On Fri, 17 Jan 1997 13:47:49 -0500 
 "Chris G. Demetriou" <cgd@CS.cmu.edu> wrote:

 > So, every time the FreeBSD VM system comes up, somebody from NetBSD
 > says that "it has portability problems," and invariably somebody from
 > FreeBSD says "no it doesn't."

I am going on comments made to me by Matt Green, who did a fair
amount of work to attempt a port of the FreeBSD VM code to NetBSD,
and by others who have mentioned their intent to write
a veneer layer to make MMUs on other architectures emulate
the i386 MMU.  The latter is what concerns me the most; in the
Mach portability model, the pmap module is supposed to hide
machine-dependencies.  If this is the case, why bother emulating
another MMU?

Jason R. Thorpe                                       thorpej@nas.nasa.gov
NASA Ames Research Center                               Home: 408.866.1912
NAS: M/S 258-6                                          Work: 415.604.0935
Moffett Field, CA 94035                                Pager: 415.428.6939