From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LL0B8-0000HK-IX for qemu-devel@nongnu.org; Thu, 08 Jan 2009 14:04:26 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LL0B7-0000Gx-Kh for qemu-devel@nongnu.org; Thu, 08 Jan 2009 14:04:26 -0500 Received: from [199.232.76.173] (port=55822 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LL0B7-0000Gu-En for qemu-devel@nongnu.org; Thu, 08 Jan 2009 14:04:25 -0500 Received: from qw-out-1920.google.com ([74.125.92.147]:34252) by monty-python.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1LL0B6-0000gB-Qe for qemu-devel@nongnu.org; Thu, 08 Jan 2009 14:04:25 -0500 Received: by qw-out-1920.google.com with SMTP id 5so4160339qwc.4 for ; Thu, 08 Jan 2009 11:04:22 -0800 (PST) Message-ID: <49664E2F.6000902@codemonkey.ws> Date: Thu, 08 Jan 2009 13:04:15 -0600 From: Anthony Liguori MIME-Version: 1.0 Subject: Re: [Qemu-devel] qemu: block.c: introducing "fmt:FMT:" prefix to image-filenames References: <496642BD.4010706@redhat.com> <20090108185256.GA8669@redhat.com> In-Reply-To: <20090108185256.GA8669@redhat.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Reply-To: qemu-devel@nongnu.org List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: "Daniel P. Berrange" , qemu-devel@nongnu.org Cc: Uri Lublin Daniel P. Berrange wrote: > On Thu, Jan 08, 2009 at 08:15:25PM +0200, Uri Lublin wrote: > >> The purpose of this prefix is to >> 1. Provide a way to know the backing file format without probing >> it (setting the format upon creation time). >> 2. Enable using qcow2 format (and others) over host block devices. >> (only if the user specifically asks for it). >> >> If no fmt:FMT: is provided we go back to probing. >> > > I still don't like the fact that this is inventing a second syntax > for specifying format that's different to the syntax used for the > existing -drive parameter, which is > > -drive file=/some/path,format=qcow2,....other disk options... > > >> backing file format is qcow2 (even though it's on a host block device) >> $ qemu-img create -b fmt:qcow2:/dev/loop0 -f qcow2 /tmp/uuu.qcow2 >> > > I'd prefer to see a '-F' flag to specify format of backing file and > leave syntax of existing -b arg alone > > $ qemu-img create -F qcow2 -b /dev/loop0 -f qcow2 /tmp/uuu.qcow2 > You may have multiple backing images. I don't see how you can do fix this without encoding the information in the path, or changing qcow2. Regards, Anthony Liguori >> force backing file format to raw (no probing) >> $ qemu-img create -f raw /tmp/image1.raw 10G >> $ qemu-img create -b fmt:raw:/tmp/image1.raw -f qcow2 /tmp/image1.qcow2 >> > > $ qemu-img create -F raw -b /tmp/image1.raw -f qcow2 /tmp/image1.qcow2 > > >> Use together with other protocols, e.g. nbd >> $ qemu-nbd -v -n --snapshot -t -k /tmp/uuu.socket >> fmt:qcow2:/tmp/images/uuu.qcow2 & >> > > Should just add a -f arg to qemu-nbd to specify format so it > follows qemu-img style, eg > > $ qemu-nbd -v -n --snapshot -t -k /tmp/uuu.socket \ > -f qcow2 /tmp/images/uuu.qcow2 & > > >> $ qemu-img info nbd:unix:/tmp/uuu.socket >> $ qemu-system-x86_64 -snapshot -hda nbd:unix:/tmp/uuu.socket >> >> Or fat >> $ qemu-system-x86_64 -hda fmt:qcow2:/tmp/uuu.qcow2 -hdb >> fat:floppy:/tmp/images >> > > This is unneccessary, since -hda is deprecated, and there's a > new -drive arg that already has ability to set format explicitly, > as well as many other flags that you need when setting up disks. > > $ qemu-system-x86_64 \ > -drive index=0,format=qcow2,file=/tmp/uuu.qcow2 \ > -drive index=1,format=fat:floppy,file=/tmp/images > > Regards, > Daniel >