HEADS UP: amd64 users! SMP code drop committed.

The subject should be pretty self explanatory.  However, this commit trips
some of the landmines in the nVidia nForce3 Pro-150 chipset and/or reference
bios.  

Boards known to be broken by the commit:
ASUS SK8N: two problems.. 
1) requires 'device atpic' and that you run in 'mixed mode', even though
this is expressly prohibited by the acpi spec.
2) the bios is broken and doesn't return the correct _CRS values for the
interrupts after switching into apic mode.  This causes level triggered pci
interrupts to set up on the edge-triggered PIC which leads to much unhappiness.

Gigabyte K8N-Pro:  two problems
1) same missing 8254 timer -> apic connection
2) the bios appears to be outright *wrong* in apic mode.  For example, it
reports that the onboard ethernet is at irq 19, when in fact the interrupts
appear to arrive at irq 21 instead.

I have a couple of workarounds in mind.  I have not tried it yet, but the
quickest thing might be to comment out these lines in sys/conf/files.amd64:

amd64/acpica/madt.c             optional        acpi
amd64/amd64/apic_vector.S       standard
amd64/amd64/io_apic.c           standard
amd64/amd64/local_apic.c        standard
amd64/amd64/mptable.c           optional        mptable
amd64/amd64/mptable_pci.c       optional        mptable pci

and add 'device atpic' to your kernel config.

You may also try 'set hint.acpi.0.disabled=1' in your loader.  Be sure to
leave out the mptable options as well, and include the atpic device.

I have an SK8N as my desktop at home and a K8N Pro as my home crashbox, so
rest assured that I'll sort something out real quick. :-)

sledge.freebsd.org is now running in SMP, as is the loaner 4-way Opteron
that I have for testing.

Cheers,
-Peter
--
Peter Wemm - peter_at_wemm.org; peter_at_FreeBSD.org; peter_at_yahoo-inc.com
"All of this is for nothing if we don't go to the stars" - JMS/B5