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Hard Real-Time?

Is there already a way to do "hard real time" on NetBSD?  

To me, "hard real time" means from an external pin going 'high' to the 1st instruction of my driver executing is on the order of (up to) 10 usec.

Many eons ago, I did this on BSD4.3 VAX 785 and achieved <  about 100 usec jitter.  It was a Royal Pain to do, since so many places in the kernel turned off interrupts as it massaged various data structures.  The pain was to find every one of those and break them down to absolutely minimize the time interrupts were turned off.

But it worked:  Here it is controlling various hopping machines:  I'm sitting controlling the thing; the umbilical goes back to a UNIBUS interface in the VAX.  Timesharing only slowed down; it did not stop during operation.

I'm especially interested in getting the RPi to operate 'hard real time' on NetBSD.  I mainly want to use the RPi to control a robot -- low  level as well has higher-level planning/control.

Thanks for any pointers,

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