From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40380) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V6e6H-0000Di-JF for qemu-devel@nongnu.org; Tue, 06 Aug 2013 06:02:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V6e6B-0007tH-Km for qemu-devel@nongnu.org; Tue, 06 Aug 2013 06:02:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:16599) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V6e6B-0007tA-DF for qemu-devel@nongnu.org; Tue, 06 Aug 2013 06:02:39 -0400 Date: Tue, 6 Aug 2013 13:04:14 +0300 From: "Michael S. Tsirkin" Message-ID: <20130806100414.GE11051@redhat.com> References: <20130805151723.GF877@redhat.com> <1970367422.9695773.1375718517492.JavaMail.root@redhat.com> <20130805161833.GA4244@redhat.com> <51FFD6CE.5090302@redhat.com> <20130805182628.GC4244@redhat.com> <20130806072152.GK10891@redhat.com> <20130806083309.GA11051@redhat.com> <20130806083625.GF8218@redhat.com> <5200B78D.2060708@suse.de> <20130806092027.GK8218@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline In-Reply-To: <20130806092027.GK8218@redhat.com> Content-Transfer-Encoding: quoted-printable Subject: Re: [Qemu-devel] [SeaBIOS] [PATCH] don't expose pvpanic device in the UI List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Gleb Natapov Cc: Marcel Apfelbaum , seabios@seabios.org, qemu-devel@nongnu.org, Gerd Hoffmann , Paolo Bonzini , Andreas =?iso-8859-1?Q?F=E4rber?= On Tue, Aug 06, 2013 at 12:20:27PM +0300, Gleb Natapov wrote: > On Tue, Aug 06, 2013 at 10:45:01AM +0200, Andreas F=E4rber wrote: > > Am 06.08.2013 10:36, schrieb Gleb Natapov: > > > On Tue, Aug 06, 2013 at 11:33:10AM +0300, Michael S. Tsirkin wrote: > > >> On Tue, Aug 06, 2013 at 10:21:52AM +0300, Gleb Natapov wrote: > > >>>> If you see a mouse in a room, how likely is it that there's > > >>>> a single mouse there? > > >>>> > > >>>> This is a PV technology which to me looks like it was > > >>>> rushed through and not only set on by default, but > > >>>> without a way to disable it - apparently on the assumption > > >>>> there's 0 chance it can cause any damage. Now that > > >>>> we do know the chance it's not there, why not go back > > >>>> to the standard interface, and why not give > > >>>> users a chance to enable/disable it? > > >>> You should be able to disable it with: -device pvpanic,ioport=3D0 > > >> > > >> Doesn't work for me. > > > Bug that should be fixed. With this command line _STA should return > > > zero. > > >=20 > > >> Besides, both -device pvpanic and use of ioport=3D0 to disable it > > >> are completely undocumented. > > >> > > > Not the only undocumented thing in QEMU command line :) > > [snip] > >=20 > > I disagree: -device adds a device, not removes one. It will still be > > present. > >=20 > I assume you are answering to the quote about ioport=3D0, not > documentation here. ioport=3D0 does not removes the device, it disables > it. The claim was it cannot be disabled, it can (assuming no bugs), but > it should not be. >=20 > > I am neutral as to whether qemu-system-x86_64 should have it enabled = by > > default or not. But if we want to suppress it, then -nodefaults shoul= d > > disable it. Since libvirt uses that though, it would mean libvirt wou= ld > > need to add it back, whether via user's XML domain config or by libvi= rt > > itself based on some version/etc. heuristics. > >=20 > There is no clear definition of what -nodefaults should or should not > do. > Should it disable PV ACPI hotplug device? > Should it create a machine > with no mmio/io regions registered at all? We can't change the meaning for existing devices. So we need to keep everything that it historically included. But it's a good question whether e.g. ACPI hotplug for q35 should be a separate device, and disabled with -nodefaults. >=20 > -- > Gleb. pvpanic presents itself as a separate device, this is different from PV ACPI hotplug which is part of PIIX.