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Date: Mon, 22 Nov 2010 16:50:29 +0200
From: "Michael S. Tsirkin" <mst@redhat.com>
Subject: Re: [Qemu-devel] Re: [PATCH] PCI: Bus number from the bridge, not
	the device
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To: Gleb Natapov <gleb@redhat.com>
Cc: Isaku Yamahata <yamahata@valinux.co.jp>, Alex Williamson <alex.williamson@redhat.com>, Markus Armbruster <armbru@redhat.com>, qemu-devel@nongnu.org

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

-- 
MST