I ran some additional tests on my ASUS P54TP4 motherboard.

The keyboard controller reset will reboot my computer.

The triple fault/watchdog reset from a null IDT will hang my computer.
The triple fault/watchdog reset from an unmapped TLB will hang my computer.

The behavior is identical whether or not disable_intr() is called.

I would presume there are some motherboards where the keyboard
controller toggle hangs them and the other attempts reboot them, hence
we have a problem?

==John