From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:57016) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SFuRh-00025i-AD for qemu-devel@nongnu.org; Thu, 05 Apr 2012 17:42:29 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SFuRY-0001kG-CV for qemu-devel@nongnu.org; Thu, 05 Apr 2012 17:42:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:24729) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SFuRY-0001gQ-4d for qemu-devel@nongnu.org; Thu, 05 Apr 2012 17:42:12 -0400 Message-ID: <4F7E11A9.6050401@redhat.com> Date: Thu, 05 Apr 2012 15:42:01 -0600 From: Eric Blake MIME-Version: 1.0 References: <1333481889-11285-1-git-send-email-aliguori@us.ibm.com> In-Reply-To: <1333481889-11285-1-git-send-email-aliguori@us.ibm.com> Content-Type: multipart/signed; micalg=pgp-sha256; protocol="application/pgp-signature"; boundary="------------enigF24E7690F38BF48EDED7B108" Subject: Re: [Qemu-devel] [RFC PATCH] pc: change default machine model and versions List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Anthony Liguori Cc: qemu-devel@nongnu.org, Michael Roth , Ayal Baron , Avi Kivity , Jiri Denemark , Andreas Faerber This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enigF24E7690F38BF48EDED7B108 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 04/03/2012 01:38 PM, Anthony Liguori wrote: > N.B. This is a small patch with significant implications. Please read > carefully. >=20 > With this patch, we will not introduce any more '-M pc-1.x' beyond 'pc-= 1.0'. > We will not introduce a new 'pc-X.Y' until the QEMU 2.0 release (1Q 201= 4). > Instead, we will introduce a 'pc-next' machine type that is *not* the d= efault > machine type. If you omit a '-M' option, you will get '-M pc-1.0'. Ho= wever, > if you want to test the latest and greatest, you will need to use an ex= plicit > '-M pc-next'. >=20 > The main motivation for this change is to provide stronger migration > compatibility statements. Namely, our migration policy would be: >=20 > 1) '-M pc-1.0' will be fully supported for all QEMU 1.x and QEMU 2.x re= leases. > Migrating when using '-M pc-1.0' will work across any version of 1.x= or 2.x. > Failures here would be treated as a release blocker. >=20 > 2) '-M pc-2.0' will be introduced in QEMU 2.0, and supported throughout= the 2.x > and 3.x release cycles. New machine types are introduced only ever= y two > years and migration is supported for an additional two years for a = total > of four years. >=20 > 3) '-M pc-next' will be fully supported for all QEMU releases. Migrati= ng > between QEMU versions using '-M pc-next' is guaranteed to either suc= ceed or > fail gracefully. Not failing gracefully would be considered a relea= se > blocker. In general, only power users should consider using '-M pc-= next'. Sounds reasonable from my point of view on libvirt's perspective. We may have a minor bit of work to make it all happen, but as long as there is an advertisement of the name pc-next as a valid machine name, it should be enough for us to key off of when deciding whether we are talking to old or new qemu and adjust our command line generation accordingly. CC'ing Jiri Denemark, as the libvirt engineer most closely tied to machine name issues. --=20 Eric Blake eblake@redhat.com +1-919-301-3266 Libvirt virtualization library http://libvirt.org --------------enigF24E7690F38BF48EDED7B108 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Public key at http://people.redhat.com/eblake/eblake.gpg Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iQEcBAEBCAAGBQJPfhGpAAoJEKeha0olJ0NqNFAH/18dnjb1DJdRpozZQEo6iVFx gOSE3u1k9BTLXQm1dskKGYAhz/aIt2EugJgmlJ8DhI2zjX+A/giOOC91aEqFV73F x5B4TOw7J8BKyODxSulrZ/Zzw9yaHGxLT3BxzyZNeXFcYwHwegmMYeYb/h7Omi6c TOa9aTW4vyOMpwt3SFJaHfVRF1NXaKzwnkSOn08eevNlGLyxeJpDDCUXV1o4e9Th ezfSCmBG8luLdfzRxMTA7e1i29EehKSGwO4PaOJmAJFStlR2MPaqW0Aa6vK3W/lD bQxpqUBt7xfyUK0VQJoGffrAOwoj/6akJQ8TkiEuNEidf+H58wwi/lkkQnIEKR8= =emL6 -----END PGP SIGNATURE----- --------------enigF24E7690F38BF48EDED7B108--