Re: [Lse-tech] irqs and large systems

[Anton B. <an...@sa...>]

Hi,

> 	We've been thinking that if we had a thing, called
> NR_IVECS, that was the same as NR_IRQS on most platforms, 
> we could code around the problem.  Then, NR_IVECS could
> be 256 on ia64, and NR_IRQS could be whatever it needs
> to be.  We would use NR_IVECS in many of the places that
> NR_IRQS is currently used.

If you think of NR_IRQS as NR_IVECS then it should work out OK. The
only time when you need the real irq number is when printing it
out in the driver (check out how sparc has the irq_atoi() macro).

For example during boot on ppc64 we renumber the high irqs so that
they fill up an empty slot < NR_IRQS (we dont care which one). When we
take an irq we look up a mapping of real -> "virtual" irqs and call that
handler.

Anton