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

From: Segher Boessenkool <[email-masked]>
Date: Thu, 17 May 2007 21:27:17 +0200

> +	 * We must write a positive value to the decrementer to clear
> +	 * the interrupt on the IBM 970 CPU series.  In periodic mode,
> +	 * this happens when the decrementer gets reloaded later, but
> +	 * in one-shot mode, we have to do it here since an event handler
> +	 * may skip loading the new value...

Nothing special about 970 here -- on *every* PowerPC,
a decrementer exception exists as long as the high
bit of the decrementer equals 1.  BookE is different
of course.  Some other CPUs might deviate from the
architecture as well.

Segher