At 01:37 PM 30-04-99 +0200, you wrote:
>Hi!
>
>Sometimes, while creating an rt-application, i make
>a mistake, so that an rt-task hangs in a while- or for-loop.
>Consequence: rt_task_wait() is never reached, so that the machine
>hangs completly.
>
>I experienced, that it is even more important to
>have an emergency exit for this situation instead of
>having MMU-Support (like Pierre Cloutier suggested in his
>recent posting).
>
>So my idea is to have an interrupt service-routine (ISR) tied
>to the interrupt-pin of the parallel port. When the system
>hangs, then you only have to push a button connected to
>the interrupt pin and the ISR will stop all RT-Tasks by
>calling rt_suspend (except the linux idle-task). Then you can
>(re)access standard linux and unload all rt-task.
I would think that a lower priority "untested task" could be supervised by
a higher priority periodic "supervisory" task i.e the watchdog concept.
Why bother to hardwire the parallel port interrupt for that?
I do not see a defense against "rogue" pointers unless there is a way to
use the MMU.
_______________________________________________________
Pierre Cloutier
Tel: (450)-659-9186
Fax: (450)-659-0014
POSEIDON CONTROLS INC
_______________________________________________________
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