From: Andi Kleen Date: Tue, 26 Sep 2006 08:52:27 +0000 (+0200) Subject: [PATCH] i386: Enable NMI watchdog by default X-Git-Tag: v2.6.19-rc1~1077^2~203 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=1de84979dfc527c422abf63f27beabe43892989b;p=linux-2.6 [PATCH] i386: Enable NMI watchdog by default 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 --- diff --git a/arch/i386/kernel/nmi.c b/arch/i386/kernel/nmi.c index 8e4ed930ce..6e5085d5d2 100644 --- a/arch/i386/kernel/nmi.c +++ b/arch/i386/kernel/nmi.c @@ -21,6 +21,7 @@ #include #include #include +#include #include #include @@ -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;