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Message-ID: <alpine.LFD.2.00.1010032202570.14550@localhost6.localdomain6>
Date: Sun, 3 Oct 2010 22:04:50 +0200 (CEST)
From: Thomas Gleixner <tglx@...utronix.de>
To: "Eric W. Biederman" <ebiederm@...ssion.com>
cc: Benjamin Herrenschmidt <benh@...nel.crashing.org>,
LKML <linux-kernel@...r.kernel.org>, linux-arch@...r.kernel.org,
Linus Torvalds <torvalds@...l.org>,
Andrew Morton <akpm@...ux-foundation.org>, x86@...nel.org,
Peter Zijlstra <peterz@...radead.org>,
Paul Mundt <lethal@...ux-sh.org>,
Russell King <linux@....linux.org.uk>,
David Woodhouse <dwmw2@...radead.org>,
Jesse Barnes <jbarnes@...tuousgeek.org>,
Yinghai Lu <yinghai@...nel.org>,
Grant Likely <grant.likely@...retlab.ca>
Subject: Re: [patch 46/47] powerpc: Use new irq allocator
On Sun, 3 Oct 2010, Thomas Gleixner wrote:
> On Sun, 3 Oct 2010, Eric W. Biederman wrote:
>
> > Thomas Gleixner <tglx@...utronix.de> writes:
> >
> > >> That would make things much cleaner and in fact move one large step
> > >> toward being able to make powerpc virq scheme generic, which seems to be
> > >> a good idea from what I've heard :-)
> > >
> > > Yep.
> >
> > I'm not certain about making the ppc virq scheme generic. Maybe it is
> > just my distorted impression but I have the understanding that ppc irq
> > numbers mean nothing and are totally unstable whereas on x86 irq numbers
> > in general are stable (across kernel upgrades and changes in device
> > probe order) and the irq number has a useful hardware meaning. Which
> > means you don't have to go through several layers of translation tables
> > to figure out which hardware pin you are talking about.
>
> Nobody is forced to use it, but we have already several instances of
> virq mapping implementations in arch/*. Having a generic
> infrastructure for this makes a ton of sense.
Forgot to say: With MSI and dynamic allocated irqs the stable numbers
are completely meaningless. So where is the point ?
Thanks,
tglx
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