Terminal paging in the kernel

[Henry Spencer]

Our experiences with kernel paging here parallel Steve Zimmerman's:
extensive skepticism in the beginning (including me), total acceptance
after a little bit of real experience.  Ours isn't even as fancy as
Steve's, and we love it just the same.  (Ours is essentially the one
Geoff Collyer posted a while ago; he got it from us.  We do not yet
have a turn-paging-off-temporarily character, but plan to add one.)
Try it, you'll like it.  Really.

I would like to add one thing to Steve's fairly complete rebuttal of
the critics.  Another criticism that has been seen is:

	The current kernel doesn't know anything about all the
	strange terminals out there.  It is dreadfully unclean
	to add virtual-terminal stuff to it.

Well, I would argue the last part at some length, if the virtual-
terminal stuff is being added for some useful purpose like implementing
a window system.  But I don't need to argue that here, because the
first part of this objection is full of s**t.  Have you ever looked
at the definition of, say, the NL1 delay bit?  This is found in very
nearly every Unix in existence, and it is custom-tuned for a terminal
that nobody in his right mind has used for a decade.  The V7 Unix
kernel contains a fairly complete virtual-terminal system for hardcopy
terminals circa 1972.  About half the bits in the tty mode are dedicated
to this exact purpose.  So please don't complain about putting code
that knows about terminals into the kernel; it's been there all along.
The problem is that it was never updated to match modern terminals.
-- 
				Henry Spencer @ U of Toronto Zoology
				{allegra,ihnp4,linus,decvax}!utzoo!henry