Date: Thu, 7 Dec 2006 12:08:16 +0100
From: Ingo Molnar <mingo@elte.hu>
To: Len Brown <lenb@kernel.org>
Cc: linux-kernel@vger.kernel.org, Andrew Morton <akpm@osdl.org>, ak@suse.de
Subject: Re: [patch] ACPI, i686, x86_64: fix laptop bootup hang in init_acpi()
Message-ID: <20061207110816.GC11207@elte.hu>
References: <20061206223025.GA17227@elte.hu> <200612061857.30248.len.brown@intel.com>
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* Len Brown <len.brown@intel.com> wrote:

> c. disable the NMI whenever the ACPI interpeter is running
>    (who knows, maybe this isn't limited to the _INI case, but
>     could cause a hang at some other time -- only the
>     BIOS AML writers knows....)

i have tested this by forcing the NMI frequency to 10,000 per second, 
and never saw any other problem. So at least this particular laptop 
should be OK.

So i /think/ this should be enough - the _INI case should be limited to 
bootup - or can it trigger during module load too? The IO-APIC based NMI 
watchdog should really only involve the southbridge (whose 
initialization package has this problem, in my guesstimation - do you 
agree?) and not random other devices - so once we have booted up we 
should be fine from this particular issue. acpi_nmi_disable()/enable() 
does a cross-IPI to all CPUs, so it can be quite heavy-handed - i'm not 
sure we want it for every interpreter invocation.

	Ingo
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