From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:53820) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XDJAC-0002tc-WD for qemu-devel@nongnu.org; Fri, 01 Aug 2014 16:10:58 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XDJA8-0007KI-0J for qemu-devel@nongnu.org; Fri, 01 Aug 2014 16:10:52 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57066) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XDJA7-0007K4-Ff for qemu-devel@nongnu.org; Fri, 01 Aug 2014 16:10:47 -0400 Message-ID: <53DBF43F.9050804@redhat.com> Date: Fri, 01 Aug 2014 16:10:39 -0400 From: John Snow MIME-Version: 1.0 References: <5396A617.5020209@msgid.tls.msk.ru> <5396A6E7.8030400@redhat.com> <5396BD5C.6010507@msgid.tls.msk.ru> <87y4x2xzx3.fsf@blackfin.pond.sub.org> In-Reply-To: <87y4x2xzx3.fsf@blackfin.pond.sub.org> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] Are -cdrom/-hda (or -drive if=ide) supposed to work in q35? List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Kevin Wolf Cc: Paolo Bonzini , Michael Tokarev , Markus Armbruster , =?ISO-8859-1?Q?Andreas_F=E4rber?= , qemu-devel On 06/12/2014 05:03 AM, Markus Armbruster wrote: > Michael Tokarev writes: > >> 10.06.2014 10:34, Paolo Bonzini wrote: >>> Il 10/06/2014 08:30, Michael Tokarev ha scritto: >>>> Hello. >>>> >>>> The question is: are the drive shortcuts - -cdrom, -hda, -hdb etc - >>>> supposed to work in -machine q35 too? Or are they merely ignored? >>>> >>>> qemu-system-x86_64 -machine q35 -cdrom foo.img >> [] >>> It should work. I remember some complications due to AHCI not >>> having slaves, but it is a bug. >> It looks like the "short" -drive if=ide option does not connect the >> created drive to any bus at all. With the above command, or with >> -drive if=ide,index=*,bus=*, info qtree does not show the drive at >> all. While -drive if=none,id=X -device ide-cd,drive=X connects the >> drive to the right bus just fine. > -drive mixes up configuration of backend and frontend (a.k.a. device > model), as follows: > > 1. It always defines a backend. "info block" shows them. > > 2. It always defines a few frontend configuration bits for the device > models to pick up. > > 3. Except with if=none, it posts a request to board code to create a > suitable frontend. It's up to the board code to honor, reject or > ignore the request. The i440FX boards honor it, the Q35 boards > ignore it. > > Nobody has gotten around to making the Q35 boards honor it, in part > because there has been some confusion on what if=ide is supposed to > mean on Q35. Should it connect an ide-hd / ide-cd in SATA mode or in > legacy PATA mode? > > I've always argued for SATA, because for me if=ide does *not* imply a > specific kind of HBA any more than if=scsi does, and the "natural" > HBA for Q35 is AHCI in SATA mode. > > Kevin (cc'ed) has argued for a way to make it connect in legacy PATA > mode. I'd be fine with that, as long as it's off by default. > > Patches welcome. > Kevin, (or anyone else with an opinion for that matter), what is the reasoning behind wanting -cdrom to use the old PATA interfaces? For at least the immediate future, the AHCI device doesn't support the mixed-mode SATA/PATA access models, though I suppose we could, it seems like a more obvious and simple solution to just allow the shorthand syntactic sugar commands to use the native bus of the system until you specify otherwise. I think I will probably begin writing a patch under this assumption unless there is a better technical reason not to. --J