Subject: Re: Linux 2.6.21-rc1
From: Thomas Gleixner <tglx@linutronix.de>
Reply-To: tglx@linutronix.de
To: Daniel Walker <dwalker@mvista.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>,
       Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, mingo@elte.hu
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Date: Wed, 21 Feb 2007 20:23:12 +0100
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On Wed, 2007-02-21 at 10:23 -0800, Daniel Walker wrote:
> Right, but eventually there isn't a regular timer interrupt through the
> io-apic. I don't think in the past IRQ0 stops without the system
> crashing, so check_timer() could assume the timer (IRQ0) is _always_
> regular.
> 
> do you know what the requirement are for routing the NMI through the
> io-apic? 

Sorry. I checked. switching PIT off really breaks nmi_watchdog=1, as
this just mirrors IRQ#0 to the NMI. No IRQ#0 from PIT, no NMI

We could keep PIT running with an empty interrupt handler when
nmi_watchdog=1 is set, but this interferes nicely with broadcasting.

Does nmi_watchdog=2 work ? We might switch to that, when a local APIC is
available. 

	tglx


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