From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42917) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V1fQa-0002yw-IY for qemu-devel@nongnu.org; Tue, 23 Jul 2013 12:27:09 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V1fQZ-0008M9-M1 for qemu-devel@nongnu.org; Tue, 23 Jul 2013 12:27:08 -0400 Received: from mx1.redhat.com ([209.132.183.28]:13276) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V1fQZ-0008Lt-FM for qemu-devel@nongnu.org; Tue, 23 Jul 2013 12:27:07 -0400 Received: from int-mx01.intmail.prod.int.phx2.redhat.com (int-mx01.intmail.prod.int.phx2.redhat.com [10.5.11.11]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r6NGR6rb010356 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Tue, 23 Jul 2013 12:27:06 -0400 Message-ID: <51EEAED9.6050308@redhat.com> Date: Tue, 23 Jul 2013 10:27:05 -0600 From: Eric Blake MIME-Version: 1.0 References: <20130723161903.GL2477@redhat.com> In-Reply-To: <20130723161903.GL2477@redhat.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="gr580P7Ccmaao7ip3jjGPHXgAgTmPPpxG" Subject: Re: [Qemu-devel] [libvirt] [PATCH 6/7] qemu: Probe QEMU binary for host CPU List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: libvir-list@redhat.com, "qemu-devel@nongnu.org" This is an OpenPGP/MIME signed message (RFC 4880 and 3156) --gr580P7Ccmaao7ip3jjGPHXgAgTmPPpxG Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable [adding qemu] On 07/23/2013 10:19 AM, Daniel P. Berrange wrote: > On Tue, Jul 23, 2013 at 06:11:35PM +0200, Jiri Denemark wrote: >> Since QEMU and kvm may filter some host CPU features or add efficientl= y >> emulated features, asking QEMU binary for host CPU data provides >> better results when we later use the data for building guest CPUs. >> --- >> + virCommandAddArg(cmd, "-machine"); >> + virCommandAddArgFormat(cmd, "%s,accel=3Dkvm", >> + qemuCaps->machineTypes[0]); >> + >=20 >=20 > This code is causing us to invoke the QEMU binary multiple times, > which is something we worked really hard to get away from. I really, > really don't like this as an approach. QEMU needs to be able to > give us the data we need here without multiple invocations. >=20 > eg, by allowing the monitor command to specify 'kvm' vs 'qemu' > when asking for data, so you can interrogate it without having > to re-launch it with different accel=3DXXX args. We don't know if -machine accel=3Dkvm is a valid option until after issuing some QMP commands, but now we are forced to reinvoke a new qemu with -machine accel=3Dkvm enabled in order to get the query to give us accurate answers. I agree that this is less than desirable; hopefully the qemu folks can help us figure out a solution, now that we are bringing attention to the issue. --=20 Eric Blake eblake redhat com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --gr580P7Ccmaao7ip3jjGPHXgAgTmPPpxG Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.13 (GNU/Linux) Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Thunderbird - http://www.enigmail.net/ iQEcBAEBCAAGBQJR7q7ZAAoJEKeha0olJ0NqXtoH/0Ah9EdYIEx0FbatbK4d1uMd T8+FtcRyO2BDsNFHbVVr4/u9Cb8akhjkRzRt5+1sFqN/HhtTNUHJSLN8p/vAryTf RjQf00B7Km5dRDWzQEzXusr/qZkkECsy3CY9hobd98zCNI8ZqVL7noTeiCQXhJJx fyQrLlNGE5H8WUx4rHPoYgR5D2TwOfYKGwVT5FXMCDDWfIz3WRYRZV2MW+bhX5Cg YfPnYrUOg2PxBKXt921kEcKTaG5+IUU7J6XOWLHx88g6BGiw8hawXlD1KwicksfR fQi9Fy3DwW7WM9vENKQDHySYbOk7QvjsTC+VEQTyTvruEtrgMsTLVNwb+qexwak= =j/XV -----END PGP SIGNATURE----- --gr580P7Ccmaao7ip3jjGPHXgAgTmPPpxG--