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

18 files changed, 464 insertions, 181 deletions

diff --git a/sys/sys/conf.h b/sys/sys/conf.h
index 739c3fe..8128fa7 100644
--- a/sys/sys/conf.h
+++ b/sys/sys/conf.h
@@ -46,7 +46,6 @@
 #include <sys/queue.h>
 #endif
 
-struct tty;
 struct snapdata;
 struct devfs_dirent;
 struct cdevsw;
@@ -85,13 +84,11 @@ struct cdev {
 	u_long		si_usecount;
 	u_long		si_threadcount;
 	union {
-		struct tty *__sit_tty;
 		struct snapdata *__sid_snapdata;
 	} __si_u;
 	char		__si_namebuf[SPECNAMELEN + 1];
 };
 
-#define si_tty		__si_u.__sit_tty
 #define si_snapdata	__si_u.__sid_snapdata
 
 #ifdef _KERNEL
diff --git a/sys/sys/file.h b/sys/sys/file.h
index 6f7dc00..461b7e8 100644
--- a/sys/sys/file.h
+++ b/sys/sys/file.h
@@ -62,6 +62,7 @@ struct socket;
 #define	DTYPE_MQUEUE	7	/* posix message queue */
 #define	DTYPE_SHM	8	/* swap-backed shared memory */
 #define	DTYPE_SEM	9	/* posix semaphore */
+#define	DTYPE_PTS	10	/* pseudo teletype master device */
 
 #ifdef _KERNEL
 
diff --git a/sys/sys/linedisc.h b/sys/sys/linedisc.h
deleted file mode 100644
index 659aa4b..0000000
--- a/sys/sys/linedisc.h
+++ /dev/null
@@ -1,141 +0,0 @@
-/*-
- * Copyright (c) 1990, 1993
- *	The Regents of the University of California.  All rights reserved.
- * Copyright (c) 2004
- *	Poul-Henning Kamp.  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.
- *
- *	@(#)conf.h	8.5 (Berkeley) 1/9/95
- * $FreeBSD$
- */
-
-#ifndef _SYS_LINEDISC_H_
-#define	_SYS_LINEDISC_H_
-
-#ifdef _KERNEL
-
-struct tty;
-
-typedef int l_open_t(struct cdev *dev, struct tty *tp);
-typedef int l_close_t(struct tty *tp, int flag);
-typedef int l_read_t(struct tty *tp, struct uio *uio, int flag);
-typedef int l_write_t(struct tty *tp, struct uio *uio, int flag);
-typedef int l_ioctl_t(struct tty *tp, u_long cmd, caddr_t data,
-		      int flag, struct thread *td);
-typedef int l_rint_t(int c, struct tty *tp);
-typedef int l_start_t(struct tty *tp);
-typedef int l_modem_t(struct tty *tp, int flag);
-
-/*
- * Line discipline switch table
- */
-struct linesw {
-	l_open_t	*l_open;
-	l_close_t	*l_close;
-	l_read_t	*l_read;
-	l_write_t	*l_write;
-	l_ioctl_t	*l_ioctl;
-	l_rint_t	*l_rint;
-	l_start_t	*l_start;
-	l_modem_t	*l_modem;
-};
-
-extern struct linesw *linesw[];
-extern int nlinesw;
-
-int ldisc_register(int , struct linesw *);
-void ldisc_deregister(int);
-#define LDISC_LOAD 	-1		/* Loadable line discipline */
-
-l_read_t	l_noread;
-l_write_t	l_nowrite;
-l_ioctl_t	l_nullioctl;
-
-static __inline int
-ttyld_open(struct tty *tp, struct cdev *dev)
-{
-
-	return ((*linesw[tp->t_line]->l_open)(dev, tp));
-}
-
-static __inline int
-ttyld_close(struct tty *tp, int flag)
-{
-
-	return ((*linesw[tp->t_line]->l_close)(tp, flag));
-}
-
-static __inline int
-ttyld_read(struct tty *tp, struct uio *uio, int flag)
-{
-
-	return ((*linesw[tp->t_line]->l_read)(tp, uio, flag));
-}
-
-static __inline int
-ttyld_write(struct tty *tp, struct uio *uio, int flag)
-{
-
-	return ((*linesw[tp->t_line]->l_write)(tp, uio, flag));
-}
-
-static __inline int
-ttyld_ioctl(struct tty *tp, u_long cmd, caddr_t data, int flag,
-    struct thread *td)
-{
-
-	return ((*linesw[tp->t_line]->l_ioctl)(tp, cmd, data, flag, td));
-}
-
-static __inline int
-ttyld_rint(struct tty *tp, int c)
-{
-
-	return ((*linesw[tp->t_line]->l_rint)(c, tp));
-}
-
-static __inline int
-ttyld_start(struct tty *tp)
-{
-
-	return ((*linesw[tp->t_line]->l_start)(tp));
-}
-
-static __inline int
-ttyld_modem(struct tty *tp, int flag)
-{
-
-	return ((*linesw[tp->t_line]->l_modem)(tp, flag));
-}
-
-#endif /* _KERNEL */
-
-#endif /* !_SYS_LINEDISC_H_ */
diff --git a/sys/sys/param.h b/sys/sys/param.h
index 773f24f..c0415b0 100644
--- a/sys/sys/param.h
+++ b/sys/sys/param.h
@@ -57,7 +57,7 @@
  *		is created, otherwise 1.
  */
 #undef __FreeBSD_version
-#define __FreeBSD_version 800044	/* Master, propagated to newvers */
+#define __FreeBSD_version 800045	/* Master, propagated to newvers */
 
