Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 6 Aug 2002 15:18:47 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 6 Aug 2002 15:18:47 -0400 Received: from chaos.analogic.com ([204.178.40.224]:63108 "EHLO chaos.analogic.com") by vger.kernel.org with ESMTP id ; Tue, 6 Aug 2002 15:18:42 -0400 Date: Tue, 6 Aug 2002 15:24:54 -0400 (EDT) From: "Richard B. Johnson" Reply-To: root@chaos.analogic.com To: "Randy.Dunlap" cc: linux-kernel@vger.kernel.org, abraham@2d3d.co.za Subject: Re: ethtool documentation In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2723 Lines: 68 On Tue, 6 Aug 2002, Randy.Dunlap wrote: > > Abraham vd Merwe wrote: > | What is the difference between the supported and advertising fields? > | What is MII? (as in the SUPPORTED_MII feature?). > > MII: (is this a serious question ?): > [from a National Semi. ethernet repeater design Application Note] > The Medium Independent Interface, as specified in the IEEE 802.3u/D5.3 > standard, is designed to support the PHY/MAC interface. > > | > ETHTOOL_GEEPROM > | > ETHTOOL_SEEPROM > | > > | > Get/set EEPROM data. These commands expect a 'struct ethtool_eeprom > | > *' > | > argument. This struct has a magic number, an offset and length > | > pair, and a > | > data field. If the offset+length are longer than the maximum size, > | > the extra is silently ignored. > | > | Wouldn't it have been better to make this 'n character device which can > | be read from / written to just like a normal file (/dev/nvram-like > | interface) - > | that way applications can actually use unused eeprom space. > > I wouldn't care for this. There's nothing 'normal' about this > EEPROM space, and apps generally won't know where there might be > some 'unused eeprom space'. > > -- > ~Randy The EEPROM (SEEPROM) on these NICS is used to contain the startup configuration bits and the IEEE Station Address. This must be a unique number that is assigned so that there is no other such number in (preferably) the world, and certainly in the LAN. If you let a user write to this area, you will allow the user to destroy the connectivity on a LAN. If you provide an ioctl() to write new SEEPROM contents, it had better be disabled in code that user's (any, including root) can execute because, if caught, your company may lose it's IEEE Station Addresses and never again be allowed to configure Ethernet Controllers. Because of this, there is no such thing as 'unused eeprom space' in the Ethernet Controllers. Be careful about putting this weapon in the hands of the 'public'. All you need is for one Linux Machine on a LAN to end up with the same IEEE Station Address as another on that LAN and connectivity to everything on that segment will stop. You do this once at an important site and Linux will get a very black eye. Cheers, Dick Johnson Penguin : Linux version 2.4.18 on an i686 machine (797.90 BogoMips). The US military has given us many words, FUBAR, SNAFU, now ENRON. Yes, top management were graduates of West Point and Annapolis. - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/