The venerable X/mmap problem

[Justin Hibbits]

I think that mmap() problem from a year ago (physical memory isn't mapped
correctly so writes to the end cause problems) has come back.  I just
installed Nathan's 20100418-SNAP snapshot on my G4, and subsequently svn
up'd and rebuilt world/kernel.  Since then, going into X causes the machine
to hang within a few minutes.  Staying out of X it does not hang.

- Justin