 #ifndef LOCORE
 #include <sys/types.h>
diff --git a/sys/sys/proc.h b/sys/sys/proc.h
index 3779591..0b919b2 100644
--- a/sys/sys/proc.h
+++ b/sys/sys/proc.h
@@ -72,10 +72,10 @@
  * (c)		const until freeing
  */
 struct session {
-	int		s_count;	/* (m) Ref cnt; pgrps in session. */
+	u_int		s_count;	/* Ref cnt; pgrps in session - atomic. */
 	struct proc	*s_leader;	/* (m + e) Session leader. */
 	struct vnode	*s_ttyvp;	/* (m) Vnode of controlling tty. */
-	struct tty	*s_ttyp;	/* (m) Controlling tty. */
+	struct tty	*s_ttyp;	/* (e) Controlling tty. */
 	pid_t		s_sid;		/* (c) Session ID. */
 					/* (m) Setlogin() name: */
 	char		s_login[roundup(MAXLOGNAME, sizeof(long))];
@@ -644,8 +644,6 @@ MALLOC_DECLARE(M_ZOMBIE);
 #define	NO_PID		100000
 
 #define	SESS_LEADER(p)	((p)->p_session->s_leader == (p))
-#define	SESSHOLD(s)	((s)->s_count++)
-#define	SESSRELE(s)	sessrele(s)
 
 
 #define	STOPEVENT(p, e, v) do {						\
@@ -807,7 +805,8 @@ void	pstats_fork(struct pstats *src, struct pstats *dst);
 void	pstats_free(struct pstats *ps);
 int	securelevel_ge(struct ucred *cr, int level);
 int	securelevel_gt(struct ucred *cr, int level);
-void	sessrele(struct session *);
+void	sess_hold(struct session *);
+void	sess_release(struct session *);
 int	setrunnable(struct thread *);
 void	setsugid(struct proc *p);
 int	sigonstack(size_t sp);
diff --git a/sys/sys/resource.h b/sys/sys/resource.h
index d01b0bd..03fbd70 100644
--- a/sys/sys/resource.h
+++ b/sys/sys/resource.h
@@ -93,8 +93,9 @@ struct rusage {
 #define	RLIMIT_SBSIZE	9		/* maximum size of all socket buffers */
 #define RLIMIT_VMEM	10		/* virtual process size (inclusive of mmap) */
 #define	RLIMIT_AS	RLIMIT_VMEM	/* standard name for RLIMIT_VMEM */
+#define	RLIMIT_NPTS	11		/* pseudo-terminals */
 
