From owner-freebsd-hackers@FreeBSD.ORG  Thu Jan 27 15:51:34 2005
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
Delivered-To: freebsd-hackers@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 1397A16A4CE
	for <freebsd-hackers@freebsd.org>;
	Thu, 27 Jan 2005 15:51:34 +0000 (GMT)
Received: from smtpout-2.priv.cc.uic.edu (smtpout-2.cc.uic.edu
	[128.248.155.233])
	by mx1.FreeBSD.org (Postfix) with SMTP id 4A5A843D1F
	for <freebsd-hackers@freebsd.org>;
	Thu, 27 Jan 2005 15:51:33 +0000 (GMT)	(envelope-from zholla1@uic.edu)
Received: (qmail 15497 invoked from network); 27 Jan 2005 09:51:32 -0600
Received: from icarus.cc.uic.edu (128.248.155.80)
  by smtpout-2.cc.uic.edu with SMTP; 27 Jan 2005 09:51:32 -0600
Date: Thu, 27 Jan 2005 09:51:32 -0600 (CST)
From: Zera William Holladay <zholla1@uic.edu>
X-X-Sender: zholla1@icarus.cc.uic.edu
To: Jacques Fourie <jf@trispen.com>
In-Reply-To: <41F90140.3020705@trispen.com>
Message-ID: <Pine.GSO.4.58.0501270937010.22912@icarus.cc.uic.edu>
References: <41F90140.3020705@trispen.com>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
cc: freebsd-hackers@freebsd.org
Subject: Re: kernel vm question
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Technical Discussions relating to FreeBSD
	<freebsd-hackers.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-hackers>
List-Post: <mailto:freebsd-hackers@freebsd.org>
List-Help: <mailto:freebsd-hackers-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-hackers>,
	<mailto:freebsd-hackers-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 27 Jan 2005 15:51:34 -0000



On Thu, 27 Jan 2005, Jacques Fourie wrote:

> Hi,
>
> I have a kernel module with the following entry point :
>
> static int test_modevent(module_t mod, int type, void *unused)
> {
>    int s;
>    unsigned char *p = NULL;
>    unsigned char v = 0x55;
>
>    switch (type)
>      {
>      case MOD_LOAD:
>        p = (unsigned char *)ip_output;

What is ip_output?  Do you believe it is a function or variable?  It might
help if you just state to yourself in your native language what you want
to do here.

>        s = splhigh();
>
>        v = p[0];                   /* Page fault without this line */
>        p[0] = v;

The above makes no sense.  Why would you assign v to p[0] and then set
p[0] to the value of v?  What is the error message you get?  Also, it
might help to compile with -Wall since it help to catch some subtle
errors.

Good luck,

-Zera