Remove the modified tte bit and add a softwrite bit. Mappings are only
writeable if they have been written to, thus in general modify just
duplicates the write bit. The softwrite bit makes it easier to distinguish
mappings which should be writeable but are not yet modified.
Move the exec bit down one, it was being sign extended when used as an
immediate operand.
Use the lock bit to mean tsb page and remove the tsb bit. These are the
only form of locked (tsb) entries we support and we need to conserve bits
where possible.
Implement pmap_copy_page and pmap_is_modified and friends.
Detect mappings that are being being upgraded from read-only to read-write
due to copy-on-write and update the write bit appropriately.
Make trap_mmu_fault do the right thing for protection faults, which is
necessary to implement copy on write correctly. Also handle a bunch
more userland trap types and add ktr traces.
- mostly complete kernel pmap support, and tested but currently turned
off userland pmap support
- low level assembly language trap, context switching and support code
- fully implemented atomic.h and supporting cpufunc.h
- some support for kernel debugging with ddb
- various header tweaks and filling out of machine dependent structures
