linux-kernel - Re: [RFC][PATCH] nmi watchdog: handle NMI_IO_APIC on nmi

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Message-ID: <20081023033540.GF28317@cathedrallabs.org>
Date:	Wed, 22 Oct 2008 23:35:40 -0400
From:	Aristeu Rozanski <aris@...vo.org>
To:	"Maciej W. Rozycki" <macro@...ux-mips.org>
Cc:	Ingo Molnar <mingo@...e.hu>, Thomas Gleixner <tglx@...utronix.de>,
	Vivek Goyal <vgoyal@...hat.com>, linux-kernel@...r.kernel.org
Subject: Re: [RFC][PATCH] nmi watchdog: handle NMI_IO_APIC on nmi_watchdog

> > > but this stops all NMIs, not just the IO-APIC generated ones, doesnt it? 
> > external NMIs would come by LINT1, no?
> 
>  Correct.
> 
> > after reading a lot and talking with Vivek, what I understood was that 8259 is
> > also connected to LINT0, so timer interrupts would be reported both in
> > IOAPIC and on LINT0. LVT0 is being configured on setup_nmi() to generate
> > an NMI. Also, the same timer interrupt would generate an regular interrupt
> > coming from IOAPIC. Clearing the APIC_DM_NMI on LVT0 would disable the
> > NMI delivery, but not the regular interrupt.
> > or am I missing something here?
> 
>  You are correct.  The routing of the 8254 timer interrupt may vary, but 
> the NMI watchdog it drives, if supported, always uses the LINT0 input of 
> all the local APICs.
thanks

>  You seem to be writing in reply to a very old thread -- please make sure 
> your concerns are still valid with current code.  For example we have an 
> implementation of __acpi_nmi_disable() now, which is exactly your proposed 
> one.
didn't noticed that, sorry.

-- 
Aristeu

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