Re: [Xenomai-core] Clockevent/clocksource.

[Gilles Chanteperdrix <gilles.chanteperdrix@xenomai.org>]

Gilles Chanteperdrix wrote:
 > Philippe Gerum wrote:
 >  > Gilles Chanteperdrix wrote:
 >  > > Hi,
 >  > > 
 >  > > I would like to implement the (I-pipe) AT91 timer management as
 >  > > clocksource/clockevent, however, I have a question, how does one choose
 >  > > the "shift" value in struct clocksource and struct clock_event_device ?
 >  > > 
 >  > 
 >  > http://ixlabs.cs.pub.ro/category/projects/linux-kernel-library/
 > 
 > Looks like the thing is working. A concern though: the hardware timer
 > used on AT91 wraps fast, so if we want the tsc to work correctly, the
 > timer needs to tick every 20ms (which makes using the clock events
 > framework pretty useless, but it is mostly useful for other reasons: it
 > allows me to test Xenomai on ARM in the clock events case). I have set
 > the clock event max_delta_ns member to these 20ms, however when
 > inserting the nucleus module, the max_delta_ns member is set to
 > ULONG_MAX, so my question is: will the nucleus take care of ticking
 > every 20ms ?

Ok. This is now how max_delta_ns is supposed to be used anyway: enabling
NO_HZ breaks the tsc, even if max_delta_ns is not set to ULONG_MAX.

-- 


					    Gilles Chanteperdrix.