Native Client uses segmentation on x86 32-bit. Quoting from the paper: http://research.google.com/pubs/pub34913.html http://research.google.com/pubs/pub34913.ht

Native Client uses segmentation on x86 32-bit. Quoting from the paper: http://research.google.com/pubs/pub34913.html http://research.google.com/pubs/pub34913.html "The main contributions of this work are: ... using x86 segments for ... reduced overhead."