[Qemu-devel] [Bug 919242] Re: qemu-img convert to VDI corrupts image

[Serge Hallyn <919242@bugs.launchpad.net>]

Hi Stefan,

thanks for the fix.  Should I queue it up in the Ubuntu package, or
should I wait on that?

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https://bugs.launchpad.net/bugs/919242

Title:
  qemu-img convert to VDI corrupts image

Status in QEMU:
  Fix Committed
Status in “qemu-kvm” package in Ubuntu:
  Fix Committed

Bug description:
  Hello,  thanks to all for the great work on qemu, an excellent
  technology.

  There appears to be a serious bug in qemu-img 1.0, yielding silent
  corruption when converting an image to VDI format.  After conversion
  to  VDI, an image with WinNT4sp6 (NTFS) yields a boot failure (details
  below) -- presumably due to some corruption, since the image works
  fine as the source .vhd (from virtualPC6), and also when converted to
  QCOW2 or VMDK format.

  TEST CASE:
  OS X 10.6.8 on Intel i5
  Qemu 1.0 from mac "ports"  (macports.org)
  The source BaseDrive.vhd image is from VirtualPC6 (Mac)
  $ qemu-img info BaseDrive.vhd
  image: BaseDrive.vhd
  file format: vpc
  virtual size: 2.0G (2096898048 bytes)
  disk size: 190M

  The image has a fresh Windows NT4sp6 NTFS installation.  It's from VirtualPC6 (Connectix)  inside a .vhdp package directory on OS X.  Convert via:
    qemu-img convert -f vpc -O vdi BaseDrive.vhd  BaseDrive.vdi

  Now run the resulting vdi file with: 
    qemu-system-i386 -cpu pentium BaseDrive.vdi
  On boot, NT4 crashes with
  STOP: c000026c {Unable to Load Device Driver}
  \??\C:\WINNT\system32\win32k.sys device driver could not be loaded.
  Error Status was 0xc0000221

  Both qemu 1.0, and VirtualBox 4.1.8 yield the same error on this VDI.

  Conversion of the exact same image to QCOW2 or VMDK format yields a working image (ie. qemu and VirtualBox boot fine):
    qemu-img convert -f vpc -O qcow2 BaseDrive.vhd  BaseDrive.qcow2
    OR
    qemu-img convert -f vpc -O vmdk BaseDrive.vhd  BaseDrive.vmdk

  Furthermore, I tested converting from raw, qcow2, and vmdk  to vdi,
  and in all these cases the original format boots, but the converted
  VDI fails to boot as above.

  Along the way, I think I also tested a VDI natively created and
  installed from VirtualBox, which did boot fine in qemu.  Thus the
  problem appears to be not in qemu-system-i386 reading the VDI, rather
  in the qemu-img conversion to VDI.

  
  SEVERITY: CRITICAL
  The severity of this bug is critical as it appears to produce a silently corrupted VDI image.  (which is presumably the cause of the boot failure; though I have not explicitly check-disked the resulting VDI image).  It also impedes easy inter-use between qemu and VirtualBox.

  WORKAROUND:
  The workaround is to use the VMDK format instead of VDI. 
  VMDK is supported by both qemu and VirtualBox (and vmWare).

  
  I can supply a test VHD/QCOW2/VMDK image if desired to reproduce the bug.   (but it's large, 190M)

  -- jbthiel

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