patch 9.1.0321: Garbled output on serial terminals with XON/XOFF flow control Commit: https://github.com/vim/vim/commit/49528da8a60f8fd38ca491d6ccec47dfccf5f23c Author: Anton Sharonov <anton.sharonov@gmail.com> Date: Sun Apr 14 20:02:24 2024 +0200 patch 9.1.0321: Garbled output on serial terminals with XON/XOFF flow control Problem: When used terminal with XON/XOFF flow control, vim tries to still make CTRL-S mapping available, which results in severe screen corruption, especially on large redraws, and even spurious inputs (John Tsiombikas) Solution: Disallow CTRL-S mapping if such terminal is recognized. Don't remove IXON from the bitmask inversion. (Anton Sharonov) *** When started like this: TERM=vt420 vim :set termcap shows "t_xon=y" map <C-S> :echo "abc"<CR> does nothing (after <C-S> output freezes and subsequent <C-Q> unfreezes it) *** When started like this: TERM=xterm vim :set termcap shows "t_xon=" map <C-S> :echo "abc"<CR> works (after <C-S> one see "abc" string echo-ed) fixes: #12674 closes: #14542 Signed-off-by: Anton Sharonov <anton.sharonov@gmail.com> Signed-off-by: Christian Brabandt <cb@256bit.org>

--- a/runtime/doc/term.txt
+++ b/runtime/doc/term.txt
@@ -1,4 +1,4 @@
-*term.txt*      For Vim version 9.1.  Last change: 2024 Feb 28
+*term.txt*      For Vim version 9.1.  Last change: 2024 Apr 14
 
 
 		  VIM REFERENCE MANUAL    by Bram Moolenaar
@@ -382,7 +382,7 @@ The options are listed below.  The assoc
 the last two characters of the option name.  Only one termcap code is
 required: Cursor motion, 't_cm'.
 
-The options 't_da', 't_db', 't_ms', 't_xs', 't_xn' represent flags in the
+The options 't_da', 't_db', 't_ms', 't_xs', 't_xn', 't_xo' represent flags in the
 termcap.  When the termcap flag is present, the option will be set to "y".
 But any non-empty string means that the flag is set.  An empty string means
 that the flag is not set.  't_CS' works like this too, but it isn't a termcap
@@ -441,6 +441,11 @@ OUTPUT CODES						*terminal-output-codes
 								*t_xn* *'t_xn'*
 	t_xn	if non-empty, writing a character at the last screen cell
 		does not cause scrolling
+								*t_xo* *'t_xo'*
+	t_xo	if non-empty, terminal uses xon/xoff handshaking, mapping
+		CTRL-S will not be possible then, since it is used for flow
+		control (used by vt420 terminal).  Setting this flag has only
+		an effect when starting Vim.
 	t_ZH	italics mode					*t_ZH* *'t_ZH'*
 	t_ZR	italics end					*t_ZR* *'t_ZR'*