Integrate the new MPSAFE TTY layer to the FreeBSD operating system.

The last half year I've been working on a replacement TTY layer for the
FreeBSD kernel. The new TTY layer was designed to improve the following:

- Improved driver model:

  The old TTY layer has a driver model that is not abstract enough to
  make it friendly to use. A good example is the output path, where the
  device drivers directly access the output buffers. This means that an
  in-kernel PPP implementation must always convert network buffers into
  TTY buffers.

  If a PPP implementation would be built on top of the new TTY layer
  (still needs a hooks layer, though), it would allow the PPP
  implementation to directly hand the data to the TTY driver.

- Improved hotplugging:

  With the old TTY layer, it isn't entirely safe to destroy TTY's from
  the system. This implementation has a two-step destructing design,
  where the driver first abandons the TTY. After all threads have left
  the TTY, the TTY layer calls a routine in the driver, which can be
  used to free resources (unit numbers, etc).

  The pts(4) driver also implements this feature, which means
  posix_openpt() will now return PTY's that are created on the fly.

- Improved performance:

  One of the major improvements is the per-TTY mutex, which is expected
  to improve scalability when compared to the old Giant locking.
  Another change is the unbuffered copying to userspace, which is both
  used on TTY device nodes and PTY masters.

Upgrading should be quite straightforward. Unlike previous versions,
existing kernel configuration files do not need to be changed, except
when they reference device drivers that are listed in UPDATING.

Obtained from:		//depot/projects/mpsafetty/...
Approved by:		philip (ex-mentor)
Discussed:		on the lists, at BSDCan, at the DevSummit
Sponsored by:		Snow B.V., the Netherlands
dcons(4) fixed by:	kan

