From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:60952) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XwqjT-0000e8-Rk for qemu-devel@nongnu.org; Fri, 05 Dec 2014 06:07:38 -0500 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1XwqjN-0003r5-MH for qemu-devel@nongnu.org; Fri, 05 Dec 2014 06:07:31 -0500 Received: from mx1.redhat.com ([209.132.183.28]:45311) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1XwqjN-0003r1-FR for qemu-devel@nongnu.org; Fri, 05 Dec 2014 06:07:25 -0500 Date: Fri, 5 Dec 2014 12:07:19 +0100 From: Kevin Wolf Message-ID: <20141205110719.GB6040@noname.str.redhat.com> References: <1417775209-11812-1-git-send-email-kwolf@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1417775209-11812-1-git-send-email-kwolf@redhat.com> Subject: Re: [Qemu-devel] [PATCH] vhdx: Return true for bdrv_has_zero_init List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org Cc: amulya.lokesha@emc.com, jcody@redhat.com, stefanha@redhat.com, mreitz@redhat.com Am 05.12.2014 um 11:26 hat Kevin Wolf geschrieben: > Like for most other image formats, vhdx images read as all zero in qemu > after their creation (we're taking advantage from the fact that qemu has > just created the image, because PAYLOAD_BLOCK_NOT_PRESENT actually means > undefined rather than zeroed according to the spec). Brain fart, self-NACK. This obviously means that 'qemu-img convert' still can't leave zeros in the source file unwritten in the destination, otherwise we're corrupting data. qemu would still read them correctly, but other implementations might not. We'd have to write the BAT for dynamic images with PAYLOAD_BLOCK_ZERO for all clusters before we can make this change. Jeff, do you want to fix this? Kevin