QNX Tick Timer

In QNX4 the kernel runs on timer tick. BUt in QNX6, kernel is message based. is it necessary to have a prtiodic timer for running the kernal

Please correct, if worng

The timer tick is used for time sliced round robin scheduling in both versions of QNX.

It isn’t strictly necessary to have a timer tick, unless you want adaptive partitioning, time slicing, and timers to work ;-)

I am being facetious of course, but it is true that the kernel would work (just without timers, time-slicing & AP) if there were no timer IRQ.

It is actually not that uncommon on a new board bring-up to have a non-functional timer IRQ, and it is quite surprising how long it takes to notice that it isn’t working…

I think that is pretty much how pre-NT versions of Windows worked.