Re: [Qemu-devel] qemu-kvm guest which won't 'cont' (emulation failure?)

[Chris Webb]

Kevin Wolf <address@hidden> writes:

> Am 24.10.2011 12:00, schrieb Chris Webb:
> > I have qemu monitor access and can even strace the relevant qemu process if
> > necessary: is it possible to use this to diagnose what's caused this guest
> > to stop, e.g. the unsupported instruction if it's an emulation failure?
> 
> Another common cause for stopped VMs are I/O errors, for example writes
> to a sparse image when the disk is full.

This guest are backed by LVM LVs so I don't think they can return EFULL, but I
could imagine read errors, so I've just done a trivial test to make sure I can
read them end-to-end:

  0015# dd 
if=/dev/mapper/guest\:e549f8e1-4c0e-4dea-826a-e4b877282c07\:ide\:0\:0 
of=/dev/null bs=1M
  3136+0 records in
  3136+0 records out
  3288334336 bytes (3.3 GB) copied, 20.898 s, 157 MB/s

  0015# dd 
if=/dev/mapper/guest\:e549f8e1-4c0e-4dea-826a-e4b877282c07\:ide\:0\:1 
of=/dev/null bs=1M
  276+0 records in
  276+0 records out
  289406976 bytes (289 MB) copied, 1.85218 s, 156 MB/s

Is there any way to ask qemu why a guest has stopped, so I can distinguish IO
problems from emulation problems from anything else?

Cheers,

Chris.