Re: [PATCH 4/5] Centralise NO_IRQ definition

From: Ingo Molnar
Date: Mon Nov 21 2005 - 16:35:23 EST

* Paul Mackerras <paulus@xxxxxxxxx> wrote:

> Ingo Molnar writes:
> > is there any architecture where irq 0 is a legitimate setting that could
> > occur in drivers, and which would make NO_IRQ define of 0 non-practical?
> Yes, G5 powermacs have the SATA controller on irq 0. So if we can't
> use irq 0, I can't get to my hard disk. :) Other powermacs also use
> irq 0 for various things, as do embedded PPC machines.

oh well [*]. Then it's gotta be the !dev->irq.valid thing i guess. OTOH
that has some disadvantages too: any normal access to dev-> will
mean implicit 0xffffffff (or 0xffffffffffffffff) masking generated by
the compiler. Also, unless there's some compiler trick, tons of drivers
will be affected - because dev->irq isnt valid anymore. A quick grep
suggests 5381 lines of code affected, spread out in 917 files. Quite
impractical. So we are back to square one and Matthew's patch(es).


[*] is there any weird architecture that hardcodes IRQ -1 to some
device? ;-)
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