-#define	RLIM_NLIMITS	11		/* number of resource limits */
+#define	RLIM_NLIMITS	12		/* number of resource limits */
 
 #define	RLIM_INFINITY	((rlim_t)(((uint64_t)1 << 63) - 1))
 /* XXX Missing: RLIM_SAVED_MAX, RLIM_SAVED_CUR */
diff --git a/sys/sys/resourcevar.h b/sys/sys/resourcevar.h
index cd80cd4..0a867d1 100644
--- a/sys/sys/resourcevar.h
+++ b/sys/sys/resourcevar.h
@@ -91,6 +91,7 @@ struct uidinfo {
 	LIST_ENTRY(uidinfo) ui_hash;	/* (c) hash chain of uidinfos */
 	long	ui_sbsize;		/* (b) socket buffer space consumed */
 	long	ui_proccnt;		/* (b) number of processes */
+	long	ui_ptscnt;		/* (b) number of pseudo-terminals */
 	uid_t	ui_uid;			/* (a) uid */
 	u_int	ui_ref;			/* (b) reference count */
 };
@@ -106,6 +107,7 @@ void	 calcru(struct proc *p, struct timeval *up, struct timeval *sp);
 int	 chgproccnt(struct uidinfo *uip, int diff, rlim_t maxval);
 int	 chgsbsize(struct uidinfo *uip, u_int *hiwat, u_int to,
 	    rlim_t maxval);
+int	 chgptscnt(struct uidinfo *uip, int diff, rlim_t maxval);
 int	 fuswintr(void *base);
 struct plimit
 	*lim_alloc(void);
diff --git a/sys/sys/syscall.h b/sys/sys/syscall.h
index 3b1b2c1..a92fc9f 100644
--- a/sys/sys/syscall.h
+++ b/sys/sys/syscall.h
@@ -3,7 +3,7 @@
  *
  * DO NOT EDIT-- this file is automatically generated.
  * $FreeBSD$
- * created from FreeBSD: src/sys/kern/syscalls.master,v 1.242 2008/03/31 12:06:55 kib Exp 
+ * created from FreeBSD: head/sys/kern/syscalls.master 178888 2008-05-09 23:03:00Z julian 
  */
 
 #define	SYS_syscall	0
@@ -419,4 +419,5 @@
 #define	SYS_renameat	501
 #define	SYS_symlinkat	502
 #define	SYS_unlinkat	503
-#define	SYS_MAXSYSCALL	504
+#define	SYS_posix_openpt	504
+#define	SYS_MAXSYSCALL	505
diff --git a/sys/sys/syscall.mk b/sys/sys/syscall.mk
index b0172f4..b09938a 100644
--- a/sys/sys/syscall.mk
+++ b/sys/sys/syscall.mk
@@ -1,7 +1,7 @@
 # FreeBSD system call names.
 # DO NOT EDIT-- this file is automatically generated.
 # $FreeBSD$
-# created from FreeBSD: src/sys/kern/syscalls.master,v 1.242 2008/03/31 12:06:55 kib Exp 
+# created from FreeBSD: head/sys/kern/syscalls.master 178888 2008-05-09 23:03:00Z julian 
 MIASM =  \
 	syscall.o \
 	exit.o \
@@ -367,4 +367,5 @@ MIASM =  \
 	readlinkat.o \
 	renameat.o \
 	symlinkat.o \
-	unlinkat.o
+	unlinkat.o \
+	posix_openpt.o
diff --git a/sys/sys/sysproto.h b/sys/sys/sysproto.h
index feb582a..fe2a229 100644
--- a/sys/sys/sysproto.h
+++ b/sys/sys/sysproto.h
@@ -3,7 +3,7 @@
  *
  * DO NOT EDIT-- this file is automatically generated.
  * $FreeBSD$
- * created from FreeBSD: src/sys/kern/syscalls.master,v 1.242 2008/03/31 12:06:55 kib Exp 
+ * created from FreeBSD: head/sys/kern/syscalls.master 178888 2008-05-09 23:03:00Z julian 
  */
 
