usage.xml « chapters « usermanual « docs - openembedded - Classic OpenEmbedded Development Tree

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<chapter id="chapter_using_bitbake_and_oe">
  <title>Using bitbake and OpenEmbedded</title>

  <section id="usage_introduction" xreflabel="introduction">
    <title>Introduction</title>

    <para>If you're reading this manual you probably already have some idea of
    what OpenEmbedded is all about, which is taking a lot of software and
    creating something that you can run on another device. This involves
    downloading some source code, compiling it, creating packages (like .deb
    or .rpm) and/or creating boot images that can be written to flash on the
    device. The difficulties of cross-compiling and the variety of devices
    which can be supported lead to a lot more complexity in an OpenEmbedded
    based distribution than you'd find in a typical desktop distribution
    (where which cross-compiling isn't needed).</para>

    <para>A major part of OpenEmbedded deals with compiling source code for
    various projects. For each project this generally requires the same basic
    set of tasks:</para>

    <orderedlist>
      <listitem>
        <para>Download the source code, and any supporting files (such as
        initscripts);</para>
      </listitem>

      <listitem>
        <para>Extract the source code and apply any patches that might be
        wanted;</para>
      </listitem>

      <listitem>
        <para>Configure the software if needed (such as is done by running the
        configure script);</para>
      </listitem>

      <listitem>
        <para>Compile everything;</para>
      </listitem>

      <listitem>
        <para>Package up all the files into some package format, like .deb or
        .rpm or .ipk, ready for installation.</para>
      </listitem>
    </orderedlist>

    <para>There's nothing particular unusual about this process when building
    on the machine the package is to be installed on. What makes this
    difficult is:</para>

    <orderedlist>
      <listitem>
        <para>Cross-compiling: cross-compiling is difficult, and lots of
        software has no support for cross-compiling - all packages included in
        OE are cross-compiled;</para>
      </listitem>

      <listitem>
        <para>Target and host are different: This means you can't compile up a
        program and then run it - it's compiled to run on the target system,
        not on the system compiling it. Lots of software tries to build and
        run little helper and/or test applications and this won't work when
        cross-compiling.</para>
      </listitem>

      <listitem>
        <para>Tool chains (compiler, linker etc) are often difficult to
        compile. Cross tool chains are even more difficult. Typically you'd go
        out and download a tool chain made by someone else - but not when you're
        using OE. In OE the entire toolchain is built as part of the process.
        This may make things take longer initially and may make it more
        difficult to get started but makes it easier to apply patches and test
        out changes to the tool chain.</para>
      </listitem>
    </orderedlist>

    <para>Of course there's a lot more to OE then just compiling packages
    though. Some of the features that OE supports includes:</para>

    <itemizedlist>
      <listitem>
        <para>Support for both glibc and uclibc;</para>
      </listitem>

      <listitem>
        <para>Support for building for multiple target devices from the one
        code base;</para>
      </listitem>

      <listitem>
        <para>Automatically building anything that is required for the package
        to compile and/or run (build and run time dependencies);</para>
      </listitem>

      <listitem>
        <para>Creation of flash and disk images of any one of a number of
        types (jffs2, ext2.gz, squashfs etc) for booting directly on the
        target device;</para>
      </listitem>

      <listitem>
        <para>Support for various packaging formats;</para>
      </listitem>

      <listitem>
        <para>Automatic building all of the cross-compiling tools you'll
        need;</para>
      </listitem>

      <listitem>
        <para>Support for "native" packages that are built for the host
        computer and not for the target and used to help during the build
        process;</para>
      </listitem>
    </itemizedlist>

    <para>The rest of this chapter assumes you have mastered the Getting Start
    guides to OpenEmbedded (see the OpenEmbedded web site for details), and
    therefore have an appropriately configured setup and that you have managed
    to actually build the cross-compilers for your target. This section talks
    you through some of the background on what is happening with the aim of
    helping you understand how to debug and develop within
    OpenEmbedded.</para>

    <para>You'll also note a lot of references to variables that define specific
    directories or change the behaviour of some part of the build process. You
    should refer to <xref linkend="chapter_recipes" /> for full details on
    these variables.</para>
  </section>

  <section id="usage_configuration" xreflabel="configuration">
    <title>Configuration</title>

    <para>Configuration covers basic items such as where the various files can
    be found and where output should be placed to more specific items such as
    which hardware is being targeted and what features you want to have
    included in the final image. The main configuration areas in OE
    are:</para>

    <variablelist>
      <varlistentry>
        <term>conf/machine</term>

        <listitem>
          <para>This directory contains machine configuration information. For
          each physical device a configuration file is required in this
          directory that describes various aspects of the device, such as
          architecture of the device, hardware features of the device (does it
          have usb? a keyboard? etc), the type of flash or disk images needed
          for the device, the serial console settings (if any) etc. If you are
          adding support for a new device you would need to create a machine
          configuration in this directory for the device.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>conf/distro</term>

        <listitem>
          <para>This directory contains distribution related files. A
          distribution decides how various activities are handled in the final
          image, such as how networking is configured, if usb devices will be
          supported, what packaging system is used, which libc is used
          etc.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>conf/bitbake.conf</term>

        <listitem>
          <para>This is the main bitbake configuration file. This file is not
          to be edited but it is useful to look at it since it declares a
          larger number of the predefined variables used by OE and controls a
          lot of the base functionality provided by OE.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>conf/local.conf</term>

