Dear Albert ARIBAUD,
Am 30.11.2010 09:22, schrieb Albert ARIBAUD:
Le 30/11/2010 08:06, Andreas Bießmann a écrit :
r8 is used for gd and should therefore be left alone
I'm surprised that this did not break things so far... Whatever value r8 ended with was used as the address of GD.
Well r8 is set in arch/arm/include/asm/global_data.h
---8<--- #define DECLARE_GLOBAL_DATA_PTR register volatile gd_t *gd asm ("r8") --->8---
The GD is then later on allocated in board_init_f
---8<--- /* Pointer is writable since we allocated a register for it */ gd = (gd_t *) (CONFIG_SYS_INIT_SP_ADDR); /* compiler optimization barrier needed for GCC >= 3.4 */ __asm__ __volatile__("": : :"memory");
memset ((void*)gd, 0, sizeof (gd_t)); --->8---
Therefore r8 is free, when we use it in relocate_code, isn't it?
After a quick look I haven't found out where r8 is *set* to GD, though... Will have to look this up tonight.
Signed-off-by: Andreas Bießmannandreas.devel@googlemail.com
I don't know if this is really needed, but we use --fixed-r8 compiler flag for all arm boards. Albert, can you shed some light on that?
ffixed-r8 is for the C compiler. The assembler cannot honor ffixed-r8 since register usage is decided by the programmer in each instruction.
I do know that. Therefore this patch to do _not_ use r8 in assembler.
/* relative fix: increase location by offset */
- ldr r1, [r0]
- add r1, r1, r9
- ldr r1, [r0] /* r1<- address of symbol */
- add r1, r1, r9 /* r1<- relocated address of symbol */
I'd like to see a less ambiguous comment here, but I'm not sure what's best. Any suggestions?
Not currently, this was just slipped in by fast preperation of that patch.
fixnext:
- str r1, [r0]
- str r1, [r0] /* store back content of r1 */
Nak. This comment paraphrases the instruction.
dito
regards
Andreas Bießmann