Le 30/11/2010 09:35, Andreas Bießmann a écrit : > 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---
... which is why I could not find "r8" allocation :) ... Thanks. So yes, we need to keep r8, and yes, we were lucky that the start.S code did run at all with a corrupted r8 -- fixing that may remove some weird behaviors we could see, Can you do a pass on other ARM archs which must be fixed too? >> 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 I'd rather have no comment than a paraphrase of the code, but I'd rather have an imperfect yet at least partly helpful comment than no comment at all for assembly language code. > regards > > Andreas Bießmann Amicalement, -- Albert. _______________________________________________ U-Boot mailing list U-Boot@lists.denx.de http://lists.denx.de/mailman/listinfo/u-boot