documentation: poky-ref-manual - edits to machine and distro features

Fixes [YOCTO #3292]

I added more detail about the list of machine and distro features
to the introductory paragraphs of these sections.  This information
came from Paul Eggleton.

(From yocto-docs rev: a032f8e49222f6b628eb7d337b967da51a3d7581)

Signed-off-by: Scott Rifenbark <scott.m.rifenbark@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

1 files changed, 19 insertions, 1 deletions

diff --git a/documentation/poky-ref-manual/ref-features.xml b/documentation/poky-ref-manual/ref-features.xml
index fd0bd29ff7..2178d2a322 100644
--- a/documentation/poky-ref-manual/ref-features.xml
+++ b/documentation/poky-ref-manual/ref-features.xml
@@ -30,6 +30,15 @@
         <para>
             The items below are features you can use with  
             <link linkend='var-DISTRO_FEATURES'><filename>DISTRO_FEATURES</filename></link>.
+            Features do not have a one-to-one correspondence to packages, and they can 
+            go beyond simply controlling the installation of a package or packages. 
+            Sometimes a feature can influence how certain recipes are built.
+            For example, a feature might determine whether a particular configure option 
+            is specified within <filename>do_configure</filename> for a particular
+            recipe.
+        </para>
+
+        <para>
             This list only represents features as shipped with the Yocto Project metadata:
             <itemizedlist>
                 <listitem><para><emphasis>alsa:</emphasis> ALSA support will be included (OSS compatibility 
@@ -77,7 +86,16 @@
         <para>
             The items below are features you can use with  
             <link linkend='var-MACHINE_FEATURES'><filename>MACHINE_FEATURES</filename></link>.
-            This list only represents features as shipped with the Yocto Project metadata:
+            Features do not have a one-to-one correspondence to packages, and they can 
+            go beyond simply controlling the installation of a package or packages. 
+            Sometimes a feature can influence how certain recipes are built.
+            For example, a feature might determine whether a particular configure option 
+            is specified within <filename>do_configure</filename> for a particular
+            recipe.
+        </para>
+
+        <para>
+            This feature list only represents features as shipped with the Yocto Project metadata:
             <itemizedlist>
                 <listitem><para><emphasis>acpi:</emphasis> Hardware has ACPI (x86/x86_64 only)
                     </para></listitem>