TSC and 8254 interaction

["daniel sheltraw" <l5gibson@hotmail.com>]

Sorry Paolo

I still do not understand the interaction between the TSC and 8254 for 
oneshot scheduling. Is there any documentation on this (besides the source)?

Daniel


>From: Paolo Mantegazza <mantegazza@aero.polimi.it>
>To: daniel sheltraw <l5gibson@hotmail.com>
>Subject: Re: one last clock question (for now)
>Date: Mon, 10 Jul 2000 11:04:19 +0200
>
>daniel sheltraw wrote:
> >
> > Thamks again Paolo
> >
> > One more question. How does the STC use the 8254 counter 0 to generate
> > the interrupt that signals the next premption point.
> >
> > That's it for a while. Thanks soo much,
> > Daniel
>
>The interval to be awaited for the next clock interrupt is computed by
>using the TSC, or the continuously running 8254 counter 2 emulating it
>on 3/486. That interval is converted into 8254 counter units and counter
>0 is programmed accodingly with 2 outb. Note that it is set in oneshot
>mode, once for all, when the rt timer is started.
>
>The actual code can be seen in rt_schedule and in the rt_timer_handler
>in RTAI schedulers.
>
>Ciao, Paolo.

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