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Message-ID: <4A15C92A.9030300@s5r6.in-berlin.de>
Date: Thu, 21 May 2009 23:35:38 +0200
From: Stefan Richter <stefanr@...6.in-berlin.de>
To: David Miller <davem@...emloft.net>
CC: linux1394-devel@...ts.sourceforge.net,
linux-hotplug@...r.kernel.org, netdev@...r.kernel.org,
linux-kernel@...r.kernel.org, fenlason@...hat.com
Subject: Re: [PATCH] ieee1394: eth1394: use "firewire%d" instead of "eth%d"
as interface name
David Miller wrote:
> From: Stefan Richter <stefanr@...6.in-berlin.de>
> Date: Thu, 21 May 2009 22:13:50 +0200
>
>> But I mildly disagree with the notion that the kernel can't start off
>> with more qualification of the names than merely ensuring their
>> uniqueness. Or the other way around: Even an entirely meaningless
>> prefix would be better than "eth..", or no prefix if that's possible,
>> because eth suspiciously sounds like Ethernet with which the misnamed
>> RFC 2734 driver eth1394 has very little to do.
>
> Even the driver source file is named "ethXXX"! All of the macros
> in the driver are named ETH*. The eth1394hdr looks eerily similar
> to a real ethernet header except that it lacks a source MAC
> address. It's addressing information plus a 16-bit (wow, why that
> size huh?) protocol field. A lot like ethernet.
Sure, because
1. eth1394 was initially written with an eye on how Linux Ethernet
drivers look like (for quite a while it didn't implement RFC 2734),
2. by nature, RFC 2734 as an IP encapsulation can't be very different
from Ethernet. As it happens, RFC 2734 indeed reuses a certain
16 bits wide protocol type field in its encapsulation header, with
familar values such as 0x0800.
[BTW, the rest of the struct eth1394hdr is not the encapsulation header
which goes out to the wire, it's only used internally by the driver. The
real on-the-wire headers are 20...28 bytes wide, depending on
transaction mode and link fragmentation, and there are 4 bytes trailing
data CRC.]
--
Stefan Richter
-=====-=-=== -=-= -==-=
http://arcgraph.de/sr/
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