Panic while running make buildworld in single user mode

[Justin Smith]

This was with the cvsup-current version of 12/10/2003.

The debugger printed:

TPTE AT 0xbfc20c0c IS ZERO @ VA 0x8303000

PANIC: bad PTE cpuid=0;

STOPPED AT debugger+0x55 xchgl %ebx,in_debugger 0


(To post this, I recompiled the kernel with scheduler=SCHED_4BSD rather 
then SCHED_ULE, and did a build world, installworld).

FreeBSD jsmith.org 5.2-RC FreeBSD 5.2-RC #0: Fri Dec 12 09:22:42 EST 
2003     root@:/usr/obj/usr/src/sys/MYKERNEL  i386

the MYKERNEL config is essentially GENERIC with

device          atapicam

defined.