kernel panic, "unaligned access"

[Ed Vielmetti]

"poe" is a decstation 3100 running ultrix 4.1.  it recently crashed
for no apparent reason.  here's a stack trace to show what happened,
and the most useful of the uerf messages.

nothing obvious in here that clues me in on what's up, I'm writing it
off for now to a stray gamma ray.

--Ed

********************************* ENTRY     3. *********************************

----- EVENT INFORMATION -----

EVENT CLASS                             ERROR EVENT
OS EVENT TYPE                  200.     PANIC
SEQUENCE NUMBER                936.
OPERATING SYSTEM                        ULTRIX 32
OCCURRED/LOGGED ON                      Wed Mar  6 15:20:03 1991 EST
OCCURRED ON SYSTEM                      poe.aa.ox.co
SYSTEM ID                 x82011601     HW REV: x1
                                        FW REV: x16
                                        CPU TYPE: R2000A/R3000
PROCESSOR TYPE                          KN01
PANIC MESSAGE                           unaligned access

********************************* ENTRY     4. *********************************

----- EVENT INFORMATION -----

EVENT CLASS                             ERROR EVENT
OS EVENT TYPE                  117.     ERROR & STATUS REGS
SEQUENCE NUMBER                935.
OPERATING SYSTEM                        ULTRIX 32
OCCURRED/LOGGED ON                      Wed Mar  6 15:20:03 1991 EST
OCCURRED ON SYSTEM                      poe.aa.ox.co
SYSTEM ID                 x82011601     HW REV: x1
                                        FW REV: x16
                                        CPU TYPE: R2000A/R3000
PROCESSOR TYPE                          KN01

----- ERROR & STATUS REGS -----

CAUSE                     x10000010
                                        EXCEPTION CODE ADR ERR (LOAD OR INST
                                         _FETCH)
EPC                       x8008D794
STATUS                    x0000FF34     CURRENT INTERRUPT STATE DISABLED
                                        CURRENT MODE KERNEL
                                        PREVIOUS INTERUPT STATE ENABLED
                                        PREVIOUS MODE KERNEL
                                        OLD INTERUPT STATE ENABLED
                                        OLD MODE USER
                                        SW INTERRUPT 0 ENABLED
                                        SW INTERRUPT 1 ENABLED
                                        HW INTERRUPT 0 ENABLED
                                        HW INTERRUPT 1 ENABLED
                                        HW INTERRUPT 2 ENABLED
                                        HW INTERRUPT 3 ENABLED
                                        HW INTERRUPT 4 ENABLED
                                        HW INTERRUPT 5 ENABLED
                                        CACHE STATE NORMAL
VIRTUAL ADDRESS           x0001000B
SP                        xFFFFDE3C

poe% dbx -k ./vmunix.0 ./vmcore.0
(dbx) where
>  0 boot(paniced = 0, arghowto = 0) 
	["../../machine/mips/machdep.c":568, 0x800f54b4]
   1 subr_prf.panic(s = 0x8013cecc = "unaligned access") 
	["../../sys/subr_prf.c":1165, 0x8009dee0]
   2 kn01trap_error(ep = 0x8023b6a8, code = 3241116672,
        sr = 2149617064, cause = 268435472, signo = 0xffffdd74) 
	["../../machine/mips/kn01.c":514, 0x800f1ab0]
   3 trap.trap(ep = 0xffffdd98, code = 2149616896, sr = 65332, 
        cause = 268442744) 
	["../../machine/mips/trap.c":447, 0x800fdf34]
   4 VEC_trap() 
	["../../machine/mips/locore.s":742, 0x800f3b0c]
   5 .block201 
	["../../sys/kern_exit.c":314, 0x8008d790]
   6 kern_exit.exit(rv = 0) 
	["../../sys/kern_exit.c":314, 0x8008d790]
   7 rexit() 
	["../../sys/kern_exit.c":221, 0x8008d3e0]
   8 syscall(ep = 0xffffdf5c, code = 1, sr = 65340, cause = 32) 
	["../../machine/mips/trap.c":1074, 0x800ff350]
   9 VEC_syscall() 
	["../../machine/mips/locore.s":797, 0x800f3b94]
  10 entry.start() 
	[0x409904]
(dbx)