Strange vkernel crash

[Dave Hayes]

# cd /usr/src
# cvs up -r DragonFly_RELEASE_1_8_Slip sys
? sys/compile/DFCD
? sys/config/DFCD
? sys/config/DFCD_DEV
dfdev# cd sys/config 
dfdev# config VKERNEL
Kernel build directory is ../compile/VKERNEL
dfdev# cd ../compile/VKERNEL ; make depend ; make
<time passes>
# ./kernel.debug -m 64m -r /var/vkernel/rootimg.01
Using memory file: /var/vkernel/memimg.000000
Copyright (c) 2003, 2004, 2005, 2006, 2007 The DragonFly Project.
Copyright (c) 1992-2003 The FreeBSD Project.
Copyright (c) 1979, 1980, 1983, 1986, 1988, 1989, 1991, 1992, 1993, 1994
        The Regents of the University of California. All rights reserved.
DragonFly 1.8.1-RELEASE #0: Tue Apr  3 09:01:12 PDT 2007
    root at cddev.foo.com:/usr/src/sys/compile/VKERNEL
real memory = 67108864 (65536K bytes)
avail memory = 62545920 (61080K bytes)
md0: Malloc disk
initclocks
IP packet filtering initialized, divert disabled, rule-based forwarding 
enabled, default to accept, logging disabled
DUMMYNET initialized (011031)
IPsec: Initialized Security Association Processing.
Mounting root from ufs:vkd0a
panic: vm_fault: unrecoverable fault at 0x492fe000 in entry 0x82a8ea0
Trace beginning at frame 0x5877a764
(null)(820a5c5,8286940,8224cb0,5877a794,1) at 0x80b323e
(null)() at 0x80b323e
Debugger("panic")
Stopped at      0x81f306d:      movb    $0,0x82b2ab8
db> 

Hm. So attaching gdb:

dfdev# gdb /usr/src/sys/compile/VKERNEL/kernel.debug <pid of process>
GNU gdb 6.2.1
Copyright 2004 Free Software Foundation, Inc.
GDB is free software, covered by the GNU General Public License, and you are
welcome to change it and/or distribute copies of it under certain conditions.
Type "show copying" to see the conditions.
There is absolutely no warranty for GDB.  Type "show warranty" for details.
This GDB was configured as "i386-dragonfly"...
Attaching to program: /usr/src/sys/compile/VKERNEL/kernel.debug, process 73149
Reading symbols from /usr/lib/libc.so.6...done.
Loaded symbols for /usr/lib/libc.so.6
Reading symbols from /usr/libexec/ld-elf.so.2...done.
Loaded symbols for /usr/libexec/ld-elf.so.2
0x482a1710 in read () from /usr/lib/libc.so.6
(gdb) bt
#0  0x482a1710 in read () from /usr/lib/libc.so.6
#1  0x081fdb58 in vconsgetc (dev=0x825c0a0) at ../../platform/vkernel/platform/
console.c:262
#2  0x080db64a in cngetc () at ../../kern/tty_cons.c:470
#3  0x08079e4a in db_readline (lstart=0x8252560 "", lsize=120) at 
. ./../ddb/db_input.c:315
#4  0x08079f5e in db_read_line () at ../../ddb/db_lex.c:55
#5  0x08078bf3 in db_command_loop () at ../../ddb/db_command.c:467
#6  0x0807b77c in db_trap (type=3, code=0) at ../../ddb/db_trap.c:71
#7  0x081f2eb8 in kdb_trap (type=3, code=0, regs=0x5877a450)
    at ../../platform/vkernel/i386/db_interface.c:151
#8  0x081f5a41 in kern_trap (frame=0x8250640) at ../../platform/vkernel/i386/tr
ap.c:790
#9  0x081f6645 in exc_segfault (signo=5, info=0x5877a71c, ctxp=0x5877a43c)
    at ../../platform/vkernel/i386/exception.c:94
#10 0xbfbfffd8 in ?? ()
#11 0x00000005 in ?? ()
#12 0x5877a71c in ?? ()
#13 0x5877a43c in ?? ()
#14 0x00000000 in ?? ()
#15 0x081f6631 in init_exceptions () at ../../platform/vkernel/i386/exception.c
:74
#16 0x080b3253 in panic (fmt=0x8224cb0 "vm_fault: unrecoverable fault at %p in 
entry %p")
    at ../../kern/kern_shutdown.c:765
#17 0x081d5740 in vm_fault (map=0x82a4e20, vaddr=1227874304, fault_type=1 
'\001', fault_flags=3)
    at ../../vm/vm_fault.c:300
#18 0x081f5bb2 in trap_pfault (frame=0x5877a890, usermode=0, eva=1227878396)
    at ../../platform/vkernel/i386/trap.c:912
#19 0x081f59e4 in kern_trap (frame=0x8250640) at ../../platform/vkernel/i386/tr
ap.c:688
#20 0x081f6645 in exc_segfault (signo=11, info=0x5877ab5c, ctxp=0x5877a87c)
    at ../../platform/vkernel/i386/exception.c:94
#21 0xbfbfffd8 in ?? ()
#22 0x0000000b in ?? ()
#23 0x5877ab5c in ?? ()
#24 0x5877a87c in ?? ()
#25 0x00000000 in ?? ()
#26 0x081f6631 in init_exceptions () at ../../platform/vkernel/i386/exception.c
:74
#27 0x081d5b76 in vm_fault_page (map=0x58772f00, vaddr=0, fault_type=0 '\0', 
fault_flags=136644160,
    errorp=0x5877ac94) at ../../vm/vm_fault.c:579
#28 0x081f8351 in copyout (kaddr=0x5877acbb, udaddr=0xbfbfffff, len=1)
    at ../../platform/vkernel/platform/copyio.c:169
#29 0x081f842c in subyte (base=0x3, byte=3) at ../../platform/vkernel/platform/
copyio.c:212
#30 0x08091994 in start_init (dummy=0x0) at ../../kern/init_main.c:530
#31 0x081f6796 in fork_trampoline () at ../../platform/vkernel/i386/fork_tramp.
s:78

What is going on here?
------
Dave Hayes - Consultant - Altadena CA, USA - dave at jetcafe.org 
>>> The opinions expressed above are entirely my own <<<

One only fights what one thinks is real.