Ok, the domU lost its network again. Here is what the console said after
reboot:

...
xbd0 at xenbus0 id 36352: Xen Virtual Block Device Interface
xbd0: using event channel 5
xbd1 at xenbus0 id 36360: Xen Virtual Block Device Interface
xbd1: using event channel 6
xbd2 at xenbus0 id 36368: Xen Virtual Block Device Interface
xbd2: using event channel 7
xennet0 at xenbus0 id 0: Xen Virtual Network Interface
xennet0: MAC address 00:16:3e:50:03:f7
xennet0: using event channel 8
unknown type console at xenbus0 id 0 not configured
backend_changed backend

After that I needed to xm shutdown the domU.

My Google search showed some similar problems but the authors were
telling about migration and so on which I definitly didn't do. As I
wrote in the original mail, the domU ran for 3 weeks without
problems/crashes.

Maybe worthable to mention: First the domU was used with Xen 2 (thus
with the netbsd3.1 xen2 kernel) and when I updated the dom0 to support
xen3 I simply used the netbsd3.1 xen3 kernel. I hope that it was the
correct way of doing it?


Many greetings,
Damian