From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Miller Subject: on the topic of alternate MAC addresses Date: Tue, 23 Oct 2007 18:05:34 -0700 (PDT) Message-ID: <20071023.180534.59659315.davem@davemloft.net> Mime-Version: 1.0 Content-Type: Text/Plain; charset=us-ascii Content-Transfer-Encoding: 7bit Cc: jeff@garzik.org To: netdev@vger.kernel.org Return-path: Received: from 74-93-104-97-Washington.hfc.comcastbusiness.net ([74.93.104.97]:52244 "EHLO sunset.davemloft.net" rhost-flags-OK-FAIL-OK-OK) by vger.kernel.org with ESMTP id S1752546AbXJXBFH (ORCPT ); Tue, 23 Oct 2007 21:05:07 -0400 Sender: netdev-owner@vger.kernel.org List-Id: netdev.vger.kernel.org I've been meaning to bring this up. A lot of cards that support multiple MAC addresses in hardware provide pre-cooked lists of alternate MAC addresses. This is either done via EEPROM, NVRAM, or OpenFirmware device properties. For example, the Sun Neptune cards can provide an array of up to 16 alternate MAC addresses per-port. We should provide a way to export these lists to userspace. Perhaps an ethtool thing, Jeff? Once we have this, virtualization implementations can probe for and use them. Currently they have no way to discover these things so probably they just generate their own using some algorithm.