Re: [Qemu-devel] qemu -netdev tun/tap support can't handle macvtap type devices

["Daniel P. Berrange" <berrange@redhat.com>]

On Wed, Dec 07, 2016 at 12:30:31PM +0000, Peter Maydell wrote:
> On 7 December 2016 at 12:04, Daniel P. Berrange <berrange@redhat.com> wrote:
> > On Wed, Dec 07, 2016 at 12:01:14PM +0000, Peter Maydell wrote:
> >> The usual suggested workaround is to use the -netdev fd option, like
> >>   fd=3 3<>/dev/tap$(< /sys/class/net/tap0/ifindex)
> >> (which gets the shell to open the right /dev/tap device).
> >> Unfortunately this isn't compatible with multi-queue support
> >> because netdev complains
> >> "ifname=, script=, downscript=, vnet_hdr=, helper=, queues=, fds=,
> >> and vhostfds= are invalid with fd="
> >> so you can't pass options like "queues=4"...
> >
> > FWIW you should be able to instead do
> >
> >    fds=3 3<>/dev/tap$(< /sys/class/net/tap0/ifindex)
> >
> > note 'fds' plural, instead of 'fd'
> 
> What's the difference between that and the "usual suggested workaround"
> I described above that doesn't work with queues=... ?

It just seems the 'queues' param always wants you to use 'fds' instead
of 'fd' - 'fds' takes a comma-separated list of FDs - one per queue
and 'fd' only takes a single FD.

Regards,
Daniel
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