Potential source of interrupt aliasing

[M. Warner Losh]

In message: <200504110231.j3B2VOYr047361 at apollo.backplane.com>
            Matthew Dillon <dillon at apollo.backplane.com> writes:
:     * PCI busses only have 4 interrupt lines (A, B, C, and D).

PCI Slots have only 4 interrupts.  The BUS can have the interrupt
lines wired in an arbitrary manner.  That's why we need to have $PIR
parsing.

Warner