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Date: Mon, 10 Mar 2003 04:50:43 +0100
From: Segher Boessenkool <segher@koffie.nl>
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To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Albert Cahalan <albert@users.sourceforge.net>,
       "Albert D. Cahalan" <acahalan@cs.uml.edu>,
       oprofile-list@lists.sourceforge.net, linuxppc-dev@lists.linuxppc.org,
       o.oppitz@web.de, afleming@motorola.com, linux-kernel@vger.kernel.org
Subject: Re: [patch] oprofile for ppc
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Benjamin Herrenschmidt wrote:
> Beware though that some G4s have a nasty bug that prevents
> using the performance counter interrupt (and the thermal interrupt
> as well).

MPC7400 version 1.2 and lower have this problem.

 > The problem is that if any of those fall at the same
> time as the DEC interrupt, the CPU messes up it's internal
> state and you lose SRR0/SRR1, which means you can't recover
> from the exception.

But the worst that happens is that you lose that process, isn't
it?  Not all that big a problem, esp. since the window in which
this can happen is very small.


Segher

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