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[Bug 1338277] Re: Ubuntu 14.04 + QEmu 2.0 + KSM = 1, makes Windows 2008 R2 guests to crash (BSOD)


** Also affects: linux (Ubuntu)
   Importance: Undecided
       Status: New

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  Ubuntu 14.04 + QEmu 2.0 + KSM = 1, makes Windows 2008 R2 guests to
  crash (BSOD)

Status in “linux” package in Ubuntu:
Status in “qemu” package in Ubuntu:

Bug description:

  I'm trying to run Windows 2008 as a QEmu guest on my Ubuntu 14.04 but,
  after lots of tests, I figured out that it doesn't work, QEmu makes
  Windows 2008 to crash, and it is not a Windows fault, I'm pretty sure
  that it is a QEmu bug.

  Lab environment (5 servers):

  3 physical servers: Dell R610

  2 physycal servers: IBM x3650

  * Where Windows crash (5 servers tested) ?

  Ubuntu 14.04 + QEmu 2.0 + VirtIO 0.1-81 = Windows 2008 crash every

  - Installed with "apt-get install ubuntu-virt-server".

  * Where Windows do not crash (5 servers tested) ?

  Ubuntu 14.04 + Xen 4.4 +  gplpv_Vista2008x64_1.0.1092.9 = Windows
  working smoothly

  - Installed with "apt-get install xen-system-amd64".

  So, after removing QEmu from my environment, and using Xen instead,
  all Windows guests are now running without any crash.

  What kind of information, can I provide for you guys, to deep debug
  this QEmu problem ?

  Plus, it is interesting to note that a lot of times, all Windows
  guests (on top of QEmu / KVM) crashes at the exactly the same time!
  So, it can not be a problem within each Windows guest, but at the
  Hypervisor itself! Something happen there, that affects almost all
  Windows guests simultaneously.

  Also, it worth to mention that this problem is probably affecting
  clouds based on OpenStack IceHouse, on top of Ubuntu + QEmu 2.0...




  NOTE: I'm using KSM (Kernel Samepage Merging) with QEmu, to save RAM.
  It seems that when with Xen (+QEmu / HVM), KSM is not used :'( , but
  it is enabled ( 1 > /sys/kernel/mm/ksm/run at Dom0's kernel). I did
  not tried to disable KSM to see if Windows becomes more stable on QEmu

  Also, I did not run tests on this environment with Ubuntu 12.04.4 (or
  12.04.4 with Ubuntu Cloud Archives, to get newer versions of QEmu (but
  not 2.0) for old LTS).

  CURIOSITY: On older hardware, like Dell R1950, and at my old Intel
  Desktop Core i7, I'm running Windows 2008 and 7, on Ubuntu 14.04 with
  QEmu 2.0 without any crash... I really like to figure out why QEmu is
  crashing Windows guests on Dell R610 and on IBM x3650...

  Attaching the VM's configuration files on next posts...


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