[Qemu-devel] [Bug 1088617] [NEW] qemu-system-mipsel save/restore broken

[Brendan Dolan-Gavitt]

Public bug reported:

Save and restore on mipsel seems to be broken (tested with commit
1c97e303d4ea80a2691334b0febe87a50660f99d). To reproduce:

1. Download debian_squeeze_mipsel_standard.qcow2 and vmlinux-2.6.32-5
-4kc-malta from from http://people.debian.org/~aurel32/qemu/mipsel/

2. Boot the system. I had to ^D past a Bus error in fsck, which may be another 
bug (haven't investigated). The command line used was:
qemu-system-mipsel -M malta -kernel vmlinux-2.6.32-5-4kc-malta -hda 
debian_squeeze_mipsel_standard.qcow2 -append "root=/dev/sda1 console=tty0" -k 
en-us -vnc :0

3. Once the system is booted, go to the monitor and do "savevm booted".
Then quit.

4. Re-run qemu-system-mipsel again with "-loadvm booted". The guest
system comes back but is hung (the monitor remains responsive, however).

I also captured a debug log, which is attached. The immediate cause of
the freeze seems to be that it's stuck in a loop repeatedly handling the
same page fault over and over.

** Affects: qemu
     Importance: Undecided
         Status: New


** Tags: mipsel-softmmu

** Attachment added: "Debug log on restore with int,in_asm enabled"
   
https://bugs.launchpad.net/bugs/1088617/+attachment/3456526/+files/mipsrestore.log.gz

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https://bugs.launchpad.net/bugs/1088617

Title:
  qemu-system-mipsel save/restore broken

Status in QEMU:
  New

Bug description:
  Save and restore on mipsel seems to be broken (tested with commit
  1c97e303d4ea80a2691334b0febe87a50660f99d). To reproduce:

  1. Download debian_squeeze_mipsel_standard.qcow2 and vmlinux-2.6.32-5
  -4kc-malta from from http://people.debian.org/~aurel32/qemu/mipsel/

  2. Boot the system. I had to ^D past a Bus error in fsck, which may be 
another bug (haven't investigated). The command line used was:
  qemu-system-mipsel -M malta -kernel vmlinux-2.6.32-5-4kc-malta -hda 
debian_squeeze_mipsel_standard.qcow2 -append "root=/dev/sda1 console=tty0" -k 
en-us -vnc :0

  3. Once the system is booted, go to the monitor and do "savevm
  booted". Then quit.

  4. Re-run qemu-system-mipsel again with "-loadvm booted". The guest
  system comes back but is hung (the monitor remains responsive,
  however).

  I also captured a debug log, which is attached. The immediate cause of
  the freeze seems to be that it's stuck in a loop repeatedly handling
  the same page fault over and over.

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