From 2dcf8c45934e4632a7d5780afc0058554245f1f1 Mon Sep 17 00:00:00 2001
From: Michael Gmelin <grembo@FreeBSD.org>
Date: Sat, 27 Jun 2020 16:31:04 +0000
Subject: [PATCH] Document new kern.tty_info_kstacks tunable.

Reviewed by:	manpages (imp), 0mp
Differential Revision:	https://reviews.freebsd.org/D25488
---
 share/man/man4/termios.4 | 12 ++++++++++--
 1 file changed, 10 insertions(+), 2 deletions(-)

diff --git a/share/man/man4/termios.4 b/share/man/man4/termios.4
index 9478c87c158f..77d972f1534b 100644
--- a/share/man/man4/termios.4
+++ b/share/man/man4/termios.4
@@ -28,7 +28,7 @@
 .\"	@(#)termios.4	8.4 (Berkeley) 4/19/94
 .\" $FreeBSD$
 .\"
-.Dd December 26, 2009
+.Dd June 27, 2020
 .Dt TERMIOS 4
 .Os
 .Sh NAME
@@ -761,6 +761,13 @@ command in the foreground, its process ID, the symbolic
 wait channel, the number of user and system seconds used,
 the percentage of cpu the process is getting, and the resident
 set size of the process.
+.Pp
+In case the
+.Xr sysctl 8
+variable
+.Va kern.tty_info_kstacks
+is set to a non-zero value, the running thread's stack is
+written to the terminal (e.g., for debugging purposes).
 .El
 .Pp
 The
@@ -1586,4 +1593,5 @@ the values in the header
 .Xr tcsendbreak 3 ,
 .Xr tcsetattr 3 ,
 .Xr tcsetsid 3 ,
-.Xr tty 4
+.Xr tty 4 ,
+.Xr stack 9