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From: Mikael Pettersson <>
Subject: Re: [PATCH] NMI watchdog documentation
Date: Thu, 31 Jul 2003 23:25:09 +0200 (MEST)	[thread overview]
Message-ID: <> (raw)

On Thu, 31 Jul 2003 08:44:48 +0300, Ville Herva wrote:
>Uuh, sorry. Is the one below ok by you for submission to Linus and Marcelo?
>-- v --
>--- linux/Documentation/nmi_watchdog.txt	Sun Jul 27 19:58:26 2003
>+++ linux~/Documentation/nmi_watchdog.txt	Tue Jul 29 21:08:01 2003
>@@ -1,9 +1,11 @@
>-Is your ix86 system locking up unpredictably? No keyboard activity, just
>+[NMI watchdog is available for x86 and x86-64 architectures]
>+Is your system locking up unpredictably? No keyboard activity, just
> a frustrating complete hard lockup? Do you want to help us debugging
> such lockups? If all yes then this document is definitely for you.
>-On Intel and similar ix86 type hardware there is a feature that enables
>+On many x86/x86-64 type hardware there is a feature that enables
> us to generate 'watchdog NMI interrupts'.  (NMI: Non Maskable Interrupt
> which get executed even if the system is otherwise locked up hard).
> This can be used to debug hard kernel lockups.  By executing periodic
>@@ -20,6 +22,15 @@
> kernel debugging options, such as Kernel Stack Meter or Kernel Tracer,
> may implicitly disable the NMI watchdog.]
>+For x86-64, the needed APIC is always compiled in, and the NMI watchdog is
>+always enabled with I/O-APIC mode (nmi_watchdog=1). Currently, local APIC
>+mode (nmi_watchdog=2) does not work on x86-64.
>+Using local APIC (nmi_watchdog=2) needs the first performance register, so
>+you can't use it for other purposes (such as high precision performance
>+profiling.) However, at least oprofile and the perfctr driver disable the
>+local APIC NMI watchdog automatically.
> To actually enable the NMI watchdog, use the 'nmi_watchdog=N' boot
> parameter.  Eg. the relevant lilo.conf entry:

Looks Ok to me.


             reply	other threads:[~2003-07-31 21:25 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2003-07-31 21:25 Mikael Pettersson [this message]
  -- strict thread matches above, loose matches on Subject: below --
2003-07-30 22:53 [PATCH] NMI watchdog documentation Mikael Pettersson
2003-07-31  5:44 ` Ville Herva
2003-07-30 19:20 Mikael Pettersson
2003-07-30 19:40 ` Ville Herva
2003-07-30 19:18 Mikael Pettersson
2003-07-29 10:37 Mikael Pettersson
2003-07-29 16:06 ` Andi Kleen
2003-07-29 17:53   ` Ville Herva
2003-07-23 17:43 Ville Herva
2003-07-28 17:53 ` Andi Kleen
2003-07-28 19:21   ` Ville Herva

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