Re: [PATCH v4 04/14] PCI/P2PDMA: Clear ACS P2P flags for all devices behind switches

Logan Gunthorpe
2018-05-08T19:13:40Z

On 08/05/18 10:50 AM, Christian König wrote:
> E.g. transactions are initially send to the root complex for
> translation, that's for sure. But at least for AMD GPUs the root complex
> answers with the translated address which is then cached in the device.
>
> So further transactions for the same address range then go directly to
> the destination.

Sounds like you are referring to Address Translation Services (ATS).
This is quite separate from ACS and, to my knowledge, isn't widely
supported by switch hardware.

Logan
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