Re: Why is double_fault serviced by a trap gate?

From: Andi Kleen (ak@suse.de)
Date: Thu Dec 07 2000 - 13:29:58 EST


On Thu, Dec 07, 2000 at 07:11:57PM +0100, Maciej W. Rozycki wrote:
> On Thu, 7 Dec 2000, Andi Kleen wrote:
>
> > How often does the NMI watchdog handler run ?
>
> HZ times per second.

Interesting. One of my ports references for PCs lists

0044 r/w PIT counter 3 (PS/2, EISA)
                used as fail-safe timer. generates an NMI on time out.
                for user generated NMI see at 0462.

I don't know if modern PCs still provide this counter, but if yes it could
be used for a slow NMI watchdog that only runs every 30s or so.

-Andi
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