 #ifndef _SYS_SYSPROTO_H_
@@ -1630,6 +1630,9 @@ struct unlinkat_args {
 	char path_l_[PADL_(char *)]; char * path; char path_r_[PADR_(char *)];
 	char flag_l_[PADL_(int)]; int flag; char flag_r_[PADR_(int)];
 };
+struct posix_openpt_args {
+	char flags_l_[PADL_(int)]; int flags; char flags_r_[PADR_(int)];
+};
 int	nosys(struct thread *, struct nosys_args *);
 void	sys_exit(struct thread *, struct sys_exit_args *);
 int	fork(struct thread *, struct fork_args *);
@@ -1987,6 +1990,7 @@ int	readlinkat(struct thread *, struct readlinkat_args *);
 int	renameat(struct thread *, struct renameat_args *);
 int	symlinkat(struct thread *, struct symlinkat_args *);
 int	unlinkat(struct thread *, struct unlinkat_args *);
+int	posix_openpt(struct thread *, struct posix_openpt_args *);
 
 #ifdef COMPAT_43
 
@@ -2569,6 +2573,7 @@ int	freebsd4_sigreturn(struct thread *, struct freebsd4_sigreturn_args *);
 #define	SYS_AUE_renameat	AUE_RENAMEAT
 #define	SYS_AUE_symlinkat	AUE_SYMLINKAT
 #define	SYS_AUE_unlinkat	AUE_UNLINKAT
+#define	SYS_AUE_posix_openpt	AUE_POSIXOPENPT
 
 #undef PAD_
 #undef PADL_
diff --git a/sys/sys/termios.h b/sys/sys/termios.h
index 00259f1..7defbd3 100644
--- a/sys/sys/termios.h
+++ b/sys/sys/termios.h
@@ -83,10 +83,6 @@ typedef	__pid_t		pid_t;
 
 #define	_POSIX_VDISABLE	0xff
 
-#ifndef _POSIX_SOURCE
-#define	CCEQ(val, c)	((c) == (val) ? (val) != _POSIX_VDISABLE : 0)
-#endif
-
 /*
  * Input flags - software input processing
  */
@@ -112,7 +108,12 @@ typedef	__pid_t		pid_t;
 #define	OPOST		0x00000001	/* enable following output processing */
 #ifndef _POSIX_SOURCE
 #define ONLCR		0x00000002	/* map NL to CR-NL (ala CRMOD) */
-#define OXTABS		0x00000004	/* expand tabs to spaces */
+#define	TABDLY		0x00000004	/* tab delay mask */
+#define	    TAB0	    0x00000000	    /* no tab delay and expansion */
+#define	    TAB3	    0x00000004	    /* expand tabs to spaces */
+#ifndef _KERNEL
+#define	OXTABS		TAB3
+#endif /* !_KERNEL */
 #define ONOEOT		0x00000008	/* discard EOT's (^D) on output) */
 #define OCRNL		0x00000010	/* map CR to NL on output */
 #define ONOCR		0x00000020	/* no CR output at column 0 */
@@ -143,7 +144,9 @@ typedef	__pid_t		pid_t;
 #define	CDTR_IFLOW	0x00040000	/* DTR flow control of input */
 #define CDSR_OFLOW	0x00080000	/* DSR flow control of output */
 #define	CCAR_OFLOW	0x00100000	/* DCD flow control of output */
-#define	MDMBUF		0x00100000	/* old name for CCAR_OFLOW */
+#ifndef _KERNEL
+#define	MDMBUF		CCAR_OFLOW
+#endif /* !_KERNEL */
 #endif
 
