New pmap status update

Howdy folks (and to all those celebrating in the US, happy =
Thanksgiving=E2=80=A6)

Just wanted to provide a quick status update on the new pmap module.

Thanks to help from Isaki-san and Tsusui-san, a bunch of platforms have =
been adapted and several critical bugs ironed out.  I think we=E2=80=99re =
ready for some more rigorous testing, and also some help in adapting =
some of the remaining platforms.

First off, where we are in terms of =E2=80=9Chow well does it work?=E2=80=9D=


- virt68k runs very well with the new pmap, including with large (e.g. =
3GB) memory configurations.  That platform has switched to using the new =
pmap by default.

- hp300 and luna68k boot up to multi-user on 68030 and at least =
single-user on 68040 (probably will boot multi-user, fingers crossed :-)

- news68k has been adapted, but the last time this platform was tested, =
there was an issue (possibly related to external cache?)

- x68k has been lightly tested before the most recent fixes for 68040.

Work still to be done:

- mvme68k and next68k have been adapted, but not tested yet.

- cesfic has yet to be adapted.  This one will be easy, but I don=E2=80=99=
t know anyone who has a board, so it will probably go untested.

- amiga and Atari need to be adapted, but they=E2=80=99re going to be =
much more difficult due to the very different start-up code.

- mac68k needs to be adapted.  Looks to be not hard like amiga, but not =
easy like some of the others.

- Needs testing on 68020 (should Just Work) and 68060 (probably not any =
worse than 68040).

- Needs testing on HP MMU systems.

-- thorpej