Date:	Sat, 08 Oct 2011 14:08:45 +0400
From:	Michael Tokarev <mjt@....msk.ru>
To:	netdev <netdev@...r.kernel.org>
Subject: e100 + VLANs?

Yesterday I tried to use 802.1Q VLAN tagging with an (oldish)
e100-driven network card, identified by lspci like this:

 00:12.0 Ethernet controller: Intel Corporation 82557/8/9/0/1 Ethernet Pro 100 (rev 02)

Just to discover that it does not quite work: packets of
size 1497+ bytes gets lost.

This appears to be a classical problems in this case -
something forgot to allocate extra 4 bytes for the
packets.

There's at least one bugreport from 2008 (!) about this
very issue: http://bugs.centos.org/view.php?id=2719
which is still open.

The kernel I tried this on was 2.6.32, I checked git log
for drivers/net/e100.c - there was no changes up to
current version which may be related to this issue.

The question: is this a driver problem or hardware? If
it's the driver, can it be fixed? And if it's hardware,
can the driver notify the user somehow - like, by refusing
to enable VLAN (sub)devices maybe?

Yesterday it was actually a bit more complicated for me,
since the card in question was used to connect to our
ISP, and they use fixed MAC address per port, so I had
to find another NIC which is a) able to work with VLAN
tags properly, and b) is able to change its mac address.
Lucky I had a VIA RhineIII which does both :)

Thanks,

/mjt
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