 
@@ -230,6 +233,10 @@ struct termios {
 
 #ifndef _KERNEL
 
+#ifndef _POSIX_SOURCE
+#define	CCEQ(val, c)	((c) != _POSIX_VDISABLE && (c) == (val))
+#endif
+
 /*
  * Commands passed to tcsetattr() for setting the termios structure.
  */
diff --git a/sys/sys/tty.h b/sys/sys/tty.h
index e887a2a..8e0e77d 100644
--- a/sys/sys/tty.h
+++ b/sys/sys/tty.h
@@ -1,19 +1,9 @@
 /*-
- * Copyright (c) 1982, 1986, 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.
- *
- * Copyright (c) 2002 Networks Associates Technologies, Inc.
+ * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
  * All rights reserved.
  *
- * Portions of this software were developed for the FreeBSD Project by
- * ThinkSec AS and NAI Labs, the Security Research Division of Network
- * Associates, Inc.  under DARPA/SPAWAR contract N66001-01-C-8035
- * ("CBOSS"), as part of the DARPA CHATS research program.
+ * Portions of this software were developed under sponsorship from Snow
+ * B.V., the Netherlands.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
@@ -23,14 +13,11 @@
  * 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
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR 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)
diff --git a/sys/sys/ttycom.h b/sys/sys/ttycom.h
index 1d97ab3..60b6145 100644
--- a/sys/sys/ttycom.h
+++ b/sys/sys/ttycom.h
@@ -73,7 +73,8 @@ struct winsize {
 						/* 23-25 obsolete or unused */
 #define	TIOCGETD	_IOR('t', 26, int)	/* get line discipline */
 #define	TIOCSETD	_IOW('t', 27, int)	/* set line discipline */
-						/* 28-69 free */
+#define	TIOCPTMASTER	 _IO('t', 28)		/* pts master validation */
+						/* 29-69 free */
 						/* 80-84 slip */
 #define	TIOCGDRAINWAIT	_IOR('t', 86, int)	/* get ttywait timeout */
 #define	TIOCSDRAINWAIT	_IOW('t', 87, int)	/* set ttywait timeout */
diff --git a/sys/sys/ttydefaults.h b/sys/sys/ttydefaults.h
index 5813bda..d120fb0 100644
--- a/sys/sys/ttydefaults.h
+++ b/sys/sys/ttydefaults.h
@@ -52,6 +52,7 @@
 #define	TTYDEF_LFLAG TTYDEF_LFLAG_ECHO
 #define	TTYDEF_CFLAG	(CREAD | CS8 | HUPCL)
 #define	TTYDEF_SPEED	(B9600)
+#define	TTYDEF_SPEED_PSEUDO (B38400)
 
