From mboxrd@z Thu Jan  1 00:00:00 1970
Return-Path: <linux-kernel-owner+w=401wt.eu-S1753734AbXLaP4N@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1753734AbXLaP4N (ORCPT <rfc822;w@1wt.eu>);
	Mon, 31 Dec 2007 10:56:13 -0500
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751004AbXLaPz7
	(ORCPT <rfc822;linux-kernel-outgoing>);
	Mon, 31 Dec 2007 10:55:59 -0500
Received: from py-out-1112.google.com ([64.233.166.179]:54944 "EHLO
	py-out-1112.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org
	with ESMTP id S1751152AbXLaPz6 (ORCPT
	<rfc822;linux-kernel@vger.kernel.org>);
	Mon, 31 Dec 2007 10:55:58 -0500
DomainKey-Signature: a=rsa-sha1; c=nofws;
        d=googlemail.com; s=gamma;
        h=message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:references;
        b=DemQpgL1bRC+l3wr5v7kAVpXADw0YhEdSXDkuXVCqrV0fSm+7avat3z/2A3Tuws7iR85GlV2JuakanDrmAioHAg/Se37GuZV4JEOBZ6/kfIH3tGVOXOMDE3fHAJuj18BUBozgu+WKLprV4Y+rAKyQLSsOh+CKvbCXyMVRZwFiFo=
Message-ID: <64bb37e0712310755k2446e67eq81d31cd476eb75e3@mail.gmail.com>
Date: Mon, 31 Dec 2007 16:55:57 +0100
From: "Torsten Kaiser" <just.for.lkml@googlemail.com>
To: "Adrian Bunk" <bunk@kernel.org>
Subject: Re: [PATCH] Force UNIX domain sockets to be built in
Cc: "Bodo Eggert" <7eggert@gmx.de>, "Jan Engelhardt" <jengelh@computergmbh.de>,
       devzero@web.de, linux-kernel@vger.kernel.org, netdev@vger.kernel.org
In-Reply-To: <20071231144255.GB13803@does.not.exist>
MIME-Version: 1.0
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: 7bit
Content-Disposition: inline
References: <alpine.LSU.0.999.0712311300020.3686@be1.lrz>
	 <20071231122419.GA13803@does.not.exist>
	 <alpine.LSU.0.999.0712311335210.3761@be1.lrz>
	 <20071231144255.GB13803@does.not.exist>
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org

On Dec 31, 2007 3:42 PM, Adrian Bunk <bunk@kernel.org> wrote:
> With CONFIG_MODULES=y the 13 EXPORT_SYMBOL's that only exist for the
> theoretical possibility of CONIG_UNIX=m waste a few hundred bytes
> of memory.

One thing I always wondered about in this discussion about wasted
EXPORT_SYMBOL's:
Shouldn't it be possible to garbage collect these?

depmod already contains code to analyze all modules to create a
dependency tree. It should not be too difficult to extend it to create
a list of all symbols that really are used by the current modules.
Everything else could be stripped to save space.

The problem with that:
* out-of-tree modules would break if they don't get lucky to only use
the remaining symbol. I would not see this as a problem, if the help
text of the garbage-collect-option would contain a note like "don't
enable this if you want out-of-tree modules".
* if you later change your .config to include additional modules you
might need to rebuild vmlinux and reboot into the new kernel.
Currently you can probably build and load new modules without a
reboot. (for example: usb drivers)

Torsten