Re: [patch] generic-hardirqs-2.6.9-rc1-mm4.patch

Russell King
2004-09-09T21:04:09Z

On Thu, Sep 09, 2004 at 04:51:53PM -0400, Scott Wood wrote:
> On Thu, Sep 09, 2004 at 09:10:38PM +0100, Russell King wrote:
> > If it uses irq_desc then ARM won't use it. irq_desc is part of the
> > far-too-restrictive x86 IRQ handlign code which is unsuitable for
> > ARM platforms.
>
> What does ARM need that irq_desc doesn't provide, and which could not
> be added? IMHO, it'd be better to fix the generic code than maintain
> completely separate implementations.

Unfortunately, to deal with this issue would mean breaking off from
planned work, so I'm not going to be in a position to do an element
by element comparison of the structures for some time.

Maybe I can look at it after the weekend though.

However, I think if you just compare:

linux/include/linux/irq.h
linux/include/asm-arm/mach/irq.h

you'll realise how inadequate the "generic" IRQ code is for ARM.

Note that IRQ handling on ARM is a multi-level affair where we have
multiple levels of interrupt controllers which need to be traversed
in software.

--
Russell King
Linux kernel 2.6 ARM Linux - http://www.arm.linux.org.uk/
maintainer of: 2.6 PCMCIA - http://pcmcia.arm.linux.org.uk/
2.6 Serial core