I compiled the VM for Linux from 3.1a sources and it gives me an
option --enable-jit and the compiled executable has the options -jit
and -spy, the latter of which I don't quite understand.

But my main question is: all these options have no noticable
effect. Are these just blanks or is the jit up and running. Did I miss
anything ?

Is there a way I can tell that a jit is doing its work ?

Also: The image will never contain compiled code, right ?