Re: [patch] x86 supports NO_IRQ convention

[Benjamin Herrenschmidt <benh@kernel.crashing.org>]

On Sun, 2008-06-22 at 19:53 -0700, David Brownell wrote:
> Hmm, x86 doesn't seem to support the NO_IRQ convention.  This means
> that portable code can't use it.  Which in turn means that there's
> no portable way for drivers to know whether they have been handed a
> valid IRQ number (zero usually being valid).  Double-plus ungood.
> 
> Signed-off-by: David Brownell <dbrownell@users.sourceforge.net>
> ---
> I suspect this has been discussed before, but I can't find any
> written resolution ...
> 
>  include/asm-x86/irq.h |    4 ++++
>  1 file changed, 4 insertions(+)
> 
> --- a/include/asm-x86/irq.h	2008-06-22 16:36:43.000000000 -0700
> +++ b/include/asm-x86/irq.h	2008-06-22 16:37:06.000000000 -0700
> @@ -3,3 +3,7 @@
>  #else
>  # include "irq_64.h"
>  #endif
> +
> +#ifndef NO_IRQ
> +#define NO_IRQ	((unsigned int)(-1))
> +#endif

NO_IRQ on x86 is 0

In fact, we explicitely changed powerpc to do the same :-) (It became
easy after I made all linux irqs be virtual, and dynamically mapped to
physical numbers).

I think Linus wants everybody to follow...

Cheers,
Ben.