OFW access from linux

[John Gilmore]

> there's no SysRq key on the XO keyboard, so you'll need to use a
> break on the serial console to invoke it...

Please.  If you're going to put this hook in, which I think is a great
idea, at least make it work on the standard hardware!  And when the
operating system is not very responsive.  That's when you'll need it
for debugging or resetting the system.  Without taking the plastic
apart, finding a part with no known suppliers, and soldering it to
your motherboard.

On Sun workstations, the "L1-A" key combination (pressed in exactly
that order, with no intervening keys or key-ups) got you into OFW or
its predecessor.  (L1 was the top left key in the keypad to the left
of the main keyboard.)  We shipped it that way for decades without
trouble.

There are some pretty obscure keys on the XO keyboard -- howabout
something like holding down the leftmost and rightmost "gradually
increasing sized dots" keys in the top row, and then pressing the
M-for-Mitch key?

	John