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From: "Rafael J. Wysocki" <rjw@sisk.pl>
To: Linus Torvalds <torvalds@linux-foundation.org>
Subject: Re: PCI PM: Restore standard config registers of all devices early
Date: Mon, 2 Feb 2009 23:33:50 +0100
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Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
       Jesse Barnes <jesse.barnes@intel.com>, Andreas Schwab <schwab@suse.de>,
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On Monday 02 February 2009, Linus Torvalds wrote:
> 
> On Mon, 2 Feb 2009, Rafael J. Wysocki wrote:
> > 
> > I think it would be easier to make ACPI allow us to run AML with interrupts
> > off.
> 
> Well, I'd agree, except I have this strong memory of us having known bugs 
> with ACPI turning hard-interrupts on again. Similarly, it uses mutexes etc 
> that simply don't work with interrupts off and/or may turn them on again 
> thanks to scheduling.
> 
> "Fixing" that seems not very easy. ACPI has a bad habit of being _really_ 
> hard to fix in this area.
> 
> I do agree that _if_ we can just fix ACPI, we wouldn't have these issues, 
> and we should  just call it with interrupts disabled with our existing 
> code. But my previous email was a "maybe we can do it like this" kind of 
> thing, which might allow us to use ACPI with none of the irq-off issues.

Well, I think both will be difficult, this way or another. :-)

I'll have a look at the ACPI thing.

Thanks,
Rafael