Hi all,

I have several KVM Guests, running Ubuntu 9.04 on a 9.04 Host. 9.04 is not exactly top of the line anymore, so I decided to move to a 12.04 Host. The guest machines are locally accessible only, there is no immediate need for an update there.

Just after I moved the first 9.04 machine to the new host the GUEST began giving me strange ATA timeouts on the console, accompanied by messages like "BUG: soft lockup - CPU#0 stuck for 95s! [scsi_eh_0:30]".

Of course, performance with those ATA timeouts and sticky CPU is intolerably bad. I started a guest VM with 12.04 and it did not exibit the problems. One of the more obvious differences between the (otherwise identically configured) machines, besides their kernel versions, of course, was this line in /proc/cpuinfo:

model name : QEMU Virtual CPU version 1.0
on 12.04:
cpu MHz : 3399.998
on 09.04:
cpu MHz : 33999.980

I wonder if that may have something to do with it.

So much for easy migration of virtualized hosts.

Any ideas on how I can get those 9.04 guests running on the new host without having to upgrade all of them to 12.04?