Panic while starting X server

[walt]

walt wrote:
Kernel/quickworld built about an hour ago.  Boots fine, but
panics when trying to start X.
I'd better start again -- I'm confused about the 'list' item
in gdb.  I'm getting a different listing now from the same dump,
so I must be doing something wrong.  Here's the whole bt:
Fatal trap 12: page fault while in kernel mode
fault virtual address   = 0x0
fault code              = supervisor read, page not present
instruction pointer     = 0x8:0x0
stack pointer           = 0x10:0xcf6bab50
frame pointer           = 0x10:0xcf6babdc
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         = 746 (XFree86)
current thread          = pri 6
interrupt mask          = none
trap number             = 12
panic: page fault
kgdb) bt
#0  dumpsys () at /usr/src/sys/kern/kern_shutdown.c:500
#1  0xc0173af0 in boot (howto=256) at /usr/src/sys/kern/kern_shutdown.c:333
#2  0xc0173f00 in poweroff_wait (junk=0xc02fdc8a, howto=-1070606609) at /usr/src/sys/kern/kern_shutdown.c:612
#3  0xc02adaa4 in trap_fatal (frame=0xcf6bab10, eva=0) at /usr/src/sys/i386/i386/trap.c:1092
#4  0xc02ad6bd in trap_pfault (frame=0xcf6bab10, usermode=0, eva=0) at /usr/src/sys/i386/i386/trap.c:981
#5  0xc02ad3fb in trap (frame={tf_fs = 24, tf_es = 16, tf_ds = 16, tf_edi = 3, tf_esi = -840292064,
      tf_ebp = -815027236, tf_isp = -815027396, tf_ebx = 0, tf_edx = -815027100, tf_ecx = 0, tf_eax = 0,
      tf_trapno = 12, tf_err = 0, tf_eip = 0, tf_cs = 8, tf_eflags = 66050, tf_esp = -1072054643, tf_ss = -840292064})
    at /usr/src/sys/i386/i386/trap.c:561
#6  0x0 in ?? ()
(kgdb) f 6
#6  0x0 in ?? ()
(kgdb) l
495     dumpsys(void)
496     {
497             int     error;
498
499             savectx(&dumppcb);
500             if (dumping++) {
501                     printf("Dump already in progress, bailing...\n");
502                     return;
503             }
504             if (!dodump)
(kgdb)
I can't figure out where that previous listing with the npx code came from.
This listing above doesn't look very useful, though.  Anyone know what I'm
doing wrong?