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

[Russell King <rmk+lkml@arm.linux.org.uk>]

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