diff --git a/Documentation/kbuild/kbuild.txt b/Documentation/kbuild/kbuild.txt
index 5177184..923f9dd 100644
--- a/Documentation/kbuild/kbuild.txt
+++ b/Documentation/kbuild/kbuild.txt
@@ -124,3 +124,10 @@
 --------------------------------------------------
 For modules use symbols from another modules.
 See more details in modules.txt.
+
+ALLSOURCE_ARCHS
+--------------------------------------------------
+For tags/TAGS/cscope targets, you can specify more than one archs
+to be included in the databases, separated by blankspace. e.g.
+
+    $ make ALLSOURCE_ARCHS="x86 mips arm" tags