From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([208.118.235.92]:52108) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SfAm1-0004RI-Uz for qemu-devel@nongnu.org; Thu, 14 Jun 2012 10:11:51 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1SfAlr-0006Y3-WB for qemu-devel@nongnu.org; Thu, 14 Jun 2012 10:11:45 -0400 Received: from mx1.redhat.com ([209.132.183.28]:64346) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1SfAlr-0006Xy-OI for qemu-devel@nongnu.org; Thu, 14 Jun 2012 10:11:35 -0400 Message-ID: <4FD9F104.1010209@redhat.com> Date: Thu, 14 Jun 2012 16:11:16 +0200 From: Kevin Wolf MIME-Version: 1.0 References: <1339598189-17933-1-git-send-email-wdongxu@linux.vnet.ibm.com> <1339598189-17933-4-git-send-email-wdongxu@linux.vnet.ibm.com> <4FD9C24A.70906@redhat.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [PATCH 4/6] qemu-img: add-cow will not support convert List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Dong Xu Wang Cc: Stefan Hajnoczi , qemu-devel@nongnu.org Am 14.06.2012 16:06, schrieb Dong Xu Wang: > On Thu, Jun 14, 2012 at 6:51 PM, Kevin Wolf wrote: >> Am 13.06.2012 16:36, schrieb Dong Xu Wang: >>> add-cow file can't live alone, must together will image_file and backing_file. >>> If we implement qemu-img convert operation for add-cow file format, we must >>> create image_file and backing_file manually, that will be confused for users, >>> so we just ignore add-cow format while doing converting. >>> >>> Signed-off-by: Dong Xu Wang >> >> NACK. >> >> This stupid "let's drop the feature, it might confuse users" attitude is >> known from Gnome, but not from qemu. >> >> There's no technical reason to forbid it and anyone who manages to >> create a valid add-cow image will also be able to specify the very same >> options to a convert command. Also, having image format specific code in >> qemu-img is evil. >> > > If I implement add-cow convert command, I am wondering which method should > I use: > 1) create add-cow, and its backing_file, and its image_file, then we > need 3 files. > 2) create add-cow(with all bitmap marked to allocated), and its > image_file, then we > need 2 files. > > 2) will be easier, I should let .add-cow file can live only with > image_file, without backing_file. > > I think both 1) and 2) need add code to qemu-img.c. Or I will have to create > image_file automaticly in add_cow_create function. > > Can you give some comments on how to implement convert? Thanks. Just leave it alone and it will work. qemu-img convert takes the same options as qemu-img create. So like for any other image you specify the backing file with -b or -o backing_file, and for add-cow images to be successfully created you also need to specify -o image_file. Kevin