[Qemu-devel] [Bug 1002121] Re: disk error when guest boot up via qcow2 image

[Yongjie Ren]

Re-tested against latest qemu-kvm master branch with commit  0a948cbb. And 
found this issue has gone.
Jan Kiszka's following patch fixed this bug.

commit 0cdd3d14447da1a04e778c219c77db8b96f9cf33
Author: Jan Kiszka
Date:   Wed Jun 6 16:28:42 2012 +0200

    kvm: i8254: Fix conversion of in-kernel to userspace state

    Due to a offset between the clock used to generate the in-kernel
    count_load_time (CLOCK_MONOTONIC) and the clock used for processing this
    in userspace (vm_clock), reading back the output of PIT channel 2 via
    port 0x61 was broken. One use cases that suffered from it was the CPU
    frequency calibration of SeaBIOS, which also affected IDE/AHCI timeouts.

    This fixes it by calibrating the offset between both clocks on
    kvm_pit_get and adjusting the kernel value before saving it in the
    userspace state. As the calibration only works while the vm_clock is
    running, we cache the in-kernel state across stopped phases.

    Signed-off-by: Jan Kiszka

** Changed in: qemu
       Status: New => Fix Released

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https://bugs.launchpad.net/bugs/1002121

Title:
  disk error when guest boot up via qcow2 image

Status in QEMU:
  Fix Released

Bug description:
  Host OS (ia32/ia32e/IA64): ia32e
  Guest OS (ia32/ia32e/IA64): ia32e
  Guest OS Type (Linux/Windows): Linux(rhel6u1)
  kvm.git Commit: 51bfd2998113e1f8ce8dcf853407b76a04b5f2a0
  qemu-kvm Commit: e54f008ef8f968cfc2f3ecab78491d180fa31efc
  Host Kernel Version:3.4.0-rc7
  Hardware: WSM-EP, Romley-EP

  
  Bug detailed description:
  --------------------------
  If I boot up a guest using qcow2 image, the guest show “disk read error”.  If 
you press some key to continue, after being automatically repaired, the guest 
can boot up.

  This should be a qemu-kvm regression.
  kvm      + qemu-kvm   =  result
  51bfd299 + e54f008e    =  bad 
  51bfd299 + b320b8b7   =  good

  Note:
  1. guest rhel6u1, guest show “disk error”
     guest rhel6u2, guest show black screen
     this phenomenon occurs at the first time to create guest
  2. create guest with raw image, this phenomenon doesn’t appear.

  
  Reproduce steps:
  ----------------
  1.start up a host with kvm (commit: 51bfd299) and use qemu-kvm 
(commit:e54f008e)
  2.qemu-img create –b /share/ia32e_rhel6u1.img –f qcow2
  /root/rhel6u1.qcow
  3.qemu-system-x86_64 -mem 1024 –hda /root/rhel6u1.qcow

  Current result:
  ----------------
  Guest console shows:
  error 25:Disk read error
  Prss any key to continue...

  
  Expected result:
  ----------------
  Guest boot up correctly

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