From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:45134) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V6gFB-00064A-Fx for qemu-devel@nongnu.org; Tue, 06 Aug 2013 08:20:12 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V6gF5-00051B-EL for qemu-devel@nongnu.org; Tue, 06 Aug 2013 08:20:05 -0400 Received: from mx1.redhat.com ([209.132.183.28]:36555) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V6gF5-000510-6l for qemu-devel@nongnu.org; Tue, 06 Aug 2013 08:19:59 -0400 Date: Tue, 6 Aug 2013 15:19:55 +0300 From: Gleb Natapov Message-ID: <20130806121955.GA8218@redhat.com> References: <51FFD6CE.5090302@redhat.com> <20130805182628.GC4244@redhat.com> <20130806072152.GK10891@redhat.com> <20130806083309.GA11051@redhat.com> <20130806083625.GF8218@redhat.com> <20130806092148.GC11051@redhat.com> <20130806093247.GL8218@redhat.com> <5200D15E.4030102@suse.de> <20130806110035.GS8218@redhat.com> <20130806120832.GB14396@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: <20130806120832.GB14396@redhat.com> 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: "Michael S. Tsirkin" Cc: minyard@acm.org, Marcel Apfelbaum , seabios@seabios.org, qemu-devel@nongnu.org, Gerd Hoffmann , Paolo Bonzini , Andreas =?utf-8?Q?F=C3=A4rber?= On Tue, Aug 06, 2013 at 03:08:32PM +0300, Michael S. Tsirkin wrote: > On Tue, Aug 06, 2013 at 02:00:35PM +0300, Gleb Natapov wrote: > > On Tue, Aug 06, 2013 at 12:35:10PM +0200, Andreas F=C3=A4rber wrote: > > > Am 06.08.2013 11:32, schrieb Gleb Natapov: > > > > On Tue, Aug 06, 2013 at 12:21:48PM +0300, Michael S. Tsirkin wrote: > > > >> On Tue, Aug 06, 2013 at 11:36:25AM +0300, Gleb Natapov wrote: > > > >>> On Tue, Aug 06, 2013 at 11:33:10AM +0300, Michael S. Tsirkin wrot= e: > > > >>>> On Tue, Aug 06, 2013 at 10:21:52AM +0300, Gleb Natapov wrote: > > > >>>>>> 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 retu= rn > > > >>> zero. > > > >> > > > >> It doesn't have anything to do with _STA: device still appears in = QOM. > > > > You said disabled, not removed. So does -global pvpanic,ioport=3D0 > > > > disables the device for you? > > > >=20 > > > >> It's a QEMU issue, devices that are added with -device are > > > >> documented in -device help and removed by dropping them from > > > >> command line. Devices added by default have no way to > > > >> be dropped from QOM except -nodefaults. > > > >> > > > > Are you saying that because pvpanic is added automatically QEMU -de= vice > > > > help does not print help about it? Why not fix that? What QEMU --he= lp > > > > issues has to do with deciding which devices should or should not be > > > > present by default? > > >=20 > > > You misunderstand: -device pvpanic,? will document that there is a > > > numeric port property, which as such is self-documenting. But there's= no > > Yes, this is how I found it. > >=20 > > > way for us to document there that port=3D0 has special meaning of "di= sable > > > this device in ACPI". > > >=20 > > Adding capability to describe a property should solve that and is a good > > idea regardless, no? "pvpanic.ioport=3Duint16" is not very descriptive. > >=20 > >=20 > > > Disabling a device usually requires to not include that device (or in > > > the future to "unrealize" it), which would require some way to suppre= ss > > > having the device created internally by default. As done for floppy, > > > serial, etc. devices in x86 IIUC, which are in the same PIO situation= as > > > the pvpanic device, except that they represent physical devices. > > > Adding some -no-pvpanic switch might be an alternative. And if not do= ne > > > already, disabling the pvpanic device should definitely be documented > > > for the man page. > > We should not add -no-pvpanic! If there is a legitimate use for > > -no-pvpanic we should go with MST suggestion and do not create it by > > default. The question is why would anyone use -no-pvpanic? Legit reason, > > not just "to remove pvpanic". >=20 > To be able to emulate a real hardware system without any PV devices. > I think it's a reasonable requirement. >=20 Qemu is so far from able to do so that I do not consider it such. -- Gleb.