Hey, On 24/11/16 02:45 AM, Christian König wrote: > E.g. it can happen that PCI device A exports it's BAR using ZONE_DEVICE. > Not PCI device B (a SATA device) can directly read/write to it because > it is on the same bus segment, but PCI device C (a network card for > example) can't because it is on a different bus segment and the bridge > can't handle P2P transactions. Yeah, that could be an issue but in our experience we have yet to see it. We've tested with two separate PCI buses on different CPUs connected through QPI links and it works fine. (It is rather slow but I understand Intel has improved the bottleneck in newer CPUs than the ones we tested.) It may just be older hardware that has this issue. I expect that as long as a failed transfer can be handled gracefully by the initiator I don't see a need to predetermine whether a device can see another devices memory. Logan -- 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
