On Wednesday 11 October 2017 07:17 AM, Tan, Jianfeng wrote: > Hi, > > Nice patch series. But I still have a small question about below flag. > > > On 10/6/2017 7:03 PM, Santosh Shukla wrote: >> Get iommu class of PCI device on the bus and returns preferred iova >> mapping mode for that bus. >> >> Patch also introduces RTE_PCI_DRV_IOVA_AS_VA drv flag. >> Flag used when driver needs to operate in iova=va mode. >> > Does this flag indicate a must to use VA as IOVA, or a nice-to-have one? In > detail, above commit log says, "needs to operate in iova=va mode", but the > comment in the patch indicates this flag means "driver supports IOVA as VA". > > If it's the latter case, I would suppose all drivers support to use VA as > IOVA, if the NICs are binded to vfio-pci (iommu mode). Please correct me if > I'm wrong. > - Any iommu backed pmd could choose to use this flag. - Reasoning for need was performance for our external mempool pmd: avoid phy2virt translation on mbuf thus save cycles.
> Thanks, > Jianfeng
