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From: John Baldwin <jhb@freebsd.org>
To: freebsd-hackers@freebsd.org
Subject: Re: NMI watchdog functionality on Freebsd
Date: Wed, 23 Jan 2013 10:25:41 -0500
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Cc: Sushanth Rai <sushanth_rai@yahoo.com>
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On Tuesday, January 22, 2013 5:40:55 pm Sushanth Rai wrote:
> Hi,
> 
> Does freebsd have some functionality similar to  Linux's NMI watchdog ? I'm 
aware of ichwd driver, but that depends to WDT to be available in the 
hardware. Even when it is available, BIOS needs to support a mechanism to 
trigger a OS level recovery to get any useful information when system is 
really wedged (with interrupt disabled). 
> 
> With Linux's NMI, APIC is programmed to periodically generate NMI and the OS 
NMI handler can check for some counters and invoke panic if the counters are 
not updated for a while. 

We currently use the local APIC timer as a timer with a normal interrupt.  
There's no reason you couldn't add a mode to make the local APIC timer operate 
in this fashion however.

-- 
John Baldwin