On Thu, Jul 12, 2018 at 09:20:41PM -0400, Samudrala, Sridhar wrote: > On 7/12/2018 6:19 PM, Siwei Liu wrote: > > On Thu, Jul 12, 2018 at 2:00 PM, Michael S. Tsirkin <m...@redhat.com> wrote: > > > On Thu, Jul 12, 2018 at 01:52:53PM -0700, Siwei Liu wrote: > > > > The definition is incomplete due to lack of spec. There's no "host" > > > > part defined yet in the host-guest interface. If match by MAC is an > > > > interface, the same must be done on the host(device) side as well, > > > > which has been agreed not the way to go. However, I don't think that's > > > > what the author intends to do by interpreting his QEMU patch - it > > > > missed the other parts as well, such as the feature negotiation and > > > > how it interacts with the paired device. > > > > > > > > What I said is that match by MAC is just a guest implementation that > > > > one can change at any time. We now have the group ID on QEMU, why > > > > still sticking to matching by MAC? It shoulnd't be a host-guest > > > > interface in the first place anyway. > > > I think that match by MAC is a simple portable way to match devices. > > > E.g. it will work seamlessly with niche things like zPCI. However > > That's a good point. I'm not sure if it's a valid assumption that zPCI > > should always use the same MAC address as that of virtio. Someone > > who's more familiar with the use case may decide and work on that. It > > means VFIO device has to take in the MAC address as an identifier to > > the "-device vfio-pci,.." QEMU option. I think there's no point to > > match device using group ID in QEMU while using MAC in the guest. > > Based on that assumption, I'd go with making VIRTIO_NET_F_STANDBY to > > match device based on group ID, while someone may come up with another > > feature bit later, say VIRTIO_NET_F_STANDBY_BY_MAC when its QEMU > > support is available. Would it make sense? > > VIRTIO_NET_F_STANDBY as defined in the guest virtio_net driver supports match > by MAC address. I think we should add support for this feature bit in QEMU. > If submitting a patch to update the spec is a pre-requisite to add this > feature bit to QEMU, i can do that.
It's not strictly a prerequisite but we need it in spec all the same, so pls do that. > As far as i understand, group id patches to QEMU are still under review. > Matching by group ID can be another feature bit that could support matching > by group id as well as MAC. > > > > -Siwei > > > > > there are other niche use-cases that aren't addressed by match by MAC > > > such as PF pass-through as a primary, and the pci bridge trick addresses > > > that at cost of some portability. > > > > > > So I see no issues supporting both mechanisms, but others on the TC > > > might feel differently. > > > > > > -- > > > MST
