and they added a panic. Apparantly this instruction is not used very often
because it went for a long time before anyone noticed. Peter Tattam started
running into the panic while emulating his OS called Petros, and through
a comparison between vmware and bochs results he believes that enter is
doing the right thing. So, I have changed the panic into a BX_ERROR for now,
and added code to ensure that it only gets printed once per bochs run.