[PATCH] i386: Enable NMI watchdog by default (1de84979) · Commits · 戴 / test

I've had good experiences with having this on by default on x86-64. It turns nasty hangs into easier to debug oopses. Enable the local APIC wdog by default for systems newer than 2004. This comes from a strange compromise: according to arjan the reason it was off by default was some old IBM systems that corrupted registered when NMI happened in SMI. Can't remember more specific, but >= 2004 should avoid these. It's probably overly broad because most older systems should be ok (and the really old systems won't be supported by the local apic watchdog anyways) Signed-off-by:

Andi Kleen <ak@suse.de>

arch/i386/kernel/nmi.c

+9 −0

Original line number	Diff line number	Diff line
		@@ -21,6 +21,7 @@
		#include <linux/sysdev.h>
		#include <linux/sysctl.h>
		#include <linux/percpu.h>
		#include <linux/dmi.h>

		#include <asm/smp.h>
		#include <asm/nmi.h>
		@@ -204,6 +205,14 @@ static int __init check_nmi_watchdog(void)
		unsigned int *prev_nmi_count;
		int cpu;

		/* Enable NMI watchdog for newer systems.
		Actually it should be safe for most systems before 2004 too except
		for some IBM systems that corrupt registers when NMI happens
		during SMM. Unfortunately we don't have more exact information
		on these and use this coarse check. */
		if (nmi_watchdog == NMI_DEFAULT && dmi_get_year(DMI_BIOS_DATE) >= 2004)
		nmi_watchdog = NMI_LOCAL_APIC;

		if ((nmi_watchdog == NMI_NONE) \|\| (nmi_watchdog == NMI_DEFAULT))
		return 0;

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