Re: [Qemu-devel] [RFC PATCH v6 0/6] Virtio refactoring.

["Michael S. Tsirkin" <mst@redhat.com>]

On Mon, Jan 07, 2013 at 08:02:32PM +0000, Peter Maydell wrote:
> On 7 January 2013 19:58, Michael S. Tsirkin <mst@redhat.com> wrote:
> > On Tue, Dec 18, 2012 at 12:30:20PM +0100, KONRAD Frédéric wrote:
> >> The modifications will be transparent to the user, as we will keep
> >> virtio-x-pci devices.
> >
> > Then what's the point of all this?
> >
> > -device virtio-pci,id=transport1 -device virtio-net,bus=transport1
> >
> > or
> >
> > -device virtio-mmio,id=transport1 -device virtio-net,bus=transport1
> >
> > Is simply an insane way to create a network device.
> 
> 1. You wouldn't create the virtio-mmio transport on the command line,
> the machine model does it (it has to because it's a sysbus device
> and it needs the address/irq lines wiring up properly), so it's just
>  "-device virtio-net" (and let qemu find the bus automatically)

Bus auto-detection sounds good and would be nice for pci too.
We had things like model=virtio originally which is pretty close.
But the issue is, how then do you pass bus specific arguments like pci
slot? This is what caused us to go the virtio-net-pci route
to begin with.

> 2. We shouldn't be making command line simplicity drive how we
> model devices inside QEMU.

Confused.  I was told that enabling
 -device virtio-pci,id=transport1 -device virtio-net,bus=transport1
is the reason we have this patchset.

> If we wanted to do that we should have
> stuck with the old -net command line arguments which are rather
> more userfriendly IMHO.

The main thing that confused people with -net was the vlans
and the need to specify -net twice.
A good UI would have been e.g. -nic model=virtio,net=user.

But one bad UI does not justify another one.

> If commandline confusion is getting to
> be a problem with all the -device foo stuff then we should probably
> fix that at the UI level.
> 
> -- PMM

I'd like to see a proposal about how we are going to do this.

-- 
MST