From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60911) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1cZeWH-0002IO-Pm for qemu-devel@nongnu.org; Fri, 03 Feb 2017 09:07:22 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1cZeWD-0004cc-VS for qemu-devel@nongnu.org; Fri, 03 Feb 2017 09:07:21 -0500 Date: Fri, 3 Feb 2017 22:07:06 +0800 From: Fam Zheng Message-ID: <20170203140706.GD28271@lemon> References: <1485443388-27253-1-git-send-email-armbru@redhat.com> <1485443388-27253-9-git-send-email-armbru@redhat.com> <9684a908-f425-82d8-046b-19cc17d01f55@redhat.com> <87r33o3emm.fsf@dusky.pond.sub.org> <2bcf4c7c-5c29-fda5-1ba3-5828600a8995@redhat.com> <8760l0ebgq.fsf@dusky.pond.sub.org> <87a8a9vuhu.fsf@dusky.pond.sub.org> <20170203110423.GC28271@lemon> <87vasrl7ls.fsf@dusky.pond.sub.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87vasrl7ls.fsf@dusky.pond.sub.org> Subject: Re: [Qemu-devel] [PATCH v2 8/8] hw: Drop superfluous special checks for orphaned -drive List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Markus Armbruster Cc: kwolf@redhat.com, qemu-block@nongnu.org, Mark Cave-Ayland , qemu-devel@nongnu.org, mreitz@redhat.com, =?iso-8859-1?Q?Herv=E9?= Poussineau , John Snow On Fri, 02/03 14:35, Markus Armbruster wrote: > > I guess the painpoint is "okay, what the heck does the machine support then?" - > > At the place where we can reliably detect orphaned drives regardless of > what the machine initialization code does, we have no idea. > > > that "3 > 2" is the good part of the old message. > > At the places that actually adopt drives, we know. But there are many > of them. Just three check for orphans. One of them gets it right > (ide/core.c), one of them gets it wrong (mips_jazz.c), and one of them > sets a problematic example (sun4m.c): if copied to a machine that lets > users configure additional SCSI HBAs, it would break if=scsi for those. > Dampens my enthusiasm for improving the error message by adding similar > checks to all the places that adopt drives. > > We could make machines declare what they support. Better, I think. So > if you have a burning desire to leave your mark in git-blame for every > machine... Could you please remind me the situation about if=scsi across all machines? If it is simply legacy and it's recommended to use "-drive if=none" and "-device ...", I think saying this in the error message is enough; or if "if=scsi" is a valid way for some machines, then maybe we can declare support limits found with your script? Fam > > > Do we have a user documentation for this? Or, can we give a hint how to figure > > that out? > > Try it out: > > for i in ide scsi floppy pflash mtd sd virtio xen > do > for ((b=0; b<4; b++)) > do > for ((u=0; u<10; u++)) > do > echo q | qemu-system-x86_64 -nodefaults -S -display none -monitor stdio -drive if=$i,bus=$b,unit=$u,file=tmp.qcow2 >/dev/null > done > done > done > > My upper bounds for bus and unit are arbitrary.