From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35638) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V59B5-0002MH-RT for qemu-devel@nongnu.org; Fri, 02 Aug 2013 02:49:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1V59Az-0001OO-NY for qemu-devel@nongnu.org; Fri, 02 Aug 2013 02:49:31 -0400 Received: from mx1.redhat.com ([209.132.183.28]:19448) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1V59Az-0001Nb-GG for qemu-devel@nongnu.org; Fri, 02 Aug 2013 02:49:25 -0400 Received: from int-mx10.intmail.prod.int.phx2.redhat.com (int-mx10.intmail.prod.int.phx2.redhat.com [10.5.11.23]) by mx1.redhat.com (8.14.4/8.14.4) with ESMTP id r726nOQV015932 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-SHA bits=256 verify=OK) for ; Fri, 2 Aug 2013 02:49:24 -0400 Message-ID: <51FB5672.4070907@redhat.com> Date: Fri, 02 Aug 2013 08:49:22 +0200 From: Gerd Hoffmann MIME-Version: 1.0 References: <51FAB912.5040203@redhat.com> In-Reply-To: <51FAB912.5040203@redhat.com> Content-Type: text/plain; charset=ISO-8859-9 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] default slot used for vga device on q35 machines List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Laine Stump Cc: qemu list Hi, > qemu-kvm -M q35 -nodefaults -nodefconfig -qmp unix:/tmp/qemu,server > -vnc :15 -vga std -usb > > Then ran "query-pci" in the qmp monitor and found that the vga device is > put at slot 1 instead of slot 2. > > My questions: > > 1) Is this difference intentional, or a bug? The vga simply goes into the first free slot. That happens to be #2 with i440fx and #1 with q35. > 2) If it's intentional, will the device always be at slot 1 (and trigger > an error if something else is also placed at slot 1), or is it just > picking the first unused slot? (that would *not* be good, because we > must be able to predict what device is in which slot and prevent them > from changing from run to run). The vga is the very first (pci) device being created (when selecting via -vga), so it gets the slots mentioned above no matter what, even though simply picking the first unused slot. > 3) Does the qxl multihead support really require that the device be at > slot 2 (as stated in the above bugzilla commend)? Or is that just a > misunderstanding/overstatement? It's not required at all. The problem is that on older qemu versions (pre-memory-api basically) it was impossible to create functional vga devices via -device due to an initialization order issue. Which implies you have to use -vga instead, which in turn implies the vga ends up in slot #2. On i440fx, but q35 didn't exist yet back then ;) cheers, Gerd