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

[Jason Wang]

On 2016年12月07日 22:32, Peter Maydell wrote:
> On 7 December 2016 at 14:24, Daniel P. Berrange <address@hidden> wrote:
> > On Wed, Dec 07, 2016 at 02:21:24PM +0000, Peter Maydell wrote:
> > > On 7 December 2016 at 14:07, Daniel P. Berrange <address@hidden> wrote:
> > > > On Wed, Dec 07, 2016 at 12:30:31PM +0000, Peter Maydell wrote:
> > > > > On 7 December 2016 at 12:04, Daniel P. Berrange <address@hidden> wrote:
> > > > > > 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.
> > > Oh, I see. That seems a bit obscure :-)
> > And pointless, because QemuOpts would have allowed use of 'fd' multiple
> > times instead of inventing a new arg.  fd=1,fd=3,fd=6 could have worked
> > fine with multi-queue :-(
> I guess the best we could do now would be to make fd= and fds= synonyms
> with both supporting either comma-separated or being specified
> multiple times ?

When multiqueue were introduced, qemu does not support such kind of 
parameters. This maybe useful (or use fd[0],fd[1]), but I'm not sure 
this is really needed consider libvirt is in charge of doing such things 
now.

> It's particularly confusing in this case that fd= doesn't work with
> queues=, because the user isn't trying to pass multiple fds, just
> the one is fine.

Since fd can only accept on file descriptor, so it implies 1 queue. For 
"fds", specifying queues seems redundant, since qemu can count the #fds 
by itself.

Thanks

> thanks
> -- PMM