On 7/8/2016 6:27 PM, Thomas Monjalon wrote: > 2016-05-11 18:24, Ferruh Yigit: >> On 5/11/2016 8:35 AM, Alejandro Lucero wrote: >>> On Tue, May 10, 2016 at 4:59 PM, Stephen Hemminger < >>> stephen at networkplumber.org> wrote: >>> >>>> On Tue, 10 May 2016 19:21:41 +0800 >>>> Zhe Tao <zhe.tao at intel.com> wrote: >>>> >>>>> Problem: >>>>> The following operations will cause the igb_uio based DPDK >>>>> operation failed. >>>>> --Any device assignment through the kvm_assign_device interface, >>>>> this can be the pci-assign method in QEMU >>>>> --VFIO group attachment operation(attach to the container) >>>>> this can happens in vfio-pci assignment in QEMU >>>> >>>> >>>> If you have an IOMMU why not use VFIO instead, it is better. >>>> >>> >>> It is not about VFIO against UIO but about how iommu domains are created >>> and destroyed by the (old) kernel when iommu=pt. So even with VFIO you can >>> have problems. >> >> Problem is in IOMMU driver but we are adding a workaround to igb_uio, if >> using VFIO solves the issue, I believe that is better workaround. >> >> 1) Is there any case IOMMU supported but VFIO is not supported? Is there >> anything forces to use igb_uio? >> >> 2) Does using VFIO solves the issue defined in problem statement? >> >>> >>> We have had problems like this and other due to our device (NFP) just >>> mapping up to 40 bits of address space. Old kernels used in LTS >>> distributions like Ubuntu are iommu buggy and you need to do things like >>> this mapping inside the driver for solving problems. By the way, using >>> SRIOV just adds more problems. It is not safe to use iommu=pt with 3.13.x >>> Ubuntu kernels. >>> >>> It would be a good thing for the original patch to identify those kernels >>> where the problem was detected. Of course, there could be more kernels with >>> the same problem but that is more work to do. >>> >B > Ping, this patch is stalled. >
I am for rejecting this patch. The patch is useful for tester / developers who use both vfio and igb_uio. But if end user has environment support to use vfio, she should use vfio instead of having workaround to use both. Thanks, ferruh
