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authorRichard Purdie <richard.purdie@linuxfoundation.org>2014-01-18 14:30:45 +0000
committerRichard Purdie <richard.purdie@linuxfoundation.org>2014-01-27 21:03:22 +0000
commitd6b8f746d46b22abb277520428e9e6fffafbb96b (patch)
treee8fec23e9b115c1eb78d46ff7d6aa47807e49966
parent76072eaa8e87f7d2f276b4b5d4778f2c882e5c34 (diff)
downloadpoky-d6b8f746d46b22abb277520428e9e6fffafbb96b.tar.gz
bitbake: user-manual-metadata: Add section about layers
(Bitbake rev: 0a99fe01dc273c548f7f83f9a7695c21184e7331) Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
-rw-r--r--bitbake/doc/user-manual/user-manual-metadata.xml40
1 files changed, 40 insertions, 0 deletions
diff --git a/bitbake/doc/user-manual/user-manual-metadata.xml b/bitbake/doc/user-manual/user-manual-metadata.xml
index 9bdf2766fb..73238fd9e5 100644
--- a/bitbake/doc/user-manual/user-manual-metadata.xml
+++ b/bitbake/doc/user-manual/user-manual-metadata.xml
@@ -615,6 +615,46 @@
615 Only variable definitions and include directives are allowed 615 Only variable definitions and include directives are allowed
616 in <filename>.conf</filename> files. 616 in <filename>.conf</filename> files.
617 </para> 617 </para>
618
619 <section id='layers'>
620 <title>Layers</title>
621
622 <para>
623 Layers allow you to isolate different types of
624 customizations from each other.
625 You might find it tempting to keep everything in one layer
626 when working on a single project.
627 However, the more modular you organize your Metadata, the
628 easier it is to cope with future changes.
629 </para>
630
631 <para>
632 To illustrate how layers are used to keep things modular,
633 consider machine customizations.
634 These types of customizations typically reside in a special layer,
635 rather than a general layer, called a Board Specific Package (BSP) Layer.
636 Furthermore, the machine customizations should be isolated from
637 recipes and Metadata that support a new GUI environment, for
638 example.
639 This situation gives you a couple of layers: one for the machine
640 configurations, and one for the GUI environment.
641 It is important to understand, however, that the BSP layer can still
642 make machine-specific additions to recipes within
643 the GUI environment layer without polluting the GUI layer itself
644 with those machine-specific changes.
645 You can accomplish this through a recipe that is a BitBake append
646 (<filename>.bbappend</filename>) file, which is described
647 later in this section.
648 </para>
649
650 <para>
651 There are certain variable specific to layers, including:
652 <itemizedlist>
653 <listitem><para><filename>LAYERDEPENDS</filename></para></listitem>
654 <listitem><para><filename>LAYERVERSION</filename></para></listitem>
655 </itemizedlist>
656 </para>
657 </section>
618 </section> 658 </section>
619 659
620 <section id='classes'> 660 <section id='classes'>