linux-kernel - Re: [patch] ACPI, i686, x86_64: fix laptop bootup hang in init

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Date:	Thu, 7 Dec 2006 12:08:16 +0100
From:	Ingo Molnar <mingo@...e.hu>
To:	Len Brown <lenb@...nel.org>
Cc:	linux-kernel@...r.kernel.org, Andrew Morton <akpm@...l.org>,
	ak@...e.de
Subject: Re: [patch] ACPI, i686, x86_64: fix laptop bootup hang in init_acpi()

* Len Brown <len.brown@...el.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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