From owner-freebsd-net@FreeBSD.ORG  Fri Mar 13 01:54:37 2009
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: freebsd-net@FreeBSD.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id 710AB1065670
	for <freebsd-net@FreeBSD.org>; Fri, 13 Mar 2009 01:54:37 +0000 (UTC)
	(envelope-from scf@FreeBSD.org)
Received: from mail.farley.org (mail.farley.org [IPv6:2001:470:1f0f:20:2::11])
	by mx1.freebsd.org (Postfix) with ESMTP id 3F1DE8FC15
	for <freebsd-net@FreeBSD.org>; Fri, 13 Mar 2009 01:54:37 +0000 (UTC)
	(envelope-from scf@FreeBSD.org)
Received: from thor.farley.org (HPooka@thor.farley.org
	[IPv6:2001:470:1f0f:20:1::5])
	by mail.farley.org (8.14.3/8.14.3) with ESMTP id n2D1sZJm007644
	for <freebsd-net@FreeBSD.org>; Thu, 12 Mar 2009 20:54:35 -0500 (CDT)
	(envelope-from scf@FreeBSD.org)
Date: Thu, 12 Mar 2009 20:54:35 -0500 (CDT)
From: "Sean C. Farley" <scf@FreeBSD.org>
To: freebsd-net@FreeBSD.org
Message-ID: <alpine.BSF.2.00.0903122048230.1704@thor.farley.org>
User-Agent: Alpine 2.00 (BSF 1167 2008-08-23)
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; format=flowed; charset=US-ASCII
X-Spam-Status: No, score=-3.2 required=3.0 tests=AWL,BAYES_00,NO_RELAYS
	autolearn=ham version=3.2.5
X-Spam-Checker-Version: SpamAssassin 3.2.5 (2008-06-10) on mail.farley.org
Cc: 
Subject: tap(4) SIOCSIFMTU patch
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Networking and TCP/IP with FreeBSD <freebsd-net.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
	<mailto:freebsd-net-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-net>
List-Post: <mailto:freebsd-net@freebsd.org>
List-Help: <mailto:freebsd-net-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-net>,
	<mailto:freebsd-net-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Fri, 13 Mar 2009 01:54:37 -0000

Here is a patch[1] that will allow the MTU to be set higher than 1500 on 
a tap(4) interface.  I ran into the need to do this when I had em0 set 
to 9000 and tried to bridge em0 with tap0 (MTU 1500) for QEMU.  A bridge 
interface will not allow interfaces with different MTU's to be added to 
it.

Since I have touched little inside the kernel, I thought it best if 
others take a look at it first.

Sean
   1. http://people.freebsd.org/~scf/if_tap-SIOCSIFMTU.patch
-- 
scf@FreeBSD.org