Serial debug broken in recent -CURRENT?

[Andrew Gallatin]

Sam Leffler writes:
 > It reliably locks up for me when you break into a running system; set a 
 > breakpoint; and then continue.  Machine is UP+HTT.  Haven't tried other 
 > machines.

Perhaps related, perhaps a red-herring:   With a single P4 + HTT, +
SMP kernel, if I break into the ddb debugger on a serial console, the
machine locks solid about 1 in 4 times.

This is with a kernel from mid August.  I have been too busy / too
wimpy to upgrade past ATAng.

Drew