From owner-freebsd-current Wed Jun 10 23:56:27 1998 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id XAA06852 for freebsd-current-outgoing; Wed, 10 Jun 1998 23:56:27 -0700 (PDT) (envelope-from owner-freebsd-current@FreeBSD.ORG) Received: from cimlogic.com.au (cimlog.lnk.telstra.net [139.130.51.31]) by hub.freebsd.org (8.8.8/8.8.8) with ESMTP id XAA06845 for ; Wed, 10 Jun 1998 23:56:20 -0700 (PDT) (envelope-from jb@cimlogic.com.au) Received: (from jb@localhost) by cimlogic.com.au (8.8.8/8.8.7) id QAA18095; Thu, 11 Jun 1998 16:59:35 +1000 (EST) (envelope-from jb) From: John Birrell Message-Id: <199806110659.QAA18095@cimlogic.com.au> Subject: Re: floating point usage within the kernel - howto ? In-Reply-To: <199806110443.GAA21849@labinfo.iet.unipi.it> from Luigi Rizzo at "Jun 11, 98 06:43:08 am" To: luigi@labinfo.iet.unipi.it (Luigi Rizzo) Date: Thu, 11 Jun 1998 16:59:35 +1000 (EST) Cc: mike@smith.net.au, current@FreeBSD.ORG X-Mailer: ELM [version 2.4ME+ PL40 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Luigi Rizzo wrote: > they want to run a P-I-D controller (and more generic controllers > if this goes well) to control a few motors, for didactical purposes. What update rate do they need that requires the code to run in the kernel? > The used to do the same thing under DOS, by hooking this 'real-time' > task to the timer interrupt. I am trying to push them to use FreeBSD > (and an LKM for this module) so that they can easily access the > controller across the network or via the web, use high level stuff > for visualization, etc. I would still do the PID computation in user-space and just use an ioctl to the lkm driver that talks to whatever I/O they have. It would need to be a pretty high speed application to require the code in the kernel and even then it would likely have a dedicated controller anyway. If they want to program like DOS, that's what they should use. 8-) -- John Birrell - jb@cimlogic.com.au; jb@freebsd.org http://www.cimlogic.com.au/ CIMlogic Pty Ltd, GPO Box 117A, Melbourne Vic 3001, Australia +61 418 353 137 To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message