From owner-freebsd-current@FreeBSD.ORG  Thu Nov 27 15:04:16 2003
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id 100BD16A4CE
	for <freebsd-current@freebsd.org>;
	Thu, 27 Nov 2003 15:04:16 -0800 (PST)
Received: from harmony.village.org (rover.bsdimp.com [204.144.255.66])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 178E143FBF
	for <freebsd-current@freebsd.org>;
	Thu, 27 Nov 2003 15:04:15 -0800 (PST)	(envelope-from imp@bsdimp.com)
Received: from localhost (warner@rover2.village.org [10.0.0.1])
	by harmony.village.org (8.12.9p2/8.12.9) with ESMTP id hARN4Dlg065869;
	Thu, 27 Nov 2003 16:04:13 -0700 (MST)
	(envelope-from imp@bsdimp.com)
Date: Thu, 27 Nov 2003 16:04:12 -0700 (MST)
Message-Id: <20031127.160412.69381954.imp@bsdimp.com>
To: tlambert2@mindspring.com
From: "M. Warner Losh" <imp@bsdimp.com>
In-Reply-To: <3FC59E89.77203100@mindspring.com>
References: <46117.1069866997@critter.freebsd.dk>
	<3FC59E89.77203100@mindspring.com>
X-Mailer: Mew version 2.1 on Emacs 21.3 / Mule 5.0 (SAKAKI)
Mime-Version: 1.0
Content-Type: Text/Plain; charset=us-ascii
Content-Transfer-Encoding: 7bit
cc: phk@phk.freebsd.dk
cc: freebsd-current@freebsd.org
Subject: Re: requesting vinum help
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 27 Nov 2003 23:04:16 -0000

In message: <3FC59E89.77203100@mindspring.com>
            Terry Lambert <tlambert2@mindspring.com> writes:
: There is no such thing as "bit rot"; there is only code that
: is unmaintained by the people who change interfaces out from
: under it.

Actually, there is such a thing as code rot.  Over time the
fundamental assumptions that a piece of code makes are tested as the
interfaces and subsystems it depends on evolve and change.  These
assumptions can be very subtle sometimes, and difficult to find and
test.

Vinum is hard to test because it requires multiple disks to test
with.  In addition, many problems with vinum are shown only under
heavy work load, which may be difficult to simulate.

Put in historical terms, the following code used to work:

void foo(char *c)
{
	*c = 'F';
}

int
main(int argc, char **argv)
{
	foo("fred");
}

but subtle changes in compiler technology over the years have made
this code fail now.

Warner