Re: [Qemu-devel] [PATCH 00/12] Multiqueue virtio-net

[Michael S. Tsirkin]

On Wed, Jan 16, 2013 at 09:09:49AM -0600, Anthony Liguori wrote:
> Jason Wang <address@hidden> writes:
> 
> > On 01/15/2013 03:44 AM, Anthony Liguori wrote:
> >> Jason Wang <address@hidden> writes:
> >>
> >>> Hello all:
> >>>
> >>> This seires is an update of last version of multiqueue virtio-net support.
> >>>
> >>> Recently, linux tap gets multiqueue support. This series implements basic
> >>> support for multiqueue tap, nic and vhost. Then use it as an 
> >>> infrastructure to
> >>> enable the multiqueue support for virtio-net.
> >>>
> >>> Both vhost and userspace multiqueue were implemented for virtio-net, but
> >>> userspace could be get much benefits since dataplane like parallized 
> >>> mechanism
> >>> were not implemented.
> >>>
> >>> User could start a multiqueue virtio-net card through adding a "queues"
> >>> parameter to tap.
> >>>
> >>> ./qemu -netdev tap,id=hn0,queues=2,vhost=on -device 
> >>> virtio-net-pci,netdev=hn0
> >>>
> >>> Management tools such as libvirt can pass multiple pre-created fds through
> >>>
> >>> ./qemu -netdev tap,id=hn0,queues=2,fd=X,fd=Y -device
> >>> virtio-net-pci,netdev=hn0
> >> I'm confused/frightened that this syntax works.  You shouldn't be
> >> allowed to have two values for the same property.  Better to have a
> >> syntax like fd[0]=X,fd[1]=Y or something along those lines.
> >
> > Yes, but this what current a StringList type works for command line.
> > Some other parameters such as dnssearch, hostfwd and guestfwd have
> > already worked in this way. Looks like your suggestions need some
> > extension on QemuOps visitor, maybe we can do this on top.
> 
> It's a silly syntax and breaks compatibility.  This is valid syntax:
> 
> -net tap,fd=3,fd=4
> 
> In this case, it means 'fd=4' because the last fd overwrites the first
> one.
> 
> Now you've changed it to mean something else.  Having one thing mean
> something in one context, but something else in another context is
> terrible interface design.
> 
> Regards,
> 
> Anthony Liguori

Aha so just renaming the field 'fds' would address this issue?