Re: [patch] enabling APIC and NMI watchdog on UP systems

From: Keith Owens (kaos@ocs.com.au)
Date: Thu Sep 28 2000 - 20:08:52 EST


On Fri, 29 Sep 2000 03:03:30 +0200 (CEST),
Ingo Molnar <mingo@elte.hu> wrote:
>
>On Fri, 29 Sep 2000, Keith Owens wrote:
>
>> [...] You prefer to make NMI for UP mandatory, change the existing
>> behaviour and force people who use performance counters to turn off
>> EVNTSEL1 themselves. [...]
>
>no, AFAIK there is no performance counter support in the vanilla kernel,
>but there is an NMI oopser.

arch/i386/kernel/msr.c has been there since at least 2.4.0-test1. A
web search reveals a lot of other patches for performance counter
libraries on Linux. http://www.scl.ameslab.gov/Projects/Rabbit/ is a
good start, it indicates that people are already using the counters.

>And even if there was performance counter
>support, having a default NMI oopser on UP *is* a much higher priority.

Agreed, having the support is a high priority. Changing the default
behaviour of the performance counters is where we differ.

>and there is no forcing here. nmi_watchdog=0 on bootup and the NMI
>watchdog is disabled. (right now this is not enforced for the APIC-NMI,
>but thats a detail.)

I originally did that but it users have to tweak their boot files
whenever they install a new kernel. Making it a config option
propagates the user's requirements from one kernel build to another.

Let's just agree to disagree and put your patch in the mainline kernel.

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