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SubjectRe: [patch] io-apic-2.1.98-B
Date
From
Linus Torvalds wrote:
>
>
>
> On Sun, 26 Apr 1998, David S. Miller wrote:
> >
> > I'd like to have the self-IPI part, but I would _really_ really
> > prefer to not have the counter, until somebody convices me that it
> > has to be there (and that implies giving a reason other than "some
> > ne2000 card has problems", because the problems you see sound like
> > they might be problems for other people regardless of any io-apic
> > issues).
> >
> > Ok, but one question, to a clueless driver developer, what should we
> > expect him to think that:
>
> Note that the counter I was talking about was the "counter of delayed
> interrupts", ie the counter that tells us how many interrupts happened
> during processing of another interrupt or during "disable_irq()". I think
> that counter should not be a counter at all, but a single bit of
> information, because that is how the hardware does it for all other cases
> where we disable interrupts.

It just hit me (figuratively): are you allowing interrupts to occur
while the driver is still pondering about what to do in the mean time?

On level triggered interrupts (which you need to support shared
interrupts), wouldn't this create an interrupt loop?

(i.e. a new interrupt occurs before the driver has had a chance to
tell the hardware "yes, I'm looking into your problem".)

If I remember correctly, the symptoms are "hard lockup", most likely
the keyboard hotkeys won't work any more.


Regards,

Roger.

P.S. I'm in favor of allowing nesting in "dis/en-able " routines. This
way you can call a subroutine without having to know the innards
(wether or not it disables the interrupts itself), and you can call it
from two different environments (with the interrupts already off, or
with them still on), without having to worry too much.


--
If it's there and you can see it, it's REAL |___R.E.Wolff@BitWizard.nl |
If it's there and you can't see it, it's TRANSPARENT | Tel: +31-15-2137555 |
If it's not there and you can see it, it's VIRTUAL |__FAX:_+31-15-2138217 |
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