1 files changed, 0 insertions, 205 deletions

diff --git a/sys/kern/tty_conf.c b/sys/kern/tty_conf.c
deleted file mode 100644
index 77a9593..0000000
--- a/sys/kern/tty_conf.c
+++ /dev/null
@@ -1,205 +0,0 @@
-/*-
- * Copyright (c) 2004 Poul-Henning Kamp.  All rights reserved.
- * Copyright (c) 1982, 1986, 1991, 1993
- *	The Regents of the University of California.  All rights reserved.
- * (c) UNIX System Laboratories, Inc.
- * All or some portions of this file are derived from material licensed
- * to the University of California by American Telephone and Telegraph
- * Co. or Unix System Laboratories, Inc. and are reproduced herein with
- * the permission of UNIX System Laboratories, Inc.
- *
- * Redistribution and use in source and binary forms, with or without
- * modification, are permitted provided that the following conditions
- * are met:
- * 1. Redistributions of source code must retain the above copyright
- *    notice, this list of conditions and the following disclaimer.
- * 2. Redistributions in binary form must reproduce the above copyright
- *    notice, this list of conditions and the following disclaimer in the
- *    documentation and/or other materials provided with the distribution.
- * 4. Neither the name of the University nor the names of its contributors
- *    may be used to endorse or promote products derived from this software
- *    without specific prior written permission.
- *
- * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
- * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
- * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
- * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
- * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
- * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
- * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
- * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
- * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
- * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
- * SUCH DAMAGE.
- *
- *	@(#)tty_conf.c	8.4 (Berkeley) 1/21/94
- */
-
-#include <sys/cdefs.h>
-__FBSDID("$FreeBSD$");
-
-#include "opt_compat.h"
-
-#include <sys/param.h>
-#include <sys/systm.h>
-#include <sys/tty.h>
-#include <sys/conf.h>
-
-#ifndef MAXLDISC
-#define MAXLDISC 9
-#endif
-
-static l_open_t		l_noopen;
-static l_close_t	l_noclose;
-static l_rint_t		l_norint;
-static l_start_t	l_nostart;
-
-/*
- * XXX it probably doesn't matter what the entries other than the l_open
- * entry are here.  The l_nullioctl and ttymodem entries still look fishy.
- * Reconsider the removal of nullmodem anyway.  It was too much like
- * ttymodem, but a completely null version might be useful.
- */
-
-static struct linesw nodisc = {
-	.l_open = 	l_noopen,
-	.l_close =	l_noclose,
-	.l_read = 	l_noread,
-	.l_write = 	l_nowrite, 
-	.l_ioctl = 	l_nullioctl, 
-	.l_rint = 	l_norint, 
-	.l_start = 	l_nostart, 
-	.l_modem = 	ttymodem
-};
-
-static struct linesw termios_disc = {
-	.l_open = 	tty_open,
-	.l_close =	ttylclose,
-	.l_read = 	ttread,
-	.l_write = 	ttwrite, 
-	.l_ioctl = 	l_nullioctl, 
-	.l_rint = 	ttyinput, 
-	.l_start = 	ttstart, 
-	.l_modem = 	ttymodem
-};
-
-#ifdef COMPAT_43
-#  define ntty_disc		termios_disc
-#else
-#  define ntty_disc		nodisc
-#endif
-
-struct linesw *linesw[MAXLDISC] = {
-	&termios_disc,		/* 0 - termios */
-	&nodisc,		/* 1 - defunct */
-	&ntty_disc,		/* 2 - NTTYDISC */
-	&nodisc,		/* 3 - loadable */
-	&nodisc,		/* 4 - SLIPDISC */
-	&nodisc,		/* 5 - PPPDISC */
-	&nodisc,		/* 6 - NETGRAPHDISC */
-	&nodisc,		/* 7 - loadable */
-	&nodisc,		/* 8 - loadable */
-};
-
-int	nlinesw = sizeof (linesw) / sizeof (linesw[0]);
-
-#define LOADABLE_LDISC 7
-
-/*
- * ldisc_register: Register a line discipline.
- *
- * discipline: Index for discipline to load, or LDISC_LOAD for us to choose.
- * linesw_p:   Pointer to linesw_p.
- *
- * Returns: Index used or -1 on failure.
- */
-
-int
-ldisc_register(int discipline, struct linesw *linesw_p)
-{
-	int slot = -1;
-
-	if (discipline == LDISC_LOAD) {
-		int i;
-		for (i = LOADABLE_LDISC; i < MAXLDISC; i++)
-			if (linesw[i] == &nodisc) {
-				slot = i;
-				break;
-			}
-	} else if (discipline >= 0 && discipline < MAXLDISC) {
-		slot = discipline;
-	}
-
-	if (slot != -1 && linesw_p)
-		linesw[slot] = linesw_p;
-
-	return slot;
-}
-
-/*
- * ldisc_deregister: Deregister a line discipline obtained with
- * ldisc_register.
- *
- * discipline: Index for discipline to unload.
- */
-
-void
-ldisc_deregister(int discipline)
-{
-
-	if (discipline < MAXLDISC)
-		linesw[discipline] = &nodisc;
-}
-
-/*
- * "no" and "null" versions of line discipline functions
- */
-
-static int
-l_noopen(struct cdev *dev, struct tty *tp)
-{
-
-	return (ENODEV);
-}
-
-static int
-l_noclose(struct tty *tp, int flag)
-{
-
-	return (ENODEV);
-}
-
-int
-l_noread(struct tty *tp, struct uio *uio, int flag)
-{
-
-	return (ENODEV);
-}
-
-int
-l_nowrite(struct tty *tp, struct uio *uio, int flag)
-{
-
-	return (ENODEV);
-}
-
-static int
-l_norint(int c, struct tty *tp)
-{
-
-	return (ENODEV);
-}
-
-static int
-l_nostart(struct tty *tp)
-{
-
-	return (ENODEV);
-}
-
-int
-l_nullioctl(struct tty *tp, u_long cmd, char *data, int flags, struct thread *td)
-{
-
-	return (ENOIOCTL);
-}