</para>
</section>
+ <section id='append-bbappend-files'>
+ <title>Append Files</title>
+
+ <para>
+ Append files, which are files that have the
+ <filename>.bbappend</filename> file extension, add or
+ extend build information to an existing
+ recipe file.
+ </para>
+
+ <para>
+ BitBake expects every append file to have a corresponding recipe file.
+ Furthermore, the append file and corresponding recipe file
+ must use the same root filename.
+ The filenames can differ only in the file type suffix used
+ (e.g. <filename>formfactor_0.0.bb</filename> and
+ <filename>formfactor_0.0.bbappend</filename>).
+ </para>
+
+ <para>
+ Information in append files overrides the information in the
+ similarly-named recipe file.
+ </para>
+ </section>
+
<section id='configuration-files'>
<title>Configuration Files</title>
added during the project development process.
</para>
</section>
+
+ <section id='layers'>
+ <title>Layers</title>
+
+ <para>
+ Layers allow you to isolate different types of
+ customizations from each other.
+ While you might find it tempting to keep everything in one layer
+ when working on a single project, the more modular you organize
+ your metadata, the easier it is to cope with future changes.
+ </para>
+
+ <para>
+ To illustrate how you can use layers to keep things modular,
+ consider machine customizations.
+ These types of customizations typically reside in a special layer,
+ rather than a general layer, called a Board Specific Package (BSP) Layer.
+ Furthermore, the machine customizations should be isolated from
+ recipes and metadata that support a new GUI environment, for
+ example.
+ This situation gives you a couple of layers: one for the machine
+ configurations and one for the GUI environment.
+ It is important to understand, however, that the BSP layer can still
+ make machine-specific additions to recipes within
+ the GUI environment layer without polluting the GUI layer itself
+ with those machine-specific changes.
+ You can accomplish this through a recipe that is a BitBake append
+ (<filename>.bbappend</filename>) file.
+ </para>
+ </section>
</section>
<section id='obtaining-bitbake'>