The confusion arises when some language developers decide to ignore or break existing ABI for a particular platform. There are general ways to call procedures

The confusion arises when some language developers decide to ignore or break existing ABI for a particular platform. There are general ways to call procedures - there machine instructions for this. ABI defines how exactly parameters and return values should be passed - using, registers or stack or both. As long as you follow the rules there is no difficulty in calling everything you wish. The whole idea of JVM as something disconnected from reality^W OS and hardware is simply wrong, and all the confusion is the consequence of that premature decision. Of course, slogan "you don't have to know" always wins.