From owner-freebsd-questions  Fri Apr 19 07:01:55 1996
Return-Path: owner-questions
Received: (from root@localhost)
          by freefall.freebsd.org (8.7.3/8.7.3) id HAA06755
          for questions-outgoing; Fri, 19 Apr 1996 07:01:55 -0700 (PDT)
Received: from xi.dorm.umd.edu (root@xi.dorm.umd.edu [129.2.152.45])
          by freefall.freebsd.org (8.7.3/8.7.3) with ESMTP id HAA06747
          for <freebsd-questions@FreeBSD.ORG>; Fri, 19 Apr 1996 07:01:51 -0700 (PDT)
Received: from localhost (smpatel@localhost [127.0.0.1]) by xi.dorm.umd.edu (8.7.5/8.6.12) with SMTP id KAA02777; Fri, 19 Apr 1996 10:01:06 -0400 (EDT)
Date: Fri, 19 Apr 1996 10:01:06 -0400 (EDT)
From: Sujal Patel <smpatel@umiacs.umd.edu>
X-Sender: smpatel@xi.dorm.umd.edu
To: Hollerer <eeg@telecom.at>
cc: freebsd-questions@FreeBSD.ORG
Subject: Re: How can I read/write from/to an I/O-port?
In-Reply-To: <317764B2.6DCC0261@telecom.at>
Message-ID: <Pine.NEB.3.92.960419095909.1260C-100000@xi.dorm.umd.edu>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
Sender: owner-questions@FreeBSD.ORG
X-Loop: FreeBSD.org
Precedence: bulk

On Fri, 19 Apr 1996, Hollerer wrote:

> Under Linux a /dev/port exits to write/read to/from an I/O-port.
> Does a similar /dev/??? exits under FreeBSD or must I write
> a little device driver for this?

After you open /dev/io as read-only, you can then use inb & outb from
machine/cpufunc.h--

#include <stdio.h>
#include <sys/fcntl.h>
#include <machine/cpufunc.h>

main()
{
	open ("/dev/io", O_RDONLY);
	outb (0x3f8, 0xff);
}


Sujal