From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:36437) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z5Gv7-0006H8-2J for qemu-devel@nongnu.org; Wed, 17 Jun 2015 13:14:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1Z5Gv1-0006Z0-V6 for qemu-devel@nongnu.org; Wed, 17 Jun 2015 13:14:37 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60183) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1Z5Gv1-0006YX-PA for qemu-devel@nongnu.org; Wed, 17 Jun 2015 13:14:31 -0400 Message-ID: <5581AAF0.3000307@redhat.com> Date: Wed, 17 Jun 2015 19:14:24 +0200 From: Paolo Bonzini MIME-Version: 1.0 References: <1434117956-4929-1-git-send-email-dslutz@verizon.com> <20150617160826-mutt-send-email-mst@redhat.com> <558180A0.8040708@redhat.com> <20150617161716-mutt-send-email-mst@redhat.com> <558183C1.3010402@redhat.com> <20150617162836-mutt-send-email-mst@redhat.com> <55819D8F.3000003@redhat.com> <20150617182322-mutt-send-email-mst@redhat.com> <5581A844.9090203@Gmail.com> In-Reply-To: <5581A844.9090203@Gmail.com> Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH v7 0/9] Add limited support of VMware's hyper-call rpc List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Don Slutz , "Michael S. Tsirkin" Cc: qemu-devel@nongnu.org, Markus Armbruster , Don Slutz , Luiz Capitulino , Anthony Liguori , =?windows-1252?Q?Andreas_F=E4rber?= , Richard Henderson On 17/06/2015 19:03, Don Slutz wrote: > On 06/17/15 12:29, Michael S. Tsirkin wrote: >> On Wed, Jun 17, 2015 at 06:17:19PM +0200, Paolo Bonzini wrote: >>> >>> >>> On 17/06/2015 16:29, Michael S. Tsirkin wrote: >>>> On Wed, Jun 17, 2015 at 04:27:13PM +0200, Paolo Bonzini wrote: >>>>> >>>>> >>>>> On 17/06/2015 16:18, Michael S. Tsirkin wrote: >>>>>>>> Yes, that's what was done for parallel and pcspk as well. There's no >>>>>>>> infrastructure to avoid it. >>>>>>>> >>>>>>>> Paolo >>>>>> How do you mean? We have multiple ways to keep devices >>>>>> compatible with old versions. >>>>>> Set a new property to skip the extra stuff. >>>>> >>>>> Not if the device didn't have a vmstate at all, unfortunately. >>>> >>>> Skip creating the device completely for old machine types. >>> >>> Which device? The vmstate is tied to the same device that has always >>> been created. >> >> Just disable the new functionality. Make it behave in >> a compatible way. >> >>> we enable this thing by default (why do we?) >> >> Sigh. There is a very simple way to add a device in qemu: let user >> request it with -device. If one does this, one gets to maintain the >> resulting mess without bothering with pc maintainers in any way. >> >> But of course, everyone implementing a new feature feels it's such a >> great thing, and completel zero risk, it must be part of the default >> machine. Guess what, one then gets to bother with versioning from day 0. >> >>>>>> this seems like a big deal ... >>>>> >>>>> The PC speaker device is also enabled by default. >>>> >>>> This is historical, isn't it? >>> >>> Yes, but it has broken 2.3->2.2 migration. >>> >>> Let's just stop fighting windmills. >>> >>> Paolo >> >> I don't see what you are saying. Suddenly guest visible >> changes within a machine type are ok? >> >> So we have a bug, need to fix it, preferably before piling up >> more features. The best way imho is for 2.4 to avoid >> this device unless requested explicitly. >> > > My take on this is that Michael would like me to have a vmport_rpc=on > option, just like vmport=on (which already exists). With a default of off. It wouldn't be enough, because dc->vmsd would be non-NULL anyway. (But yes, that option would be a good thing anyway). Paolo