On Apr 28, 2005, at 8:14 PM, just me wrote:

> can someone explain shortly ? or give me a good link to read about  
> it ?

VM (in the context you're referring to) stands for "virtual memory".   
It is a generic term.

UVM is the name of NetBSD's virtual memory subsystem.

As for the differences between UVM and Mach VM (what NetBSD had  
before UVM), read Chuck Cranor's dissertation, or one of his other  
papers.  Google for "Cranor UVM".

-- thorpej