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 3/4] man/man3/termios.3: document that output baud rate has priority
Date: Mon, 29 Jun 2026 06:59:07 -0700 [thread overview]
Message-ID: <20260629135910.143781-4-hpa@zytor.com> (raw)
In-Reply-To: <20260629135910.143781-1-hpa@zytor.com>
Many devices, including the good old 8250 series UARTs, cannot handle
different input and output baud rates. POSIX defines the output rate
as taking priority, and Linux follows this. Explicitly document this.
Signed-off-by: H. Peter Anvin <hpa@zytor.com>
---
man/man3/termios.3 | 4 ++++
1 file changed, 4 insertions(+)
diff --git a/man/man3/termios.3 b/man/man3/termios.3
index f563923fc7cf..84b10cb7d68c 100644
--- a/man/man3/termios.3
+++ b/man/man3/termios.3
@@ -1127,6 +1127,10 @@ The input and output baud rates are stored in the
.I termios
structure.
.P
+If a certain device does not support different input and output
+baud rates, the output baud rate is used for both if they are
+programmed to be different.
+.P
.BR cfgetospeed ()
and
.BR cfgetobaud ()
--
2.54.0
next 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 ` H. Peter Anvin [this message]
2026-06-29 13:59 ` [PATCH v2 4/4] man/man3/termios.3: document that cfsetispeed(..., 0) is deprecated H. Peter Anvin
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