Problem running 8.1R on KVM with AMD hosts

[Jung-uk Kim]

On Thursday 30 September 2010 02:57 pm, Luke Marsden wrote:
> Hi FreeBSD-stable,
>
> > > 1. Please, build your kernel with debug symbols.
> > > 2. Show kgdb output
>
> I could not convince the kernel to dump (it was looping forever but
> not panicing), but I have managed to compiled a kernel with
> debugging symbols and DDB which immediately drops into the debugger
> when the problem occurs, see screenshot at:
>
>         http://lukemarsden.net/kvm-panic.png

It seems MCA capability is advertised by the CPUID translator but 
writing to the MSRs causes GPF.  In other words, it seems like a CPU 
emulator bug.  A simple workaround is 'set hw.mca.enabled=0' from the 
loader prompt.  If it works, add hw.mca.enabled="0" 
in /boot/loader.conf to make it permanent.  MCA does not make any 
sense in emulation any way.

Jung-uk Kim