linux-kernel - Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver

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Date:	Fri, 18 May 2007 15:04:49 +1000
From:	Benjamin Herrenschmidt <benh@...nel.crashing.org>
To:	Segher Boessenkool <segher@...nel.crashing.org>
Cc:	Sergei Shtylyov <sshtylyov@...mvista.com>, linuxppc-dev@...abs.org,
	tglx@...utronix.de, mingo@...e.hu, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 2.6.21-rt2] PowerPC: decrementer clockevent driver


> 
> Yes, on some implementations there can be other conditions that
> make a decrementer exception go away; there is no contradiction
> here (thankfully).  My wording was sloppy.

Some CPUs have the DEC exceptions basically edge triggered (yeah I know
it sucks). That's why, among others, the IRQ soft-disable code has code
to re-trigger DEC exceptions ASAP (by setting it to 1.. note that we
could probably use 0 here, we've been a bit conservative).

Ben.


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