From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 20326 invoked by alias); 7 Mar 2010 17:33:07 -0000 Received: (qmail 20318 invoked by uid 22791); 7 Mar 2010 17:33:07 -0000 X-SWARE-Spam-Status: No, hits=-2.5 required=5.0 tests=AWL,BAYES_00,SPF_HELO_PASS X-Spam-Check-By: sourceware.org Received: from www.meduna.org (HELO meduna.org) (92.240.244.38) by sourceware.org (qpsmtpd/0.43rc1) with ESMTP; Sun, 07 Mar 2010 17:33:03 +0000 Received: from dial-78-141-95-31-orange.orange.sk ([78.141.95.31] helo=[192.168.130.27]) by meduna.org with esmtpsa (TLS1.0:DHE_RSA_AES_256_CBC_SHA1:32) (Exim 4.69) (envelope-from ) id 1NoKLU-00021i-DL for ecos-devel@sourceware.org; Sun, 07 Mar 2010 18:32:58 +0100 Message-ID: <4B93E33A.9050807@meduna.org> Date: Sun, 07 Mar 2010 17:33:00 -0000 From: Stanislav Meduna User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.8) Gecko/20100227 Lightning/1.0b1 Thunderbird/3.0.3 MIME-Version: 1.0 To: ecos-devel@sourceware.org Subject: Re: Port to Atmel ARM9 Microcontroller SAM9G45 References: <4B8F5EB7.4090402@televic.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit X-Authenticated-User: stano@meduna.org X-Authenticator: dovecot_plain X-Spam-Score: -7.9 X-Spam-Score-Int: -78 X-Exim-Version: 4.69 (build at 30-Sep-2008 18:26:44) X-Date: 2010-03-07 18:32:58 X-Connected-IP: 78.141.95.31:3901 X-Message-Linecount: 58 X-Body-Linecount: 46 X-Message-Size: 2158 X-Body-Size: 1527 X-Received-Count: 1 X-Recipient-Count: 1 X-Local-Recipient-Count: 1 X-Local-Recipient-Defer-Count: 0 X-Local-Recipient-Fail-Count: 0 X-IsSubscribed: yes Mailing-List: contact ecos-devel-help@ecos.sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: ecos-devel-owner@ecos.sourceware.org X-SW-Source: 2010-03/txt/msg00005.txt.bz2 On 04.03.2010 10:38, Richard Rauch wrote: > - small footprint > - good realtime behaviour > - very short interrupt latency times, minimal overhead for task context > switching > - available for small microcontrollers (arm7,cortex m3) And last but not least: in my opinion the eCos structure is cleaner and there is a lot less dependencies between various parts of the operating system. >> Maybe you can help me defending eCos ;-). >From my experience it is nearly impossible to write a non-trivial realtime application for Linux - in my opinion it simply is not there yet. I tried to port an application using realtime timers and ethernet networking to a variant of OSADL linux (http://www.osadl.org/). I ended hunting deadlocks and priority inversion cases over the whole system, had kernel softirq threads in uninterruptible sleeps (that shouldn't happen except hardware failure). I spoke to other developers who tried Linux for this kind of stuff and they had similar experience. The same application works like a charm under eCos or without using the realtime threads. I'd recommend Linux in following cases: - no or soft realtime - you need virtual memory - you need to load code dynamically - having separate processes instead of threads is an advantage - userspace/kernelspace isolation is needed - you need something (e.g. a driver) only the linux provides and don't have time/resources to port it Otherwise the eCos is better bet for an embedded device. Regards -- Stano