Re: linux interrupt handling problem

yodaiken@chelm.cs.nmt.edu
Tue, 9 Nov 1999 08:26:37 -0700


On Tue, Nov 09, 1999 at 03:54:54PM +0000, Alan Cox wrote:
> It depends a lot on your architecture. On some Mac68K boxes for example
> we have no full IRQ masking facility except the CPU, and level triggered
> irqs. So the moment you unmask an IRQ you get the irq and you cannot drop
> the IRQ level in a handler until the irq cause is cleared.
>
> It makes it umm.. fun

Especially for RTLinux. This is also a problem on SPARC s-bus devices
where the handler is supposed to do something to clear the interrupt.
On some systems with particularly stupid interrupt handling architectures,
RTLinux will only be able to either support periodic tasks or require
patches to all devices handlers.

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