On Thu, Oct 04, 2012 at 10:28:00AM -0600, Alex Williamson wrote: > There are a couple questions in the link above. Since the devices don't > expose a PCIe capability, we probably need to add a check to look at the > upstream device and verify we're not on a legacy bus where ACS can't be > enforced. You can certainly do that, but for existing hardware (with an AMD IOMMU) this check would never be true. These devices are always on a seperate south-bridge chip which is connected to the north-bridge via PCIe. So the topology where you find these devices is always the same in an AMD IOMMU system. > Then there's the general question of whether the confirmation > of no peer-to-peer applies to every case where we might see this device > (some of them seem to have history that pre-dates this specific package > implementation) or do we need to try to identify specific package > properties in addition to just a device ID? The device ids are kept the same to maintain compatability with older software. Besides that, my statement about the peer-2-peer safety is true for all south-bridges that you can find in an AMD IOMMU capable system. Regards, Joerg -- AMD Operating System Research Center Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach General Managers: Alberto Bozzo Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632 -- To unsubscribe from this list: send the line "unsubscribe linux-pci" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
