Kernel DDB doesn't work in VM ?

[Yuri]

I have kernel configured with options KDB and DDB.
But when kernel panic occurs while running as VBox VM, VBox takes over 
and says: "A critical error occurred while running the virtual machine", 
etc. It doesn't drop into DDB. Pressing Ok closes VM, pressing "Ignore" 
leaves it in hung state.

sysctl debug.kdb.enter=1 also causes the above behavior as if panic has 
occurred.

Is it possible to make DDB kick in while running as VM?

Yuri