From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35628) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bkR8c-0001bJ-RY for qemu-devel@nongnu.org; Thu, 15 Sep 2016 03:31:15 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1bkR8Y-0007oh-T4 for qemu-devel@nongnu.org; Thu, 15 Sep 2016 03:31:14 -0400 Received: from indium.canonical.com ([91.189.90.7]:35915) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1bkR8Y-0007od-N4 for qemu-devel@nongnu.org; Thu, 15 Sep 2016 03:31:10 -0400 Received: from loganberry.canonical.com ([91.189.90.37]) by indium.canonical.com with esmtp (Exim 4.76 #1 (Debian)) id 1bkR8X-0001fx-Bl for ; Thu, 15 Sep 2016 07:31:09 +0000 Received: from loganberry.canonical.com (localhost [127.0.0.1]) by loganberry.canonical.com (Postfix) with ESMTP id 56D052E80CB for ; Thu, 15 Sep 2016 07:31:09 +0000 (UTC) MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: quoted-printable Date: Thu, 15 Sep 2016 07:24:26 -0000 From: ChristianEhrhardt <1536487@bugs.launchpad.net> Reply-To: Bug 1536487 <1536487@bugs.launchpad.net> Sender: bounces@canonical.com References: <20160121062724.15018.99449.malonedeb@wampee.canonical.com> Message-Id: <20160915072427.12059.7587.malone@gac.canonical.com> Errors-To: bounces@canonical.com Subject: [Qemu-devel] [Bug 1536487] Re: Unable to migrate pc-i440fx-2.4 KVM guest from QEMU 2.5.0 to QEMU 2.4.1 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Serge, Paulo - thank you both! I already had the patch but I think it was good to discuss and list the expected behavior not only for me, but for whoever else that comes by this or a similar case. -- = You received this bug notification because you are a member of qemu- devel-ml, which is subscribed to QEMU. https://bugs.launchpad.net/bugs/1536487 Title: Unable to migrate pc-i440fx-2.4 KVM guest from QEMU 2.5.0 to QEMU 2.4.1 Status in QEMU: Fix Released Status in qemu package in Ubuntu: Fix Released Status in qemu source package in Xenial: Triaged Bug description: When migrating a pc-i440fc-2.4 KVM guest from QEMU 2.5.0 to QEMU 2.4.1, the target QEMU errors out: =C2=A0=C2=A0qemu-system-x86_64: error while loading state for instance 0x= 0 of device 'fw_cfg' This appears to be related to the addition of a DMA interface to fw_cfg last October: =C2=A0=C2=A0http://lists.nongnu.org/archive/html/qemu- devel/2015-10/msg04568.html "info qtree" on the source QEMU shows that the DMA interface for fw_cfg had been enabled: =C2=A0=C2=A0bus: main-system-bus =C2=A0=C2=A0=C2=A0=C2=A0type System =C2=A0=C2=A0=C2=A0=C2=A0... =C2=A0=C2=A0=C2=A0=C2=A0dev: fw_cfg_io, id "" =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0iobase =3D 1296 (0x510) =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0dma_iobase =3D 1300 (0x514) =C2=A0=C2=A0=C2=A0=C2=A0=C2=A0=C2=A0dma_enabled =3D true Incidentally, this guest had just undergone a migration from QEMU 2.4.1 to QEMU 2.5.0, so it looks like DMA was enabled simply through the migration. It seems to me that the DMA interface for fw_cfg should only be enabled on pc-i440fx-2.5 machines or higher. To manage notifications about this bug go to: https://bugs.launchpad.net/qemu/+bug/1536487/+subscriptions