files which Compaq open-sourced (with a BSD license).
This commit adds support for proper PCI interrupt mapping and much
better support for swizzling between "standard" isa IRQs and the stdio
irqs used by the t2. This also adds enabling/disabling/eoi support
for AlphaServer 2100A machines. The 2100A (or lynx) interrupt
hardware is is very different (and much nicer) than the 2100.
Previously, only AS2100 and AS2000 machines worked.
This commits also lays the groundwork for supporting ExtIO modules.
These modules are essentially a second hose. This work is left
unfinished pending testing on real hardware. Wilko tells me that
ExtIO modules are quite rare, and may not actually exist in the wild.
Obtained from: Tru64
Tested by: wilko
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