for this, it is desirable that as much of the normal runtime interface as
possible still continue to work.  of course, kprobes proper can't be used.  but
otherwise, maps, basic I/O transport calls ... should all work.

As for packaging under user/, it would be easier to use if the user level
simulations lived within the main directory, and enabled by #ifdef macros (e.g.
TEST_MODE set by the translator)

no longer high priority

Closing this. The existing user-level testing for runtime and the translator
seem to be adequate.  It is not possible to improve much on that without major
work and it would never be good enough because we cannot accurately simulate the
contention  that occurs in the kernel.  It is much more important at this point
to work on real world tests that actually load modules into running kernels.