Setting a dump device from db> ?

[Alan Somers]

Is it possible to set a dump device from loader.conf or from the db>
prompt?  I'm trying to investigate a panic in mpr(4), but I can only
reproduce it during the boot, before rc(8) has set my dump device.  It
looks like ada(4) initializes before mpr(4), so I should be able to
dump to an ada device, if only I can figure out how.  If not, I
suppose I'll have to try gdb over firewire.

-Alan