documentation/poky-ref-manual/ref-variables.xml: update PREFERRED_PROVIDER

I added sterner wording on usage and provided an example.

(From yocto-docs rev: 32e07fafadb602b93c9f7b8a78e5baf4c7e1ab5e)

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

1 files changed, 11 insertions, 3 deletions

diff --git a/documentation/poky-ref-manual/ref-variables.xml b/documentation/poky-ref-manual/ref-variables.xml
index d224ed9978..777a91b81f 100644
--- a/documentation/poky-ref-manual/ref-variables.xml
+++ b/documentation/poky-ref-manual/ref-variables.xml
@@ -822,10 +822,18 @@
 
         <glossentry id='var-PREFERRED_PROVIDER'><glossterm>PREFERRED_PROVIDER</glossterm>
             <glossdef>
-                <para>If multiple recipes provide an item, this variable
+                <para>
+                    If multiple recipes provide an item, this variable
                     determines which recipe should be given preference. 
-                    The variable should be set to the <filename>$PN</filename> of the recipe 
-                    to which you want to give precedence.</para>
+                    The variable must always be suffixed with the name of the 
+                    provided item, and should be set to the 
+                    <filename>$PN</filename> of the recipe 
+                    to which you want to give precedence.
+                    Here is an example:
+                    <literallayout class='monospaced'>
+     PREFERRED_PROVIDER_virtual/xserver = "xserver-xf86"
+                    </literallayout>
+                </para>
             </glossdef>
         </glossentry>