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SubjectRe: question on odd APIC behavior
Date
Am Donnerstag 15 November 2007 schrieb Maciej W. Rozycki:
> On Thu, 15 Nov 2007, Oliver Neukum wrote:

> > I am seeing an interrupt for an UHCI on #20 CPU1 also arriving on
> > #19 CPU0, triggering the spurious interrupt detection.
>
> Well, if you see spurious interrupt detection triggered, then it is not a
> problem with the interrupt being delivered multiple times (that's handled
> silently by the interrupt dispatched), but likely the interrupt line being
> deasserted too late. Does it happen frequently? If your ERR counter in
> /proc/interrupts increments quite fast, then perhaps a driver does not
> handle interrupts well enough for your system. Or there is noise on an
> interrupt line.
>
> You would have to provide more information to get more accurate feedback.

On irq 20, there's an UHCI, on irq 19 is an EHCI. For every interrupt on 20
there's a spurious interrupt on 19. USB devices on bus of the controller on 20
work. So I know all interrupts are seen. ERR does not increase. Interrupts
for devices on the bus of the controller on 19 arrive at 19 only.
As far as I can determine there are really interrupts on both CPUs on
different vectors for one physical interrupt request.

Regards
Oliver
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