Re: [Qemu-devel] using -net dump with tap networking

[Stefan Hajnoczi]

On Tue, Feb 19, 2013 at 06:50:22PM +0100, Markus Armbruster wrote:
> Stefan Hajnoczi <address@hidden> writes:
> 
> > On Tue, Feb 19, 2013 at 09:53:07AM +0100, Markus Armbruster wrote:
> >> Stefan Hajnoczi <address@hidden> writes:
> >> 
> >> > On Tue, Feb 19, 2013 at 12:37:28PM +1100, Alexey Kardashevskiy wrote:
> >> >> On 14/02/13 21:26, Stefan Hajnoczi wrote:
> >> >> 
> >> >> >>>>Now I want to enable network dump. With the old "-net" syntax
> >> >> >>>> I could do
> >> >> >>>>that with "-net dump" but I cannot with the new syntax, tried many
> >> >> >>>>variants, none works. What would the correct syntax be for
> >> >> >>>> the case above?
> >> >> 
> >> >> The question was about new "-netdev" interface.
> >> >> 
> >> >> >I would do:
> >> >> >
> >> >> >qemu-system-ppc64 ...
> >> >> >       -net tap,ifname=tap0,script=qemu-ifup.sh
> >> >> >       -net nic,model=virtio
> >> >> >       -net dump,file=./dump.lan.qemu.virtio
> >> >> >
> >> >> 
> >> >> The answer is about old "-net" interface which I know how to use.
> >> >> 
> >> >> Does this mean that there is no way to use "dump" with "-netdev tap"?
> >> >
> >> > It is not possible using just -netdev/-device.  The closest you can get
> >> > is:
> >> >
> >> >   $ qemu -netdev hubport,hubid=1,id=hubport0 \
> >> >          -device virtio-net-pci,netdev=hubport0,... \
> >> >   -net tap,vlan=1,... \
> >> >   -net dump,vlan=1,...
> >> 
> >> Care to explain briefly how hubport works, and how it's connected to the
> >> legacy "vlan" feature?
> >
> > -netdev hubport instantiates a new port on a hub with "vlan" number
> > hubid=<number>.
> >
> > hubport is a -netdev, so it allows you to hook up a NIC to a hub using
> > -netdev/-device syntax.
> >
> > This is just playing games with syntax, we still have a hub in between
> > the virtio-net-pci, tap, and dump devices.  I didn't check if the
> > offload features get plumbed through, but I wouldn't count on it.
> 
> Thanks.
> 
> Would you mind documenting net backend hubport in qemu-options.hx?  Was
> forgotten in commit f6c874e3.

Sure.

Stefan