From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:42396) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1dSiFf-0002x4-LH for qemu-devel@nongnu.org; Wed, 05 Jul 2017 07:13:49 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1dSiFc-0004oy-C7 for qemu-devel@nongnu.org; Wed, 05 Jul 2017 07:13:47 -0400 Received: from mx1.redhat.com ([209.132.183.28]:56722) by eggs.gnu.org with esmtps (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.71) (envelope-from ) id 1dSiFc-0004op-2z for qemu-devel@nongnu.org; Wed, 05 Jul 2017 07:13:44 -0400 References: <1499237876.3041.4.camel@linux.intel.com> <6ad73f55-c48a-c083-e0ef-b8ac162ec989@redhat.com> <20170705110757.GF22008@redhat.com> From: Thomas Huth Message-ID: Date: Wed, 5 Jul 2017 13:13:36 +0200 MIME-Version: 1.0 In-Reply-To: <20170705110757.GF22008@redhat.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] change x86 default machine type to Q35? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: Chao Peng , qemu-devel@nongnu.org, "Tian, Kevin" , Eduardo Habkost , "Michael S. Tsirkin" , Marcel Apfelbaum , Paolo Bonzini , Laszlo Ersek On 05.07.2017 13:07, Daniel P. Berrange wrote: > On Wed, Jul 05, 2017 at 10:14:23AM +0200, Thomas Huth wrote: >> Hi, >> >> On 05.07.2017 08:57, Chao Peng wrote: >>> >>> Q35 has been in QEMU for quite a while. Compared to the current default >>> i440FX, Q35 is probably not that mature and not widely used, however in >>> some case, Q35 has advantages, for example, in supporting new features. >>> For instance, we have some features require PCI-e support which is only >>> available on Q35 and some others need it for EFI support. It is of >>> course not necessary to change it as the default but if more and more >>> features have dependencies on Q35 because of requiring much more modern >>> features then I think it may be worth to do so. In such case we can have >>> more people to use it and find problems we may know or not know. >> >> Yes, IMHO at one point in time, we should switch the default machine >> type to q35. The i440FX is really quite old... >> >>> There are certainly some drawbacks: >>> - Compatibility: current code or script may need adjustment >> >> That might be a real concern ... so I think a good point in time to >> switch to the q35 machine type would be when we switch to the next major >> version number of QEMU, i.e. when we switch to version 3.0. If the users >> see a new major version number, they might be more willing to accept >> such major changes (yeah, I know, we've discussed in the past that >> version numbers are just numbers ... but still, there is some kind of >> psychological aspect to this, too, I think) > > Most users aren't even aware of version numbers of QEMU - they'll just > take whatever their distro has provided run it. The notion that their > latest distro version happened to pull in a "major" version instead of > previously pulling in a "minor" version is invisible to everyone, > except the minority of people who care about the low level details. Well, but those users who do not care at all hopefully use libvirt, GNOME boxes or a similar management layer to start their virtual machines, so it should not matter for them at all. Thomas