Re: [PATCH 4/5] Centralise NO_IRQ definition

[Linus Torvalds]

On Tue, 22 Nov 2005, David Woodhouse wrote:
> 
> This is true. If we're suddenly going to start pretending that IRQ 0
> isn't a valid interrupt merely on the basis that "x86 doesn't use it"¹,
> then we can't really go making an exception to allow us to use IRQ 0 on
> i386.

Of _course_ "irq0" is a valid irq. On PC's, it's usually the timer 
interrupt.

It's the "dev->irq" _cookie_ zero that means it is does not have an irq.

If you have a physical "irq 0" that is bound to a device, it needs a 
cookie, and that cookie can't be 0, because that means the device has no 
interrupt.

How hard is that to understand? Why do people mix these up?

		Linus