Something else I noticed...  Init is trying to execve, but the more I try
booting up, the less likely it seems that init's child shows up in the
process table in DDB.  And I haven't been getting any output on the console,
nor has the access time changed on /dev/console.

db> ps
 PID             PPID       PGRP        UID S   FLAGS          COMMAND    WAIT
 9                  0          0          0 3 0x20204         aiodoned aiodone
 8                  0          0          0 3 0x20204          ioflush  syncer
 7                  0          0          0 3 0x20204           reaper  reaper
 6                  0          0          0 3 0x20204       pagedaemon pgdaemo
 5                  0          0          0 3 0x20284            nfsio  nfsidl
 4                  0          0          0 3 0x20284            nfsio  nfsidl
 3                  0          0          0 2 0x20204            nfsio
 2                  0          0          0 3 0x20284            nfsio  nfsidl
>1                  0          0          0 7  0x4004             init
 0                 -1          0          0 3 0x20204          swapper schedul

The flags for init are telling; the process is loaded into memory (0x4), and
the process called execve (0x4000).  So init is trying to fork and call execve,
but nothing's happening.  Very strange.

-Mark