From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1LKcZ7-0003dm-6U for qemu-devel@nongnu.org; Wed, 07 Jan 2009 12:51:37 -0500 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1LKcZ5-0003cI-97 for qemu-devel@nongnu.org; Wed, 07 Jan 2009 12:51:36 -0500 Received: from [199.232.76.173] (port=50151 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1LKcZ5-0003cB-4Y for qemu-devel@nongnu.org; Wed, 07 Jan 2009 12:51:35 -0500 Received: from cantor2.suse.de ([195.135.220.15]:46456 helo=mx2.suse.de) by monty-python.gnu.org with esmtps (TLS-1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1LKcZ4-00063x-N8 for qemu-devel@nongnu.org; Wed, 07 Jan 2009 12:51:34 -0500 Received: from Relay1.suse.de (relay-ext.suse.de [195.135.221.8]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by mx2.suse.de (Postfix) with ESMTP id A57C2484C6 for ; Wed, 7 Jan 2009 18:51:32 +0100 (CET) Message-ID: <4964ECEA.8090600@suse.de> Date: Wed, 07 Jan 2009 18:56:58 +0100 From: Kevin Wolf MIME-Version: 1.0 Subject: Re: [Qemu-devel] qcow1 compression References: <200901071824.40113.uli@suse.de> In-Reply-To: <200901071824.40113.uli@suse.de> Content-Type: text/plain; charset=ISO-8859-1 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: qemu-devel@nongnu.org Ulrich Hecht schrieb: > I have received a bug report from one of our users about compression in > qcow(1). He converted disk images to qcow with compression, and the > resulting images did not work. I looked into block-qcow.c and found > several huge and, as it seems, long-standing bugs. For instance, > QCOW_OFLAG_COMPRESSED is never set anywhere, causing compressed data to > be returned verbatim on reading. > > I'd like to get people's opinion on whether there is any point in fixing > this stuff, considering that there is qcow2, and that it never worked to > begin with. Perhaps a patch removing it would make more sense... It definitely worked at some point and a quick look seems to show that the last patch to block-qcow.c (Rev 4673) breaks it. Despite the commit comment, the code wasn't all that dead: allocate == 2 is different from allocate == 1. Reverting that patch should be enough (and possibly adding a comment so that it won't be broken again in future). Kevin