Re: IRQF_TIMER | IRQF_SHARED ?

From: Thomas Gleixner
Date: Mon Dec 12 2011 - 18:38:48 EST


On Mon, 12 Dec 2011, Andres Salomon wrote:

> On Mon, 12 Dec 2011 16:41:25 +0100
> Jens Rottmann <JRottmann@xxxxxxxxxxxxxxxxxx> wrote:
>
> > But I did not fail to notice that _none_ of the code in
> > drivers/clocksource/ uses IRQF_SHARED, obviously this must be
> > deliberate.
>
> Hm, maybe tglx knows? For my part, I don't think it would be a
> problem, but I can imagine the reason for not sharing being clock drift
> or something to that effect.

No, you can share a timer irq. The other drivers don't have the SHARED
flag set because they are on exclusive irq lines, which is the sane
thing to do. shared irqs suck and you figure that out once you try to
use that shared timer irq on a preempt-rt enabled kernel.

Thanks,

tglx

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