[U-Boot] [PATCH] arm: at91: support for the Calao USB-A9263 board (based on AT91SAM9263)

[Heiko Schocher]

Hello Andreas,

Am 29.10.2013 07:26, schrieb Andreas Bießmann:
> Dear Mateusz Kulikowski,
>
> On 28.10.13 22:30, Mateusz Kulikowski wrote:
>> Hi Bo Shen,
>>
>> Thanks for the check, please see below.
>>
>> On 28.10.2013 05:57, Bo Shen wrote:
>>> Hi Mateusz Kulikowski,
>>>     Add Andreas in loop.
>>>
>>> On 10/28/2013 03:34, Mateusz Kulikowski wrote:
>
>>>> +
>>>> +#define CONFIG_SYS_TEXT_BASE 0x23f00000
>>>
>>> This address should be considered as u-boot is top down map, so if
>>> your system only 64MiB, there is only 1MiB left.
>>
>> I don't understand something here:
>> - this address is hardcoded in AT91bootstrap (as well as image size -
>> 0x31000),
>>
>> - I can change it, but it will not boot on "stock" board - should we force
>> people to recompile AT91bootstrap if they want to use new U-Boot?
>> or
>> - Should I add low-level initialization to boot U-Boot from Dataflash
>> without AT91bootstrap (this is a bit more work)?
>> or
>> - There is another way I'm not aware of (perhaps relocate U-Boot in RAM)?
>
> The crux is that in fact u-boot is relocating u-boot in any case (the
> most cases). It will place some stuff at the very top of the RAM (gd_t,
> malloc arena, stack, ...) and calculate depending on some runtime values
> (reserved ram, display vram, ...) where to place the resulting u-boot
> image. The u-boot image will be placed right after the reserved place to
> fill up the whole top of your RAM.
> Therefore it depends on your compile time and runtime setup if there
> will be an overlapping between running u-boot image and resulting place
> when doing the relocation. It is likely to collide with the running
> u-boot image while relocating if it is placed just 1MiB from top of the RAM.
>
> We decided to change at91bootstrap and u-boot for to have another load
> address for some boards in the past cause of real problems there. There
> where strange errors like running system but crashing when using a
> specific command.

Yep, see this on my recently posted boards too ...

> I really recommend to leave a bit more space for u-boot runtime code to
> do it's relocation ad therefore use a smaller ram location.
> The best would be to get SPL working ASAP to have the setup of load

Full Ack.

> address in just one piece of code ... A long outstanding wish of mine,
> but had no time to implement.
>
> Bo and Heiko, could you both please post some RFC of your code to get
> this in line?

I just started with it, I have only serial running under SPL Code,
need to write a small nand driver ... clean up ... and then I can
post a RFC ... hope to do this soon ...

bye,
Heiko
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