Re: [PATCH 5/5] x86: update nr_irqs according cpu num

From: H. Peter Anvin
Date: Fri Jan 08 2010 - 16:24:35 EST

On 01/08/2010 12:10 PM, Eric W. Biederman wrote:
> I don't know if we ever actually perform vector sharing. The only case
> I recall where the code could share vectors is if the firmware tables
> told us to irq sources were the same interrupt. I don't think that
> happens. We do have the remains of support for vector sharing
> in the code but I don't think it is utilized. MSI interrupts certainly
> can not share vectors.

We probably will need to support that at some point, though, simply
because it's not all that hard to construct a system in which there are
more MSI-X interrupts than there are possible vectors in the system.

Until then we can do 224 * nr_cpus_ids, but it's still not the right thing.

> Yes. It was enough of a pain the first pass at it that we wound
> up with nr_irqs, a value that can vary at boot time.
> Once YH's radix tree changes get it in. A war on NR_IRQS and nr_irqs
> seems appropriate.



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