On Thu, Jan 20, 2011 at 09:44:05AM +0100, Gerd Hoffmann wrote:
Hi,
For (2), you cannot use bus=X,addr=Y because it makes assumptions about
the PCI topology which may change in newer -M pc's.
Why should the PCI topology for 'pc' ever change?
We'll probably get q35 support some day, but when this lands I
expect we'll see a new machine type 'q35', so '-m q35' will pick the
ich9 chipset (which will have a different pci topology of course)
and '-m pc' will pick the existing piix chipset (which will continue
to look like it looks today).
If the topology does ever change (eg in the kind of way anthony
suggests, first bus only has the graphics card), I think libvirt
is going to need a little work to adapt to the new topology,
regardless of whether we currently specify a bus= arg to -device
or not. I'm not sure there's anything we could do to future proof
us to that kind of change.