www.delorie.com/archives/browse.cgi   search  
Mail Archives: cygwin/2025/08/23/05:00:41

DMARC-Filter: OpenDMARC Filter v1.4.2 delorie.com 57N90eFq2638205
Authentication-Results: delorie.com; dmarc=pass (p=none dis=none) header.from=cygwin.com
Authentication-Results: delorie.com; spf=pass smtp.mailfrom=cygwin.com
DKIM-Filter: OpenDKIM Filter v2.11.0 delorie.com 57N90eFq2638205
Authentication-Results: delorie.com;
dkim=pass (1024-bit key, unprotected) header.d=cygwin.com header.i=@cygwin.com header.a=rsa-sha256 header.s=default header.b=goGq7ZUU
X-Recipient: archive-cygwin AT delorie DOT com
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org 728433858C42
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=cygwin.com;
s=default; t=1755939637;
bh=rY8TX03KSRmpZH3BrH8AXSSqXyK0BeefU6xATUbYiX0=;
h=To:Subject:Date:List-Id:List-Unsubscribe:List-Archive:List-Post:
List-Help:List-Subscribe:From:Reply-To:From;
b=goGq7ZUUz9e1Bq/HA1ed+1rGOqHirwgUYYLhbwG7hCklcQ9GYMNU2LxmuiaZ+BXqi
mYK+9vhu5FbeV5sFYtZHsksP49N7S3S9c5MFw3s3u0JOt6HAV7DWimxgA2Ki6iUmFK
6ptIoLtGUc8fVZuIN9n7/BFdNEYCxixoTQgp3TTQ=
X-Original-To: cygwin AT cygwin DOT com
Delivered-To: cygwin AT cygwin DOT com
DMARC-Filter: OpenDMARC Filter v1.4.2 sourceware.org E39BC3858D35
ARC-Filter: OpenARC Filter v1.0.0 sourceware.org E39BC3858D35
ARC-Seal: i=1; a=rsa-sha256; d=sourceware.org; s=key; t=1755939601; cv=none;
b=ZYEzjSfVK8DM05XtCmzr4GIyrQ5ZCq4+zBUd/qnL1THQHyb0bDWlCv4gCtbYptJ+O7FaW7nshRrtmMxTEpdqk3TEa1qbb83d3IafS9glCe+ZUHYtkhTmOGSfHHoRs3rPibSp4zPPCke0Y+g+ZDFMYR00DWgzpglIekBO68uuXYE=
ARC-Message-Signature: i=1; a=rsa-sha256; d=sourceware.org; s=key;
t=1755939601; c=relaxed/simple;
bh=SkjZMEc9retuYngL2Aj1sVw3v36et/MCKJGltw2ahdo=;
h=DKIM-Signature:MIME-Version:Message-ID:From:To:Subject:Date;
b=XNb4/vpTY175W9pDVnGI0AZ2YJO72Nb1cZXWfZqV3Jl90gLJbiZzlXtsJn+OFuyFgGIB1o0LvfjnPi4DSnA8U3sKr4hnF9Qo9D9YG6E3BiGCqH1kIImkPsgBk7Yx+H3rv9uwSGjFuCe+a0m8rmIcibsHulluZARo/jjLOtqLUsk=
ARC-Authentication-Results: i=1; server2.sourceware.org
DKIM-Filter: OpenDKIM Filter v2.11.0 sourceware.org E39BC3858D35
X-UI-Sender-Class: 814a7b36-bfc1-4dae-8640-3722d8ec6cd6
MIME-Version: 1.0
Message-ID: <trinity-2790f897-f2e1-4d68-902c-ba78c971033e-1755939599350@trinity-msg-rest-webde-webde-live-9664b9c5-qdngg>
To: cygwin AT cygwin DOT com
Subject: 3.6.4-1.x86_64 Windows 10 serial port issue with initial 0 baudrate
Date: Sat, 23 Aug 2025 08:59:59 +0000
X-UI-CLIENT-META-MAIL-DROP: W10=
X-Provags-ID: V03:K1:u02GjodLTkTD3R4k/5Be1jWHzmZ9v6+eXkfIrTzD1KT/VhsO676cVRwpSrGjT/T76kC80
dfaaqfOWUx1gezKvcm0YabJifxESN/kOT2RQMHINXtv73vScaJC5ZRwWzDcQymiQcN/DxRYMEbXO
sTZPlGwv+d/4ViR0Cshs/H25IYZOSPdaGg1h44Wq+/NRS6P3byzezzHh4z8PeHL88JD+VsrnUavg
wF0vkMNEe/SjFPfiRzODbAL/GXQSzHE4DMxa6COkR+fUZ3Ug+lU6F6grcC4vvzItzFXfy+sq1J9w
3vMZc2SugxPuQB0kSEhJK1t9It3ZJ9Q0XJZ3Ob/Alj3viZ6W98n4X96BKUteSX8NCtVBGvy+Oqps
5GnN8growUV
UI-OutboundReport: notjunk:1;M01:P0:UmyZKNgk/eA=;/0wHwBe5WTcZMiab2JM4KwNeuc6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X-BeenThere: cygwin AT cygwin DOT com
X-Mailman-Version: 2.1.30
List-Id: General Cygwin discussions and problem reports <cygwin.cygwin.com>
List-Archive: <https://cygwin.com/pipermail/cygwin/>
List-Post: <mailto:cygwin AT cygwin DOT com>
List-Help: <mailto:cygwin-request AT cygwin DOT com?subject=help>
List-Subscribe: <https://cygwin.com/mailman/listinfo/cygwin>,
<mailto:cygwin-request AT cygwin DOT com?subject=subscribe>
From: =?utf-8?q?Stefan_Alth=C3=B6fer_via_Cygwin?= <cygwin AT cygwin DOT com>
Reply-To: =?UTF-8?Q?Stefan_Alth=C3=B6fer?= <Stefan DOT Althoefer AT web DOT de>
Sender: "Cygwin" <cygwin-bounces~archive-cygwin=delorie DOT com AT cygwin DOT com>
X-MIME-Autoconverted: from base64 to 8bit by delorie.com id 57N90eFq2638205

