This is from a 4.99.49 kernel and userland built from sources dated 
2008-01-24 21:14:50 UTC

Usually, I run build.sh on the machine that actually contains the 
source, but this time I ran it on another host.  The entire /usr/src and 
/usr/obj directories were NFS-mounted.  The crash happens about 30 or 40 
minutes after starting build.sh and it happens at different places, so I 
don't think it's data-specific;  rather I suspect some strange race 
condition.  The back-traces don't seem terribly usefule (maybe gdb is 
out-of-sync with the trap stack-frame again?).

Anyone got any hints as to what might be wrong here?

(gdb) target kvm netbsd.2.core
#0  0xffffffff802dd275 in cpu_reboot (howto=260, bootstr=<value 
optimized out>)
     at /usr/src/sys/arch/amd64/amd64/machdep.c:662
662                     dumpsys();
(gdb) bt
#0  0xffffffff802dd275 in cpu_reboot (howto=260, bootstr=<value 
optimized out>)
     at /usr/src/sys/arch/amd64/amd64/machdep.c:662
#1  0xffffffff8025f9a8 in panic (
     fmt=0xffffffff803bf2b8 <Address 0xffffffff803bf2b8 out of bounds>)
     at /usr/src/sys/kern/subr_prf.c:230
#2  0xffffffff802def84 in trap (frame=0xffff800048fa9170)
     at /usr/src/sys/arch/amd64/amd64/trap.c:264
#3  0xffffffff80100fda in calltrap ()
#4  0xffffffff8025e14b in kprintf (
     fmt0=0xfc000000 <Address 0xfc000000 out of bounds>, oflags=Cannot 
access memory at address 0xffffffffffffff7c
)
     at /usr/src/sys/kern/subr_prf.c:1417
Previous frame inner to this frame (corrupt stack?)
(gdb)

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