From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ben Woodard Subject: WiFi and changed MAC addrs Date: Wed, 05 Sep 2007 08:20:44 -0700 Message-ID: <46DEC94C.9010301@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: netdev@vger.kernel.org Return-path: Received: from mx1.redhat.com ([66.187.233.31]:40309 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757119AbXIEPVj (ORCPT ); Wed, 5 Sep 2007 11:21:39 -0400 Received: from int-mx1.corp.redhat.com (int-mx1.corp.redhat.com [172.16.52.254]) by mx1.redhat.com (8.13.1/8.13.1) with ESMTP id l85FLbur009369 for ; Wed, 5 Sep 2007 11:21:37 -0400 Received: from pobox.corp.redhat.com (pobox.corp.redhat.com [10.11.255.20]) by int-mx1.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l85FLbxk013361 for ; Wed, 5 Sep 2007 11:21:37 -0400 Received: from [10.11.15.17] (vpn-15-17.rdu.redhat.com [10.11.15.17]) by pobox.corp.redhat.com (8.13.1/8.13.1) with ESMTP id l85FLYP9014890 for ; Wed, 5 Sep 2007 11:21:35 -0400 Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org I just spent basically a day of my weekend grappling with this problem http://wiki.xensource.com/xenwiki/XenWifi before I understood it well enough to realize that the fact that Xen changed the MAC addr for my WiFi card was the root cause of the problem. This got me thinking: If a particular piece of hardware will refuse to send frames after the MAC address has been changed, then shouldn't the card's driver refuse to allow a change of the MAC address and return an error in response to the IOCTL that tries to change it? I can't think of a situation where this wouldn't be the right thing to do. However, before I submit a patch to fix this, does anyone else know of any special cases that I might need to deal with? Also is behavior of refusing to send frames with a non-hardware specified MAC address part of the WiFi spec or is it particular to certain WiFi cards? IOW at what level do I need to fix it? Should I just fix it for the Intel cards that I've tested or do I need to fix it for all WiFi cards? -ben