From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:48846) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V8yXl-0000U1-7N for qemu-devel@nongnu.org; Mon, 12 Aug 2013 16:16:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V8yXf-0007Ts-7j for qemu-devel@nongnu.org; Mon, 12 Aug 2013 16:16:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44122) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V8yXe-0007Ti-Vu for qemu-devel@nongnu.org; Mon, 12 Aug 2013 16:16:39 -0400 Date: Mon, 12 Aug 2013 23:18:14 +0300 From: "Michael S. Tsirkin" Message-ID: <20130812201814.GA2713@redhat.com> References: <1376316104-11269-1-git-send-email-aliguori@us.ibm.com> <20130812145436.GA31779@redhat.com> <877gfr9bqu.fsf@codemonkey.ws> <20130812180922.GA1309@redhat.com> <878v06brz6.fsf@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <878v06brz6.fsf@codemonkey.ws> Subject: Re: [Qemu-devel] [PATCH v2] pc: drop external DSDT loading List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: qemu-devel@nongnu.org, Gerd Hoffmann On Mon, Aug 12, 2013 at 02:59:24PM -0500, Anthony Liguori wrote: > "Michael S. Tsirkin" writes: > > > On Mon, Aug 12, 2013 at 10:20:41AM -0500, Anthony Liguori wrote: > >> "Michael S. Tsirkin" writes: > >> > >> > On Mon, Aug 12, 2013 at 09:01:44AM -0500, Anthony Liguori wrote: > >> >> This breaks migration and is unneeded with modern SeaBIOS. > >> >> > >> >> Signed-off-by: Anthony Liguori > >> > > >> > Hmm don't we want to keep it around for machine types > >> > 1.4.0 and 1.5.0? > >> > >> Hrm, why? > > > > Well this modifies the contents of ROM which > > is loaded from FW CFG and isn't migrated, correct? > > If guest is migrated from 1.6 to 1.5 > > while it is loading the ROM, > > it will likely get a corrupted table. > > No, if you migrate from 1.6 to 1.5 the ROM is untouched. ROMs aren't > migrated so it doesn't really matter. Clarifying this on IRC, what was meant here is that -acpi is uncommon so bios typically checks and sees nothing in the ACPI FW CFG entry, and this check is atomic. So this works, by luck. > > If you migrate from 1.5 while reading the ROM contents, then badness can > ensue but that's already the case without this patch. > > Regards, > > Anthony Liguori Well there's a difference between can and will :) But yes, some future version will likely break it anyway. Reviewed-by: Michael S. Tsirkin > > > > > >> Regards, > >> > >> Anthony Liguori > >> > >> > > >> > By the way, copy stable as well? > >> > Loading it unconditonally is a cross > >> > version migration bug that we probably want to fix > >> > on stable branch - disabling for 1.3.0 and older. > >> > > >> >> --- > >> >> v1 -> v2 > >> >> - Still load external DSDT for q35 > >> >> --- > >> >> hw/i386/pc_piix.c | 1 - > >> >> 1 file changed, 1 deletion(-) > >> >> > >> >> diff --git a/hw/i386/pc_piix.c b/hw/i386/pc_piix.c > >> >> index 95c45b8..311574a 100644 > >> >> --- a/hw/i386/pc_piix.c > >> >> +++ b/hw/i386/pc_piix.c > >> >> @@ -103,7 +103,6 @@ static void pc_init1(MemoryRegion *system_memory, > >> >> OBJECT(icc_bridge), NULL); > >> >> > >> >> pc_cpus_init(cpu_model, icc_bridge); > >> >> - pc_acpi_init("acpi-dsdt.aml"); > >> >> > >> >> if (kvm_enabled() && kvmclock_enabled) { > >> >> kvmclock_create(); > >> >> -- > >> >> 1.8.0