From mboxrd@z Thu Jan 1 00:00:00 1970 From: Aijaz Baig Subject: Re: help needed with EXPORT_SYMBOL Date: Mon, 23 Aug 2010 10:44:08 +0530 Message-ID: <1282540448.4080.86.camel@aijazbaig1-desktop> References: <1282373834.4080.79.camel@aijazbaig1-desktop> Reply-To: aijazbaig1@gmail.com Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Cc: linux-kernel@vger.kernel.org To: netfilter-devel@vger.kernel.org, jengelh@medozas.de Return-path: Received: from mail-iw0-f174.google.com ([209.85.214.174]:50512 "EHLO mail-iw0-f174.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752682Ab0HWFOT (ORCPT ); Mon, 23 Aug 2010 01:14:19 -0400 In-Reply-To: <1282373834.4080.79.camel@aijazbaig1-desktop> Sender: netfilter-devel-owner@vger.kernel.org List-ID: Hello, Yeah I do understand that part, but there has to be a way to do what I am trying to do here isn't it? And can anyone tell me can kallsyms_lookup() be used in such a situation? If yes than how do I use it? Regards, Aijaz On Sat, Aug 21, 2010 at 2:53 PM, Jan Engelhardt wrote: On Saturday 2010-08-21 08:57, Aijaz Baig wrote: >So why is it that when my netfilter module is exporting something to >the kernel and im tryin to use it from within a core kernel file, the >compiler flags a 'undefined reference to' error? There, you answered yourself. Exports only go one way. And that is core -> module -> module. On Sat, 2010-08-21 at 12:27 +0530, Aijaz Baig wrote: > Hello, > > Ive been trying to EXPORT a SYMBOL from a netfilter module (actually a > hook) to the KERNEL. Various modules seem to export various symbols to > the kernel (or so it seems), an example being x_tables which exports a > whole lot of functions like xt_register_target and so on and all other > netfilter modules which use these functions dont seem to have any > problems. > > So why is it that when my netfilter module is exporting something to the > kernel and im tryin to use it from within a core kernel file, the > compiler flags a 'undefined reference to' error? > > I googled and came to the conclusion from the kernelnewbies mailing list > that using kallsyms_lookup() seems to be the answer or is it? > So, if I do intend to use kallsyms_lookup how do I use it? There aren't > so many instances of it being used it seems. > > Ive seen it being used in dev/core.c like so: > symname = kallsyms_lookup((unsigned long)sym, &symsize,&offset,&modname, > namebuf); > > I am basically trying to call a function that MY module EXPORTs inside > one of the core linux routines. This would also mean that my netfilter > module must be compiled (and linked also maybe?..not so sound with link > time stuff) before the address becomes visible so that kallsyms_lookup > can find it. So do I really shd be using it and if so, how? > > Any input is appreciated. > > Regards, > Aijaz Baig. > >