From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1NdQr9-0003ZW-SM for qemu-devel@nongnu.org; Fri, 05 Feb 2010 11:16:31 -0500 Received: from [199.232.76.173] (port=34187 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1NdQr9-0003ZM-C3 for qemu-devel@nongnu.org; Fri, 05 Feb 2010 11:16:31 -0500 Received: from Debian-exim by monty-python.gnu.org with spam-scanned (Exim 4.60) (envelope-from ) id 1NdQr7-0000l2-S0 for qemu-devel@nongnu.org; Fri, 05 Feb 2010 11:16:31 -0500 Received: from mx20.gnu.org ([199.232.41.8]:26874) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1NdQr7-0000ka-HF for qemu-devel@nongnu.org; Fri, 05 Feb 2010 11:16:29 -0500 Received: from mail2.shareable.org ([80.68.89.115]) by mx20.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1NdQr6-0006IN-Mt for qemu-devel@nongnu.org; Fri, 05 Feb 2010 11:16:28 -0500 Date: Fri, 5 Feb 2010 16:16:20 +0000 From: Jamie Lokier Subject: Re: [Qemu-devel] [PATCH 2/4] block: add block topology options Message-ID: <20100205161620.GB18601@shareable.org> References: <20100129190417.GA25237@lst.de> <20100129190440.GA25287@lst.de> <4B69C7DF.9000900@codemonkey.ws> <20100205130956.GA17475@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100205130956.GA17475@lst.de> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Christoph Hellwig Cc: "Martin K. Petersen" , qemu-devel@nongnu.org Christoph Hellwig wrote: > On Wed, Feb 03, 2010 at 01:00:47PM -0600, Anthony Liguori wrote: > > But I don't think this is the wrong place to do it. The > > BlockDriverState reflects that backing device, not the emulated device > > itself. In this case, you're trying to set a property of the emulated > > device. > > I think that's very borderline. While the emulated device exposes these > properties, they are in fact a property of the backing storage, the > right sector and min/max I/O sizes are determined by the backing storage > device. > > > I think these need to be qdev properties of the respective devices. > > From a UI perspective, you can still expose -drive options for the end > > user to consume, but this data should be associated with the devices > > themselves. > > In addition to not really beeing more logical this would be a lot more > effort. We'd need to add properties to all the device, which means > including dealing with the n+1 ide variants, the virtio-pci proxy, etc. > > If you believe it really needs to be in the qdev properties I'll > implement it, but I suspect the current version is a better idea. If you move your VM to a new system with different backing devices, sometimes you want to be sure there is no guest-visible change. Or even if you just replace a drive - you might prefer confidence that the guest sees no change. Even if you just convert between qcow2 and a raw block device, or the other way, you'll sometimes want to be sure it's not guest-visible. -- Jamie