[libvirt] Re: Supporting vhost-net and macvtap in libvirt for QEMU

> The more interesting invocation of vhost-net though is one where the > vhost-net device backs directly to a physical network card. In this > mode, vhost should get considerably better performance than the current > implementation. I don't know the syntax yet, but I think it's > reasonable to assume that it will look something like -net > tap,dev=eth0. The effect will be that eth0 is dedicated to the guest. > Ok, so in this model you have to create a dedicated ethXX device for every guest, no sharing ?

> I think there are a few ways libvirt could support vhost-net in this > second mode. The simplest would be to introduce a new tag similar to > <source network='br0'>. In fact, if you probed the device type for the > network parameter, you could probably do something like <source > network='eth0'> and have it Just Work. > > Another model would be to have libvirt see an SR-IOV adapter as a > network pool whereas it handled all of the VF management. Considering > how inflexible SR-IOV is today, I'm not sure whether this is the best model. > Agreed, given the hardware limitations I don't see that it is worth the bother. This new mode is not really what we'd call 'bridging' in libvirt network XML format, so I think we'll want to define a new type of network config for it in libvirt. Perhaps <network type='physical'> <source dev='eth0'/> </network> Or type='passthru'