From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35042) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V6fkZ-0001U3-At for qemu-devel@nongnu.org; Tue, 06 Aug 2013 07:48:34 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V6fkT-0007T0-B3 for qemu-devel@nongnu.org; Tue, 06 Aug 2013 07:48:27 -0400 Received: from mx1.redhat.com ([209.132.183.28]:23395) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V6fkT-0007Su-33 for qemu-devel@nongnu.org; Tue, 06 Aug 2013 07:48:21 -0400 From: Markus Armbruster 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> <20130806101953.GC13680@redhat.com> <20130806104442.GR8218@redhat.com> <5200D806.5030509@suse.de> <20130806111637.GU8218@redhat.com> Date: Tue, 06 Aug 2013 13:48:17 +0200 In-Reply-To: <20130806111637.GU8218@redhat.com> (Gleb Natapov's message of "Tue, 6 Aug 2013 14:16:37 +0300") Message-ID: <87r4e7doqm.fsf@blackfin.pond.sub.org> MIME-Version: 1.0 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, Gerd Hoffmann , Anthony Liguori , Paolo Bonzini , Marcel Apfelbaum , Andreas =?utf-8?Q?F=C3=A4rber?= Gleb Natapov writes: > On Tue, Aug 06, 2013 at 01:03:34PM +0200, Andreas F=C3=A4rber wrote: >> Am 06.08.2013 12:44, schrieb Gleb Natapov: >> > On Tue, Aug 06, 2013 at 01:19:53PM +0300, Michael S. Tsirkin wrote: >> >>>> 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 -dev= ice >> >>> help does not print help about it? Why not fix that? What QEMU --help >> >>> issues has to do with deciding which devices should or should not be >> >>> present by default? >> >> >> >> No, I'm saying what I said: that there's no way to remove a device >> >> added by default except -nodefaults, and no way to >> >> find out what does -nodefaults exclude so you >> >> can add things you need back selectively. >> >> >> > And what are the rules that govern device exclusion from -nodefaults >> > list? Why -nodefaults does not create empty machine? >>=20 >> We have -M none to create an empty machine. >>=20 >> FWIW -M q35 does not create all Q35 devices, there's -readconfig >> docs/q35-chipset.cfg for the rest. The criteria certainly is not >> migratability, since ICH9 AHCI (part of -M q35) is unmigratable, >> unfortunately. >> One practical reason not to create everything via config is that we >> cannot create SysBusDevices via -device when they require MMIO mapping >> or IRQ setup. Support wiring up a machine without board code, just configuration has been the ever-distant goal of the qdev effort. >> For ISADevices such as pvpanic that's not a problem. >> Anthony has proposed QOM'ifying MemoryRegions and qemu_irq as solution >> to do the wiring-up from command line or config file, but those attempts >> got stuck a long time ago. >>=20 > But -M creates not only things that cannot be created from a command > line, it includes some default set of devices, so what is the criteria > for those? I'm not aware of defined, coherent criteria. I can give you descriptive rather than prescriptive, though. Used to be "whatever anyone felt users would want". It's now "whatever has always been there, plus whatever survives interminable bikeshedding^W^Wvigorous debate.