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Date: Tue, 21 Nov 2006 08:59:16 +1100
From: Paul Mackerras <paulus@samba.org>
To: Arnd Bergmann <arnd@arndb.de>
Subject: Re: [PATCH 01/22] powerpc: convert idle_loop to use hard_irq_disable()
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Cc: Arnd Bergmann <arnd.bergmann@de.ibm.com>, linuxppc-dev@ozlabs.org,
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Arnd Bergmann writes:

> I got a bug report that I believe might be fixed by this
> patch. The problem seems to be that with soft-disabled
> interrupts in power_save, we can still get external exceptions
> on Cell, even if we are in pause(0) a.k.a. sleep state.

[snip]

> -				local_irq_disable();
> +				hard_irq_disable();

This would mean that any platform-specific power_save function that
wants to re-enable interrupts (as the pseries ones do) would have to
do hard_irq_enable instead of local_irq_enable.  Also, I don't think
this change will be good on iSeries.

What we want is an irq-disable function that is like local_irq_disable
but also clears MSR_EE and the hard irq enabled flag (provided we
aren't running on iSeries).

Paul.