From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail.zytor.com (terminus.zytor.com [198.137.202.136]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 380E332470A for ; Mon, 29 Jun 2026 13:59:33 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782741575; cv=none; b=lTruxCHG2frH88/e/v+XtVx1e5PlKmapRowHqyuXXuBL0f+G+yiIoavZ8GUV++ce1k/cNCaFX0wl0pGV0zHYCWWsKml83tJ97zy/V36LGdCxbFuU2SooY1QPKd7SfUMVLGngXOfWXEL/X6JwzTC/Vlgi2YzYvdaJQpRMg0gr6fs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1782741575; c=relaxed/simple; bh=w+H1ZCcMTvws8FL56ICbteoedvAJyN6sar1sjuQxxxo=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=mqoUNzlx4DZ/DMzGvQ4nV7Cgd5/ZsA8v1izPV1T4KKYyLImnDkMjkp8pF2jcRefTa+t9jh6ozHWlgU3zutFySRh0Phyf8TLmlKR38al4izlcJW+VwLUG9fe7w1NJY33D719IhxUhr6EkssPr+DnAOPiNu7kpVxhkR+zAZhSGvwE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com; spf=pass smtp.mailfrom=zytor.com; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b=RYySFaV+; arc=none smtp.client-ip=198.137.202.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=zytor.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=zytor.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=zytor.com header.i=@zytor.com header.b="RYySFaV+" Received: from mail.zytor.com ([IPv6:2601:646:8081:7da1:4462:691a:e05c:b745]) (authenticated bits=0) by mail.zytor.com (8.18.1/8.17.1) with ESMTPSA id 65TDxPvk370711 (version=TLSv1.3 cipher=TLS_AES_256_GCM_SHA384 bits=256 verify=NO); Mon, 29 Jun 2026 06:59:27 -0700 DKIM-Filter: OpenDKIM Filter v2.11.0 mail.zytor.com 65TDxPvk370711 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=zytor.com; s=2026062701; t=1782741568; bh=brzRaGiVtUBJjsBA5uAqptetg3eOg1zkqx7LzZuGLDg=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=RYySFaV+Lee1c2GJCcH6T1IH8B9x88s6JxekDEi2J/jK9WwHIbhPiq6XhqcEwnmiR fO4PUQKdxtysBWm8hJpuAeGM5YMbNI4rTQn+PZS0LQURpIx9rr+2bofXVRqY2S9S3u 1BfSlaVRzATDe3P57T1V/ckQ8M6Rpr7Uq5PbuaLUBL7j+GcvGxI151IUSxDzzHTV0H haTzcrs8NhMOPS7gv1jX1DVPg0kQxbKHnsBgGWKuAD7ZHCWG5bMkrXbAiCqGfqsT9K J+W/r9GLpaUdRUJITQwDvwQTsjOLox81o7uQscWpe7QmWOrzVL8I7VF7IwPIKBQIQO WeAqFmTtQ8Jvg== From: "H. Peter Anvin" To: Alejandro Colomar Cc: "H . Peter Anvin" , 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 Message-ID: <20260629135910.143781-4-hpa@zytor.com> X-Mailer: git-send-email 2.54.0 In-Reply-To: <20260629135910.143781-1-hpa@zytor.com> References: <20260629135910.143781-1-hpa@zytor.com> Precedence: bulk X-Mailing-List: linux-man@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 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 --- 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