What does irq_canonicalize mean?

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* What does irq_canonicalize mean?
@ 2007-07-23 13:12 jidong xiao
  2007-07-23 13:46 ` Alan Cox
  0 siblings, 1 reply; 2+ messages in thread
From: jidong xiao @ 2007-07-23 13:12 UTC (permalink / raw)
  To: linux-kernel

I found this function, inside include/asm-i386/irq.h or
include/asm-x86_64/irq.h,

static __inline__ int irq_canonicalize(int irq)
{
	return ((irq == 2) ? 9 : irq);
}

there is no comments,so I am totally confused what does this function
mean, why there is a "2", and why there is a "9"?

Thanks
Jason Xiao

^ permalink raw reply	[flat|nested] 2+ messages in thread

* Re: What does irq_canonicalize mean?
  2007-07-23 13:12 What does irq_canonicalize mean? jidong xiao
@ 2007-07-23 13:46 ` Alan Cox
  0 siblings, 0 replies; 2+ messages in thread
From: Alan Cox @ 2007-07-23 13:46 UTC (permalink / raw)
  To: jidong xiao; +Cc: linux-kernel

On Mon, 23 Jul 2007 21:12:22 +0800
"jidong xiao" <jidong.xiao@gmail.com> wrote:

> I found this function, inside include/asm-i386/irq.h or
> include/asm-x86_64/irq.h,

ISA bus interrupt 2 is remapped to 9 on 16bit PC ISA bus platforms. Thus
the user idea of "IRQ 2" is different to the hardware one

^ permalink raw reply	[flat|nested] 2+ messages in thread

end of thread, other threads:[~2007-07-23 13:40 UTC | newest]

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2007-07-23 13:12 What does irq_canonicalize mean? jidong xiao
2007-07-23 13:46 ` Alan Cox

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