From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262497AbVGFXq4 (ORCPT ); Wed, 6 Jul 2005 19:46:56 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262493AbVGFUHn (ORCPT ); Wed, 6 Jul 2005 16:07:43 -0400 Received: from tag.witbe.net ([81.88.96.48]:401 "EHLO tag.witbe.net") by vger.kernel.org with ESMTP id S262465AbVGFSgg (ORCPT ); Wed, 6 Jul 2005 14:36:36 -0400 Message-Id: <200507061836.j66IaWD27125@tag.witbe.net> Reply-To: From: "Paul Rolland" To: Cc: Subject: Spy'ing characters sent to serial port. Date: Wed, 6 Jul 2005 20:36:32 +0200 Organization: AS2917 MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit X-Mailer: Microsoft Office Outlook, Build 11.0.6353 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1441 Thread-Index: AcWCWaGEKSLPIe2NSZuIDBdWjyoVMQ== Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hello, We have a machine connected to a modem using the serial port, and from time to time, the modem complains the machine sent him a full 2K buffer (in fact, 2047 bytes) which were already sent. We've been investigating at the application level, using strace to monitor what is sent to the serial port, and at no time such a buffer is sent. This problem is occuring on a random basis, and attempts to reproduce it in a test environment failed to date. Is it possible to '(log|copy|...)' the chars that are sent on the serial port to some other place (without altering too much the performance of the machine, we are running the port a 9600bps), at the lowest level ? Or is there a known issue of the serial port (or tty) buffer being resent on the line in some weird conditions ? Any change done on ->head and ->tail handling that could fix that ? This problem is with Linux 2.4.27 (I know 2.4.31 is out, but nothing related to that is present in the Changelog) Regards, Paul