 /*
  * Control Character Defaults
diff --git a/sys/sys/ttydevsw.h b/sys/sys/ttydevsw.h
new file mode 100644
index 0000000..a4f5afb
--- /dev/null
+++ b/sys/sys/ttydevsw.h
@@ -0,0 +1,158 @@
+/*-
+ * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Portions of this software were developed under sponsorship from Snow
+ * B.V., the Netherlands.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _SYS_TTYDEVSW_H_
+#define	_SYS_TTYDEVSW_H_
+
+#ifndef _SYS_TTY_H_
+#error "can only be included through <sys/tty.h>"
+#endif /* !_SYS_TTY_H_ */
+
+/*
+ * Driver routines that are called from the line discipline to adjust
+ * hardware parameters and such.
+ */
+typedef int tsw_open_t(struct tty *);
+typedef void tsw_close_t(struct tty *);
+typedef void tsw_outwakeup_t(struct tty *);
+typedef void tsw_inwakeup_t(struct tty *);
+typedef int tsw_ioctl_t(struct tty *, u_long, caddr_t, struct thread *);
+typedef int tsw_param_t(struct tty *, struct termios *);
+typedef int tsw_modem_t(struct tty *, int, int);
+typedef int tsw_mmap_t(struct tty *, vm_offset_t, vm_paddr_t *, int);
+typedef void tsw_free_t(void *);
+
+struct ttydevsw {
+	unsigned int	tsw_flags;	/* Default TTY flags. */
+
+	tsw_open_t	*tsw_open;	/* Device opening. */
+	tsw_close_t	*tsw_close;	/* Device closure. */
+
+	tsw_outwakeup_t	*tsw_outwakeup;	/* Output available. */
+	tsw_inwakeup_t	*tsw_inwakeup;	/* Input can be stored again. */
+
+	tsw_ioctl_t	*tsw_ioctl;	/* ioctl() hooks. */
+	tsw_param_t	*tsw_param;	/* TIOCSETA device parameter setting. */
+	tsw_modem_t	*tsw_modem;	/* Modem sigon/sigoff. */
+
+	tsw_mmap_t	*tsw_mmap;	/* mmap() hooks. */
+
+	tsw_free_t	*tsw_free;	/* Destructor. */
+};
+
+static __inline int
+ttydevsw_open(struct tty *tp)
+{
+	tty_lock_assert(tp, MA_OWNED);
+	MPASS(!tty_gone(tp));
+
+	return tp->t_devsw->tsw_open(tp);
+}
+
+static __inline void
+ttydevsw_close(struct tty *tp)
+{
+	tty_lock_assert(tp, MA_OWNED);
+	MPASS(!tty_gone(tp));
+
+	tp->t_devsw->tsw_close(tp);
+}
+
+static __inline void
+ttydevsw_outwakeup(struct tty *tp)
+{
+	tty_lock_assert(tp, MA_OWNED);
+	MPASS(!tty_gone(tp));
+
+	/* Prevent spurious wakeups. */
+	if (tp->t_flags & TF_STOPPED)
+		return;
+	if (ttyoutq_bytesused(&tp->t_outq) == 0)
+		return;
+
+	tp->t_devsw->tsw_outwakeup(tp);
+}
+
+static __inline void
+ttydevsw_inwakeup(struct tty *tp)
+{
+	tty_lock_assert(tp, MA_OWNED);
+	MPASS(!tty_gone(tp));
+
+	/* Prevent spurious wakeups. */
+	if (tp->t_flags & TF_HIWAT_IN)
+		return;
+
+	tp->t_devsw->tsw_inwakeup(tp);
+}
+
+static __inline int
+ttydevsw_ioctl(struct tty *tp, u_long cmd, caddr_t data, struct thread *td)
+{
+	tty_lock_assert(tp, MA_OWNED);
+	MPASS(!tty_gone(tp));
+
+	return tp->t_devsw->tsw_ioctl(tp, cmd, data, td);
+}
+
+static __inline int
+ttydevsw_param(struct tty *tp, struct termios *t)
+{
+	MPASS(!tty_gone(tp));
+
+	return tp->t_devsw->tsw_param(tp, t);
+}
+
+static __inline int
+ttydevsw_modem(struct tty *tp, int sigon, int sigoff)
+{
+	MPASS(!tty_gone(tp));
+
+	return tp->t_devsw->tsw_modem(tp, sigon, sigoff);
+}
+
+static __inline int
+ttydevsw_mmap(struct tty *tp, vm_offset_t offset, vm_paddr_t *paddr, int nprot)
+{
+	MPASS(!tty_gone(tp));
+
+	return tp->t_devsw->tsw_mmap(tp, offset, paddr, nprot);
+}
+
