Re: [Qemu-devel] [PATCH] virtio-net: Remove RX_EXTRA feature

[Alex Williamson <alex.williamson@hp.com>]

On Mon, 2009-06-15 at 14:48 +0930, Rusty Russell wrote:
> On Sun, 14 Jun 2009 11:01:37 pm Alex Williamson wrote:
> > On Sun, Jun 14, 2009 at 3:39 AM, Michael S. Tsirkin<mst@redhat.com> wrote:
> > > On Fri, Jun 12, 2009 at 01:17:04PM -0600, Alex Williamson wrote:
> > >> No need to use a feature bit to identify the RX modes.  The guest
> > >> will get an error back if the backend doesn't support these controls.
> > >>
> > >> Signed-off-by: Alex Williamson <alex.williamson@hp.com>
> > >
> > > What's the motivation here - are we running out of feature bits already?
> > > Using feature bits for everything makes the interface more consistent
> > > and IMO easier to use.
> >
> > See the thread starting here:
> >
> > http://lists.gnu.org/archive/html/qemu-devel/2009-06/msg00519.html
> >
> > Both Rusty and Mark voted against the feature bit.
> 
> Not quite.  I was unclear.  I support the use of a feature bit.  My question 
> is more meta.

Oh, ok.  Let's put this patch on hold then.

> Features do need justification.  (Not much, but some).  It's hard to see the 
> use case where this feature offers significant advantages over promisc.  Without 
> that, I'd wait until someone reports a need.

Thanks for clarifying, a need has been reported.  DMX is a proprietary
OS that intends to run on KVM and make use of virtio-net.  They would
like to be able to toggle unicast and multicast independently as well as
mask broadcast traffic.  The original series re-arranged some of the
filter code in the virtio-net backend that allows these filter options
to drop out nicely.  Thanks,

Alex