Yes, plan9 boots fine (LinuxBios is on a separate disk on chip, that
we can substitute with the original BIOS anytime we want.  That's
where we get things like conf.npage0, conf.npage1, etc, which P9 does
not calculate correctly if there's no BIOS)...

As it currently stands, on two different types of southbridges (cyrix
and ALI) irregardless of how configured (or misconfigured) the IRQs
end up, we're unable to get an interrupt at all...

Next step is comparing 8259's registers with the ones from a normally
booted p9.