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SubjectRe: [RFC] Fix NMI watchdog documentation
On Sat, 24 May 2003, Carl-Daniel Hailfinger wrote:

> Documentation/nmi_watchdog.txt does not say which CONFIG_XYZ option has
> to be enabled to use the NMI watchdog, but it mentions that IO-APIC is
> somewhat related.
> Documentation/ is equally unclear. The NMI watchdog is
> mentioned as related to CONFIG_SMP, and the help text for
> CONFIG_X86_UP_APIC says: "The local APIC supports [..] the NMI watchdog"
> That does not necessarily mean that NMI is compiled in once local APIC
> support is selected.
> Can someone please shed some light on this issue? I'm willing to create
> a patch to fix the docs once I know if the NMI watchdog is compiled in
> alsways or on what it depends.

For nmi_watchdog=1 the NMI watchdog uses the programmable interval timer
to trigger interrupt events via the IOAPIC. with nmi_watchdog=2 we use the
performance counters on the processor to trigger these events. IOAPICs
are generally found on SMP motherboards (but there are UP boards with
them, it's chipset dependent). Generally i686+ (save some Athlons and a
few other processors) will work with nmi_watchdog=2.

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