[coreboot] 16 GPUs on one board

Aaron Durbin adurbin at google.com
Mon Jan 8 20:12:27 CET 2018


On Thu, Jan 4, 2018 at 1:33 PM, Arthur Heymans <arthur at aheymans.xyz> wrote:

> Hi
>
> What target are you on?
>
> Coreboot tries to locate all PCI BAR's below 4G in the PCI_MMIO region and
> above the lower DRAM
> limit (the rest of the DRAM is mapped above 4G). Typically a GPU takes
> around 256M but I guess that could be more nowadays. If that doesn't fit
> in the PCI MMIO region, it will have troubles and probably not boot.
>
> The real fix would be to have coreboot locate BAR's above 4G too.
>
> At least that is what I think is going on here...
>

That is most likely the case.


>
> (sry for top posting it felt like the answer was better in one block)
>
> Adam Talbot <ajtalbot1 at gmail.com> writes:
>
> > -Coreboot
> > I am totally off the deep end and don't know where else to turn for
> help/advice. I am trying to get 16 GPU's on one motherboard. Whenever I
> attach more then 3~5 GPU's to a single motherboard, it fails to post. To
> make matters worse, my post
> > code reader(s) don't seem to give me any good error codes. Or at least
> nothing I can go on.
> >
> > I am using PLX PEX8614 chips (PCIe 12X switch) to take 4 lanes and pass
> them to 8 GPU's, 1 lane per GPU. Bandwidth is not an issues as all my code
> runs native on the GPUs. Depending on the motherboard, I can get up to 5
> GPU's to post. After
> > many hours of debugging, googling, and trouble shooting, I am out of
> ideas.
> >
> > At this point I have no clue. I think there is a hardware, and a BIOS
> component? Can you help me understand the post process and where the hang
> up is occurring? Do you think Coreboot will get around this hangup and, if
> so, can you advise a
> > motherboard for me to test with?
> >
> > Its been a long time sense I last compiled linuxbios. ;-)
> >
> > Thanks
> > -Adam
>
> Kind regards
>
> --
> Arthur Heymans
>
> --
> coreboot mailing list: coreboot at coreboot.org
> https://mail.coreboot.org/mailman/listinfo/coreboot
>
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