From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:40174) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V6lSU-0007AI-UU for qemu-devel@nongnu.org; Tue, 06 Aug 2013 13:54:18 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V6lSN-00071a-EQ for qemu-devel@nongnu.org; Tue, 06 Aug 2013 13:54:10 -0400 Received: from cantor2.suse.de ([195.135.220.15]:52621 helo=mx2.suse.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V6lSN-00071J-4y for qemu-devel@nongnu.org; Tue, 06 Aug 2013 13:54:03 -0400 Message-ID: <52013836.4000601@suse.de> Date: Tue, 06 Aug 2013 19:53:58 +0200 From: =?UTF-8?B?QW5kcmVhcyBGw6RyYmVy?= MIME-Version: 1.0 References: <703333176.9515483.1375697447963.JavaMail.root@redhat.com> <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> In-Reply-To: <20130806092027.GK8218@redhat.com> Content-Type: text/plain; charset=UTF-8 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: "Michael S. Tsirkin" , seabios@seabios.org, qemu-devel@nongnu.org, =?UTF-8?B?SGVydsOpIFBvdXNzaW5lYXU=?= , Gerd Hoffmann , Paolo Bonzini , Marcel Apfelbaum Am 06.08.2013 11:20, schrieb Gleb Natapov: > On Tue, Aug 06, 2013 at 10:45:01AM +0200, Andreas F=C3=A4rber 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. >>> >>>> 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] >> >> I disagree: -device adds a device, not removes one. It will still be >> present. >> > I assume you are answering to the quote about ioport=3D0, not > documentation here. Answering to all of i) additional -device pvpanic,ioport=3D0 to disable another one, ii) ioport=3D0 to disable a certain device and iii) either being an undocumented feature to disable devices. ;) "Disabled" here referring both to not in PIO/ACPI/etc. and to not present in the QOM composition tree. In the end with pvpanic being an ISADevice, this goes back to my large series for Herv=C3=A9's i87312 Super I/O chipset, where we discussed what would be involved in having a reconfigurable ISADevice not listen on some port/IRQ. We haven't decided on a solution yet (reconfiguring the i87312 from guest will assert or be ignored), and I strongly disagree to the solution of ioport=3D0 magic as general solution - either we should use realized=3Dfalse (which then drops any VMStateDescription from migration) or revive my earlier attempts to add an explicit boolean ISADevice::enabled state, which would correspond to EEPROM-based reconfiguration of the plugged-in ISA card. Which of course would only help ISADevices but not MMIO-based SysBusDevices... Andreas --=20 SUSE LINUX Products GmbH, Maxfeldstr. 5, 90409 N=C3=BCrnberg, Germany GF: Jeff Hawn, Jennifer Guild, Felix Imend=C3=B6rffer; HRB 16746 AG N=C3=BC= rnberg