linux. Includes task-base,
                  and parts of opie.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>gpe-image</literal></term>
              <listitem>
                <para>Build a <ulink url="http://opie.handhelds.org/">GPE
                  Palmtop Environment</ulink> based kernel and rootfs. The GPE
                  provides a user interface environment for palmtop/handheld
                  computers running the GNU/Linux or any other UNIX-like
                  operating system.
                </para>
              </listitem>
            </varlistentry>
          </variablelist>
        </para>
      </section>

      <section><title>Tasks</title>
        <para>
          <variablelist>
            <varlistentry>
              <term><literal>task-base</literal></term>
              <listitem>
                <para>Build a kernel and core packages for a basic
                  installation. You won't be able to do much more than ssh to
                  the machine if this is all that is installed.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>task-dvb</literal></term>
              <listitem>
                <para>Meta-package for DVB application (DVB = Digital Video
                Broadcasting).
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>task-python-everything</literal></term>
              <listitem>
                <para>All of python.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>task-native-sdk</literal></term>
              <listitem>
                <para>Mata-package for native (on-device) SDK.
                </para>
              </listitem>
            </varlistentry>
          </variablelist>
        </para>
      </section>

      <section><title>Meta</title>
        <para>
          <variablelist>
            <varlistentry>
              <term><literal>meta-opie</literal></term>
              <listitem>
                <para>Build all OPIE related packages and some more for OPIE
                  based usage.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>meta-gpe</literal></term>
              <listitem>
                <para>Basic packages to go with gpe-image.
                </para>
              </listitem>
            </varlistentry>
          </variablelist>
        </para>
      </section>

      <section><title>Other</title>
        <para>
          <variablelist>
            <varlistentry>
              <term><literal>helloworld</literal></term>
              <listitem>
                <para>Builds a static executable that prints hello
                  world then loops infinitely.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>world</literal></term>
              <listitem>
                <para>Build everything. This takes a long time, a lot
                  of network bandwidth, and a lot of disc space. Can also
                  break your toolchain.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>package-index</literal></term>
              <listitem>
                <para>Target to update the "feed" files to reflect the current
                  set of .ipk's that exist in the deploy directory. Commonly
                  used after building some packages individually to update the
                  feed and allow them to be installed via a package manager or
                  the ipkg command line tools.
                </para>
              </listitem>
            </varlistentry>

            <varlistentry>
              <term><literal>virtual/kernel</literal></term>
              <listitem>
                <para>Builds the appropriate kernel for your device.</para>
              </listitem>
            </varlistentry>
          </variablelist>
        </para>
      </section>
    </section>
  </section>
</chapter>