On Thu, Feb 3, 2011 at 1:01 AM, Aneesh V aneesh@ti.com wrote:
Hi Albert,
On Wednesday 02 February 2011 07:07 PM, Albert ARIBAUD wrote:
Hi Aneesh,
Le 02/02/2011 14:17, Aneesh V a écrit :
Hello Wolfgang, Albert,
On Tuesday 01 February 2011 03:33 PM, Wolfgang Denk wrote:
Dear Aneesh V,
In message4D47C1C9.1020002@ti.com you wrote:
Why would that be necessary? Just put the BSS segment in SDRAM, and everything is fine, isn't it?
SDRAM is initialized by the SPL. So, bss can not be initialized and used until SDRAM initialization is complete. I would prefer to have
Yes, this is normal.
rest of the bss in internal RAM so that it's available as soon as we enter C code.
Well, you probably have to decide if you want an easy solution with the restictions of the internal RAM size, or a somewhat more complex solution with much more powerful resources.
I tried putting bss in SDRAM and it works for me. I just had to put a couple of variables explicitly in .data section.
You mean data that would have ended in BSS but that you moved to .data? Why?
Yes. These are variables that otherwise would go to BSS. I do this because I need them before SDRAM initialization. One of this is the gd structure. I allocate gd structure in .data that is in IRAM. Why I need gd before SDRAM? Because I try to initialize serial console as early as possible and this code has some reference to gd.
Which is a perfectly normal scenario and the way things have always been. There should have been no need to shuffle gd around because of console initialisation.
And as I understand it, gd itself does not get statically 'allocated' in the u-boot image per-se (i.e. not in .data and not in .bss) - Only the pointer to it is allocated. In most arches, this pointer is itself not in .data or .bss but rather in a fixed reserved register. In the new x86 (final patches coming soon), the pointer is allocated in .data with a preset initialised value pointing into Cache-As-RAM (i.e. IRAM). Prior to relocation, the gd pointer variable points to somewhere in IRAM / CAR and after relocation, gd gets copied into the heap and the gd pointer adjusted to point to the new permanent copy.
Regards,
Graeme