From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:59504) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V9GFm-0003re-SB for qemu-devel@nongnu.org; Tue, 13 Aug 2013 11:11:30 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V9GFe-0003W7-3V for qemu-devel@nongnu.org; Tue, 13 Aug 2013 11:11:22 -0400 Received: from cantor2.suse.de ([195.135.220.15]:54497 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V9GFd-0003VF-T5 for qemu-devel@nongnu.org; Tue, 13 Aug 2013 11:11:14 -0400 Message-ID: <520A4C8C.7090202@suse.de> Date: Tue, 13 Aug 2013 17:11:08 +0200 From: =?ISO-8859-1?Q?Andreas_F=E4rber?= MIME-Version: 1.0 References: <20130813125349.GA28317@redhat.com> <87a9klllyz.fsf@codemonkey.ws> <520A48C0.5000205@redhat.com> In-Reply-To: <520A48C0.5000205@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [PATCH for-1.6] pc: fix up pc initialization List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Paolo Bonzini Cc: Anthony Liguori , marcel.a@redhat.com, "Michael S. Tsirkin" , qemu-devel@nongnu.org, Michael Roth , Gerd Hoffmann , Igor Mammedov Am 13.08.2013 16:54, schrieb Paolo Bonzini: > Il 13/08/2013 16:11, Anthony Liguori ha scritto: >>>> Fix this up, clean up a trivial code duplication >>>> and add a comment explaining why we special-case 1.5 >>>> with respect to pvpanic. >>>> >>>> Reported-by: Markus Armbruster >>>> Signed-off-by: Michael S. Tsirkin >> Thanks for catching this. I'm a little disturbed by this. I use git-= am >> --3way specifically to avoid problems from fuzzing but I guess merge >> artifacts are possible. >> >=20 > I wonder if we shouldn't disable pvpanic in 1.5 too, one-off behavior i= s > ugly and likely no one will notice. I had rejected the previous attempt to completely disable pvpanic device because it looked to me as if this compatibility aspect had been forgotten. I didn't imagine the resulting code to look as ugly though, with us "skipping" _1_5 to not have 1.5 overwrite has_pvpanic for 1.6+. mst suggested to patch stable-1.5 to disable it there, too. I am not against but have doubts as to how well that works with migration, since 1.5.3 is still a bit off and I would expect 1.5.2 -> 1.6.0 migration to work without guest-visible changes... We could argue that having to use -M pc-i440fx-1.5 we can also expect users to add -device pvpanic; question would be how to convey that knowledge of if-you-use-pc-x.y-then-you-also-need-to-do-Z to users, which compat_props usually handle under the hood. We could misuse pvpanic.ioport=3D0 for that purpose until we have a better solution. Regards, Andreas --=20 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=FCrnberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imend=F6rffer; HRB 16746 AG N=FCrnbe= rg