Re: [Qemu-devel] Re: [PATCH] PCI: Bus number from the bridge, not the device

[Gleb Natapov <gleb@redhat.com>]

On Mon, Nov 22, 2010 at 04:56:16PM +0200, Michael S. Tsirkin wrote:
> On Mon, Nov 22, 2010 at 04:52:32PM +0200, Gleb Natapov wrote:
> > On Mon, Nov 22, 2010 at 04:50:29PM +0200, Michael S. Tsirkin wrote:
> > > On Mon, Nov 22, 2010 at 03:04:51PM +0200, Gleb Natapov wrote:
> > > > On Mon, Nov 22, 2010 at 10:16:57AM +0200, Michael S. Tsirkin wrote:
> > > > > On Mon, Nov 22, 2010 at 09:37:07AM +0200, Gleb Natapov wrote:
> > > > > > > > > It's probably required to make them stable anyway.
> > > > > > > > > 
> > > > > > > > Why?
> > > > > > > 
> > > > > > > To avoid bus renumbering on reboot after you add a pci-to-pci bridge.
> > > > > > > 
> > > > > > Why should qemu care?
> > > > > 
> > > > > Stable bus numbering is a feature *users* care about, because
> > > > > some Guest OSes get confused when a card gets moved to another
> > > > > bus.
> > > > > 
> > > > So if user cares about it it should not change HW configuration of QEMU.
> > > > I guess those OSes knows how to handle hot-pluggable equipment otherwise
> > > > they will get confused on real HW too. Why QEMU should care to preserve
> > > > something in a face of configuration change?
> > > > 
> > > > --
> > > > 			Gleb.
> > > 
> > > We've been there, weren't we? See
> > > http://fedoraproject.org/wiki/Features/KVM_Stable_PCI_Addresses#KVM_Stable_PCI_Addresses
> > > 
> > This is about stable HW configuration.
> 
> Exactly. We have the same need for nested bridges and devices behind
> them.
> 
And now you are talking about topology, not guest assigned bus numbers.
So suddenly you are on my side? I don't even get what are you arguing
about at this point.

--
			Gleb.