From mboxrd@z Thu Jan 1 00:00:00 1970 Return-path: Received: from mx1.redhat.com ([209.132.183.28]:29653 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756881Ab1ESRPC (ORCPT ); Thu, 19 May 2011 13:15:02 -0400 Subject: Re: [PATCH] Add libertas_disablemesh module parameter to disable mesh interface From: Dan Williams To: Sascha Silbe Cc: linux-wireless , devel , John@xo15-sascha.sascha.silbe.org, W.Linville@xo15-sascha.sascha.silbe.org, linville@tuxdriver.com, libertas-dev , netdev , linux-kernel Date: Thu, 19 May 2011 12:16:58 -0500 In-Reply-To: <1305290935-sup-4547@xo15-sascha.sascha.silbe.org> References: <1305118354-17337-1-git-send-email-silbe@activitycentral.com> <1305169898.8054.19.camel@dcbw.foobar.com> <1305290935-sup-4547@xo15-sascha.sascha.silbe.org> Content-Type: text/plain; charset="UTF-8" Message-ID: <1305825421.3271.8.camel@dcbw.foobar.com> (sfid-20110519_191555_971558_E601FABE) Mime-Version: 1.0 Sender: linux-wireless-owner@vger.kernel.org List-ID: On Fri, 2011-05-13 at 15:16 +0200, Sascha Silbe wrote: > Excerpts from Dan Williams's message of Thu May 12 05:11:36 +0200 2011: > > On Wed, 2011-05-11 at 14:52 +0200, Sascha Silbe wrote: > > > This allows individual users and deployments to disable mesh support at > > > runtime, i.e. without having to build and maintain a custom kernel. > > > Does the mesh interface somehow cause problems, even when nothing is > > using it? > > Some people suspect it does, but there's no hard data showing that. But > then the problems are often hard to reproduce in the first place, so > proving a correlation with mesh is even harder. That's not an excuse for not finding and fixing the problem though. What problems are we actually talking about here? > The hardware based mesh support is based on an outdated draft of > 802.11s and not interoperable with any other device AFAIK. For most > users Ad-hoc networks are the better option. Disabling mesh support as > low-level as possible makes it less likely that any remains are causing > trouble. With at least four layers (firmware, kernel, NM, Sugar) > involved in managing connectivity and one of the (firmware) being closed > source, I prefer to simplify things by eliminating three layers for > functionality we don't intend to use. It makes debugging (and > blaming ;) ) a lot easier. > > In the field, mesh support is currently disabled using > /sys/class/net/eth0/lbs_mesh. However, it comes back after resume > (possibly only if powercycled) and needs to be disabled again by > post-resume hacks. Race conditions with NM are possible. That's a parameter handled by the driver; so shouldn't we make sure it's respected again on resume? > A user space option would be to teach NM to disable mesh support (at > runtime - we don't want to ship a custom NM package). I'd expect the > patch to be much more invasive than the one posted for libertas. Not really, but we already have on/off for a bunch of other stuff, I don't see why we can't add one for OLPC mesh. Dan