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authorWolfgang Denk <wd@denx.de>2008-02-14 22:43:22 +0100
committerWolfgang Denk <wd@denx.de>2008-02-14 22:43:22 +0100
commite7670f6c1e52ae6d2a43ff75a8bcfa7a5c86e47b (patch)
treec105ae64bb203f93e670ef11b3256a4a3086c0ad /README
parent3c234efa693bc59906c2be55c7918ecbb55392ea (diff)
PPC: Use r2 instead of r29 as global data pointer
R29 was an unlucky choice as with recent toolchains (gcc-4.2.x) gcc will refuse to use load/store multiple insns; instead, it issues a list of simple load/store instructions upon function entry and exit, resulting in bigger code size, which in turn makes the build for a few boards fail. Use r2 instead. Signed-off-by: Wolfgang Denk <wd@denx.de>
Diffstat (limited to 'README')
-rw-r--r--README4
1 files changed, 2 insertions, 2 deletions
diff --git a/README b/README
index a5ffbb5ad15..b4966a0df66 100644
--- a/README
+++ b/README
@@ -3499,7 +3499,7 @@ GCC's implementation.
For PowerPC, the following registers have specific use:
R1: stack pointer
- R2: TOC pointer
+ R2: reserved for system use
R3-R4: parameter passing and return values
R5-R10: parameter passing
R13: small data area pointer
@@ -3508,7 +3508,7 @@ For PowerPC, the following registers have specific use:
(U-Boot also uses R14 as internal GOT pointer.)
- ==> U-Boot will use R29 to hold a pointer to the global data
+ ==> U-Boot will use R2 to hold a pointer to the global data
Note: on PPC, we could use a static initializer (since the
address of the global data structure is known at compile time),