From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mail.tpi.com ([70.99.223.143]:3881 "EHLO mail.tpi.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751079AbZITQtN (ORCPT ); Sun, 20 Sep 2009 12:49:13 -0400 Message-ID: <4AB65CFE.7090101@canonical.com> Date: Sun, 20 Sep 2009 10:49:02 -0600 From: Tim Gardner Reply-To: tim.gardner@canonical.com MIME-Version: 1.0 To: "Luis R. Rodriguez" CC: linux-wireless@vger.kernel.org, Greg KH , Johannes Berg Subject: Re: [RFC] compat-2.6: mangle symbols for driver-select References: <20090919205545.GA18080@bombadil.infradead.org> <4AB5A5A7.3020107@canonical.com> <43e72e890909200743h74934657nc056c9e6dcb14e90@mail.gmail.com> In-Reply-To: <43e72e890909200743h74934657nc056c9e6dcb14e90@mail.gmail.com> Content-Type: text/plain; charset=UTF-8; format=flowed Sender: linux-wireless-owner@vger.kernel.org List-ID: Luis R. Rodriguez wrote: > On Sat, Sep 19, 2009 at 8:46 PM, Tim Gardner wrote: >> Luis R. Rodriguez wrote: >>> Today at the summit we spoke about mangling symbols for driver-slect. >>> Here's a quick nasty take on this but without doing this for driver-select >>> specifically just for testing. It seems to compile, but someone more >>> motivated >>> may want to test and make this apply somehow only for driver-select or >>> perhaps >>> when a -D define is used. >>> >>> Reason for this is to help distributions / OEMs / ODMs who want to replace >>> just *one* driver with compat-wireless. >>> >> I think it would be better to generate the list of mangled symbols >> dynamically. > > Agreed, that is the part I left out, as a TODO to someone interested. > I'm working on a patch (it works with 2.6.31), but I need to test with older kernels. >> In older Ubuntu releases (before depmod behavior was >> corrected), we have to run a 'munge' script to preface all of the exported >> symbols so that a compat-wireless driver references the compat-wireless >> protocol stack symbols. See the attached munge script for compat-wireless on >> 2.6.24. > > Please correct me if I'm wrong but I believe the script seems to do > what I did just that it actually edited the files with the changes, I > prefer the way I did this as it requires less work to maintain and > understand IMHO. > I'm fine with that, in fact its a bit faster since my munge script is a bit slow. It'll also make dealing with kernel version dependent symbol munge exceptions a bit simpler. One thing that is worth mentioning is that the module names need to be changed for older user space environments, otherwise depmod mucks things up in interesting ways. >> We can either do something like this for compat-wireless, or we >> could use a subset of this logic to generate the list of symbols contained >> within the '#ifdef CONFIG_COMPAT_WIRELESS_MANGLE' clause. > > So I was under the impression you would use this only if you are using > ./scripts/driver-select to select one driver out of the whole tree, > but it seems you actually use this for all the drivers on > compat-wireless for the Ubuntu linux-backports-modules package. I take > it you put lbm stuff then into some /lib/modules/$(uname)/compat/ and > use a sort of /etc/depmod.d/01-compat.conf to prefer compat over > updates/ or kernel/ ? For LBM I've taken a scorched earth approach, i.e., _all_ drivers in compat-wireless get built. The vast bulk of users that I deal with are only interested in one driver, but I don't know a priori _which_ driver. The use case where they would want to use a mainline driver at the same time as a different compat-wireless driver is fairly rare (which my approach makes impossible). rtg -- Tim Gardner tim.gardner@canonical.com