+static __inline void
+ttydevsw_free(struct tty *tp)
+{
+	MPASS(tty_gone(tp));
+
+	tp->t_devsw->tsw_free(tty_softc(tp));
+}
+
+#endif /* !_SYS_TTYDEVSW_H_ */
diff --git a/sys/sys/ttydisc.h b/sys/sys/ttydisc.h
new file mode 100644
index 0000000..dd170e6
--- /dev/null
+++ b/sys/sys/ttydisc.h
@@ -0,0 +1,105 @@
+/*-
+ * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Portions of this software were developed under sponsorship from Snow
+ * B.V., the Netherlands.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _SYS_TTYDISC_H_
+#define	_SYS_TTYDISC_H_
+
+#ifndef _SYS_TTY_H_
+#error "can only be included through <sys/tty.h>"
+#endif /* !_SYS_TTY_H_ */
+
+struct cv;
+struct thread;
+struct tty;
+struct uio;
+
+/* Top half routines. */
+void	ttydisc_open(struct tty *);
+void	ttydisc_close(struct tty *);
+int	ttydisc_read(struct tty *, struct uio *, int);
+int	ttydisc_write(struct tty *, struct uio *, int);
+void	ttydisc_optimize(struct tty *);
+
+/* Bottom half routines. */
+void	ttydisc_modem(struct tty *, int);
+#define ttydisc_can_bypass(tp) ((tp)->t_flags & TF_BYPASS)
+int	ttydisc_rint(struct tty *, char, int);
+size_t	ttydisc_rint_bypass(struct tty *, char *, size_t);
+void	ttydisc_rint_done(struct tty *);
+size_t	ttydisc_getc(struct tty *, void *buf, size_t);
+int	ttydisc_getc_uio(struct tty *, struct uio *);
+
+/* Error codes for ttydisc_rint(). */
+#define	TRE_FRAMING	0x01
+#define	TRE_PARITY	0x02
+#define	TRE_OVERRUN	0x04
+#define	TRE_BREAK	0x08
+
+static __inline size_t
+ttydisc_read_poll(struct tty *tp)
+{
+
+	tty_lock_assert(tp, MA_OWNED);
+
+	return ttyinq_bytescanonicalized(&tp->t_inq);
+}
+
+static __inline size_t
+ttydisc_write_poll(struct tty *tp)
+{
+
+	tty_lock_assert(tp, MA_OWNED);
+
+	return ttyoutq_bytesleft(&tp->t_outq);
+}
+
+static __inline size_t
+ttydisc_rint_poll(struct tty *tp)
+{
+
+	tty_lock_assert(tp, MA_OWNED);
+
+	return ttyinq_bytesleft(&tp->t_inq);
+}
+
+static __inline size_t
+ttydisc_getc_poll(struct tty *tp)
+{
+
+	tty_lock_assert(tp, MA_OWNED);
+
+	if (tp->t_flags & TF_STOPPED)
+		return (0);
+
+	return ttyoutq_bytesused(&tp->t_outq);
+}
+
+#endif /* !_SYS_TTYDISC_H_ */
diff --git a/sys/sys/ttyqueue.h b/sys/sys/ttyqueue.h
new file mode 100644
index 0000000..3e72fef
--- /dev/null
+++ b/sys/sys/ttyqueue.h
@@ -0,0 +1,157 @@
+/*-
+ * Copyright (c) 2008 Ed Schouten <ed@FreeBSD.org>
+ * All rights reserved.
+ *
+ * Portions of this software were developed under sponsorship from Snow
+ * B.V., the Netherlands.
+ *
+ * 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.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 AUTHOR 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.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef _SYS_TTYQUEUE_H_
+#define	_SYS_TTYQUEUE_H_
+
+#ifndef _SYS_TTY_H_
+#error "can only be included through <sys/tty.h>"
+#endif /* !_SYS_TTY_H_ */
+
+struct tty;
+struct ttyinq_block;
+struct ttyoutq_block;
+struct uio;
+
+/* Data input queue. */
+struct ttyinq {
+	TAILQ_HEAD(ttyinq_bhead, ttyinq_block) ti_list;
+	struct ttyinq_block		*ti_startblock;
+	struct ttyinq_block		*ti_reprintblock;
+	struct ttyinq_block		*ti_lastblock;
+	unsigned int			ti_begin;
+	unsigned int			ti_linestart;
+	unsigned int			ti_reprint;
