NOTE
The PIIX4E can connect each PIRQ line internally to one IRQ signal (3, 4, 5, 7, 9, 11, 14, or 15). Typically, a device that does not share a PIRQ line will have a unique interrupt. However, in certain interrupt-constrained situations, it is possible for two or more of the PIRQ lines to be connected to the same IRQ signal.