        <listitem>
          <para>This is the end-user specific configuration. This file needs
          to be copied and edited and is used to specify the various working
          directories, the machine to build for and the distribution to
          use.</para>
        </listitem>
      </varlistentry>
    </variablelist>
  </section>

  <section id="usage_workspace" xreflabel="workspace">
    <title>Work space</title>

    <para>Let's start out by taking a look at a typical working area. Note
    that this may not be exactly what you see - there are a lot of options that
    can effect exactly how things are done, but it gives us a pretty good idea
    of whats going on. What we are looking at here is the tmp directory (as
    specified by TMPDIR in your local.conf):<screen>$ <command>find</command> tmp -maxdepth 2 -type d 
tmp
tmp/stamps
tmp/cross
tmp/cross/bin
tmp/cross/libexec
tmp/cross/lib  
tmp/cross/share
tmp/cross/sh4-linux
tmp/cache
tmp/cache/titan
tmp/work
tmp/work/busybox-1.2.1-r13
tmp/work/libice-1_1.0.3-r0 
tmp/work/arpwatch-2.1a15-r2
...
tmp/rootfs
tmp/rootfs/bin
tmp/rootfs/usr
tmp/rootfs/media
tmp/rootfs/dev  
tmp/rootfs/var  
tmp/rootfs/lib  
tmp/rootfs/sbin 
tmp/rootfs/mnt  
tmp/rootfs/boot 
tmp/rootfs/sys  
tmp/rootfs/proc 
tmp/rootfs/etc  
tmp/rootfs/home 
tmp/rootfs/tmp  
tmp/sysroots
tmp/pkgdata
tmp/deploy
tmp/deploy/addons
tmp/deploy/ipk   
tmp/deploy/sources
tmp/deploy/images</screen></para>

    <para>The various top level directories under tmp include:</para>

    <variablelist>
      <varlistentry>
        <term>stamps</term>

        <listitem>
          <para>Nothing of interest to users in here. These time stamps are
          used by bitbake to keep track of what tasks it has completed and
          what tasks it still has outstanding. This is how it knows that
          certain actions have been completed and it doesn't need to do them
          again.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>cross</term>

        <listitem>
          <para>Contains the cross-compiler toolchain. That is the gcc and
          binutils that run on the host system but produce output for the
          target system.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>cache</term>

        <listitem>
          <para>Nothing of interest to users in here. This contains the
          bitbake parse cache and is used to avoid the need to parse all of
          the recipes each time bitbake is run. This makes bitbake a lot
          faster on the 2nd and subsequent runs.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>work</term>

        <listitem>
          <para>The work directory. This is the directory in which all
          packages are built - this is where the source code is extract,
          patches applied, software configure, compiled, installed and
          package. This is where you'll spend most of you time looking when
          working in OE.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>rootfs</term>

        <listitem>
          <para>The generated root filesystem image for your target device.
          This is the contents of the root filesystem (NOTE: fakeroot means it
          doesn't have the correct device special nodes and permissions to use
          directly).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>sysroots</term>

        <listitem>
          <para>Contains the staging area, which is used to store natively
          compiled tools and and libraries and headers for the target that are
          required for building other software.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>deploy</term>

        <listitem>
          <para>Contains the final output from OE. This includes the
          installation packages (typically .ipkg packages) and flash and/or
          disk images. This is where you go to get the final product.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>When people refer to the <emphasis>"tmp directory"</emphasis> this
    is the directory they are talking about.</para>

    <para>To perform a complete rebuild from scratch you would usually rename
    or delete tmp and then restart your build. I recommend keeping one old
    version of tmp around to use for comparison if something goes wrong with
    your new build. For example:<screen>$ <command>rm</command> -fr tmp.OLD
$ <command>mv</command> tmp tmp.OLD
$ <command>bitbake</command> bootstrap-image</screen></para>

    <section id="usage_workdir" xreflabel="work directory">
      <title>work directory (tmp/work)</title>

      <para>The work directory is where all source code is unpacked into,
      where source is configured, compiled and packaged. In other words this
      is where all the action happens. Each bitbake recipe will produce a
      corresponding subdirectory in the work directory. The subdirectory
      name will contain the recipe name, version and the release number (as
      defined by the PR variable within the recipe).</para>

      <para>Here's an example of a few of the subdirectories under the work
      directory:<screen>$ <command>find</command> tmp/work -maxdepth 1 -type d | head -4
tmp/work
tmp/work/busybox-1.2.1-r13
tmp/work/libice-1_1.0.3-r0
tmp/work/arpwatch-2.1a15-r2</screen>You can see the first three (of
      several hundred) recipes here and they are for release 13 of busybox
      1.2.1, release 0 of libice 1.1.0.3 and release 2 of arpwatch 2.1a15.
      It's also possible that you may just have a sub directory for your
      targets architecture and operating system in which case these
      directories will be in that additional subdirectory, as shown
      here:<screen>$ <command>find</command> tmp/work -maxdepth 2 -type d | head -4
tmp/work
tmp/work/sh4-linux
tmp/work/sh4-linux/busybox-1.2.1-r13
tmp/work/sh4-linux/libice-1_1.0.3-r0
tmp/work/sh4-linux/arpwatch-2.1a15-r2</screen></para>

      <para>The <emphasis role="bold">sh4-linux</emphasis> directory in the
      above example is a combination of the target architecture (sh4) and
      operating system (linux). This subdirectory has been added by the use of
      one of OpenEmbedded's many features. In this case it's the
      <emphasis>multimachine</emphasis> feature which is used to allow builds
      for multiple targets within the one work directory and can be enabled on
      a per distribution basis. This feature enables the sharing of native and
      architecture neutral packages and building for multiple targets that
      support the same architecture but require different linux kernels (for
      example). We'll assume multimachine isn't being used for the rest of
      this chapter, just remember to add the extra directory if your
      distribution is using it.</para>

      <para>Using lzo 1.08 as an example we'll examine the contents of the
      working directory for a typical recipe:<screen>$ <command>find</command> tmp/work/lzo-1.08-r14 -maxdepth 1
tmp/work/lzo-1.08-r14
tmp/work/lzo-1.08-r14/temp
tmp/work/lzo-1.08-r14/lzo-1.08
tmp/work/lzo-1.08-r14/install
tmp/work/lzo-1.08-r14/image</screen></para>

      <para>The directory, <emphasis
      role="bold">tmp/work/lzo-1.08-r14</emphasis>, is know as the
      <emphasis>"working directory"</emphasis> for the recipe and is specified
      via the <emphasis role="bold">WORKDIR</emphasis> variable in bitbake.
      You'll sometimes see recipes refer directly to <emphasis
      role="bold">WORKDIR</emphasis> and this is the directory they are
      referencing. The <emphasis role="bold">1.08</emphasis> is the version of
      lzo and <emphasis role="bold">r14</emphasis> is the release number, as
      defined by the <emphasis role="bold">PR</emphasis> variable within the
      recipe.</para>

      <para>Under the working directory (<emphasis
      role="bold">WORKDIR</emphasis>) there are four subdirectories:</para>

      <variablelist>
        <varlistentry>
          <term>temp</term>

          <listitem>
            <para>The temp directories contains logs and in some cases scripts
            that actually implement specific tasks (such as a script to
            configure or compile the source).</para>

            <para>You can look at the logs in this directory to get more
            information into what happened (or didn't happen). This is usually
            the first thing to look at when things are going wrong and these
            usually need to be included when reporting bugs.</para>

            <para>The scripts can be used to see what a particular task, such
            as configure or compile, is trying to do.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>lzo-1.08</term>

          <listitem>
            <para>This is the unpacked source code directory, which was
            created when the lzo source code was extracted in this directory.
            The name and format of this directory is therefore dependent on
            the actual source code packaging. Within recipes this directory is
            referred to as <emphasis role="bold">S</emphasis> and is usually
            expected to be named like this, that is
            <emphasis>"&lt;name&gt;-&lt;version&gt;"</emphasis>. If the source
            code extracts to somewhere else then that would need to be
            declared in the recipe by explicitly setting the value of the
            variable <emphasis role="bold">S</emphasis> to the appropriate
            directory.</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>image</term>

          <listitem>
            <para>The image directory (or destination directory) is where the
            software needs to be installed into in order to be packaged. This
            directory is referred to as <emphasis role="bold">D</emphasis> in
            recipes. So instead of installing binaries into <emphasis
            role="bold">/usr/bin</emphasis> and libraries into <emphasis
            role="bold">/usr/lib</emphasis> for example you would need to
            install into <emphasis role="bold">${D}/usr/bin</emphasis> and
            <emphasis role="bold">${D}/usr/lib</emphasis> instead. When
            installed on the target the ${D} will be not be included so
            they'll end up in the correct place. You definitely don't want
            files on your host system being replaced by cross-compiled
            binaries for your target!</para>
          </listitem>
        </varlistentry>

        <varlistentry>
          <term>install</term>

          <listitem>
            <para>The install directory is used to split the installed files
            into separate packages. One subdirectory is created per package to
            be generated and the files are moved from the image directory
            (<emphasis role="bold">D</emphasis>) over to this directory, and
            into the appropriate package subdirectory, as each packaging
            instruction is processed. Typically there will be separate
            documentation (<emphasis>-doc</emphasis>), debugging
            (<emphasis>-dbg</emphasis>) and development
            (<emphasis>-dev</emphasis>) packages automatically created. There
            are variables such as <emphasis role="bold">FILES_</emphasis> and
            <emphasis role="bold">PACKAGES</emphasis> used in recipes which
            control the separation of various files into individual
            packages.</para>
          </listitem>
        </varlistentry>
      </variablelist>

      <para>So lets show some examples of the useful information you now have
      access to.</para>

      <para>How about checking out what happened during the configuration of
      lzo? Well that requires checking the log file for configure that is
      generated in the temp directory:<screen>$ <command>less</command> tmp/work/lzo-1.08-r14/temp/log.do_configure.*
...
checking whether ccache sh4-linux-gcc -ml -m4 suffers the -fschedule-insns bug... unknown
checking whether ccache sh4-linux-gcc -ml -m4 suffers the -fstrength-reduce bug... unknown
checking whether ccache sh4-linux-gcc -ml -m4 accepts -fstrict-aliasing... yes
checking the alignment of the assembler... 0
checking whether to build assembler versions... no
configure: creating ./config.status
config.status: creating Makefile
config.status: creating examples/Makefile
config.status: creating include/Makefile
config.status: creating ltest/Makefile
config.status: creating minilzo/Makefile
config.status: creating src/Makefile
config.status: creating tests/Makefile
config.status: creating config.h
config.status: executing depfiles commands</screen></para>

      <para>Or perhaps you want to see how the files were distributed into
      individual packages prior to packaging? The install directory is where
      the files are split into separate packages and so that shows us which
      files end up where:<screen>$ <command>find</command> tmp/work/lzo-1.08-r14/install
tmp/work/lzo-1.08-r14/install
tmp/work/lzo-1.08-r14/install/lzo-doc
tmp/work/lzo-1.08-r14/install/lzo-dbg
tmp/work/lzo-1.08-r14/install/lzo-dbg/usr
tmp/work/lzo-1.08-r14/install/lzo-dbg/usr/lib
tmp/work/lzo-1.08-r14/install/lzo-dbg/usr/lib/.debug
tmp/work/lzo-1.08-r14/install/lzo-dbg/usr/lib/.debug/liblzo.so.1.0.0
tmp/work/lzo-1.08-r14/install/lzo-dev
tmp/work/lzo-1.08-r14/install/lzo-dev/usr
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/include
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/include/lzo2a.h
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/include/lzo1y.h
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/include/lzo1.h
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/include/lzo1b.h
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/include/lzo1f.h
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/include/lzoconf.h
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/include/lzo1x.h
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/include/lzo16bit.h
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/include/lzo1a.h
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/include/lzo1z.h
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/include/lzoutil.h
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/include/lzo1c.h
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/lib
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/lib/liblzo.a
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/lib/liblzo.so
tmp/work/lzo-1.08-r14/install/lzo-dev/usr/lib/liblzo.la
tmp/work/lzo-1.08-r14/install/lzo.shlibdeps
tmp/work/lzo-1.08-r14/install/lzo-locale
tmp/work/lzo-1.08-r14/install/lzo
tmp/work/lzo-1.08-r14/install/lzo/usr
tmp/work/lzo-1.08-r14/install/lzo/usr/lib
tmp/work/lzo-1.08-r14/install/lzo/usr/lib/liblzo.so.1
tmp/work/lzo-1.08-r14/install/lzo/usr/lib/liblzo.so.1.0.0</screen></para>
    </section>
  </section>

  <section id="usage_tasks" xreflabel="tasks">
    <title>Tasks</title>

    <para>When you go about building and installing a software package there
    are a number of tasks that you generally follow with most software
    packages. You probably need to start out by downloading the source code,
    then unpacking the source code. Maybe you need to apply some patches for
    some reason. Then you might run the configure script of the package,
    perhaps passing it some options to configure it to your liking. Then you
    might run "make install" to install the software. If you're actually going
    to make some packages, such as .deb or .rpm, then you'd have additional
    tasks you'd perform to make them.</para>

    <para>You find that building things in OpenEmbedded works in a similar way
    - there are a number of tasks that are executed in a predefined order for
    each recipe. Many of the tasks correspond to those listed above like
    <emphasis>"download the source"</emphasis>. In fact you've probably
    already seen some of the names of these tasks - bitbake displays them as
    they are processed:<screen>$ <command>bitbake</command> lzo
NOTE: Psyco JIT Compiler (http://psyco.sf.net) not available. Install it to increase performance.
NOTE: Handling BitBake files: \ (4541/4541) [100 %]
NOTE: Parsing finished. 4325 cached, 0 parsed, 216 skipped, 0 masked.
NOTE: build 200705041709: started

OE Build Configuration:
BB_VERSION     = "1.8.2"
OE_REVISION    = "&lt;unknown&gt;"
TARGET_ARCH    = "sh4"
TARGET_OS      = "linux"
MACHINE        = "titan"
DISTRO         = "erouter"
DISTRO_VERSION = "0.1-20070504"
TARGET_FPU     = ""

NOTE: Resolving missing task queue dependencies
NOTE: preferred version 2.5 of glibc not available (for item virtual/sh4-linux-libc-for-gcc)
NOTE: Preparing Runqueue
NOTE: Executing runqueue
NOTE: Running task 208 of 226 (ID: 11, /home/lenehan/devel/oe/build/titan-glibc-25/recipes/lzo/lzo_1.08.bb, <emphasis
          role="bold">do_fetch</emphasis>)
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_fetch</emphasis>: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_fetch</emphasis>: completed
NOTE: package lzo-1.08: completed
NOTE: Running task 209 of 226 (ID: 2, /home/lenehan/devel/oe/build/titan-glibc-25/recipes/lzo/lzo_1.08.bb, <emphasis
          role="bold">do_unpack</emphasis>)
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_unpack</emphasis>: started
NOTE: Unpacking /home/lenehan/devel/oe/sources/lzo-1.08.tar.gz to /home/lenehan/devel/oe/build/titan-glibc-25/tmp/work/lzo-1.08-r14/
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_unpack</emphasis>: completed
NOTE: package lzo-1.08: completed
NOTE: Running task 216 of 226 (ID: 3, /home/lenehan/devel/oe/build/titan-glibc-25/recipes/lzo/lzo_1.08.bb, <emphasis
          role="bold">do_patch</emphasis>)
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_patch</emphasis>: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_patch</emphasis>: completed
NOTE: package lzo-1.08: completed
NOTE: Running task 217 of 226 (ID: 4, /home/lenehan/devel/oe/build/titan-glibc-25/recipes/lzo/lzo_1.08.bb, <emphasis
          role="bold">do_configure</emphasis>)
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_configure</emphasis>: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_configure</emphasis>: completed
NOTE: package lzo-1.08: completed
NOTE: Running task 218 of 226 (ID: 12, /home/lenehan/devel/oe/build/titan-glibc-25/recipes/lzo/lzo_1.08.bb, <emphasis
          role="bold">do_qa_configure</emphasis>)
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_qa_configure</emphasis>: started
NOTE: Checking sanity of the config.log file
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_qa_configure</emphasis>: completed
NOTE: package lzo-1.08: completed
NOTE: Running task 219 of 226 (ID: 0, /home/lenehan/devel/oe/build/titan-glibc-25/recipes/lzo/lzo_1.08.bb, <emphasis
          role="bold">do_compile</emphasis>)
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_compile</emphasis>: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_compile</emphasis>: completed
NOTE: package lzo-1.08: completed
NOTE: Running task 220 of 226 (ID: 1, /home/lenehan/devel/oe/build/titan-glibc-25/recipes/lzo/lzo_1.08.bb, <emphasis
          role="bold">do_install</emphasis>)
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_install</emphasis>: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_install</emphasis>: completed
NOTE: package lzo-1.08: completed
NOTE: Running task 221 of 226 (ID: 5, /home/lenehan/devel/oe/build/titan-glibc-25/recipes/lzo/lzo_1.08.bb, <emphasis
          role="bold">do_package</emphasis>)
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_package</emphasis>: started
NOTE: DO PACKAGE QA
NOTE: Checking Package: lzo-dbg
NOTE: Checking Package: lzo
NOTE: Checking Package: lzo-doc
NOTE: Checking Package: lzo-dev
NOTE: Checking Package: lzo-locale
NOTE: DONE with PACKAGE QA
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_package</emphasis>: completed
NOTE: package lzo-1.08: completed
NOTE: Running task 222 of 226 (ID: 8, /home/lenehan/devel/oe/build/titan-glibc-25/recipes/lzo/lzo_1.08.bb, <emphasis
          role="bold">do_package_write</emphasis>)
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_package_write</emphasis>: started
Packaged contents of lzo-dbg into /home/lenehan/devel/oe/build/titan-glibc-25/tmp/deploy/ipk/sh4/liblzo-dbg_1.08-r14_sh4.ipk
Packaged contents of lzo into /home/lenehan/devel/oe/build/titan-glibc-25/tmp/deploy/ipk/sh4/liblzo1_1.08-r14_sh4.ipk
NOTE: Not creating empty archive for lzo-doc-1.08-r14
Packaged contents of lzo-dev into /home/lenehan/devel/oe/build/titan-glibc-25/tmp/deploy/ipk/sh4/liblzo-dev_1.08-r14_sh4.ipk
NOTE: Not creating empty archive for lzo-locale-1.08-r14
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_package_write</emphasis>: completed
NOTE: package lzo-1.08: completed
NOTE: Running task 223 of 226 (ID: 6, /home/lenehan/devel/oe/build/titan-glibc-25/recipes/lzo/lzo_1.08.bb, do_populate_sysroot)
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_populate_sysroot</emphasis>: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_populate_sysroot</emphasis>: completed
NOTE: package lzo-1.08: completed
NOTE: Running task 224 of 226 (ID: 9, /home/lenehan/devel/oe/build/titan-glibc-25/recipes/lzo/lzo_1.08.bb, do_qa_staging)
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_qa_staging</emphasis>: started
NOTE: QA checking staging
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_qa_staging</emphasis>: completed
NOTE: package lzo-1.08: completed
NOTE: Running task 225 of 226 (ID: 7, /home/lenehan/devel/oe/build/titan-glibc-25/recipes/lzo/lzo_1.08.bb, do_distribute_sources)
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_distribute_sources</emphasis>: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_distribute_sources</emphasis>: completed
NOTE: package lzo-1.08: completed
NOTE: Running task 226 of 226 (ID: 10, /home/lenehan/devel/oe/build/titan-glibc-25/recipes/lzo/lzo_1.08.bb, do_build)
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_build</emphasis>: started
NOTE: package lzo-1.08-r14: task <emphasis role="bold">do_build</emphasis>: completed
NOTE: package lzo-1.08: completed
NOTE: Tasks Summary: Attempted 226 tasks of which 213 didn't need to be rerun and 0 failed.
NOTE: build 200705041709: completed</screen><note>
        <para>The output may look different depending on the version of
        bitbake being used, and some tasks are only run when specific options
        are enabled in your distribution. The important point to note is that
        the various tasks are being run and bitbake shows you each time it
        starts and completes a task.</para>
      </note></para>

    <para>So there's a set of tasks here which are being run to generate the
    final packages. And if you'll notice that every recipe runs through the
    same set of tasks (ok I'll admit that it is possible that some additional
    tasks could be run for some recipes, but we'll talk about that later). The
    tasks that you'll need to be most familiar with are:</para>

    <variablelist>
      <varlistentry>
        <term>fetch</term>

        <listitem>
          <para>The <emphasis>fetch</emphasis> task is responsible for
          fetching any source code that is required. This means things such as
          downloading files and checking out from source control repositories
          such as git or svn.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>unpack</term>

        <listitem>
          <para>The <emphasis>unpack</emphasis> task is responsible for
          extracting files from archives, such as <emphasis
          role="bold">.tar.gz</emphasis>, into the working area and copying
          any additional files, such as init scripts, into the working
          area.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>patch</term>

        <listitem>
          <para>The <emphasis>patch</emphasis> task is responsible for
          applying any patches to the unpacked source code</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>configure</term>

        <listitem>
          <para>The <emphasis>configure</emphasis> task takes care of the
          configuration of the package. Running a configure script
          (<emphasis>"./configure &lt;options&gt;"</emphasis>) is probably the
          form of configuration that is most recognized but it's not the only
          configuration system that exists.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>compile</term>

        <listitem>
          <para>The <emphasis>compile</emphasis> task actually compiles the
          software. This could be as simple as running <emphasis
          role="bold">make</emphasis>.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>populate_sysroot (stage)</term>

        <listitem>
          <para>The <emphasis>populate_sysroot</emphasis> task (stage is an
          alternate, easier to type name, that can be used to refer to this
          task) is responsible for making available libraries and headers (if
          any) that may be required by other packages to build. For example if
          you compile zlib then it's headers and the library need to be made
          available for other applications to include and link against.</para>

          <note>
            <para>This is different from the <emphasis>install</emphasis> task
            in that this is responsible for making available libraries and
            headers for use during build on the development host. Therefore
            it is libraries which normally have to stage things while
            applications normally don't need to. The
            <emphasis>install</emphasis> task on the other hand is making
            files available for packaging and ultimately installation on the
            target.</para>
          </note>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>install</term>

        <listitem>
          <para>The <emphasis>install</emphasis> task is responsible for
          actually installing everything. This needs to install the
          software into the destination directory, <emphasis
          role="bold">D</emphasis>. This directory won't actually be a part of
          the final package though. In other words if you install something
          into <emphasis role="bold">${D}/bin</emphasis> then it will end up
          in the <emphasis role="bold">/bin</emphasis> directory in the
          package and therefore on the target.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>package</term>

        <listitem>
          <para>The <emphasis>package</emphasis> task takes the installed
          files and splits them into separate directories under the <emphasis
          role="bold">${WORKDIR}/install</emphasis> directory, one per
          package. It moves the files for the destination directory, <emphasis
          role="bold">${D}</emphasis>, that they were installed in into the
          appropriate packages subdirectory. Usually there will be a main
          package, a separate documentation (-doc), development (-dev) and
          debugging packages (-dbg) for example.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>package_write</term>

        <listitem>
          <para>The <emphasis>package_write</emphasis> task is responsible for
          taking each packages subdirectory and creating any actual
          installation package, such as .ipk, .deb or .rpm. Currently .ipk is
          the only fully supported packing format although .deb packages are
          being actively worked on. It should be reasonably easy for an
          experienced OpenEmbedded developer to add support for any other
          packaging formats they might required.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <note>
      <para>You'll notice that the bitbake output had tasks prefixed with
      <emphasis>do_</emphasis>, as in <emphasis>do_install</emphasis> vs
      <emphasis>install</emphasis>. This is slightly confusing but any task
      <emphasis>x</emphasis> is implemented via a function called
      <emphasis>do_x</emphasis> in the class or recipe where it is defined.
      Some places refer to the tasks via their name only and some with the
      <emphasis>do</emphasis> prefix.</para>
    </note>

    <para>You will almost certainly notice tasks beyond the ones above - there are
    various methods available to insert additional tasks into the tasks
    sequence. As an example the <emphasis
    role="bold">insane.bbclass</emphasis>, which performs various QA checks,
    does these checks by inserting a new task called
    <emphasis>qa_configure</emphasis> between the
    <emphasis>configure</emphasis> and <emphasis>compile</emphasis> tasks and
    another new task called <emphasis>qa_staging</emphasis> between
    <emphasis>populate_sysroot</emphasis> and <emphasis>build</emphasis>
    tasks. The former validates the result of the
    <emphasis>configure</emphasis> task and the later the results of the
    <emphasis>populate_sysroot</emphasis> task.</para>

    <para>To determine the full list of tasks available for a specific recipe
    you can run bitbake on the recipe and asking it for the full list of
    available tasks:<screen>$ <command>bitbake</command> -b recipes/perl/perl_5.8.8.bb -c listtasks
NOTE: package perl-5.8.8: started
NOTE: package perl-5.8.8-r11: task do_listtasks: started
do_fetchall
do_listtasks
do_rebuild
do_compile
do_build
do_populate_sysroot
do_mrproper
do_fetch
do_configure
do_clean
do_package
do_unpack
do_install
do_package_write
do_distribute_sources
do_showdata
do_qa_configure
do_qa_staging
do_patch
NOTE: package perl-5.8.8-r11: task do_listtasks: completed
NOTE: package perl-5.8.8: completed
$ </screen></para>

    <para>If you're being observant you'll note that
    <emphasis>listtasks</emphasis> is in fact a task itself, and that the
    <emphasis role="bold">-c</emphasis> option to bitbake allows you to
    explicitly run specific tasks. We'll make use of this in the next section
    when we discuss working with a recipe.</para>
  </section>

  <section id="usage_workwithsinglerecipe"
           xreflabel="working with a single recipe">
    <title>Working with a single recipe</title>

    <para>During development you're likely to often find yourself working on a
    single bitbake recipe - maybe trying to fix something or add a new version
    or perhaps working on a totally new recipe. Now that you know all about
    tasks you can use that knowledge to help speed up the development and
    debugging process.</para>

