Very, very hard, if you mean kernel threads running in parallel. However, if the other cores run separate kernel instances (machine partitioning, separate memory and everything) that would be more achieveable. UNSW call this the clustered micokernel approach.

Thanks for that. Kind of what I expected. I wonder if the problem could be simplified if techniques from deterministic/stable multithreading could be incorporated somehow to simplify the formalization (http://dl.acm.org/citation.cfm?id=2566590.2500875)