the simulator had VPU tracing support proposed here:
	https://sourceware.org/ml/gdb/2001-02/msg00267.html

and committed here:
	https://sourceware.org/git/?p=binutils-gdb.git;a=commitdiff;h=01816cd804ec526927f53f0e408dae8c6ea269f2

but nowhere can i seem to find a description of what the "VPU" actually is.
the references to cgen doesn't lead anywhere as a grep of the cgen tree doesn't 
match anything.  the only user in the sim tree is msp430, and it uses it for
generic cpu register tracing.  i would guess that it means "video processing 
unit" as Google would lead me to believe, but that doesn't make sense in the
cgen/sim context.  same for "virtual processing unit".

can anyone shed some light on this ?
-mike