From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S932707AbcFNSfc (ORCPT ); Tue, 14 Jun 2016 14:35:32 -0400 Received: from shards.monkeyblade.net ([149.20.54.216]:48669 "EHLO shards.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932336AbcFNSfZ convert rfc822-to-8bit (ORCPT ); Tue, 14 Jun 2016 14:35:25 -0400 Date: Tue, 14 Jun 2016 14:35:21 -0400 (EDT) Message-Id: <20160614.143521.2085426866285759820.davem@davemloft.net> To: pali.rohar@gmail.com Cc: gregkh@linuxfoundation.org, andrew@lunn.ch, mario_limonciello@dell.com, hayeswang@realtek.com, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, linux-usb@vger.kernel.org, anthony.wong@canonical.com Subject: Re: [PATCH v6] r8152: Add support for setting pass through MAC address on RTL8153-AD From: David Miller In-Reply-To: <201606141847.36109@pali> References: <201606141828.10969@pali> <20160614164017.GB14477@kroah.com> <201606141847.36109@pali> X-Mailer: Mew version 6.7 on Emacs 24.5 / Mule 6.0 (HANACHIRUSATO) Mime-Version: 1.0 Content-Type: Text/Plain; charset=iso-8859-1 Content-Transfer-Encoding: 8BIT X-Greylist: Sender succeeded SMTP AUTH, not delayed by milter-greylist-4.5.12 (shards.monkeyblade.net [149.20.54.216]); Tue, 14 Jun 2016 11:35:25 -0700 (PDT) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org From: Pali Rohár Date: Tue, 14 Jun 2016 18:47:36 +0200 > You have never seen two ethernet cards with same MAC addresses? Right I > have not seen two USB, but there is non zero chance that could happen. It would be an error scenerio, and something to be avoided. It is a valid and correct assumption that one is able to put several devices at the same time on the same physical network and expect it to work. The behavior added by the change in question invalidates that. I'm trying to consider the long term aspects of this, which is that if more devices adopt this scheme we're in trouble if we blindly interpret the MAC address in this way. This firmware MAC property facility seems to be designed with only an extremely narrow use case being considered.