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, 39 insertions, 76 deletions

diff --git a/usr.sbin/pstat/pstat.8 b/usr.sbin/pstat/pstat.8
index 3dd67a6..c3f7e60 100644
--- a/usr.sbin/pstat/pstat.8
+++ b/usr.sbin/pstat/pstat.8
@@ -35,7 +35,7 @@
 .\"     @(#)pstat.8	8.5 (Berkeley) 5/13/94
 .\" $FreeBSD$
 .\"
-.Dd April 1, 2007
+.Dd August 20, 2008
 .Dt PSTAT 8
 .Os
 .Sh NAME
@@ -153,100 +153,63 @@ with these headings:
 .Bl -tag -width indent
 .It LINE
 Device name.
-.It RAW
-Number of characters in raw input queue.
+.It INQ
+Number of characters that can be stored in the input queue.
 .It CAN
-Number of characters in canonicalized input queue.
-.It OUT
-Number of characters in output queue.
-.It IHIWT
-High water mark for input.
-.It ILOWT
+Number of characters in the input queue which can be read.
+.It LIN
+Number of characters in the input queue which cannot be read yet.
+.It LOW
+Low water mark for input.
+.It OUTQ
+Number of characters that can be stored in the output queue.
+.It USE
+Number of bytes in the output queue.
+.It LOW
 Low water mark for input.
-.It OHWT
-High water mark for output.
-.It LWT
-Low water mark for output.
 .It COL
 Calculated column position of terminal.
+.It SESS
+Kernel address of the session structure.
+.It PGID
+Process group for which this is the controlling terminal.
 .It STATE
 Miscellaneous state variables encoded thus:
 .Pp
 .Bl -tag -width indent -compact
-.It T
-delay timeout in progress
-.It W
-waiting for open to complete
-.It O
-open
-.It F
-outq has been flushed during DMA
+.It I
+init/lock-state device nodes present
 .It C
-carrier is on
-.It c
-connection open
+callout device nodes present
+.It O
+opened
+.It G
+gone
 .It B
-busy doing output
-.It A
-process is waiting for space in output queue
-.It a
-process is waiting for output to complete
-.It X
-open for exclusive use
-.It S
-output stopped (ixon flow control)
-.It m
-output stopped (carrier flow control)
-.It o
-output stopped (CTS flow control)
-.It d
-output stopped (DSR flow control)
-.It K
-input stopped
+busy in
+.Xr open 2
 .It Y
 send SIGIO for input events
-.It D
-state for lowercase
-.Ql \e
-work
-.It E
-within a
-.Ql \e.../
-for PRTRUB
 .It L
 next character is literal
-.It P
-retyping suspended input (PENDIN)
-.It N
-counting tab width, ignore FLUSHO
+.It H
+high watermark reached
+.It X
+open for exclusive use
+.It S
+output stopped (ixon flow control)
 .It l
 block mode input routine in use
-.It s
-i/o being snooped
 .It Z
 connection lost
 .El
-.It SESS
-Kernel address of the session structure.
-.It PGID
-Process group for which this is the controlling terminal.
-.It DISC
-Line discipline;
-.Ql term
-for
-TTYDISC
-or
-.Ql ntty
-for
-NTTYDISC
-or
-.Ql slip
-for
-SLIPDISC
-or
-.Ql ppp
-for
-PPPDISC.
+.Pp
+The
+.Ql i
+and
+.Ql o
+characters refer to the previous character, to differentiate between
+input and output.
 .El
 .It Fl M
 Extract values associated with the name list from the specified core.