mirrors/poky
1
0
Fork 0
mirror of https://git.yoctoproject.org/poky synced 2026-04-21 21:32:12 +02:00
Code Issues Packages Projects Releases Wiki Activity

ref-manual: edits to update-alternatives.bbclass description.

Browse Source 
Fixes YOCTO #3838

First draft of edits for this class.  Removed specific variable
definitions as they are now deprecated.  Added a general
explanation of the variable functions.  Pointed user to the
commented code in the actual class for details.  Removed
statement saying that the build system supports only one
binary per package.

(From yocto-docs rev: bd574f2c8a95470c5a44500b70743a6e039522b7)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
This commit is contained in:
Scott Rifenbark
2013-02-05 09:31:54 -06:00
committed by Richard Purdie
parent 40fde06345
commit 1263e58475
1 changed files with 23 additions and 22 deletions
Download Patch File Download Diff File Expand all files Collapse all files

45
documentation/ref-manual/ref-classes.xml
View File

@@ -85,35 +85,36 @@
<title>Alternatives - <filename>update-alternatives.bbclass</filename></title>
<para>
Several programs can fulfill the same or similar function and be installed with the same name.
This class helps the alternatives system when multiple sources provide
the same command.
This situation occurs when several programs that have the same or
similar function are installed with the same name.
For example, the <filename>ar</filename> command is available from the
<filename>busybox</filename>, <filename>binutils</filename> and
<filename>elfutils</filename> packages.
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:
<itemizedlist>
<listitem><para><filename>ALTERNATIVE_NAME</filename> &dash; The name of the
binary that is replaced (<filename>ar</filename> in this example).</para></listitem>
<listitem><para><filename>ALTERNATIVE_LINK</filename> &dash; The path to
the resulting binary (<filename>/bin/ar</filename> in this example).</para></listitem>
<listitem><para><filename>ALTERNATIVE_PATH</filename> &dash; The path to the
real binary (<filename>/usr/bin/ar.binutils</filename> in this example).</para></listitem>
<listitem><para><filename>ALTERNATIVE_PRIORITY</filename> &dash; The priority of
the binary.
The version with the most features should have the highest priority.</para></listitem>
</itemizedlist>
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>
Currently, the OpenEmbedded build system supports only one binary per package.
To use this class, you need to define a number of variables.
These variables list alternative commands needed by a package,
provide pathnames for links, default links for targets, and
so forth.
For details on how to use this class, see the comments in the
<ulink url='&YOCTO_GIT_URL;/cgit/cgit.cgi/poky/tree/meta/classes/update-alternatives.bbclass'><filename>update-alternatives.bbclass</filename></ulink>.
</para>
<note>
You can use the <filename>update-alternatives</filename> command
directly in your recipes.
However, this class simplifies things in most cases.
</note>
</section>
<section id='ref-classes-update-rc.d'>