Re: [PATCH 4/5] Centralise NO_IRQ definition

[Ingo Molnar <mingo@elte.hu>]

* Paul Mackerras <paulus@samba.org> 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->irq.nr 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).

	Ingo

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