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Subject: Re: [PATCH] generic irq subsystem: ppc64 port
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Ingo Molnar <mingo@elte.hu>
Cc: Linux Kernel list <linux-kernel@vger.kernel.org>,
       linuxppc64-dev <linuxppc64-dev@ozlabs.org>,
       Linus Torvalds <torvalds@osdl.org>, Paul Mackerras <paulus@samba.org>,
       Christoph Hellwig <hch@infradead.org>
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On Tue, 2004-10-19 at 19:15, Ingo Molnar wrote:
> * Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:
> 
> > I still like the idea of the patch, so it would be useful if you added
> > the possibility for us to just change that behaviour, that is replace
> > all occursences of irq_descs + i with get_irq_desc() and provide a
> > generic one that just does that, with a #ifndef so that the
> > architecture can provide it's own. 
> 
> sure, we could do that. But since there are other architectures with
> large irq-vector spaces too, you might want to try to move it into the
> generic IRQ code and just provide a way to switch between 1:1 mapped and
> sparse-mapped variants.

False alert ! In fact, Paulus rewrote that stuff a while ago and I
totally forgot about it. We no longer do that, our get_irq_desc()
is nowadays just doing (&irq_desc[(irq)]). We map the large
physical interrupt numbers to "virtual" numbers that are the only
thing the generic code sees, so it's fine. 

Ben.