Re: [PATCH v3 01/11] PCI/P2PDMA: Support peer-to-peer memory

[Logan Gunthorpe]

On 24/03/18 09:28 AM, Stephen  Bates wrote:
> 1. There is no requirement for a single function to support internal DMAs but in the case of NVMe we do have a protocol specific way for a NVMe function to indicate it supports via the CMB BAR. Other protocols may also have such methods but I am not aware of them at this time.
> 
> 2. For multi-function end-points I think it is a requirement that DMAs *between* functions are supported via an internal path but this can be over-ridden by ACS when supported in the EP.
> 
> 3. For multi-function end-points there is no requirement to support internal DMA within each individual function (i.e. a la point 1 but extended to each function in a MF device). 

Yeah, that make sense. I wasn't making a huge distinction between single
and multi-function devices because from an implementation point of view
it's not that different.

Logan