And that only if your codepath is deterministic. Linux can do pretty funny stuff at times.

I've run a plasma cutter under Linux on a run-of-the-mill VIA SBC, it was actually pretty easy: just make a program setuid root, use that to disable interrupts after you've read all your data in and then just go wild on polled and precision timed IO until you're done. Re-enable interrupts and return as if nothing ever happened.