From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Sat, 25 May 2002 19:40:52 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Sat, 25 May 2002 19:39:49 -0400 Received: from bs1.dnx.de ([213.252.143.130]:57514 "EHLO bs1.dnx.de") by vger.kernel.org with ESMTP id ; Sat, 25 May 2002 19:39:46 -0400 Date: Sun, 26 May 2002 00:33:59 +0200 From: Robert Schwebel To: Linus Torvalds Cc: linux-kernel@vger.kernel.org Subject: Re: patent on O_ATOMICLOOKUP [Re: [PATCH] loopable tmpfs (2.4.17)] Message-ID: <20020526003359.Z598@schwebel.de> In-Reply-To: <20020525110830.U598@schwebel.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.3.16i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Sat, May 25, 2002 at 10:27:24AM -0700, Linus Torvalds wrote: > It results in the fact that you need to have a _clear_interface_ between > the hard realtime parts, and the stuff that isn't. Show me how you will implement a closed loop controller where the application is _not_ implemented as a kernel module. I would really love to do it this way, but unfortunately no one of the realtime programmers has found a way how it can be achieved so far. > Yes, that does imply a certain amount of good design. And it requires you > to understand which parts are time-critical, and which aren't. Unfortunately, in the automation field nearly all applications are closed-loop, and that means that the application itself is time critical. > > This is only correct for open-loop applications. Most real life apps are > > closed-loop. > > Most real life apps have nothing to do with hard-RT. Perhaps in your life :-) It's different in mine, in Karim's, Wolfgang's, Bernhard's, Steve's, Stuart's, Paolo's, Guennadi's, Thomas', Massimo's, Pierre's, Lorenzo's, Giuseppe's, Erwin's, Dave's, Ian's, Alex' (just to mention the RTAI team) and in that of all the thousands of engineers who are working with Linux and RTAI every day. Please, take into account that there are people out there wo are working with Linux in automation and control applications every day, and their bread and butter _is_ realtime stuff. My experience is that this is sometimes really hard to understand for people who normally work on problems from the IT industry, you are not the only one. Realtime may be someting exotic for "normal" PC users, but in the whole industrial embedded world it is completely different. Robert -- +--------------------------------------------------------+ | Dipl.-Ing. Robert Schwebel | http://www.pengutronix.de | | Pengutronix - Linux Solutions for Science and Industry | | Braunschweiger Str. 79, 31134 Hildesheim, Germany | | Phone: +49-5121-28619-0 | Fax: +49-5121-28619-4 | +--------------------------------------------------------+