Re: [Qemu-devel] [PATCH][RFC] qemu:virtio-net: Use TUNSETTXFILTER for MAC filtering

[Paul Brook <paul@codesourcery.com>]

> > There should be two interface points between the the vlan and the device:
> > 1) The device can indicate that it only cares about incoming (vlan to
> > device) packets sent to a subset of MAC addresses.
> > 2) The vlan can request that a device discards outgoing (device to vlan)
> > packets that don't match a subset of MAC addresses.
> >
> > Typically a emulated NIC will implement (1) and a host interface will
> > implement (2).
> >
> > The generic vlan code should be responsible for using the information
> > provided by (1) to set (2) appropriately. Remember that network devices
> > can be hotplugged.
>
> Do you think it's worthwhile for the vlan to save and consolidate
> filtering from multiple (1) sources to program (2)?  My interface is
> effectively short circuiting and letting the (1) agent set (2).  As you
> mention below, this is an optimization, so I think it's reasonable that
> if we exceed a 1x1 configuration of (1)s and (2)s, we need to reset back
> to a shared media model and do filtering in the (1) agent, which is how
> I think we should handle hotplug.

My point is that the devices themselves shouldn't know or care about this. 
Obviously a trivial implementation of combining multiple sources is to 
disable the filter if there is more than one other device.

Paul