From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1MOXHq-0003eD-9j for qemu-devel@nongnu.org; Wed, 08 Jul 2009 09:34:14 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1MOXHl-0003ai-Dj for qemu-devel@nongnu.org; Wed, 08 Jul 2009 09:34:13 -0400 Received: from [199.232.76.173] (port=60119 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1MOXHl-0003aa-7g for qemu-devel@nongnu.org; Wed, 08 Jul 2009 09:34:09 -0400 Received: from mx20.gnu.org ([199.232.41.8]:8134) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1MOXHk-00013H-Su for qemu-devel@nongnu.org; Wed, 08 Jul 2009 09:34:09 -0400 Received: from mail.codesourcery.com ([65.74.133.4]) by mx20.gnu.org with esmtp (Exim 4.60) (envelope-from ) id 1MOXHj-0003Qd-67 for qemu-devel@nongnu.org; Wed, 08 Jul 2009 09:34:07 -0400 From: Paul Brook Subject: Re: [Qemu-devel] bidirectional data exchange between guest and host without network Date: Wed, 8 Jul 2009 14:34:00 +0100 References: <59673.89.3.148.243.1246956346.squirrel@webmail.aql.fr> <20090707143925.GA14392@shareable.org> <42816.89.3.148.243.1247047400.squirrel@webmail.aql.fr> In-Reply-To: <42816.89.3.148.243.1247047400.squirrel@webmail.aql.fr> MIME-Version: 1.0 Content-Type: Text/Plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200907081434.02498.paul@codesourcery.com> List-Id: qemu-devel.nongnu.org List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: qemu-devel@nongnu.org, anthony.lannuzel@hynesim.org Cc: Lennart Sorensen >Yes, the thing is, I can not use the network, as it is used for another >purpose, so I think I have to content myself with the basic linux >filesystems. That's just not going to work. Block devices don't provide the features necessary to implement a shared filesystem, you need some other mechanism (i.e. network) for handling locking and coherence. You can't take a regular filesystem and expect it to work. You have to use a proper network/clustered filesystem. In theory SCSI has locking facilities, however this is not implemented by qemu (and probably not by your underlying storage), and AFAIK aren't used by any of the current cluster filesystems. > I tried using a fat partition with the "sync" mount option, to avoid > caching on both sides (still using virtio on /dev/sda8 on the host and > /dev/vda on the guest). >... > Is there anything related to virtio that prevents this from working, as I > think the mount option provides me with a filesystem that fulfils the > conditions you just told me ? I believe "sync" only disables the write cache. Paul