From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mailman by lists.gnu.org with tmda-scanned (Exim 4.43) id 1Lrwbf-0001Lu-Aj for qemu-devel@nongnu.org; Thu, 09 Apr 2009 11:55:59 -0400 Received: from exim by lists.gnu.org with spam-scanned (Exim 4.43) id 1Lrwba-0001Jo-Ra for qemu-devel@nongnu.org; Thu, 09 Apr 2009 11:55:58 -0400 Received: from [199.232.76.173] (port=43647 helo=monty-python.gnu.org) by lists.gnu.org with esmtp (Exim 4.43) id 1Lrwba-0001Jd-Bn for qemu-devel@nongnu.org; Thu, 09 Apr 2009 11:55:54 -0400 Received: from mail2.shareable.org ([80.68.89.115]:33286) by monty-python.gnu.org with esmtps (TLS-1.0:RSA_AES_256_CBC_SHA1:32) (Exim 4.60) (envelope-from ) id 1LrwbZ-0003gN-TI for qemu-devel@nongnu.org; Thu, 09 Apr 2009 11:55:54 -0400 Received: from jamie by mail2.shareable.org with local (Exim 4.63) (envelope-from ) id 1LrwbW-0003iy-8C for qemu-devel@nongnu.org; Thu, 09 Apr 2009 16:55:50 +0100 Date: Thu, 9 Apr 2009 16:55:50 +0100 From: Jamie Lokier Subject: Re: [Qemu-devel] buffer alignment for block backends Message-ID: <20090409155550.GA14196@shareable.org> References: <49DCA80A.1020808@eu.citrix.com> <49DCF2C0.9070704@codemonkey.ws> <49DDC66F.2000404@eu.citrix.com> <49DDF3FF.8050706@codemonkey.ws> <49DDF877.8090805@eu.citrix.com> <49DDFE1A.9040202@redhat.com> <20090409152107.GE5457@const.bordeaux.inria.fr> MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <20090409152107.GE5457@const.bordeaux.inria.fr> 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 Samuel Thibault wrote: > Gerd Hoffmann, le Thu 09 Apr 2009 15:54:34 +0200, a écrit : > > On 04/09/09 15:30, Stefano Stabellini wrote: > > >The userspace\kernelspace distinction does not make much sense in > > >minios, but yes it provides an interface to communicate with blkback in > > >dom0. This interface is used by block-vbd in qemu instead of > > >block-raw-posix when run in minios. > > > > Sit back, look again. Do you really need it being page-aligned? > > Page aligned is an optimization which comes for free when you can > already choose the alignment. > > > The xen block protocol can handle unaligned requests just fine. > > Not completely arbitrarily aligned requests. They need to be > sector-aligned. Thought about 4k sectors, to be found in new disks sometime soon? -- Jamie