[coreboot] Are multiple GPUs with lots of memory (ex: 8GB+8GB) supported in coreboot?

[Carl-Daniel Hailfinger]

On 10.02.2018 19:57, Arthur Heymans wrote:
> "Taiidan at gmx.com" <Taiidan at gmx.com> writes:
>> I would like to add this information to the wiki so I am wondering if
>> anyone has successfully used for instance dual 8GB graphics cards with
>> coreboot.
>>
> I don't think that this gpu memory is mapped into the linear memory
> space. Such a GPU will typically have a PCI memory resource BAR that is
> (only) 256M large (could be 512M or more these days).
>
>> I am not sure if this would be an issue due to coreboot only having
>> 32bit MMIO space.
>>
> It depends a bit on how things are configured but with a fairly common
> 2G mmio space below 4G I think it is unlikely for 2 external GPU's to be
> an issue.
>
> It would of course be nice to have 64bit BAR support but that would
> require substantial changes in the allocator and more importantly a lot
> of time spend in a sane and thoughtful design...

I think Myles Watson (not 100% sure) worked on an improved resource
allocator with 64 bit resource support for v3. I do not know if it ever
was merged in v4, or if that was instead a port of the v2 allocator to
v3, in which case this would be mostly what we have now. The mails about
this are mostly from 2009.

Regards,
Carl-Daniel