From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=54398 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1PKZmt-0004oE-Sk for qemu-devel@nongnu.org; Mon, 22 Nov 2010 12:03:49 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1PKZlf-0004uL-Sd for qemu-devel@nongnu.org; Mon, 22 Nov 2010 12:02:42 -0500 Received: from mx1.redhat.com ([209.132.183.28]:23814) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1PKZlf-0004u3-Lk for qemu-devel@nongnu.org; Mon, 22 Nov 2010 12:01:27 -0500 Date: Mon, 22 Nov 2010 19:01:24 +0200 From: Gleb Natapov Subject: Re: [Qemu-devel] Re: [PATCH] PCI: Bus number from the bridge, not the device Message-ID: <20101122170124.GA25606@redhat.com> References: <20101121192959.GA13157@redhat.com> <20101121203931.GA29831@redhat.com> <20101122073707.GF7948@redhat.com> <20101122081657.GA11010@redhat.com> <20101122130451.GG7948@redhat.com> <20101122145029.GA30157@redhat.com> <20101122145232.GL7948@redhat.com> <20101122145616.GC30157@redhat.com> <20101122145811.GM7948@redhat.com> <20101122164127.GA32469@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20101122164127.GA32469@redhat.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Michael S. Tsirkin" Cc: Isaku Yamahata , Alex Williamson , Markus Armbruster , qemu-devel@nongnu.org On Mon, Nov 22, 2010 at 06:41:28PM +0200, Michael S. Tsirkin wrote: > On Mon, Nov 22, 2010 at 04:58:11PM +0200, Gleb Natapov wrote: > > 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. > > I suspect that if bus numbers change, it has the same effect as topology > change on the guest. Need to test though, I'm not sure. > Hard to believe. Unplugging card with internal pci-pci bridge may change bus numbering. > > So suddenly you are on my side? I don't even get what are you arguing > > about at this point. > > By this time, I forgot, too :). > :) -- Gleb.