Hi, There's currently no mechanism for vfio that exposes WC-related operations (check if memory is WC capable, ask to WC memory) to user space module entities, such as DPDK, for example. This topic has been previously discussed in [1], [2] and [3], but there was no follow-up. This capability is very useful for DPDK, specifically to the DPDK ENA driver that uses vfio-pci, which requires memory to be WC on the TX path. Without WC, higher CPU utilization and performance degradation are observed. In the above mentioned discussions, three options were suggested: sysfs, ioctl, mmap extension (extra attributes). Was there any progress on this area? Is there someone who's looking into this? We're leaning towards the ioctl option, if there are no objections, we'd come up with an RFC. [1]: https://patchwork.kernel.org/project/kvm/patch/20171009025000.39435-1-aik@xxxxxxxxx/ [2]: https://lore.kernel.org/linux-pci/2b539df4c9ec703458e46da2fc879ee3b310b31c.camel@xxxxxxxxxxxxxxxxxxx/ [3]: https://lore.kernel.org/lkml/20210429162906.32742-2-sdonthineni@xxxxxxxxxx/ Thanks, David