+	unsigned int			ti_end;
+	unsigned int			ti_nblocks;
+};
+#define TTYINQ_DATASIZE 128
+
+/* Data output queue. */
+struct ttyoutq {
+	STAILQ_HEAD(, ttyoutq_block)	to_list;
+	struct ttyoutq_block		*to_lastblock;
+	unsigned int			to_begin;
+	unsigned int			to_end;
+	unsigned int			to_nblocks;
+};
+#define TTYOUTQ_DATASIZE (256 - sizeof(STAILQ_ENTRY(ttyoutq_block)))
+
+#ifdef _KERNEL
+/* Input queue handling routines. */
+void	ttyinq_setsize(struct ttyinq *, struct tty *, size_t);
+int	ttyinq_read_uio(struct ttyinq *, struct tty *, struct uio *,
+    size_t, size_t);
+size_t	ttyinq_write(struct ttyinq *, const void *, size_t, int);
+int	ttyinq_write_nofrag(struct ttyinq *, const void *, size_t, int);
+void	ttyinq_canonicalize(struct ttyinq *);
+size_t	ttyinq_findchar(struct ttyinq *, const char *, size_t, char *);
+void	ttyinq_flush(struct ttyinq *);
+int	ttyinq_peekchar(struct ttyinq *, char *, int *);
+void	ttyinq_unputchar(struct ttyinq *);
+void	ttyinq_reprintpos_set(struct ttyinq *);
+void	ttyinq_reprintpos_reset(struct ttyinq *);
+
+static __inline size_t
+ttyinq_getsize(struct ttyinq *ti)
+{
+	return (ti->ti_nblocks * TTYINQ_DATASIZE);
+}
+
+static __inline size_t
+ttyinq_bytesleft(struct ttyinq *ti)
+{
+	size_t len;
+
+	/* Make sure the usage never exceeds the length. */
+	len = ti->ti_nblocks * TTYINQ_DATASIZE;
+	MPASS(len >= ti->ti_end);
+
+	return (len - ti->ti_end);
+}
+
+static __inline size_t
+ttyinq_bytescanonicalized(struct ttyinq *ti)
+{
+	MPASS(ti->ti_begin <= ti->ti_linestart);
+
+	return (ti->ti_linestart - ti->ti_begin);
+}
+
+static __inline size_t
+ttyinq_bytesline(struct ttyinq *ti)
+{
+	MPASS(ti->ti_linestart <= ti->ti_end);
+
+	return (ti->ti_end - ti->ti_linestart);
+}
+
+/* Input buffer iteration. */
+typedef void ttyinq_line_iterator_t(void *, char, int);
+void	ttyinq_line_iterate_from_linestart(struct ttyinq *,
+    ttyinq_line_iterator_t *, void *);
+void	ttyinq_line_iterate_from_reprintpos(struct ttyinq *,
+    ttyinq_line_iterator_t *, void *);
+
+/* Output queue handling routines. */
+void	ttyoutq_flush(struct ttyoutq *);
+void	ttyoutq_setsize(struct ttyoutq *, struct tty *, size_t);
+size_t	ttyoutq_read(struct ttyoutq *, void *, size_t);
+int	ttyoutq_read_uio(struct ttyoutq *, struct tty *, struct uio *);
+size_t	ttyoutq_write(struct ttyoutq *, const void *, size_t);
+int	ttyoutq_write_nofrag(struct ttyoutq *, const void *, size_t);
+
+static __inline size_t
+ttyoutq_getsize(struct ttyoutq *to)
+{
+	return (to->to_nblocks * TTYOUTQ_DATASIZE);
+}
+
+static __inline size_t
+ttyoutq_bytesleft(struct ttyoutq *to)
+{
+	size_t len;
+
+	/* Make sure the usage never exceeds the length. */
+	len = to->to_nblocks * TTYOUTQ_DATASIZE;
+	MPASS(len >= to->to_end);
+
+	return (len - to->to_end);
+}
+
+static __inline size_t
+ttyoutq_bytesused(struct ttyoutq *to)
+{
+	return (to->to_end - to->to_begin);
+}
+#endif /* _KERNEL */
+
+#endif /* !_SYS_TTYQUEUE_H_ */
diff --git a/sys/sys/user.h b/sys/sys/user.h
index e8b6a1f..0af8528 100644
--- a/sys/sys/user.h
+++ b/sys/sys/user.h
@@ -250,6 +250,7 @@ struct user {
 #define	KF_TYPE_MQUEUE	7
 #define	KF_TYPE_SHM	8
 #define	KF_TYPE_SEM	9
+#define	KF_TYPE_PTS	10
 #define	KF_TYPE_UNKNOWN	255
 
 #define	KF_VTYPE_VNON	0