diff --git a/documentation/ref-manual/ref-variables.xml b/documentation/ref-manual/ref-variables.xml
index 559010b0f3..fe1c100794 100644
--- a/documentation/ref-manual/ref-variables.xml
+++ b/documentation/ref-manual/ref-variables.xml
@@ -493,6 +493,19 @@
             </glossdef>
         </glossentry>
 
+        <glossentry id='var-BB_GENERATE_MIRROR_TARBALLS'><glossterm>BB_GENERATE_MIRROR_TARBALLS</glossterm>
+            <glossdef>
+                <para>
+                    Causes tarballs of the Git repositories to be placed in the
+                    <link linkend='var-DL_DIR'><filename>DL_DIR</filename></link>
+                    directory.
+                    For performance reasons, creating and placing tarballs of
+                    the Git repositories is not the default action by the
+                    OpenEmbedded build system.
+                </para>
+            </glossdef>
+        </glossentry>
+
         <glossentry id='var-BB_NUMBER_THREADS'><glossterm>BB_NUMBER_THREADS</glossterm>
             <glossdef>
                 <para>The maximum number of tasks BitBake should run in parallel at any one time.
@@ -1283,8 +1296,20 @@ Core layer for images cannot be removed
                     <filename>DL_DIR</filename> and the build system looks there
                     first to find source tarballs.
                     <note>
-                        When wiping and rebuilding, you can preserve this
-                        directory to speed up this part of subsequent builds.
+                        <para>
+                            When wiping and rebuilding, you can preserve this
+                            directory to speed up this part of subsequent
+                            builds.
+                        </para>
+
+                        <para>
+                            Also, by default, the <filename>DL_DIR</filename>
+                            does not contain tarballs of Git directories.
+                            However, you can instruct the build process to save
+                            these tarballs to the directory by using the
+                            <link linkend='var-BB_GENERATE_MIRROR_TARBALLS'><filename>BB_GENERATE_MIRROR_TARBALLS</filename></link>
+                            variable.
+                        </para>
                     </note>
                 </para>