I haven't built a shark kernel since late October, so I'm not sure when 
this problem was introduced, but with a -current kernel source supped this 
morning, I get a boot-time panic right after the "cpu0 at mainbus..." 
message.  Unfortunately the machine then starts to recursively panic so I 
can't get into a debugger (I only got this much info by making panic put 
the cpu into an infinite loop).  Anyway the first panic is:

cpu0 at mainbus ....
Section fault in SVC mode
[u]vm_fault (0xff0fe644, fffff000, 1, 0) -> 1
panic: Halting

My config is a completely vanilla SHARK.
Richard