Trying to run AMD E9260 (Polaris 11) on NXP LS1012A-RDB

Bas Vermeulen bas at daedalean.ai
Thu Jan 10 13:31:24 UTC 2019


On Thu, Jan 10, 2019 at 11:59 AM Christian K├Ânig <
ckoenig.leichtzumerken at gmail.com> wrote:

> The PCI Express controller as instantiated on this chip does not support
> hardware coherency. All incoming PCI Express transactions are made non
> IO-coherent.
>
> Would AMDGPU still work with that PCI Express controller, or is this a
> show-stopper?
>
>
> I'm really wondering what this comment in the documentation means.
>
> As far as I know PCIe doesn't support cache coherency in the downstream
> and supporting it in the up stream is a must have.
>
So what exactly is meant here with IO-coherent?
>

I believe IO Coherent means that when PCIe writes something to CPU memory,
the caches are flushed or updated
(or in this case they aren't). I found
https://community.arm.com/processors/b/blog/posts/extended-system-coherency---part-1---cache-coherency-fundamentals

with this explanation.

Regards,

Bas Vermeulen
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