[PATCH v2 2/4] man/man3/termios.3: note that setserial(8) rate hacking is dangerous

H. Peter Anvin hpa@zytor.com
Mon Jun 29 13:59:06 GMT 2026


The use of setserial(8) to modify the 38400 baud rate was an early
hack to support baud rates beyond those standardized by POSIX. As it
is, it is a real trap for applications that actually want to use 38400
bps if a previous user has not cleaned up the setting.

Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
 man/man3/termios.3 | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/man/man3/termios.3 b/man/man3/termios.3
index cd3f9ce4d7c0..f563923fc7cf 100644
--- a/man/man3/termios.3
+++ b/man/man3/termios.3
@@ -1119,7 +1119,9 @@ constant is defined prior to using it.
 The actual bit rate corresponding to
 .B B38400
 may be altered with
-.BR setserial (8).
+.BR setserial (8);
+doing so is discouraged as it may break other applications
+later trying to use the same serial port.
 .P
 The input and output baud rates are stored in the
 .I termios
-- 
2.54.0



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