From owner-freebsd-net@FreeBSD.ORG  Sat Jul 14 03:31:05 2007
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To: "Bruce M. Simpson" <bms@FreeBSD.org>
From: Mike Karels <karels@karels.net>
In-reply-to: Your message of Sat, 14 Jul 2007 03:30:54 +0100.
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Date: Fri, 13 Jul 2007 22:27:52 -0500
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Cc: Stephen.Clark@seclark.us, Sten Daniel Soersdal <netslists@gmail.com>,
	Julian Elischer <julian@elischer.org>,
	Bill Moran <wmoran@collaborativefusion.com>, freebsd-net@FreeBSD.org
Subject: Re: 6.2 mtu now limits size of incomming packet 
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> In -CURRENT my changes to the ethernet input path maintain the use of 
> ETHER_MAX_FRAME() however the check is folded under #ifdef DIAGNOSTIC. I 
> don't recall adding this conditional or touching it so it seems to be 
> something which was already thereo radded by someone else.

It has been there at least since 6.0.  The issue is that ETHER_MAX_FRAME
is computed using ifp->if_mtu, as opposed to something like ETHER_MAX_LEN.
This is under #ifdef DIAGNOSTIC in -current, not in -stable.

> Could be pilot error; its use in -CURRENT seems to apply strictly to the 
> use of large-receive offload (LRO).

LRO relaxes the requirement, otherwise LRO packets would never pass the
check.

		Mike