diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index 90eeb2ec07..4c4927ab4e 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -9083,6 +9083,28 @@ recipes-graphics/xorg-font/font-alias_1.0.3.bb:PR = "${INC_PR}.3"
             </glossdef>
         </glossentry>
 
+        <glossentry id='var-TUNE_PKGARCH_tune'><glossterm>TUNE_PKGARCH_tune</glossterm>
+            <glossdef>
+                <para>
+                    The CPU or Application Binary Interface (ABI) specific
+                    tuning of the
+                    <link linkend='var-TUNE_PKGARCH'><filename>TUNE_PKGARCH</filename></link>.
+                </para>
+
+                <para>
+                    These tune-specific package architectures are defined in
+                    the machine include files.
+                    Here is an example of the "core2-32" tuning as used
+                    in the
+                    <filename>meta/conf/machine/include/tune-core2.inc</filename>
+                    file:
+                    <literallayout class='monospaced'>
+     TUNE_PKGARCH_tune-core2-32 = "core2-32"
+                    </literallayout>
+                </para>
+            </glossdef>
+        </glossentry>
+
         <glossentry id='var-TUNEABI'><glossterm>TUNEABI</glossterm>
             <glossdef>
                 <para>