kvm trouble

[Andrey N. Oktyabrski]

Good day.

I have a problem with DragonFly v3.4.1.5.g6a92f on kvm virtual machine. 
It hangs after some time after boot. Without panic and crashdump.

DragonFly v3.4.1.2.g0622d on another kvm works fine.

Both are x86_64

How can I help to debug it?