[U-Boot] BSS footprint of FAT very high - SPL issues

[Ulf Samuelsson]

2011-02-01 09:26, Aneesh V skrev:
> Hi Vaibhav,
>
> On Tuesday 01 February 2011 12:22 PM, Bedia, Vaibhav wrote:
>> Hi Aneesh,
>>
>> On Tuesday, February 01, 2011 10:54 AM, Aneesh V wrote:
>>> Dear Wolfgang,
>>>
>>> I had been working on creating an MMC SPL for OMAP4. OMAP boards
>>> typically support booting from the FAT partition of a removable
>>> SD/MMC card. So, we need to have FAT support in the SPL. But I am
>>> having some difficulties in adding FAT support to SPL.
>>>
>>> BSS footprint of fat.c is very high. It has three buffers each of
>>> size 64KB. To workaround this problem I have done something like
>>> below(The way x-loader works around this problem today).
>>> CONFIG_SYS_SPL_FAT_BUFFER_BASE is in SDRAM.Is this ok?
>>>
>> [...]
>>
>> I guess you will hit a similar issue with the networking related code is used (I am not sure if SPL uses it). That also requires a decent size of bss.
> Luckily we don't need networking related code in SPL.
>
> I would prefer to have rest of the BSS in internal RAM itself.
>
> best regards,
> Aneesh
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The way this problem is fixed on the AT91 is to run at91bootstrap first.
This program will initialize the SDRAM and copy u-boot to SDRAM.
at91bootstrap fits into 4 kB of code, and a small amount of RAM,
so it will run on real small CPUs.

You could try to do the same, instead of spending a lot of time,
trying to optimize.

-- 
Best Regards
Ulf Samuelsson