doc: mention chain-compiling for really old gccs

Compiling gcc 2.95.3 directly with 4.x breaks. Mention
chain-compiling as a way to get around that, and end
up with as ancient a gcc as you might like.

Signed-off-by: Erik Inge Bolsø <knan-lkml@anduin.net>
Signed-off-by: Willy Tarreau <w@1wt.eu>

diff --git a/Documentation/using-newer-gcc.txt b/Documentation/using-newer-gcc.txt
index 7834427..3f4d373 100644 (file)
--- a/Documentation/using-newer-gcc.txt
+++ b/Documentation/using-newer-gcc.txt
@@ -167,6 +167,13 @@ commands :
 
   $ make CC=kernel-gcc -j 4 dep bzImage modules modules_install
 
+7) I want to use a really old compiler, but compiling it breaks!
+-----------------------------------------------------------------
+
+Tackle the problem in stages. Compile 3.x.y as above. Then use that to
+compile 2.95.x (CC=/opt/kgcc/bin/kernel-gcc ./configure ...), install,
+use 2.95.x to compile the next compiler in the chain, continue as
+far as you'd like.
 
 Conclusion
 ==========