From: "H. Peter Anvin" <hpa@zytor.com>
To: Alejandro Colomar <alx@kernel.org>
Cc: "H . Peter Anvin" <hpa@zytor.com>,
linux-man@vger.kernel.org, libc-alpha@sourceware.org
Subject: [PATCH v2 4/4] man/man3/termios.3: document that cfsetispeed(..., 0) is deprecated
Date: Mon, 29 Jun 2026 06:59:08 -0700 [thread overview]
Message-ID: <20260629135910.143781-5-hpa@zytor.com> (raw)
In-Reply-To: <20260629135910.143781-1-hpa@zytor.com>
POSIX.1-2024 deprecated cfsetispeed(..., 0). This was always rather
confusing, since all other uses of speed_t use the Bnnn symbolic
constants, although B0 == 0 was largely universal.
Document that setting the input speed to numeric-zero meaning the same
as the output speed is deprecated, and applications should explicitly
set it to the same value as the output baud rate instead.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
man/man3/termios.3 | 3 +++
1 file changed, 3 insertions(+)
diff --git a/man/man3/termios.3 b/man/man3/termios.3
index 84b10cb7d68c..9a606e689e80 100644
--- a/man/man3/termios.3
+++ b/man/man3/termios.3
@@ -1182,6 +1182,9 @@ even when using
the input baud rate
will be equal to the output baud rate.
.P
+POSIX.1-2024 deprecated this; new code should explicitly set both the
+input and output baud rates to the same value.
+.P
.BR cfsetspeed ()
is a 4.4BSD extension.
It takes the same arguments as
--
2.54.0
prev parent reply other threads:[~2026-06-29 13:59 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-06-29 6:02 [PATCH 1/1] man/man3*: document the glibc 2.42+ baud_t termios interface H. Peter Anvin
2026-06-29 9:51 ` Alejandro Colomar
2026-06-29 13:59 ` [PATCH v2 0/4] update termios(3) for glibc 2.42+ and POSIX.1-2024 H. Peter Anvin
2026-06-29 13:59 ` [PATCH v2 1/4] man/man3*: document the glibc 2.42+ baud_t termios interface H. Peter Anvin
2026-06-30 10:39 ` Alejandro Colomar
2026-06-30 20:37 ` H. Peter Anvin
2026-06-30 21:17 ` Alejandro Colomar
2026-06-30 22:01 ` H. Peter Anvin
2026-07-01 14:53 ` Alejandro Colomar
2026-06-30 22:50 ` G. Branden Robinson
2026-06-30 20:41 ` H. Peter Anvin
2026-06-30 21:19 ` Alejandro Colomar
2026-06-29 13:59 ` [PATCH v2 2/4] man/man3/termios.3: note that setserial(8) rate hacking is dangerous H. Peter Anvin
2026-06-30 9:15 ` Alejandro Colomar
2026-06-29 13:59 ` [PATCH v2 3/4] man/man3/termios.3: document that output baud rate has priority H. Peter Anvin
2026-06-29 13:59 ` H. Peter Anvin [this message]
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