[En-Nut-Discussion] RFC - Nut/OS timer handling

Harald Kipp harald.kipp at egnite.de
Tue Jun 30 17:09:02 CEST 2009

Nathan Moore wrote:

>> Before abolishing the use of timer callbacks for network timing, I'd
>> like to hear your opinions.
> Unless something has changed recently that I haven't seen (I'm on older
> version of Nut)
> there is another problem.  While timers are no longer executed in interrupt
> context they still
> have some of the same constraints as interrupt handlers.
> Particularly they should never yield.  If they do then the context switching
> code becomes
> reentrant.  Then bad things happen.  The run queue and the timer list would
> all have to
> be handled much more carefully.

Good point. I overlooked the yield problem, which makes timer callbacks
unusable for interrupt driven I/O.


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