[coreboot] ADLO for buildrom

[Stefan Reinauer]

Rudolf Marek wrote:
>> The main question is who holds the know how on how to enable/disable
>> write protection and shadowing of the e and f segment.
>
> Well this is chipset specific (memory controller).

Exactly. Which is why I think it should not be part of a payload but
part of coreboot.
>> And: Whether we need to care at all. Can't we just leave that space
>> writable and rely on the OS not trying to overwrite the machine's BIOS?
>> I would be surprised if any OS really tried that.
>
> This is what I did exactly with the K8T890/VT8237. The chipset has the
> shadow ram prot bits even if the memory controller is in K8. But hey
> wrong setup of this caused DMA from HDD to fail if the physical memory
> target for DMA was in "shadow" memory range.
Ouch. Ok, then there is nasty stuff happening.

> To sum it up. Coreboot should handle this. ADLO/LegacyBIOS whatever
> should not touch this. We can unprotect  the shadows regions in
> coreboot. All we need is just sane memory map.
Absolutely.