qemu crash 100% CPU with Ubuntu10.04 guest (solved)

[Ben Smith]

Hi All,

I'm cross-posting this from Reddit qemu_kvm, in case it helps in some
way. I know my setup is ancient and unique; let me know if you would
like more info.

Symptoms:
1. Ubuntu10.04 32-bit guest locks up randomly between 0 and 30 days.
2. The console shows a CPU trace dump, nothing else logged on the guest or host.
3. Host system (Ubuntu20.04) 100% CPU for qemu process.

Solution:
When using virt-install, always use the "--os-variant" parameter!
e.g. --os-variant ubuntu10.04

>From the man page "--os-variant... Optimize the guest configuration
for a specific operating system".
In this case, "optimize" apparently means "stop the crashing".

I was deliberately avoiding the option because the VM was already
performing much better than expected and I didn't want to complicate
the configuration.

This was very, very painful to troubleshoot; Involving spinning up 60
VMs simultaneously, waiting for a failure, changing one parameter,
repeat. :(