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So it will likely have to be a white list. > >> > >> This came as a bit of a surprise to our PCIe architect. > > > > I don't think it is a hardware problem. > > The latest and greatest Power9 CPUs still explicitly do not support > this. I think this is another case of the HW can do it but the SW support is missing. IOMMU configuration and maybe firmware too, for instance. If I recall I saw a presentation that Coral was expected to use P2P between the network and GPU. > And, if I recall correctly, the ARM64 device we played with did > not either -- but I suspect that will differ depending on vendor. Wouldn't surprise me at all to see broken implementations in ARM64.. But even there it needs IOMMU enablement to work at all if I recall. Bascially, this is probably not a HW problem that needs a HW bit, but a OS/firmware problem to do all the enablement.. Jason