Re: [PATCH] 2.5.68 Fix IO_APIC IRQ assignment bug

Zwane Mwaikambo (zwane@linuxpower.ca)
Sun, 20 Apr 2003 19:05:20 -0400 (EDT)


On Sun, 20 Apr 2003, Linus Torvalds wrote:

> Good call.
>
> Although I suspect you need about a million interrupt sources to hit
> this, since FIRST_SYSTEM_VECTOR is somethign like 0xef, and thus you can
> hit it only when "offset" has already been incremented seven times
> (which implies that we've walked the whole vector space quite a few
> times by then).
>
> Did you actually see this on hardware?

Yes, we need to bail out in assign_irq_vector when we wrap around,
otherwise we cause collisions when programming the IOAPIC. And we also
need to avoid overruning NR_IRQS structures in setup_IO_APIC_irqs.

Zwane

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