From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 2685 invoked by alias); 3 Jul 2005 15:18:13 -0000 Mailing-List: contact ecos-discuss-help@ecos.sourceware.org; run by ezmlm Precedence: bulk List-Subscribe: List-Archive: List-Post: List-Help: , Sender: ecos-discuss-owner@ecos.sourceware.org Received: (qmail 2673 invoked by uid 22791); 3 Jul 2005 15:18:10 -0000 Received: from sta-206-168-96-204.rockynet.com (HELO hermes.chez-thomas.org) (206.168.96.204) by sourceware.org (qpsmtpd/0.30-dev) with ESMTP; Sun, 03 Jul 2005 15:18:10 +0000 Received: by hermes.chez-thomas.org (Postfix, from userid 2000) id 58A1810048E; Sun, 3 Jul 2005 09:18:08 -0600 (MDT) Received: from localhost.localdomain (localhost.localdomain [127.0.0.1]) by hermes.chez-thomas.org (Postfix) with ESMTP id 8500F100044; Sun, 3 Jul 2005 09:18:07 -0600 (MDT) From: Gary Thomas To: =?ISO-8859-1?Q?=D8yvind?= Harboe Cc: eCos Discussion In-Reply-To: <1120401601.11779.7.camel@localhost.localdomain> References: <1120401601.11779.7.camel@localhost.localdomain> Content-Type: text/plain; charset=ISO-8859-1 Date: Sun, 03 Jul 2005 15:18:00 -0000 Message-Id: <1120403887.31874.65.camel@hermes> Mime-Version: 1.0 Content-Transfer-Encoding: 8bit Subject: Re: [ECOS] Ymodem error checking X-SW-Source: 2005-07/txt/msg00028.txt.bz2 On Sun, 2005-07-03 at 16:40 +0200, Øyvind Harboe wrote: > How certain can I be that Ymodem will either: > > a) report a failure > b) receive the file correctly > > > Is adding a layer on top of Ymodem to check that the file was received > correctly ill-informed paranoia? Each [relatively small] record in the Y-modem protocol contains a simple checksum. This must match for the packet to be ACK'd Also, packets are numbered and will only be accepted in the proper order. This level of checking is sufficient (at least 99% of the time IMHO) You could always generate a binary checksum on the data and then validate that using the 'cksum' command in RedBoot. In this way, you could verify that everything was transfered correctly, a step above checking all the little pieces. The tricky part with this is that some files which are downloaded have holes in them and you'd need to make sure that both checksums assume the same value for the hole. -- ------------------------------------------------------------ Gary Thomas | Consulting for the MLB Associates | Embedded world ------------------------------------------------------------ -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss