<para>
Class files are used to abstract common functionality and share it amongst multiple
- <filename class="extension">.bb</filename> files. Any metadata usually found in a
- <filename class="extension">.bb</filename> file can also be placed in a class
+ <filename>.bb</filename> files. Any metadata usually found in a
+ <filename>.bb</filename> file can also be placed in a class
file. Class files are identified by the extension
- <filename class="extension">.bbclass</filename> and are usually placed
- in a <filename class="directory">classes/</filename> directory beneath the
- <filename class="directory">meta*/</filename> directory or the directory pointed
- by BUILDDIR (e.g. <filename class="directory">build/</filename>)in the same way as
- <filename class="extension">.conf</filename> files in the <filename
+ <filename>.bbclass</filename> and are usually placed
+ in a <filename>classes/</filename> directory beneath the
+ <filename>meta*/</filename> directory or the directory pointed
+ by BUILDDIR (e.g. <filename>build/</filename>)in the same way as
+ <filename>.conf</filename> files in the <filename
class="directory">conf</filename> directory. Class files are searched for
in BBPATH in the same was as <filename>.conf</filename> files too.
</para>
<title>The base class - <filename>base.bbclass</filename></title>
<para>
- The base class is special in that every <filename class="extension">.bb</filename>
+ The base class is special in that every <filename>.bb</filename>
file inherits it automatically. It contains definitions of standard basic
tasks such as fetching, unpacking, configuring (empty by default), compiling
(runs any Makefile present), installing (empty by default) and packaging
<para>
Several programs can fulfill the same or similar function and
- they can be installed with the same name. For example the <command>ar</command>
+ be installed with the same name.
+ For example, the <filename>ar</filename>
command is available from the "busybox", "binutils" and "elfutils" packages.
- This class handles the renaming of the binaries so multiple packages
- can be installed which would otherwise conflict and yet the
- <command>ar</command> command still works regardless of which are installed
- or subsequently removed. It renames the conflicting binary in each package
+ The <filename>update-alternatives.bbclass</filename> class handles renaming the
+ binaries so that multiple packages can be installed without conflicts.
+ The <filename>ar</filename> command still works regardless of which packages are installed
+ or subsequently removed.
+ The class renames the conflicting binary in each package
and symlinks the highest priority binary during installation or removal
of packages.
-
+ </para>
+ <para>
Four variables control this class:
</para>
-
-
- <variablelist>
- <varlistentry>
- <term>ALTERNATIVE_NAME</term>
- <listitem>
- <para>
- Name of binary which will be replaced (<command>ar</command> in this example)
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>ALTERNATIVE_LINK</term>
- <listitem>
- <para>
- Path to resulting binary ("/bin/ar" in this example)
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>ALTERNATIVE_PATH</term>
- <listitem>
- <para>
- Path to real binary ("/usr/bin/ar.binutils" in this example)
- </para>
- </listitem>
- </varlistentry>
- <varlistentry>
- <term>ALTERNATIVE_PRIORITY</term>
- <listitem>
- <para>
- Priority of binary, the version with the most features should have the highest priority
- </para>
- </listitem>
- </varlistentry>
- </variablelist>
-
+ <itemizedlist>
+ <listitem><para><filename>ALTERNATIVE_NAME</filename> ‐ The name of the
+ binary that is replaced (<filename>ar</filename> in this example).</para></listitem>
+ <listitem><para><filename>ALTERNATIVE_LINK</filename> ‐ The path to
+ the resulting binary (<filename>/bin/ar</filename> in this example).</para></listitem>
+ <listitem><para><filename>ALTERNATIVE_PATH</filename> ‐ The path to the
+ real binary (<filename>/usr/bin/ar.binutils</filename> in this example).</para></listitem>
+ <listitem><para><filename>ALTERNATIVE_PRIORITY</filename> ‐ The priority of
+ the binary.
+ The version with the most features should have the highest priority.</para></listitem>
+ </itemizedlist>
<para>
Currently, only one binary per package is supported.
</para>
<para>
During staging Bitbake installs such scripts into the <filename
class="directory">sysroots/</filename> directory. It also changes all
- paths to point into the <filename class="directory">sysroots/</filename>
+ paths to point into the <filename>sysroots/</filename>
directory so all builds which use the script will use the correct
directories for the cross compiling layout.
</para>
</para>
<para>
- Result of their work are <filename class="directory">tmp/deploy/source/</filename>
+ Result of their work are <filename>tmp/deploy/source/</filename>
subdirs with sources sorted by <glossterm><link linkend='var-LICENSE'>LICENSE</link>
</glossterm> field. If recipe lists few licenses (or has entries like "Bitstream Vera") source archive is put in each
license dir.
</para>
<para>
This means that each kernel module built is packaged separately and inter-module dependencies are
- created by parsing the <command>modinfo</command> output. If all modules are
+ created by parsing the <filename>modinfo</filename> output. If all modules are
required then installing the "kernel-modules" package will install all
packages with modules and various other kernel packages such as "kernel-vmlinux".
</para>
<para>
Only the most useful/important classes are covered here but there are
- others, see the <filename class="directory">meta/classes</filename> directory for the rest.
+ others, see the <filename>meta/classes</filename> directory for the rest.
</para>
</section>
