Date: Tue, 28 Jan 2003 12:38:11 +0100 From: Joerg Wunsch <j@uriah.heep.sax.de> To: "Greg 'groggy' Lehey" <grog@FreeBSD.org> Cc: mobile@FreeBSD.org Subject: Re: How to make an Intel EtherExpress known to xe(4)? Message-ID: <20030128123811.C73987@uriah.heep.sax.de> In-Reply-To: <20030128015118.GQ56320@wantadilla.lemis.com>; from grog@FreeBSD.org on Tue, Jan 28, 2003 at 12:21:18PM %2B1030 References: <20030125235520.A97813@uriah.heep.sax.de> <20030125230756.BC4195D06@ptavv.es.net> <20030127000131.B27981@uriah.heep.sax.de> <20030128015118.GQ56320@wantadilla.lemis.com>
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As Greg 'groggy' Lehey wrote: > OK, I've tried this one, and it now works on my machine. What would > be the implication of using this code with a card which doesn't > return the FCS? The upper layers would kill 4 bytes off the end of each packet, i. e. it'll be unusable. But my guess is that these chips do always return the FCS as part of the packet. You can easily watch this by tcpdumping ping packets: the regular ping payload data are simply counted up, you see them in the sent packet. The reply packet contains the same payload data copied over from the request packet, plus four bytes of "junk" at the end. Well, my guess is that returning the CRC can be turned off as well. The author of our driver wrote that he blindly copied the init flags from the Linux driver without understanding then... And one of the flags reads `CRC'. I guess this means we explicitly ask the card to return the CRC to us. I just decided to write a mail to DD9JN, the author of the Linux driver. -- cheers, J"org .-.-. --... ...-- -.. . DL8DTL http://www.sax.de/~joerg/ NIC: JW11-RIPE Never trust an operating system you don't have sources for. ;-) To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-mobile" in the body of the message
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