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Subject: Re: [RFC/PATCH] powerpc: Add irqtrace support to 32-bit powerpc
From: Benjamin Herrenschmidt <benh@ozlabs.org>
To: Dale Farnsworth <dale@farnsworth.org>
In-Reply-To: <20080404212952.GA15454@farnsworth.org>
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	<1207337598.19189.77.camel@johannes.berg>
	<20080404212952.GA15454@farnsworth.org>
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Date: Sat, 05 Apr 2008 09:08:40 +1100
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Cc: linuxppc-dev@ozlabs.org, Johannes Berg <johannes@sipsolutions.net>
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On Fri, 2008-04-04 at 14:29 -0700, Dale Farnsworth wrote:
> On Fri, Apr 04, 2008 at 09:33:18PM +0200, Johannes Berg wrote:
> > On Wed, 2008-04-02 at 16:15 +0200, Johannes Berg wrote:
> > > On Fri, 2008-02-01 at 12:50 -0700, Dale Farnsworth wrote:
> > > > This adds the low level irq tracing hooks for 32-bit powerpc.
> > > > This patch applies on top of Benjamin Herrenschmidt's patch that
> > > > provides similar support for 64-bit powerpc.  See
> > > > <http://ozlabs.org/pipermail/linuxppc-dev/2007-October/044361.html>
> > > > 
> > > > It seems to work on my prpmc2800 board with a ppc7447.
> > > 
> > > At first it appears to work on my powerbook (with Ben's latest version
> > > of the 64-bit patch), but then it seems to cause random corruption, I've
> > > had a crash in the ext3 code and one in console_callback(), both of
> > > which I cannot otherwise explain.
> > 
> > FWIW, same kernel without the patch works fine.
> 
> My apologies, Johannes.  I made some unwarranted assumptions about
> register usage in the lowest-level exception handlers.  While it worked
> on my 7447 board, I saw similar random failures on the 85xx (booke) system
> I tried.
> 
> Thanks for testing this.
> 
> I'll follow up with a revised patch.

BTW. We don't try to trace the EE changes in the hash code. I suppose
that's fair enough but probably worth putting a comment on somewhere.

Cheers,
Ben.