Messages in this thread |  | | Date | Sat, 24 May 2003 15:08:19 -0400 (EDT) | From | Zwane Mwaikambo <> | Subject | Re: [RFC] Fix NMI watchdog documentation |
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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/Configure.help 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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