From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=41226 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OkxaD-0008A1-51 for qemu-devel@nongnu.org; Mon, 16 Aug 2010 07:10:31 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1Okxa7-0004F7-Do for qemu-devel@nongnu.org; Mon, 16 Aug 2010 07:10:25 -0400 Received: from smtp.eu.citrix.com ([62.200.22.115]:41945) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1Okxa7-0004Ej-7C for qemu-devel@nongnu.org; Mon, 16 Aug 2010 07:10:19 -0400 Date: Mon, 16 Aug 2010 12:10:30 +0100 From: Stefano Stabellini In-Reply-To: <4C65B03A.5050306@codemonkey.ws> Message-ID: References: <1281622202-3453-15-git-send-email-stefano.stabellini@eu.citrix.com> <4C6595B5.6060300@codemonkey.ws> <4C65B03A.5050306@codemonkey.ws> MIME-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Subject: [Qemu-devel] Re: [PATCH 15/15] xen: Add a Xen specific ACPI Implementation to target-xen List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: Anthony Perard , "xen-devel@lists.xensource.com" , "qemu-devel@nongnu.org" , Stefano Stabellini On Fri, 13 Aug 2010, Anthony Liguori wrote: > On 08/13/2010 02:37 PM, Stefano Stabellini wrote: > > On Fri, 13 Aug 2010, Anthony Liguori wrote: > > > >> On 08/12/2010 09:10 AM, stefano.stabellini@eu.citrix.com wrote: > >> > >>> From: Anthony PERARD > >>> > >>> Xen currently uses a different BIOS (hvmloader + rombios) therefore the > >>> Qemu acpi_piix4 implementation wouldn't work correctly with Xen. > >>> We plan on fixing this properly but at the moment we are just adding a > >>> new Xen specific acpi_piix4 implementation. > >>> This patch is optional; without it the VM boots but it cannot shutdown > >>> properly or go to S3. > >>> > >>> > >> What's the long term plan? Will Xen adopt SeaBIOS or will you adapt > >> your BIOS to cope with our ACPI implementation? > >> > >> > > I think it shouldn't be too difficult to adapt our current BIOS, but > > we'll need few xen specific hooks in acpi_piix4. > > The price that we'll have to pay doing so is loosing live-migration > > compatibility with older xen installations. > > > > Does Xen migrate roms (like the BIOS) in such a way that the persist > after a reboot? > No, I don't think so. However it is common practice not to require any VM reboot on host upgrade. > I noticed there was only one machine type defined. In our experience, > to preserve compatibility with migration, it's useful to have versioned > machine names. We also have some special machine parameters to support > compatibility with qdev. > Thanks for the tip, we'll look into it. Knowing that we would have the BIOS problem mentioned above, we didn't try yet any save/restore or migration compatibility between old qemu-xen and new qemu. > How does Xen handle hvm migration machine model compatibility? > We use per-device save state versions and we tend to use always the same set of devices. From mboxrd@z Thu Jan 1 00:00:00 1970 From: Stefano Stabellini Subject: Re: [PATCH 15/15] xen: Add a Xen specific ACPI Implementation to target-xen Date: Mon, 16 Aug 2010 12:10:30 +0100 Message-ID: References: <1281622202-3453-15-git-send-email-stefano.stabellini@eu.citrix.com> <4C6595B5.6060300@codemonkey.ws> <4C65B03A.5050306@codemonkey.ws> Mime-Version: 1.0 Content-Type: text/plain; charset="US-ASCII" Return-path: In-Reply-To: <4C65B03A.5050306@codemonkey.ws> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xensource.com Errors-To: xen-devel-bounces@lists.xensource.com To: Anthony Liguori Cc: Anthony Perard , "xen-devel@lists.xensource.com" , "qemu-devel@nongnu.org" , Stefano Stabellini List-Id: xen-devel@lists.xenproject.org On Fri, 13 Aug 2010, Anthony Liguori wrote: > On 08/13/2010 02:37 PM, Stefano Stabellini wrote: > > On Fri, 13 Aug 2010, Anthony Liguori wrote: > > > >> On 08/12/2010 09:10 AM, stefano.stabellini@eu.citrix.com wrote: > >> > >>> From: Anthony PERARD > >>> > >>> Xen currently uses a different BIOS (hvmloader + rombios) therefore the > >>> Qemu acpi_piix4 implementation wouldn't work correctly with Xen. > >>> We plan on fixing this properly but at the moment we are just adding a > >>> new Xen specific acpi_piix4 implementation. > >>> This patch is optional; without it the VM boots but it cannot shutdown > >>> properly or go to S3. > >>> > >>> > >> What's the long term plan? Will Xen adopt SeaBIOS or will you adapt > >> your BIOS to cope with our ACPI implementation? > >> > >> > > I think it shouldn't be too difficult to adapt our current BIOS, but > > we'll need few xen specific hooks in acpi_piix4. > > The price that we'll have to pay doing so is loosing live-migration > > compatibility with older xen installations. > > > > Does Xen migrate roms (like the BIOS) in such a way that the persist > after a reboot? > No, I don't think so. However it is common practice not to require any VM reboot on host upgrade. > I noticed there was only one machine type defined. In our experience, > to preserve compatibility with migration, it's useful to have versioned > machine names. We also have some special machine parameters to support > compatibility with qdev. > Thanks for the tip, we'll look into it. Knowing that we would have the BIOS problem mentioned above, we didn't try yet any save/restore or migration compatibility between old qemu-xen and new qemu. > How does Xen handle hvm migration machine model compatibility? > We use per-device save state versions and we tend to use always the same set of devices.