From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dan Williams Subject: Re: [PATCH] dnet: Dave DNET ethernet controller driver Date: Wed, 11 Mar 2009 10:00:16 -0400 Message-ID: <1236780016.10989.9.camel@localhost.localdomain> References: <20090311.014957.117115597.davem@davemloft.net> <20090311085721.GV425@pengutronix.de> <20090311090938.E7BF7832E8B8@gemini.denx.de> <20090311.062336.238430706.davem@davemloft.net> Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: wd@denx.de, shemminger@vyatta.com, yanok@emcraft.com, linux-arm-kernel@lists.arm.linux.org.uk, netdev@vger.kernel.org, dzu@denx.de To: David Miller Return-path: Received: from mx2.redhat.com ([66.187.237.31]:40700 "EHLO mx2.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1756153AbZCKOCn (ORCPT ); Wed, 11 Mar 2009 10:02:43 -0400 In-Reply-To: <20090311.062336.238430706.davem@davemloft.net> Sender: netdev-owner@vger.kernel.org List-ID: On Wed, 2009-03-11 at 06:23 -0700, David Miller wrote: > From: Wolfgang Denk > Date: Wed, 11 Mar 2009 10:09:38 +0100 > > > How do you then handle situations where this is impossible? Say, when > > the firmware cannot write to those registers for example because the > > ethernet controller is not even powered on (to reduce power consump- > > tion), but will get powered on only in Linux when the driver gets > > loaded (i. e. on demand only, not always)? > > That's what NVRAM, CMOS, EEPROM's and other writable long-term > storage areas are for. > > To be quite honest with you, any ethernet device that doesn't > have an EEPROM where the chip instance's ethernet address is > stored is completely broken. Not having persistent MAC storage makes it quite hard from userspace to tie specific network configuration to a specific device, because (rightly so) kernel network interface names are *not* stable. And since most manufacturers don't bother to put serial numbers into things like the USB descriptors, there is now way to uniquely identify if you plug two in. LOSE. Save a kitten. Add an EEPROM. Dan