[U-Boot] [PATCH RFC 1/3] arm920t: do not set register useless

Andreas Bießmann
2010-11-30T07:06:38Z

in case we are still at relocation target address before relocation we
do not need to load the registers needed for relocation. We should
instead skip the whole relocation part and jump over to clear_bss.

Also prepare to not use target address twice. When we use a scratch
register here r6 is unchanged and can be used later on.

Signed-off-by: Andreas Bie?mann <andreas.devel@googlemail.com>
---
arch/arm/cpu/arm920t/start.S | 7 ++++---
1 files changed, 4 insertions(+), 3 deletions(-)

diff --git a/arch/arm/cpu/arm920t/start.S b/arch/arm/cpu/arm920t/start.S
index 01edb9b..71de373 100644
--- a/arch/arm/cpu/arm920t/start.S
+++ b/arch/arm/cpu/arm920t/start.S
@@ -208,15 +208,16 @@ stack_setup:
mov sp, r4

adr r0, _start
+ cmp r0, r6
+ beq clear_bss /* skip relocation */
+ mov r1, r6
ldr r2, _TEXT_BASE
ldr r3, _bss_start_ofs
add r2, r0, r3 /* r2 <- source end address */
- cmp r0, r6
- beq clear_bss

copy_loop:
ldmia r0!, {r9-r10} /* copy from source address [r0] */
- stmia r6!, {r9-r10} /* copy to target address [r1] */
+ stmia r1!, {r9-r10} /* copy to target address [r1] */
cmp r0, r2 /* until source end address [r2] */
blo copy_loop

--
1.7.3.2