From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50900) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1fqfIF-0001Jf-JH for qemu-devel@nongnu.org; Fri, 17 Aug 2018 10:00:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1fqfIC-0004Na-7b for qemu-devel@nongnu.org; Fri, 17 Aug 2018 09:59:59 -0400 Received: from mx3-rdu2.redhat.com ([66.187.233.73]:44216 helo=mx1.redhat.com) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1fqfIC-0004NJ-0Y for qemu-devel@nongnu.org; Fri, 17 Aug 2018 09:59:56 -0400 Received: from smtp.corp.redhat.com (int-mx05.intmail.prod.int.rdu2.redhat.com [10.11.54.5]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 8D24D40676C0 for ; Fri, 17 Aug 2018 13:59:55 +0000 (UTC) Message-ID: <81275e43ba20750cbf90b679e6120746d34a23c7.camel@redhat.com> From: Andrea Bolognani Date: Fri, 17 Aug 2018 15:59:49 +0200 In-Reply-To: <20180817104351.GG11124@redhat.com> References: <68a98c1b-e6dd-f2df-1499-17c2b8b583be@redhat.com> <20180817092936.GC11124@redhat.com> <20180817104351.GG11124@redhat.com> Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [libvirt] clean/simple Q35 support in libvirt+QEMU for guest OSes that don't support virtio-1.0 List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. =?ISO-8859-1?Q?Berrang=E9?=" Cc: Laine Stump , Libvirt , qemu list On Fri, 2018-08-17 at 11:43 +0100, Daniel P. Berrang=C3=A9 wrote: > On Fri, Aug 17, 2018 at 12:35:11PM +0200, Andrea Bolognani wrote: > > If we decide we want to explicitly spell out the options instead > > of relying on QEMU changing behavior based on the slot type, which > > is probably a good idea anyway, I think we should have > >=20 > > virtio-0.9 =3D> disable-legacy=3Dno,disable-modern=3Dno > > virtio-1.0 =3D> disable-legacy=3Dyes,disable-modern=3Dno > >=20 > > There's basically no reason to have a device legacy-only rather > > than transitional, and spelling out both options instead of only > > one of them just seems more robust. >=20 > From a testing POV it is desirable to be able to have legacy-only. > There is also possibility that guest OS impl 1.0 in a buggy manner, > so forcing legacy only is desirable. >=20 > The existing device still already provides a transitional option > on i440fx, and on Q35 if you do explicit placement in a PCI slot. > So I don't think there's a good reason to have a second transitional > device type, especially if we're naming it virtio-0.9, it is rather > misleading if it would be in fact able to run virtio-1.0 mode. Sounds reasonable. --=20 Andrea Bolognani / Red Hat / Virtualization