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From: Albert Kao <1759522@bugs.launchpad.net>
To: qemu-devel@nongnu.org
Subject: [Bug 1759522] Re: windows qemu-img create vpc/vhdx error
Date: Mon, 12 Apr 2021 14:59:58 -0000
Message-ID: <161823959862.29979.14372659933655095391.malone@wampee.canonical.com> (raw)
In-Reply-To: <152222836105.21062.2375148895134658603.malonedeb@chaenomeles.canonical.com>

I noticed the cloudbase version does NOT have this issue. https://cloudbase.it/qemu-img-windows/
The weilnetz version DOES have this issue. https://qemu.weilnetz.de/w64/

So, I found the source code for each release and compared them.

cloudbase https://repo.or.cz/w/qemu/ar7.git/
weilnetz https://github.com/cloudbase/qemu

git remote add origin git://repo.or.cz/qemu/ar7.git
git remote add cloudbase https://github.com/cloudbase/qemu.git
git fetch --all
git diff v2.3.0 cloudbase/v2.3.0-cloudbase

And I see that the cloudbase version comments out set_sparse(fd).

I think the solution is to remove set_sparse.
You can find it in block/file-win32.c

** Attachment added: "git diff v2.3.0 cloudbase/v2.3.0-cloudbase"

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  windows qemu-img create vpc/vhdx error

Status in QEMU:

Bug description:
  On windows, using qemu-img (version 2.11.90) to create vpc/vhdx
  virtual disk tends to fail. Here's the way to reproduce:

  1. Install qemu-w64-setup-20180321.exe

  2. Use `qemu-img create -f vhdx -o subformat=fixed disk.vhdx 512M` to create a vhdx:
     Formatting 'disk.vhdx', fmt=vhdx size=536870912 log_size=1048576 block_size=0 subformat=fixed

  3. Execute `qemu-img info disk.vhdx` gives the result, (note the `disk size` is incorrect):
     image: disk.vhdx
     file format: vhdx
     virtual size: 512M (536870912 bytes)
     disk size: 1.4M
     cluster_size: 8388608

  4. On Windows 10 (V1709), double click disk.vhdx gives an error:
     Make sure the file is in an NTFS volume and isn't in a compressed folder or volume.

     Using Disk Management -> Action -> Attach VHD gives an error:
     The requested operation could not be completed due to a virtual disk system limitation. Virtual hard disk files must be uncompressed and uneccrypted and must not be sparse.

  Comparison with Windows 10 created VHDX:

  1. Using Disk Management -> Action -> Create VHD:
     File name: win.vhdx
     Virtual hard disk size: 512MB
     Virtual hard disk format: VHDX
     Virtual hard disk type: Fixed size

  2. Detach VHDX

  3. Execute `qemu-img info win.vhdx` gives the result:
     image: win.vhdx
     file format: vhdx
     virtual size: 512M (536870912 bytes)
     disk size: 516M
     cluster_size: 33554432

  Comparison with qemu-img under Ubuntu:

  1. Version: qemu-img version 2.5.0 (Debian 1:2.5+dfsg-5ubuntu10.16),
  Copyright (c) 2004-2008 Fabrice Bellard

  2. qemu-img create -f vhdx -o subformat=fixed lin.vhdx 512M
     Formatting 'lin.vhdx', fmt=vhdx size=536870912 log_size=1048576 block_size=0 subformat=fixed

  3. qemu-img info lin.vhdx
     image: lin.vhdx
     file format: vhdx
     virtual size: 512M (536870912 bytes)
     disk size: 520M
     cluster_size: 8388608

  4. Load lin.vhdx under Windows 10 is ok

  The same thing happens on `vpc` format with or without
  `oformat=fixed`, it seems that windows version of qemu-img has some
  incorrect operation? My guess is that windows version of qemu-img
  doesn't handle the description field of vpc/vhdx, which leads to an
  incorrect `disk size` field.

To manage notifications about this bug go to:

  parent reply index

Thread overview: 11+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2018-03-28  9:12 [Qemu-devel] [Bug 1759522] [NEW] " Zixuan Wang
2018-03-28  9:16 ` [Qemu-devel] [Bug 1759522] " Zixuan Wang
2018-03-28 10:27 ` Zixuan Wang
2019-10-27  6:17 ` Adam Baxter
2020-02-10  6:25 ` Qi Zhou
2020-02-19  6:08 ` Zixuan Wang
2020-02-29  0:14 ` maro
2021-04-12 14:59 ` Albert Kao [this message]
2021-04-21  6:31 ` Thomas Huth
2021-04-21 11:39 ` Albert Kao
2021-05-05  5:16 ` Thomas Huth

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