From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 22771 invoked by alias); 18 Jun 2006 23:31:24 -0000 Received: (qmail 22763 invoked by uid 22791); 18 Jun 2006 23:31:23 -0000 X-Spam-Check-By: sourceware.org Received: from gatekeeper.tait.co.nz (HELO gatekeeper.tait.co.nz) (202.37.96.11) by sourceware.org (qpsmtpd/0.31) with ESMTP; Sun, 18 Jun 2006 23:31:21 +0000 Received: from gatekeeper.tait.co.nz (localhost.localdomain [127.0.0.1]) by localhost.tait.co.nz (Postfix) with ESMTP id 6D31D46749 for ; Mon, 19 Jun 2006 11:31:17 +1200 (NZST) Received: from sunstrike.tait.co.nz (sunstrike [172.25.40.92])by gatekeeper.tait.co.nz (Postfix) with ESMTP id 5B8B446748for ; Mon, 19 Jun 2006 11:31:17 +1200 (NZST) Received: from conversion-daemon.sunstrike.tait.co.nz by sunstrike.tait.co.nz(Sun Java System Messaging Server 6.1 (built Apr 28 2004))id <0J1200901W4VSG00@sunstrike.tait.co.nz>(original mail from john.carter@tait.co.nz) for ecos-discuss@sourceware.org;Mon, 19 Jun 2006 11:31:17 +1200 (NZST) Received: from parore ([172.25.140.12])by sunstrike.tait.co.nz (Sun Java System Messaging Server 6.1 (built Apr 282004)) with ESMTP id <0J12006MHXC5SQ60@sunstrike.tait.co.nz>; Mon,19 Jun 2006 11:31:17 +1200 (NZST) Received: from localhost ([127.0.0.1] ident=johnc)by parore with esmtp (Exim 4.34) id 1Fs6jc-0000tu-S2; Mon,19 Jun 2006 11:31:16 +1200 Date: Sun, 18 Jun 2006 23:31:00 -0000 From: John Carter In-reply-to: To: R Vamshi Krishna Cc: ecos-discuss@sourceware.org Message-id: MIME-version: 1.0 X-Mailer: Pidgeon Post Content-type: TEXT/PLAIN; format=flowed; charset=US-ASCII Content-transfer-encoding: 7BIT X-Apparently-From: mars X-Contents: May contain traces of nuts. References: <20060530075335.GG2876@lunn.ch><69dd805e0605300109k5dcf7986of596c0b5f796c6b 4@mail.gmail.com><20060530081637.GH2876@lunn.ch><20060530111112.GK2876@lunn.ch><001501c6874a$10fbb9a0$070fe644@EngAt PlayWS><003401c6885d $23027ee0$070fe644@EngAtPlayWS> X-imss-version: 2.040 X-imss-result: Passed X-imss-approveListMatch: *@tait.co.nz X-IsSubscribed: yes 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 Subject: Re: [ECOS] Hard-Realtime behaviour X-SW-Source: 2006-06/txt/msg00158.txt.bz2 On Mon, 19 Jun 2006, R Vamshi Krishna wrote: > Now this hard real-time OS would be for use in Safety-Critical Systems. We > would port the kernel to MISRA-C later stage but currently we are stuck-up at > "hardening" of eCos. Since currently most of the kernel seems to be C++, that wouldn't be "port", that would be "rewrite". ie. If MISRA-C for the kernel is a fixed requirement, you have lost right there. > This guarantee I understand cannot be given by an RTOS alone. It is the > combined guarantee by the application + RTOS. i.e. everything depends on the > way the application was developed using the features of an RTOS. Comment 1: Ecos has met all hard deadline requirements on our app... Getting our code to behave has been way more problematical than Ecos. Comment 2: Given a choice of a "harder RTOS" than ecos, "misra-c" kernel, or a faster / smarter CPU with loads of Flash/RAM, I will take the faster smarter CPU. Headroom and flexibility are more important than "guarantees". Guarantees can be broken, but headroom lets you cope with any broken guarantees and a lot more besides. Comment 3: Most "hard to meet hard deadlines" I have seen have been the result of hardware designers saying "lets skimp a bit and fix it in the software". So if you have a really hard hard to meet RT deadline, walk over to your hardware designers and talk to them about life, the universe, safety and trade offs. John Carter Phone : (64)(3) 358 6639 Tait Electronics Fax : (64)(3) 359 4632 PO Box 1645 Christchurch Email : john.carter@tait.co.nz New Zealand Carter's Clarification of Murphy's Law. "Things only ever go right so that they may go more spectacularly wrong later." >From this principle, all of life and physics may be deduced. -- Before posting, please read the FAQ: http://ecos.sourceware.org/fom/ecos and search the list archive: http://ecos.sourceware.org/ml/ecos-discuss