Re: [Qemu-devel] Re: [PATCH 9/9] Introduce VLANClientState::cleanup()

[Blue Swirl <blauwirbel@gmail.com>]

On 4/30/09, Anthony Liguori <aliguori@us.ibm.com> wrote:
> Paul Brook wrote:
>
> >
> > > Sure, you can short-ciruit the case where you have a pair of devices,
> > > but then you need to revoke posted receive descriptors.
> > >
> > >
> >
> > Isn't the same true with a point-point API? When you add a third device to
> the vlan you're going to have to break the tap-guest link, and insert a
> proxy in the middle.
> >
> >
>
>  The difference is that if you assume vlan, then you have to handle
> renegotiation of features which is not actually possible.  With virtio-net,
> once you enable guest GSO, you cannot disable it.  You would have to
> implement GSO emulation within QEMU if you wanted to disable it on the tap
> device.
>
>  If you don't assume vlan, then you can choose the least amount of features
> when in a vlan.  Then you never have to deal with this problem.
>
>  And yes, that means that if you wanted to support the existing syntax, you
> would need a flag like:
>
>  -net tap,i-will-never-add-more-devices-to-this-vlan=on
> -net nic,model=virtio
>

-net pointopoint,tap,nic,model=virtio ?