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On Mon, 2 Oct 2000, Andrea Arcangeli wrote:

> > When that is done, please don't call __sti() directly and use some macro
> > that can be overridden by the architectures.
> What do you have in mind while making this suggestion? The irq highlevel layer
> is pretty much architectural indipendent. Just run a diff between the irq.c in
> the IA32 and alpha ports. Also what about the drivers that are just using
> __sti() at the start of the irq handler right now?

m68k uses interrupt levels, so an interrupt with a higher priority can
interrupt another interrupt with a lower priority. To make things more
interesting several m68k machines don't have a seperate external interrupt
controller, so they rely on that the interrupt level isn't lowered during
an interrupt (the ide driver has an ide__sti() because of this).
I can imagine that newer lowend embedded targets have similiar problems
(on the other end I'm just looking at the s390 interrupt code which looks
also interesting).

bye, Roman

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