From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from eggs.gnu.org ([2001:4830:134:3::10]:50840) by lists.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZCMS7-0006BI-7i for qemu-devel@nongnu.org; Tue, 07 Jul 2015 02:34:00 -0400 Received: from Debian-exim by eggs.gnu.org with spam-scanned (Exim 4.71) (envelope-from ) id 1ZCMS4-0006BR-1h for qemu-devel@nongnu.org; Tue, 07 Jul 2015 02:33:59 -0400 Received: from mx-v6.kamp.de ([2a02:248:0:51::16]:42051 helo=mx01.kamp.de) by eggs.gnu.org with esmtp (Exim 4.71) (envelope-from ) id 1ZCMS3-0006BL-N4 for qemu-devel@nongnu.org; Tue, 07 Jul 2015 02:33:55 -0400 Message-ID: <559B72CD.7000409@kamp.de> Date: Tue, 07 Jul 2015 08:33:49 +0200 From: Peter Lieven MIME-Version: 1.0 References: <559ABE850200006600045FF0@relay2.provo.novell.com> <559A5B79.4010707@kamp.de> <559BA0D502000066000469BB@relay2.provo.novell.com> <559B68B2.5060402@kamp.de> <559BDB430200006600046AB4@relay2.provo.novell.com> <559B6BBE.3050500@kamp.de> <559BDFF90200006600046AD9@relay2.provo.novell.com> In-Reply-To: <559BDFF90200006600046AD9@relay2.provo.novell.com> Content-Type: text/plain; charset=windows-1252; format=flowed Content-Transfer-Encoding: 7bit Subject: Re: [Qemu-devel] vpc size reporting problem List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , To: Chun Yan Liu , qemu-devel@nongnu.org Cc: kwolf@redhat.com, mreitz@redhat.com Am 07.07.2015 um 08:19 schrieb Chun Yan Liu: > >>>> On 7/7/2015 at 02:03 PM, in message <559B6BBE.3050500@kamp.de>, Peter Lieven > wrote: >> Am 07.07.2015 um 07:59 schrieb Chun Yan Liu: >>>>>> On 7/7/2015 at 01:50 PM, in message <559B68B2.5060402@kamp.de>, Peter Lieven >>> wrote: >>>> Am 07.07.2015 um 03:50 schrieb Chun Yan Liu: >>>>>>>> On 7/6/2015 at 06:42 PM, in message <559A5B79.4010707@kamp.de>, Peter Lieven >>>>> wrote: >>>>>> Am 06.07.2015 um 11:44 schrieb Chun Yan Liu: >>>>>>> While testing with a 1GB VHD file created on win7, found that the VHD file >>>>>>> size reported on Windows is different from that is reported by qemu-img >>>>>>> info or within a Linux KVM guest. >>>>>>> >>>>>>> Created a dynamic VHD file on win7, on Windows, it is reported 1024MB >>>>>>> (2097152 sectors). But with qemu-img info or within a Linux KVM guest, >>>>>>> it is reported 1023MB (2096640 sectors). >>>>>>> >>>>>>> The values in the footer_buf are as follows: >>>>>>> creator_app: "win " >>>>>>> cylinders: 0x820 (2080) >>>>>>> heads: 0x10 (16) >>>>>>> cyl/sec: 0x3f (63) >>>>>>> current_size: 0x40000000 (1G) >>>>>>> >>>>>>> So, if using current_size, it's correct; but using CHS will get a smaller >>>>>> size. >>>>>>> Should we add a check in this case and use "current_size" instead of >>>>>>> CHS? >>>>>> >>>>>> As far as I remember the issue was and still is that there is no official >>>>>> spec that says >>>>>> use current_size in case A and CHS in case B. >>>>> Understand. >>>>> >>>>>> >>>>>> If currrent_size is greater than CHS and Windows would use CHS (we don't >>>>>> know that) we might run into issues if Qemu uses current_size. In this >>>>>> cas we would write data beyond the end of the container (from Windows >>>>>> perspective). >>>>> That's right. The fact is in our testing we found Windows does not use CHS >>>>> but current_size (from testing result), we create and get the VHD parted on >>>>> Windows, then take the VHD file into Linux KVM guest, it fails to show >>>> partition >>>>> table (since the reported disk size is shrinking, some of the partitions >>>> extend >>>>> beyond the end of the disk). >>>> >>>> Which version of Windows are you referring to? >>> Tested with WS2012R2 and Win7. >> >> Which storage driver? > I'm not sure. See from "device management" -> "disk drive", it's named as "Msft > virtual disk SCSI disk device", and from "storage controller", it has a separate > controller named as "Microsoft VHD HBA". Anyway, seems not controlled by > ATA/ATAPI. Can you change that to IDE or ATA and check which size windows reports then? Thanks, Peter