UVM pmap's locking protocol, written by Chuck Cranor. Not all of the
support for multiple processors is here yet, but the kernel does run
under moderate loads with LOCKDEBUG (all locking operations are no-ops
unless LOCKDEBUG is turned on).
This is by no means complete... there are still some possible snares
to take a look at.
caller to pass an optional 3rd argument, which is the previous level
PTE corresponding the virtual address. If this argument is non-NULL,
the table walk otherwise necessary will be bypassed.
from the mach3 versions only as much as necessary to allow the old
NetBSD/Alpha pmap code to compile. THESE WILL NOT WORK AS-IS, and at
minimum will require code to implement reference- and modified-bit
emulation.
Support for AXPpci CPUs,
Support for AlphaStation 600 CPUs,
new boot block structure, which requires an 'installboot'
program and works a lot like the NetBSD/sparc boot blocks.