ppc: Update README about the new GOT ptr.

r14 is no longer used as non volatile GOT ptr. Instead
the volatile r12 is used so be sure to do GET_GOT in
asm code when you need to access global data.

Signed-off-by: Joakim Tjernlund <Joakim.Tjernlund@transmode.se>

diff --git a/README b/README
index 7affe10..263bb05 100644 (file)
--- a/README
+++ b/README
@@ -3922,7 +3922,9 @@ For PowerPC, the following registers have specific use:
        R30:    GOT pointer
        R31:    frame pointer
 
-       (U-Boot also uses R14 as internal GOT pointer.)
+       (U-Boot also uses R12 as internal GOT pointer. r12
+       is a volatile register so r12 needs to be reset when
+       going back and forth between asm and C)
 
     ==> U-Boot will use R2 to hold a pointer to the global data