SMP kernel hanging at when testing 8254 interrupt delivery

[Chip Norkus]

David P. Reese Jr. wrote:
A UP kernel boots just fine, however when I try to boot an SMP kernel the
boot process hangs in a loop in sys/i386/isa/clock.c.
$DragonFly: src/sys/i386/isa/clock.c,v 1.4 2003/07/06 21:23:49 dillon Exp $
...
#ifdef APIC_IO
        if (apic_8254_trial) {
                
                printf("APIC_IO: Testing 8254 interrupt delivery\n");
                while (read_intr_count(8) < 6)      <-- hangs here
                        ;       /* nothing */

What is most bothersome is that the SMP kernel hoses my CMOS checksum,
hinting that this is a result of a larger problem.
I've got the same hang, but it's not hosing anything else on my system. 
 I will try and take a stab at it later tomorrow (light on sleep tonight).

My snapshot is as of about 6pm CDT today.

-wd