From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:35891) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aj5NK-0002lU-LI for qemu-devel@nongnu.org; Thu, 24 Mar 2016 09:32:38 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1aj5NG-0000sc-PS for qemu-devel@nongnu.org; Thu, 24 Mar 2016 09:32:34 -0400 Received: from mx1.redhat.com ([209.132.183.28]:46121) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1aj5NG-0000sO-KU for qemu-devel@nongnu.org; Thu, 24 Mar 2016 09:32:30 -0400 References: <1458742562-30624-1-git-send-email-den@openvz.org> <1458742562-30624-3-git-send-email-den@openvz.org> <20160323175834.GC2467@grep.be> <20160324084318.GC24831@phobos.sw.ru> <20160324093315.GA2870@grep.be> <433C735B-1BAE-47DA-9543-2E5BA2710357@alex.org.uk> <56F3D664.9010700@redhat.com> <6045D693-ADB5-4031-852B-CD9FA9BA8156@alex.org.uk> <56F3DE52.7060502@redhat.com> From: Paolo Bonzini Message-ID: <56F3EC69.8090204@redhat.com> Date: Thu, 24 Mar 2016 14:32:25 +0100 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=windows-1252 Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] [Nbd] [PATCH 2/2] NBD proto: add GET_LBA_STATUS extension List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Alex Bligh Cc: "nbd-general@lists.sourceforge.net" , Kevin Wolf , "qemu-devel@nongnu.org" , Pavel Borzenkov , "Stefan stefanha@redhat. com" , "Denis V. Lunev" , Wouter Verhelst On 24/03/2016 14:31, Alex Bligh wrote: > Sorry, I should have been clearer on the states: > > bits > 210 > > 1-- Unallocated, and hence reads as zero > -1- Allocated, and reads as zero > --1 Allocated, and reads as non-zero > > So 100 means 'definitely unallocated, will read as zero'. > > If you are saying that there is also a state called 'Unallocated, but reads > as non-zero', Yes. > that could be handled by adding a fourth bit. Same idea. One > would presume this would only ever be set in conjunction with bit 2. > My point in general was to represent all the possible states and let the client > determine what it wants to do with the information. This seems overengineered... Paolo