[U-Boot] [PATCH] devkit8000: Move CONFIG_SYS_TEXT_BASE out of bss

[Igor Grinberg]

On 12/01/11 12:16, Aneesh V wrote:
> Hi Igor,
> 
> On Thursday 01 December 2011 03:33 PM, Igor Grinberg wrote:
>> On 12/01/11 11:07, Simon Schwarz wrote:
>>> Hi Igor,
>>>
>>> this only affects Boards with SPL support - and only devkit8000.
>>>
>>> The SPL has its .bss section in SD-RAM while the rest is in SRAM -
>>> CONFIG_SYS_TEXT_BASE was in the same area as .bss. This caused trouble
>>> as the header of the u-boot.img was written before
>>> CONFIG_SYS_TEXT_BASE. In the described case this messed with the
>>> pointer to the mcc datastructure - therefore the u-boot.img file
>>> failed to be read.
>>
>> Thank you very much for the explanation.
>>
>> So as to my understanding, what happens is:
>> 1) The SPL initializes the SDRAM
>> 2) Copies its .bss section to SDRAM
>> 3) Starts loading the U-Boot image and overwrites the .bss section
>> Is the above correct?
>>
>> If it is, then why do we need the .bss in SDRAM?
> 
> U-Boot FAT implementation uses 3 buffers each of size 64 KB.
> 
>> Aren't there enough space in SRAM?
> 
> SRAM doesn't have space for such huge buffers.
> 
>> Also, is this what X-Loader did in first place?
> 
> Yes, x-loader had these buffers in SDRAM too. But instead of putting
> the .bss in SDRAM, x-loader made these huge arrays into pointer
> variables that were then made to point to the SDRAM.

Ok. Now I get the picture of what's going on there.
Never had the time to go through the code to figure this out...
Thanks for the explanation, Aneesh.


-- 
Regards,
Igor.