On Wed, Nov 01, 2017 at 05:16:27PM +0000, Jean-Philippe Brucker wrote: > On 31/10/17 21:17, Alex Williamson wrote: > > On Tue, 31 Oct 2017 19:14:38 +0000 > > Jean-Philippe Brucker <jean-philippe.brucker@xxxxxxx> wrote: > > > >> This series implements PCI pass-through using VFIO in kvmtool. We > >> introduce a new parameter to lkvm run, --vfio-group, that takes an IOMMU > >> group number as argument, and passes all devices in the group to the > >> guest. > > > > Is there a discussion somewhere that provides the reasoning behind this > > whole group choice? It seems very limiting since there exist plenty of > > examples of groups where endpoints and interconnects are both included, > > but only the former is compatible with vfio-pci in the host. It's > > currently impossible to open all of these devices. There's also no > > opportunity to create different device topologies with this > > specification (ex. multi-function vs separate devices vs downstream of > > switches/bridges/root-ports). It seems like a strange starting point > > to me, but you probably already guessed that based on the QEMU > > implementation. > > I don't think it had come up yet. My guess is that it was simpler to do > whole groups when writing the prototype (by Will) and I didn't think much > about changing the interface when I took over. I agree that the QEMU > parameter format is a lot better. > > So maybe we should have "--vfio-pci [<domain>:]<bus>:<dev>.<fn>", and > later "--vfio-platform <name.address>" etc. That certainly looks much more expressive to me. Will