    <para>Bitbake can be instructed to deal directly with a single recipe file
    by passing it via the <emphasis role="bold">-b</emphasis> parameter. This
    option takes the recipe as a parameter and instructs bitbake to process
    the named recipe only. Note that this ignores any dependencies that are in
    the recipe, so these must have already been built previously.</para>

    <para>Here's a typical example that cleans up the package (using the
    <emphasis>clean</emphasis> task) and the rebuilds it with debugging output
    from bitbake enabled:<screen>$ <command>bitbake</command> -b &lt;bb-file&gt; -c clean
$ <command>bitbake</command> -b &lt;bb-file&gt; -D</screen></para>

    <para>The options to bitbake that are most useful here are:</para>

    <variablelist>
      <varlistentry>
        <term>-b &lt;bb-file&gt;</term>

        <listitem>
          <para>The recipe to process;</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-c &lt;action&gt;</term>

        <listitem>
          <para>The action to perform, typically the name of one of the tasks
          supported by the recipe;</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-D</term>

        <listitem>
          <para>Display debugging information, use two <emphasis
          role="bold">-D</emphasis>'s for additional debugging;</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>-f</term>

        <listitem>
          <para>Force an operation. This is useful in getting bitbake to
          perform some operation it normally wouldn't do. For example, if you
          try and call the <emphasis>compile</emphasis> task twice in a row
          then bitbake will not do anything on the second attempt since it has
          already performed the task. By adding <emphasis
          role="bold">-f</emphasis> it will force it to perform the action
          regardless of if it thinks it's been done previously.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>The most common actions (used with -c) are:</para>

    <variablelist>
      <varlistentry>
        <term>fetch</term>

        <listitem>
          <para>Try to download all of the required source files, but don't do
          anything else with them.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>unpack</term>

        <listitem>
          <para>Unpack the source file but don't apply the patches yet.
          Sometimes you may want to look at the extracted, but not patched
          source code and that's what just unpacking will give you 
          (sometimes handy to get diffs generated against the original
          source).</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>patch</term>

        <listitem>
          <para>Apply any patches.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>configure</term>

        <listitem>
          <para>Performs any configuration that is required for the
          software.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>compile</term>

        <listitem>
          <para>Perform the actual compilation steps of the software.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>stage</term>

        <listitem>
          <para>If any files, such as header and libraries, will be required
          by other packages then they need to be installed into the staging
          area and that's what this task takes care of.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>install</term>

        <listitem>
          <para>Install the software in preparation for packaging.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>package</term>

        <listitem>
          <para>Package the software. Remember that this moves the files from
          the installation directory, D, into the packing install area. So to
          re-package you also need to re-install first.</para>
        </listitem>
      </varlistentry>

      <varlistentry>
        <term>clean</term>

        <listitem>
          <para>Delete the entire directory for this version of the software.
          Usually done to allow a test build with no chance of old files or
          changes being left behind.</para>
        </listitem>
      </varlistentry>
    </variablelist>

    <para>Note that each of the actions that corresponds to a task will run
    any preceding tasks that have not yet been performed. So starting with
    compile will also perform the fetch, unpack, patch and configure
    actions.</para>

    <para>A typical development session might involve editing files in the
    working directory and then recompiling until it all works:<screen>[<emphasis>... test ...</emphasis>]
$ <command>bitbake</command> -b recipes/testapp/testapp_4.3.bb -c compile -D

[<emphasis>... save a copy of main.c and make some changes ...</emphasis>]
$ <command>vi</command> tmp/work/testapp-4.3-r0/main.c
$ <command>bitbake</command> -b recipes/testapp/testapp_4.3.bb -c compile -D -f

[<emphasis>... create a patch and add it to the recipe ...</emphasis>]
$ <command>vi</command> recipes/testapp/testapp_4.3.bb

[<emphasis>... test from clean ...</emphasis>]
$ <command>bitbake</command> -b recipes/testapp/testapp_4.3.bb -c clean
$ <command>bitbake</command> -b recipes/testapp/testapp_4.3.bb

[<emphasis>... NOTE: How to create the patch is not covered at this point ...</emphasis>]</screen></para>

    <para>Here's another example showing how you might go about fixing up the
    packaging in your recipe:<screen>$ <command>bitbake</command> -b recipes/testapp/testapp_4.3.bb -c install -f
$ <command>bitbake</command> -b recipes/testapp/testapp_4.3.bb -c stage -f
$ <command>find</command> tmp/work/testapp_4.3/install
...
$ <command>vi</command> recipes/testapp/testapp_4.3.bb</screen>At this stage you play with
    the <emphasis role="bold">PACKAGE_</emphasis> and <emphasis
    role="bold">FILES_</emphasis> variables and then repeat the above
    sequence.</para>

    <para>Note how we install and then stage. This is one of those things
    where understanding the tasks helps a lot! Remember that stage moves the
    files from where they were installed into the various subdirectories
    (under <emphasis role="bold">${WORKDIR}/instal</emphasis>l) for each
    package. So if you try and run a stage task without a prior install there
    won't be any files there to stage! Note also that the stage tasks clears
    all the subdirectories in <emphasis
    role="bold">${WORKDIR}/install</emphasis> so you won't get any left over
    files. But beware, the install task doesn't clear <emphasis
    role="bold">${D}</emphasis> directory, so any left over files from a
    previous packing attempt will be left behind (which is ok if all you care
    about it staging).</para>
  </section>

