kbuild: document cc-fullversion

Signed-off-by: Sam Ravnborg <sam@ravnborg.org>

1 files changed, 14 insertions, 0 deletions

diff --git a/Documentation/kbuild/makefiles.txt b/Documentation/kbuild/makefiles.txt
index bb5306e9a5c3..e08ef8759a07 100644
--- a/Documentation/kbuild/makefiles.txt
+++ b/Documentation/kbuild/makefiles.txt
@@ -501,6 +501,20 @@ more details, with real examples.
         The third parameter may be a text as in this example, but it may also
         be an expanded variable or a macro.
 
+    cc-fullversion
+        cc-fullversion is useful when the exact version of gcc is needed.
+        One typical use-case is when a specific GCC version is broken.
+        cc-fullversion points out a more specific version than cc-version does.
+
+        Example:
+                #arch/powerpc/Makefile
+                $(Q)if test "$(call cc-fullversion)" = "040200" ; then \
+                        echo -n '*** GCC-4.2.0 cannot compile the 64-bit powerpc ' ; \
+                        false ; \
+                fi
+
+        In this example for a specific GCC version the build will error out explaining
+        to the user why it stops.
 
 === 4 Host Program support