From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from [140.186.70.92] (port=44612 helo=eggs.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1OTBYT-0003tQ-Uw for qemu-devel@nongnu.org; Mon, 28 Jun 2010 06:27:11 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.69) (envelope-from ) id 1OTBYS-0000vu-TA for qemu-devel@nongnu.org; Mon, 28 Jun 2010 06:27:09 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44885) by eggs.gnu.org with esmtp (Exim 4.69) (envelope-from ) id 1OTBYS-0000vk-IM for qemu-devel@nongnu.org; Mon, 28 Jun 2010 06:27:08 -0400 Message-ID: <4C2878EC.1040803@redhat.com> Date: Mon, 28 Jun 2010 12:26:52 +0200 From: Kevin Wolf MIME-Version: 1.0 Subject: Re: [Qemu-devel] Re: [PATCH 08/12] block: Catch attempt to attach multiple devices to a blockdev References: <1277484812-22012-1-git-send-email-armbru@redhat.com> <1277484812-22012-9-git-send-email-armbru@redhat.com> <20100626101146.GC27699@lst.de> <20100627093609.GA12016@lst.de> <4C285C51.9020003@redhat.com> <20100628101658.GA1997@lst.de> In-Reply-To: <20100628101658.GA1997@lst.de> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Christoph Hellwig Cc: kraxel@redhat.com, Markus Armbruster , qemu-devel@nongnu.org Am 28.06.2010 12:16, schrieb Christoph Hellwig: > On Mon, Jun 28, 2010 at 10:24:49AM +0200, Kevin Wolf wrote: >> How would breaking compatibility help us? For the user a USB MSD is only >> one device, so requiring two -device parameters sounds wrong. > > But it is separate devices. At least the standards compliant usb > storage devices just are a bride of scsi commands over usb and fit into > the SAM device model, which makes a difference between initiator, target > and LUN. So having a different device for the specific target vs the > initiator port makes a difference. (and yes, we're still totally missing > support for multiple luns, which would require another level of > devices). Trying to hide this is not all that useful - not anymore > useful than hiding it on a "normal" scsi host controller anyway. Maybe we need something like composed devices? So when the user asks for a USB stick, he actually gets all devices that this stick internally uses? Otherwise it becomes really hard to use -device directly. I guess the same applies for mainboards, CPUs and probably some more things, though I don't really know how these are (planned to be) done in qdev. Kevin