Jake Burkholder eb5b9c0be3 Add support for starting secondary cpus in kernel, as opposed to relying
on the loader to do it.  Improve smp startup code to be less racy and to
defer certain things until the right time.  This almost boots single user
on my dual ultra 60, it is still very fragile:

SMP: AP CPU #1 Launched!
Enter full pathname of shell or RETURN for /bin/sh:
# ls
Debugger("trapsig")
Stopped at      Debugger+0x1c:  ta              %xcc, 1
db> heh
No such command
db>
2002-03-04 07:12:36 +00:00
..
2002-02-13 15:43:42 +00:00