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SubjectRe: 2.3.49-1 -- Compilation error in traps.c in function `do_nmi'
Hi Linus.

>> spurious 8259A interrupt: IRQ7
>> keyboard: Timeout - AT keyboard not present?

> The spurious 8259A interrupt is probably just because there
> is a driver that had some timing whereby it made its own
> interrupt go away without it having ever been acknowledged
> by the CPU - so the 8259A had had time to raise it, but by
> the time the CPU got along to servicing it it wasn't there
> any more and the i8259 gives us the spurious 7 instead.

> A spurious irq7 is not necessarily a sign of anything
> really bad happening..

> The keyboard thing makes me more worried. My current
> suspicion would be that somehow a edge-triggered interrupt
> is just lost due to some magic timing issues, and it stays
> lost forever because we don't touch the keyboard controller
> unless it asks us to look at it.

> So putting the two theories would be that it's the
> _keyboard_ interrupt that the driver just made go away, and
> because it wasn't handled the machine is now dead forever
> as far as the keyboard is concerned.

> When we read the keyboard status or data ports enough to
> make the controller think we handled the interrupt, but not
> enough to realize that there isn't anything more to read,
> then..

> The simple solution to this may be just a timeout - having
> a timer that checks the keyboard every few seconds and does
> a "handle_kbd_event()" whether an interrupt came in or not.

Alternatively, and probably simpler: Any time we get a spurious
interrupt, we assume it was a keyboard interrupt - after all,
based on the above, it probably was...

Best wishes from Riley.

* Copyright (C) 1999, Memory Alpha Systems.
* All rights and wrongs reserved.

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