From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=50262 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OCYcB-0003JC-5s for qemu-devel@nongnu.org; Thu, 13 May 2010 09:38:16 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OCYc9-0006ZZ-37 for qemu-devel@nongnu.org; Thu, 13 May 2010 09:38:15 -0400 Received: from mx1.redhat.com ([209.132.183.28]:33956) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OCYc8-0006Yq-Ih for qemu-devel@nongnu.org; Thu, 13 May 2010 09:38:13 -0400 Date: Thu, 13 May 2010 10:38:06 -0300 From: Luiz Capitulino Subject: Re: [Qemu-devel] Re: [PATCH] Revive -version 'QEMU PC Emulator...' Message-ID: <20100513103806.73e51972@redhat.com> In-Reply-To: <20100513132102.GG12207@redhat.com> References: <1273696161-14332-1-git-send-email-crobinso@redhat.com> <4BEB11DD.20601@redhat.com> <4BEB142F.2000002@redhat.com> <4BEBB9C2.3050302@redhat.com> <4BEBF8D1.7060401@redhat.com> <4BEBF9A5.3070507@redhat.com> <20100513132102.GG12207@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" Cc: Jes Sorensen , aliguori@us.ibm.com, clalance@redhat.com, qemu-devel@nongnu.org, Cole Robinson On Thu, 13 May 2010 14:21:02 +0100 "Daniel P. Berrange" wrote: > On Thu, May 13, 2010 at 03:07:49PM +0200, Jes Sorensen wrote: > > On 05/13/10 15:04, Cole Robinson wrote: > > > On 05/13/2010 04:35 AM, Jes Sorensen wrote: > > >> On 05/12/10 22:48, Cole Robinson wrote: > > >> I think rather than 1, it would be better to add a patch to libvirt to > > >> catch both formats. I know Chris Lalancette already cooked up a patch > > >> for this. Combined with the 2) patch I just posted, and 3) I think that > > >> should take care of the problems. > > > > > > It doesn't solve the problem for existing libvirt installations. It's > > > not uncommon for users to track just the latest kvm releases without > > > upgrading libvirt: any future qemu or kvm release will break every > > > version of libvirt that exists today. Given that unfortunate case, I > > > still recommend reverting the 'PC' change at least for long enough for a > > > few fixed libvirt releases to make it into the wild. > > > > But that is no different from what we have today. Users who update their > > qemu and see issues with libvirt can also be asked to update libvirt. I > > have already had several cases where I needed to do that anyway. > > The general policy of QEMU has been to try and avoid known breakage of > existing apps unless unavoidable. This change introduced 100% guarenteed > breakage of every single deployment that exists today, for the sake of > removing 2 characters from a string. I really don't think this is a good > cost/benefit tradeoff & agree with Cole that I'd like to see this reverted > for the 0.13 release, and re-considered in a later release once we've had > a chance to get a preventative fix out for libvirt using -version-string > or equivalent. Agreed, we should improve client's life, not contribute with additional headaches. Regarding Cole's suggestion, instead of adding a new -version parameter you could connect to QMP, get this information from it and re-run QEMU, not sure if it's worth the trouble though.