From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:56292) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cfu8i-0000uw-PY for qemu-devel@nongnu.org; Mon, 20 Feb 2017 15:00:53 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cfu8e-0003eG-OL for qemu-devel@nongnu.org; Mon, 20 Feb 2017 15:00:52 -0500 Received: from mx1.redhat.com ([209.132.183.28]:51300) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1cfu8e-0003e6-Ff for qemu-devel@nongnu.org; Mon, 20 Feb 2017 15:00:48 -0500 References: <88232638f9ff3b17b54987624468678ea14a3037.1487286467.git.ben@skyportsystems.com> <20170217114321.6c8577e1@nial.brq.redhat.com> <918524f7-26cf-3fce-d9e3-7316ca69285b@redhat.com> <20170220102304.GC2372@work-vm> From: Eric Blake Message-ID: <3fb8499e-884c-99e8-b295-3d4603921075@redhat.com> Date: Mon, 20 Feb 2017 14:00:39 -0600 MIME-Version: 1.0 In-Reply-To: <20170220102304.GC2372@work-vm> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="XunUrte39p7eaCu5FVe1NPMfE26NtqoBI" Subject: Re: [Qemu-devel] [PATCH v8 4/8] ACPI: Add Virtual Machine Generation ID support List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Dr. David Alan Gilbert" , Laszlo Ersek Cc: Igor Mammedov , qemu-devel@nongnu.org, ben@skyportsystems.com, mst@redhat.com This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --XunUrte39p7eaCu5FVe1NPMfE26NtqoBI From: Eric Blake To: "Dr. David Alan Gilbert" , Laszlo Ersek Cc: Igor Mammedov , qemu-devel@nongnu.org, ben@skyportsystems.com, mst@redhat.com Message-ID: <3fb8499e-884c-99e8-b295-3d4603921075@redhat.com> Subject: Re: [Qemu-devel] [PATCH v8 4/8] ACPI: Add Virtual Machine Generation ID support References: <88232638f9ff3b17b54987624468678ea14a3037.1487286467.git.ben@skyportsystems.com> <20170217114321.6c8577e1@nial.brq.redhat.com> <918524f7-26cf-3fce-d9e3-7316ca69285b@redhat.com> <20170220102304.GC2372@work-vm> In-Reply-To: <20170220102304.GC2372@work-vm> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable On 02/20/2017 04:23 AM, Dr. David Alan Gilbert wrote: > * Laszlo Ersek (lersek@redhat.com) wrote: >> CC Dave >=20 > This isn't an area I really understand; but if I'm > reading this right then=20 > vmgenid is stored in fw_cfg? > fw_cfg isn't migrated >=20 > So why should any changes to it get migrated, except if it's already > been read by the guest (and if the guest reads it again aftwards what's= > it expected to read?) Why are we expecting it to change on migration? You want a new value when you load state from disk (you don't know how many times the same state has been loaded previously, so each load is effectively forking the VM and you want a different value), but for a single live migration, you aren't forking the VM and don't need a new generation ID. I guess it all boils down to what command line you're using: if libvirt is driving a live migration, it will request the same UUID in the command line of the destination as what is on the source; while if libvirt is loading from a [managed]save to restore state from a file, it will either request a new UUID directly or request auto to let qemu generate the new id. --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --XunUrte39p7eaCu5FVe1NPMfE26NtqoBI Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v2 Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJYq0rnAAoJEKeha0olJ0NqzwYH/jsdDprNzud/KsRZb16SzsvE 4hHUMe5XyaaIyarzVg6Qd+stFoP/P9R+EwtnDqMzXZZhb6y6VtsiZOe7EmmSBiHw b0WJqn6ieEK1xrh+rtNQj4Y2vgM2QQe90oGesnz+3xtVt2rTXeq+hvCsxvPY7Z3T T0BD9zDr/41f041rD159UfUQTYZe/PaURpys9DGledHF0SBO8MY2lTOQCUVyQVWK 6RBqzlHExmERa5ThHIWaQiadlKemtY44y55b3fym7G3e26uAoMYSngEQaxxDvzRH mHZABitwAGnCEW21X2mhQuElU9kAc+9L72IyZj7ZLBJBzxOJHSxv5ZWrrWRex8g= =VwcT -----END PGP SIGNATURE----- --XunUrte39p7eaCu5FVe1NPMfE26NtqoBI--