From owner-freebsd-hackers@FreeBSD.ORG  Thu Feb  8 21:29:14 2007
Return-Path: <owner-freebsd-hackers@FreeBSD.ORG>
X-Original-To: hackers@freebsd.org
Delivered-To: freebsd-hackers@FreeBSD.ORG
Received: from mx1.freebsd.org (mx1.freebsd.org [69.147.83.52])
	by hub.freebsd.org (Postfix) with ESMTP id EEB9B16A400
	for <hackers@freebsd.org>; Thu,  8 Feb 2007 21:29:14 +0000 (UTC)
	(envelope-from rizzo@icir.org)
Received: from xorpc.icir.org (xorpc.icir.org [192.150.187.68])
	by mx1.freebsd.org (Postfix) with ESMTP id DF58813C474
	for <hackers@freebsd.org>; Thu,  8 Feb 2007 21:29:14 +0000 (UTC)
	(envelope-from rizzo@icir.org)
Received: from xorpc.icir.org (localhost [127.0.0.1])
	by xorpc.icir.org (8.12.11/8.13.6) with ESMTP id l18KxAp6087851;
	Thu, 8 Feb 2007 12:59:10 -0800 (PST)
	(envelope-from rizzo@xorpc.icir.org)
Received: (from rizzo@localhost)
	by xorpc.icir.org (8.12.11/8.12.3/Submit) id l18KxArS087850;
	Thu, 8 Feb 2007 12:59:10 -0800 (PST) (envelope-from rizzo)
Date: Thu, 8 Feb 2007 12:59:10 -0800
From: Luigi Rizzo <rizzo@icir.org>
To: hackers@freebsd.org
Message-ID: <20070208125910.A87229@xorpc.icir.org>
Mime-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
User-Agent: Mutt/1.2.5.1i
Cc: 
Subject: kernel headers dependency graph ? (systm.h tangle)
X-BeenThere: freebsd-hackers@freebsd.org
X-Mailman-Version: 2.1.5
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, 08 Feb 2007 21:29:15 -0000

Hi,
Is there a tool to produce a dependency graph for C headers ?

If that matters (i.e. someone has already studied it),
i am interested in the header situation in the FreeBSD kernel.

It may be a well known thing, but i just realized
that <sys/systm.h> is entagled with <sys/libkern.h> and both bring
in a lot of other headers, and you cannot bring in simply
the string.h functions, or printf, because there is no
leaf header for them. 
I don't know if this is the only case, or there are other
'classes' which are intermixed with lots of other stuff.

I suppose the problem has been already discussed and it is just
the result of historical reasons, but is there any reason other
than ENOTIME why (to cite things that are trivial to fix while  
preserving compatibility):

- we don't have sys/string.h with all the memcpy/bcopy and friends
  that are currently spread between systm.h and libkern.h

- printf/scanf and strto*() are not in their own header;

and so on ?
 
        cheers
        luigi