Fatal trap 18: integer divide fault while in kernel mode (ACPI related?)

Got a kernel panic during boot with CURRENT (built on October 16th,
GENERIC kernel), and it seems related to ACPI and the battery in some
way.  I took a picture of it with my digital camera:

http://people.freebsd.org/~joel/panics/panic001.jpg

I also managed to get a dump:

----------------------------------------------------------------
# kgdb kernel.debug /var/crash/vmcore.1
[GDB will not be able to debug user-mode
threads: /usr/lib/libthread_db.so: Undefined symbol "libc_r_db_ops"]
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Unread portion of the kernel message buffer:
Trying to mount root from ufs:/dev/ad4s2a
<118>Loading configuration files.
<118>kernel dumps on /dev/ad4s2b
<118>Entropy harvesting:
<118> interrupts
<118> ethernet
<118> point_to_point

Fatal trap 18: integer divide fault while in kernel mode
cpuid = 1; apic id = 01
instruction pointer     = 0x20:0xc0c19448
stack pointer           = 0x28:0xd5c29b04
frame pointer           = 0x28:0xd5c29b40
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = interrupt enabled, resume, IOPL = 0
current process         = 68 (sysctl)
Physical memory: 491 MB
Dumping 35 MB: 20 4

#0  doadump () at pcpu.h:166
166     pcpu.h: No such file or directory.
        in pcpu.h
(kgdb) bt
#0  doadump () at pcpu.h:166
#1  0xc047625b in db_fncall (dummy1=-708667096, dummy2=0,
dummy3=-1062631904, 
    dummy4=0xd5c29904 "À\006ªÀ") at /usr/src/sys/ddb/db_command.c:486
#2  0xc0476067 in db_command (last_cmdp=0xc09fd944, cmd_table=0x0)
    at /usr/src/sys/ddb/db_command.c:401
#3  0xc0476122 in db_command_loop ()
at /usr/src/sys/ddb/db_command.c:453
#4  0xc0477d31 in db_trap (type=18, code=0)
at /usr/src/sys/ddb/db_main.c:221
#5  0xc06c0854 in kdb_trap (type=18, code=0, tf=0xd5c29ac4)
    at /usr/src/sys/kern/subr_kdb.c:502
#6  0xc08a2795 in trap_fatal (frame=0xd5c29ac4, eva=0)
    at /usr/src/sys/i386/i386/trap.c:858
#7  0xc08a22c4 in trap (frame=
      {tf_fs = -1061093368, tf_es = -1061027800, tf_ds = -1061027800,
tf_edi = -1026916352, tf_esi = 1, tf_ebp = -708666560, tf_isp =
-708666640, tf_ebx = -1026916288, tf_edx = 0, tf_ecx = 0, tf_eax = 0,
tf_trapno = 18, tf_err = 0, tf_eip = -1061055416, tf_cs = 32, tf_eflags
= 66118, tf_esp = -1026916336, tf_ss = 16})
at /usr/src/sys/i386/i386/trap.c:658
#8  0xc088d02a in calltrap () at /usr/src/sys/i386/i386/exception.s:138
#9  0xc0c19448 in ?? ()
Previous frame inner to this frame (corrupt stack?)
----------------------------------------------------------------

Haven't been able to reproduce it yet though.

-- 
Joel