From owner-freebsd-current@FreeBSD.ORG  Tue Feb 12 17:38:53 2008
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: current@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id B56C716A507;
	Tue, 12 Feb 2008 17:38:53 +0000 (UTC)
	(envelope-from csjp@sub.vaned.net)
Received: from sub.vaned.net (sub.vaned.net [205.200.235.40])
	by mx1.freebsd.org (Postfix) with ESMTP id 5923113C447;
	Tue, 12 Feb 2008 17:38:53 +0000 (UTC)
	(envelope-from csjp@sub.vaned.net)
Received: by sub.vaned.net (Postfix, from userid 1001)
	id DE37B1CF; Tue, 12 Feb 2008 11:38:52 -0600 (CST)
Date: Tue, 12 Feb 2008 11:38:52 -0600
From: "Christian S.J. Peron" <csjp@FreeBSD.org>
To: Alfred Perlstein <alfred@freebsd.org>
Message-ID: <20080212173852.GA27407@sub.vaned.net>
References: <20080212014057.GA6027@sub.vaned.net>
	<20080212051020.GO99258@elvis.mu.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20080212051020.GO99258@elvis.mu.org>
User-Agent: Mutt/1.4.2.3i
Cc: arch@freebsd.org, re@freebsd.org, "Christian S.J. Peron" <csjp@FreeBSD.org>,
	current@freebsd.org
Subject: Re: sysv IPC and shminfo ABI [solved]
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.5
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: Tue, 12 Feb 2008 17:38:53 -0000


After having some discussions with jhb, and reviewing the commit logs
that introduced IPC_INFO, this is a non-issue.  The whole reason this
was introduced was to satisfy Linux compatability. 

revision 1.67
date: 2001/10/28 09:29:07;  author: mr;  state: Exp;  lines: +45 -2
Introduce [IPC|SHM]_[INFO|STAT] to shmctl to make
`/compat/linux/usr/bin/ipcs -m` happy.

This was never an intented part of the FreeBSD ABI, which explains
why the structure is not made available to the user.  Although the size
has changed, it doesn't matter, because the Linux ABI layer will prepare
it's own shminfo structure as send it back out to the user.

So, I am going to make shmctl(IPC_INFO ...) for the FreeBSD ABI return
EINVAL, and I am going to add some serious comments around various points
in the kernel explaining why things are there, and how they should never
be exported.

Thanks everyone for the input.