Hi Santosh, > Look at kernel/resource.c, it exports two symbol ioport_resource and > iomem_resource and sets appropriate flag type i.e.. IORESOURCE_IO and > IORESOURCE_MEM. In virtio-net case; it creates both pci region i.e.. > _io bar and _mem bar. dpdk virtio pmd driver (<= 0.95 virtio spec) uses pci > _io bar region for device initialization as virtio headers are locate at pci > _io bar > region. Since it uses pci _iobar region so likely it update > pci_resource.[index].flag = IORESOURCE_IO. and vfio mmap function wont > handle ioresource_io (i guess). And that is why I asked same to lkml thread.
Yes, I can see that this is what I was misunderstanding (that IORESOURCE_IO isn't a BAR but rather a flag). Technically, if you also set IORESOURCE_MEM along with IORESOURCE_IO, then the BAR would be mapped by VFIO, but this sounds like a dangerous hack :) other than that, yes, I'm afraid it's up to kernel guys to add support for it. Once done, provided IO BARs are meant to be worked with the same way as MEM BARs, there's a good chance it would work out of the box with DPDK. Thanks, Anatoly
