From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MRNtz-0003IU-JC for qemu-devel@nongnu.org; Thu, 16 Jul 2009 06:09:23 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MRNtu-0003Gr-6x for qemu-devel@nongnu.org; Thu, 16 Jul 2009 06:09:22 -0400 Received: from [199.232.76.173] (port=48433 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MRNtt-0003Gn-Vk for qemu-devel@nongnu.org; Thu, 16 Jul 2009 06:09:18 -0400 Received: from outbound-dub.frontbridge.com ([213.199.154.16]:52234 helo=IE1EHSOBE001.bigfish.com) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_ARCFOUR_MD5:16) (Exim 4.60) (envelope-from ) id 1MRNtt-0004GG-DP for qemu-devel@nongnu.org; Thu, 16 Jul 2009 06:09:17 -0400 Message-ID: <4A5EFC35.4060607@amd.com> Date: Thu, 16 Jul 2009 12:08:53 +0200 From: Andre Przywara MIME-Version: 1.0 Subject: Re: [Qemu-devel] CPUID feature bits not saved with migration References: <4A5DD0B0.7070700@amd.com> <4A5DE9E5.2080809@codemonkey.ws> In-Reply-To: <4A5DE9E5.2080809@codemonkey.ws> Content-Type: text/plain; charset="ISO-8859-1"; format=flowed Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: qemu-devel@nongnu.org Anthony Liguori wrote: > Andre Przywara wrote: >> Hi, >> >> while testing the guest multi-core code, I realized that all of the >> cpuid_* values (like cpuid_ext_features,...) from CPUX86State are not >> dumped in the migration stream. Is this intentional behavior (to let >> the user specify other bits in the target?) or has this just been >> forgotten? >> Does KVM call the SET_CPUID2 ioctl after or before migration? > > The cpuid bits are specified by the user. They aren't changable by the > guest which is why they haven't been migrated. OK, I see your point. What has happened with the idea of using a separate savevm section to transfer the guest configuration parts? > > It's unclear what to do about -cpu host. If we did migrate cpuid > values, then -cpu would effectively be ignored after an incoming migration. You do not want to migrate with -cpu host, this is only for a desktop virtualization use-case where you are pretty sure that you will not migrate. I have started working on "-cpu migrate", which uses some kind of least common denominator bits for the KVM case (that is all CPUs with hardware virtualization support). Currently there seems to be not much difference to qemu64, so maybe we don't need it. Regards, Andre. -- Andre Przywara AMD-Operating System Research Center (OSRC), Dresden, Germany Tel: +49 351 448 3567 12 ----to satisfy European Law for business letters: Advanced Micro Devices GmbH Karl-Hammerschmidt-Str. 34, 85609 Dornach b. Muenchen Geschaeftsfuehrer: Thomas M. McCoy; Giuliano Meroni Sitz: Dornach, Gemeinde Aschheim, Landkreis Muenchen Registergericht Muenchen, HRB Nr. 43632