Dear Albert Aribaud,
Am 03.07.2011 um 08:56 schrieb Albert ARIBAUD:
Hi Aneesh,
Le 03/07/2011 06:47, Aneesh V a écrit :
Hi Albert,
On Saturday 02 July 2011 01:21 AM, Albert ARIBAUD wrote:
Hi Aneesh,
<snip>
I was thinking of doing that in start.S itself. I haven't looked at all the details though.
BTW, please note that I am not trying to support disjoint BSS in regular u-boot. I think it becomes complex with relocation + it doesn't seem to be worth when all SDRAM is at our disposal.
So:
- #ifdef CONFIG_PRELOADER part in start.s will just pass __bss_start
and __bss_end to the clear_bss function(assumes no relocation). 2. #else part of above will assume that bss follows text and data(or at least that __bss_start > _start), so add relocation offset to __bss_start and __bss_end, and pass them to the clear_bss()
Does that sound ok?
(note clear_bss is not a function in arch/arm/cpu/armv7/start.S, it is only a label)
So, considering what is already in arch/arm/cpu/armv7/start.S, you would just add a conditional variant to the BSS clearing code for the preloader case?
If so, and considering that you'll pass an offset of 0, why would you need that variant for? With offset=0, the code already does what you want, does it not?
we are looking forward to have relocate_code(), clear_bss(), a.s.o. implemented in c in future (as I understood the discussion around christmas about relocation). Wouldn't it be nice to implement now a SPL version of clear_bss(int start, int size) in c and skip the relocate_code() stuff in start.S completely?
As I see the normal way to boot is:
-> some start vector -> lowlevel_init -> board_init_f -> relocate_code -> board_init_r
for SPL we do not need the steps after board_init_f. board_init_f for SPL should implement the generic way to load data from predefined (compile time) source to predefined target address and branch it. Therefore a simple memset() in board_init_f could be sufficient to clear the bss.
regards
Andreas Bießmann