Re: [PATCH] ieee1394: eth1394: use "firewire%d" instead of "eth%d"as interface name

From: Stefan Richter
Date: Thu May 21 2009 - 17:36:24 EST


David Miller wrote:
From: Stefan Richter <stefanr@xxxxxxxxxxxxxxxxx>
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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