さすがだ。

Booting [/boot/kernel/kernel]...
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FreeBSD 9.0-CURRENT #5 r222170: Sun May 22 17:01:29 JST 2011
    kappi@freebsd-3651:/usr/obj/usr/src/sys/xxx i386
kernel trap 12 with interrupts disabled


Fatal trap 12: page fault while in kernel mode
fault virtual address   = 0xf0007f28
fault code              = supervisor write, page not present
instruction pointer     = 0x20:0xc062cfbd
stack pointer           = 0x28:0xc0c20bf8
frame pointer           = 0x28:0xc0c20c20
code segment            = base 0x0, limit 0xfffff, type 0x1b
                        = DPL 0, pres 1, def32 1, gran 1
processor eflags        = resume, IOPL = 0
current process         = 0 ()
trap number             = 12
panic: page fault
Uptime: 1s

デバッグできる能力が無いのでするっとr222160まで戻した。おそらく犯人はr222163だと思う。まぁ、マシンが古いから無理に更新する必要もないんだけど、さすがにbootの頭の方でパニックするとポカーンとなりますねorz