  <section id="usage_interactive_bitbake" xreflabel="interactive bitbake">
    <title>Interactive bitbake</title>

    <para>To interactively test things use:<screen>$ <command>bitbake</command> -i</screen>this
    will open the bitbake shell. From here there are a lot of commands
    available (try help).</para>

    <para>First thing you will want to do is parse all of the recipes (recent
    bitbake version do this automatically when needed, so you don't need to
    manually do this anymore):<screen>BB&gt;&gt; parse</screen>You can now
    build a specific recipe:<screen>BB&gt;&gt; build net-snmp</screen>If it
    fails you may want to clean the build before trying again:<screen>BB&gt;&gt; clean net-snmp</screen>If
    you update the recipe by editing the .bb file (to fix some issues) then
    you will want to clean the package, reparse the modified recipe, and then
    build again:<screen>BB&gt;&gt; clean net-snmp
BB&gt;&gt; reparse net-snmp
BB&gt;&gt; build net-snmp</screen>Note that you can use wildcards in the
    bitbake shell as well:<screen>BB&gt;&gt; build t*</screen></para>

    <para></para>
  </section>

  <section id="usage_devshell" xreflabel="devshell">
    <title>Devshell</title>

    <para>One of the areas in which OpenEmbedded helps you out is by setting
    various environment variables, such as <emphasis role="bold">CC</emphasis>
    and <emphasis role="bold">PATH</emphasis> etc, to values suitable for
    cross-compiling. If you wish to manually run configure scripts and compile
    files during development it would be nice to have all those values set for
    you. This is what devshell does - it provides you with an interactive
    shell with all the appropriate variables set for cross-compiling.</para>

    <section>
      <title>devshell via inherit</title>

      <para>This is the newer method of obtaining a devshell and is the
      recommended way for most users now. The newer method requires that the
      devshell class be added to your configuration by inheriting it. This is
      usually done in your <emphasis role="bold">local.conf</emphasis> or your
      distributions conf file:<screen><emphasis role="bold">INHERIT +=</emphasis> "src_distribute_local insane multimachine <emphasis
            role="bold">devshell</emphasis>"</screen></para>

      <para>With the inclusion of this class you'll find that devshell is
      added as a new task that you can use on recipes:<screen>$ <command>bitbake</command> -b recipes/lzo/lzo_1.08.bb -c listtasks
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task do_listtasks: started
<emphasis role="bold">do_devshell</emphasis>
do_fetchall
do_listtasks
do_rebuild
do_compile
do_build
do_mrproper
do_fetch
do_configure
do_clean
do_populate_sysroot
do_package
do_unpack
do_install
do_package_write
do_distribute_sources
do_showdata
do_qa_staging
do_qa_configure
do_patch
NOTE: package lzo-1.08-r14: task do_listtasks: completed
NOTE: package lzo-1.08: completed</screen></para>

      <para>To bring up the devshell you call bitbake on a recipe and ask it
      for the devshell task:<screen>$ <command>bitbake</command> -b recipes/lzo/lzo_1.08.bb -c devshell
NOTE: package lzo-1.08: started
NOTE: package lzo-1.08-r14: task do_devshell: started
[<emphasis>... devshell will appear here ...</emphasis>]
NOTE: package lzo-1.08-r14: task do_devshell: completed
NOTE: package lzo-1.08: completed</screen></para>

      <para>How the devshell appears depends on the settings of the <emphasis
      role="bold">TERMCMD</emphasis> variable - you can see the default
      settings and other possible values in <emphasis
      role="bold">conf/bitbake.conf</emphasis>. Feel free to try settings this
      to something else in your local.conf. Usually you will see a new
      terminal window open which is the devshell window.</para>

      <para>The devshell task is inserted after the patch task, so if you have
      not already run bitbake on the recipe it will download the source and
      apply any patches prior to opening the shell.</para>

      <note>
        <para>This method of obtaining a devshell works if you using <emphasis
        role="bold">bash</emphasis> as your shell, it does not work if you are
        using <emphasis role="bold">zsh</emphasis> as your shell. Other shells
        may or may not work.</para>
      </note>
    </section>

    <section>
      <title>devshell addon</title>

      <para>The devshell addon was the original method that was used to create
      a devshell.</para>

      <para>It requires no changes to your configuration, instead you simply
      build the devshell recipe:<screen>$ <command>bitbake</command> devshell</screen></para>

      <para>and then manually startup the shell. Once in the shell you'll
      usually want to change into the working directory for the recipe you are
      working on:<screen>$ <command>./tmp/deploy/addons/sh4-linux-erouter-titan-devshell</command>
bash: alias: `./configure': invalid alias name
[OE::sh4-linux-erouter-titan]:~$ cd tmp/work/lzo-1.08-r14/lzo-1.08
[OE::sh4-linux-erouter-titan]:~tmp/work/lzo-1.08-r14/lzo-1.08$</screen><note>
          <para>The name of the devshell addon depends on the target
          architecture, operating system and machine name. So you name will be
          different - just check for the appropriate name ending in
          -devshell.</para>
        </note></para>
    </section>

    <section>
      <title>Working in the devshell</title>

      <para>[To be done]</para>
    </section>
  </section>

  <section id="usage_patches" xreflabel="patching">
    <title>Patching and patch management</title>

    <para>[To be done]</para>
  </section>
</chapter>