Hi all,

I have a USB based serial port device (/dev/ttySxx) which does not work when
beeing used with cygwin programs (e.g. getty or even python).

It seems this is because the baudrate is initially zero after the device
has been created:

  $ /cygdrive/c/Windows/System32/mode.com COM72
  Status von Gerät COM72:
  -----------------------
      Baudrate:        0
      Parität:         None
      Datenbits:       0
      Stoppbits:       1
      Timeout:       OFF
      XON/XOFF:        OFF
      CTS-Handshaking: OFF
      DSR-Handshaking: OFF
      DSR-Prüfung:     OFF
      DTR-Signal:      OFF
      RTS-Signal:      ON

This makes tcgetattr fail when beeing used on this device.

  119  117652 [main] stty 2325 fcntl: 0 = fcntl(0, 4, 0x10000)
  732  118384 [main] stty 2325 fhandler_serial::tcgetattr: Invalid baud rate 0
  111  118495 [main] stty 2325 __set_errno: virtual int fhandler_serial::tcgetattr(termios*):1027 setting errno 22
  116  118611 [main] stty 2325 tcgetattr: -1 = tcgetattr(0, 0x100419060), errno 22

I assume that allmost all programs use tcgetattr before partially changing
parameters in the struct that is returned.

I suggest not to make tcgetattr fail in this case, but return B0 instead. User programs
will most likely change the bitrate setting anyhow.

After setting an initial baudrate with mode.com, the device works well with cygwin.

Regards,
Stefan Althöfer

-- 
Problem reports:      https://cygwin.com/problems.html
FAQ:                  https://cygwin.com/faq/
Documentation:        https://cygwin.com/docs.html
Unsubscribe info:     https://cygwin.com/ml/#unsubscribe-simple

- Raw text -


  webmaster     delorie software   privacy  
  Copyright © 2019   by DJ Delorie     Updated Jul 2019