Re: [Xen-devel] NR_PIRQS vs. NR_IRQS

["Jan Beulich" <jbeulich@xxxxxxxxxx>]

>>> Keir Fraser <keir.fraser@xxxxxxxxxxxxx> 13.11.08 20:19 >>>
>On 13/11/08 18:41, "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx> wrote:
>> Yes, I'm sure with a bit of finessing we could have NR_IRQS != NR_VECTORS.
>> I'm sure there'll be some barking NUMA box down the road that will require
>> something like that, but thankfully not so far.
>
>I agree with keeping this naming distinction of course, although I think
>allowing NR_IRQS > NR_VECTORS right now is not very useful. But maybe you
>have a box in mind that needs it?

I had sent a mail a few days ago on this, where IBM was testing 96 CPU
support (4-node system), and it crashing because of a PIRQ ending up in
DYNIRQ space (kernel perspective), because there being 300+ IO-APIC
pins. While the crash ought to be fixed with the subsequent patch, it's
clear that none of the devices with an accumulated pin number greater
than 255 will actually work on that system.

Jan


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