Re: [PATCH] watchdog: add pretimeout ioctl

[Corey Minyard]

Alan Cox wrote:
> Ar Maw, 2006-06-27 am 13:22 -0500, ysgrifennodd minyard@xxxxxxx:
>   
>> Some watchdog timers support the concept of a "pretimeout" which
>> occurs some time before the real timeout.  The pretimeout can
>> be delivered via an interrupt or NMI and can be used to panic
>> the system when it occurs (so you get useful information instead
>> of a blind reboot).
>>     
>
> All watchdogs can do pre-timeouts in software so possibly this should
> use a software fallback as well if you want good coverage ?
>   
I hadn't thought of that, but a software emulator could be used with
this interface, but it doesn't really help with hard lockups.  This is
primarily intended to set up watchdogs that can delver an NMI,
since even if the machine is hard-locked the NMI will come through.
Of course, there's all kinds of problems with getting the NMI to a
useful handler, but that's another story.

-Corey
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