[Qemu-devel] [Bug 1759522] Re: windows qemu-img create vpc/vhdx error

[Zixuan Wang]

Also, `force_size` suboption of `vpc` doesn't work on win version of
qemu-img.

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https://bugs.launchpad.net/bugs/1759522

Title:
  windows qemu-img create vpc/vhdx error

Status in QEMU:
  New

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.

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