From: Scott Rifenbark <srifenbark@gmail.com>
Date: Tue, 12 Jul 2016 21:10:13 +0000 (-0700)
Subject: ref-manual: Added clarifying note to the BBCLASSEXTEND variable.
X-Git-Url: http://git.ipfire.org/gitweb.cgi?a=commitdiff_plain;h=640181cce81663b0a2055592382d127eac5d63ba;p=thirdparty%2Fopenembedded%2Fopenembedded-core-contrib.git

ref-manual: Added clarifying note to the BBCLASSEXTEND variable.

Fixes [YOCTO #9909]

Added a note that talks about how the BBCLASSEXTEND mechanism
adds recipe variants.

(From yocto-docs rev: a05990ecb760519a685a1c5ddcf2ce3e048bfbf2)

Signed-off-by: Scott Rifenbark <srifenbark@gmail.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>
---

diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index 3278ccc27e0..b876bc31157 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -995,6 +995,27 @@
      BBCLASSEXTEND =+ "native nativesdk"
      BBCLASSEXTEND =+ "multilib:<replaceable>multilib_name</replaceable>"
                     </literallayout>
+                    <note>
+                        <para>
+                        Internally, the <filename>BBCLASSEXTEND</filename>
+                        mechanism generates recipe variants by rewriting
+                        variable values and applying overrides such as
+                        <filename>_class-native</filename>.
+                        For example, to generate a native version of a recipe
+                        named "foo", a
+                        <link linkend='var-DEPENDS'><filename>DEPENDS</filename></link>
+                        on "foo" is rewritten to a <filename>DEPENDS</filename>
+                        on "foo-native".
+                        </para>
+
+                        <para>
+                        No reparsing, which adds some limitations, of the
+                        recipe is done for each variant.
+                        For example, it is not possible to "include" a
+                        different file depending on the variant, since
+                        "include's" are processed when the recipe is parsed.
+                        </para>
+                    </note>
                 </para>
              </glossdef>
         </glossentry>