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

[Peter Maydell]

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:
>> > 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.

Oh, I see. That seems a bit obscure :-)

thanks
-- PMM