From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [Qemu-devel] Re: [PATCH 2/3] qemu: make cirrus init value pci spec compliant Date: Thu, 8 Oct 2009 21:39:40 +0200 Message-ID: <20091008193939.GA18838@redhat.com> References: <20091008145241.GC12275@redhat.com> <4ACE0559.5040206@redhat.com> <20091008160623.GA13710@redhat.com> <4ACE0FC6.3050908@redhat.com> <20091008184011.GA6576@shareable.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: Avi Kivity , Anthony Liguori , "qemu-devel@nongnu.org" , kvm-devel To: Jamie Lokier Return-path: Received: from mx1.redhat.com ([209.132.183.28]:7610 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754273AbZJHTmb (ORCPT ); Thu, 8 Oct 2009 15:42:31 -0400 Content-Disposition: inline In-Reply-To: <20091008184011.GA6576@shareable.org> Sender: kvm-owner@vger.kernel.org List-ID: On Thu, Oct 08, 2009 at 07:40:12PM +0100, Jamie Lokier wrote: > Avi Kivity wrote: > > On 10/08/2009 06:06 PM, Michael S. Tsirkin wrote: > > >On Thu, Oct 08, 2009 at 05:29:29PM +0200, Avi Kivity wrote: > > > > > >>On 10/08/2009 04:52 PM, Michael S. Tsirkin wrote: > > >> > > >>>PCI memory should be disabled at reset, otherwise > > >>>we might claim transactions at address 0. > > >>>I/O should also be disabled, although for cirrus > > >>>it is harmless to enable it as we do not > > >>>have I/O bar. > > >>> > > >>>Note: need bios fix for this patch to work: > > >>>currently pc-bios incorrently assumes that it does not > > >>>need to enable i/o unless device has i/o bar. > > >>> > > >>>Signed-off-by: Michael S. Tsirkin > > >> > > >>This needs to be conditional on the machine type. Old machines must > > >>retain this code for live migration to work (we need to live migrate the > > >>bios, so we can't assume the bios fix is in during live migration from > > >>older qemus). > > >> > > >No, if you migrate from older qemu you will be fine as command > > >is enabled there on init. > > > > > > > Right. > > No, I think Avi was right the first time. > > Migrating from an older qemu will be fine at first, but at the next > reset _following_ migration, it'll be running the old BIOS on a new > qemu and fail. OK but Avi was commenting on the patch that removed bit set in init, ignoring reset behaviour. So for old BIOS we want a flag not to clear I/O enable bit on reset for VGA devices. > -- Jamie