Linus Torvalds <[email protected]> writes:
> On Tue, 14 Nov 2006, Eric W. Biederman wrote:
>
>> The truth is in practice I don't think it matters because I don't
>> think anyone actually disables MSI or hypertransport interrupts.
>
> Fair enough, at least for a 2.6.19 kind of release timeframe (and that is
> what I worry about most, at least right now).
>
>> At this point I have two questions.
>> - What is the easiest path to get us to a stable 2.6.19 where
>> everything works?
>
> If people don't expect HT and MSI interrupts to be masked (and I can well
> imagine that), then I think your two-liner patch is good to go. Komuro
> seems to have acked it already, and in many ways that's the "minimal
> change" for 2.6.19 right now.
Well I just doubled checked this assertion. The one driver that uses
the hypertransport irqs doesn't call disable_irq. On the msi side
at least the forcedeth driver does call disable_irq when in msi mode.
I just doubled checked the historical behavior of the msi code and
it has never done the delayed disable thing. So not doing it there
is not a regression.
The MSI case is different. MSI is fundamentally about non-shared
interrupts, and interrupts that don't race with your DMAs. So with
MSI you don't need a status register read to process the interrupt.
In the context of Ingo's patch I don't like the idea of saddling MSI
interrupts down with the best in class work arounds for a completely
different hardware interrupt model. Although I don't doubt MSI will
get it's own set of work arounds as we come to know it better.
> I do like Ingo's patch because it seems "safe" (even if I think it might
> be a bit _overly_ safe), but it changes semantics enough that I don't like
> it for 2.6.19. Even his second version definitely changes semantics for
> level-triggered PCI interrupts, even though he fixed ExtInt/i8259 ones.
>
> So I think I'll go with your patch for now, and we can re-visit Ingo's
> thing after 2.6.19.
Sounds like a plan.
Eric
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