Replying to my own message.  How quaint.

I've seen the panic a couple more times, with both 1.5.1 and 1.5.2 kernels.
It's now happening after the boot process finishes, just after the login:
prompt appears.

Strangely enough, it doesn't happen when the boot process initiates a parity
rewrite (i.e. the reboot after a panic), which is still in progress when the
login: prompt appears.  It only appears to happen when the system is
essentially quiescent after a normal boot.

-----
panic: lockmgr: no context
Stopped at      cpu_Debugger+0x10:   blah blah blah
db> trace
at panic+e8
at lockmgr+a4
at uvm_map+c4
at uvm_km_valloc+5c
at _bus_dmamem_map+68
at siop_morecbd+138
at siop_scsicmd+9c
at scsipi_execute_xs+58
at scsi_scsipi_cmd+190
at scsipi_command+bc
at sdstart+270
at scsipi_free_xs+d0
at scsipi_done+1b8
at siop_scsicmd_end+3bc
at siop_intr+13d4
at do_pending_int+120
at lcsplx+34
at cpu_switch+30
at mi_switch+1a4
at ltsleep+294
at rf_DispatchDAG+3d4
at fork_trampoline+10
db>
-----

Somebody PLEASE tell me there's a solution for this problem.

-- monroe
------------------------------------------------------------------------
Monroe Williams                                  monroe@criticalpath.com