Re: [PATCH] HPET RTC emulation: add watchdog timer

[Andi Kleen]

On Mon, Jan 09, 2006 at 07:00:34PM +0100, lkml@xxxxxxxxxxxxxxxxxxxxxxxxx wrote:
> Andi Kleen wrote:
> > On Mon, Jan 09, 2006 at 04:43:50PM +0100, Clemens Ladisch wrote:
> > > To prevent the emulated RTC timer from stopping when interrupts
> > > are disabled for too long, implement the watchdog timer to
> > > restart it when needed.
> >
> > The interrupt handler should just read the time (it likely
> > has to do that anyways)
> 
> Not in the current implementation.

The standard HPET interrupt in x86-64 does this already at least.

> > and check for that directly.
> 
> I want to avoid the read altogether because the round trip to the
> south bridge is rather slow (1.5 microseconds with VIA chipsets).

You can use the TSC to detect it too, but it might be unreliable.

-Andi

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