From owner-freebsd-net@FreeBSD.ORG  Tue May  3 07:34:56 2005
Return-Path: <owner-freebsd-net@FreeBSD.ORG>
Delivered-To: freebsd-net@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP
	id D51BB16A4CE; Tue,  3 May 2005 07:34:56 +0000 (GMT)
Received: from ford.blinkenlights.nl (ford.blinkenlights.nl [213.204.211.2])
	by mx1.FreeBSD.org (Postfix) with ESMTP
	id 6133A43D2F; Tue,  3 May 2005 07:34:56 +0000 (GMT)
	(envelope-from sten@blinkenlights.nl)
Received: from tea.blinkenlights.nl (tea.blinkenlights.nl
	[IPv6:2001:960:301:3:a00:20ff:fe85:fa39])
	(using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits))
	(No client certificate requested)
	by ford.blinkenlights.nl (Postfix) with ESMTP id 2BF653F294;
	Tue,  3 May 2005 09:34:55 +0200 (CEST)
Received: by tea.blinkenlights.nl (Postfix, from userid 101)
	id 3F5A431D; Tue,  3 May 2005 09:07:30 +0200 (CEST)
Received: from localhost (localhost [127.0.0.1])
	by tea.blinkenlights.nl (Postfix) with ESMTP
	id 13EE130E; Tue,  3 May 2005 09:07:30 +0200 (CEST)
Date: Tue, 3 May 2005 09:07:30 +0200 (CEST)
From: Sten Spans <sten@blinkenlights.nl>
To: Mike Silbersack <silby@silby.com>
In-Reply-To: <20050502194640.Q3199@odysseus.silby.com>
Message-ID: <Pine.SOC.4.61.0505030906080.6452@tea.blinkenlights.nl>
References: <20050428135120.GB21428@cell.sick.ru>
	<427111BF.2050607@savvis.net><20050502180353.T787@odysseus.silby.com>
	<Pine.SOC.4.61.0505030116500.709@tea.blinkenlights.nl>
	<20050502194640.Q3199@odysseus.silby.com>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII; format=flowed
cc: harti@FreeBSD.org
cc: Gleb Smirnoff <glebius@FreeBSD.org>
cc: net@FreeBSD.org
cc: jmg@FreeBSD.org
Subject: Re: if_tap unaligned access problem
X-BeenThere: freebsd-net@freebsd.org
X-Mailman-Version: 2.1.1
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: Tue, 03 May 2005 07:34:57 -0000

On Mon, 2 May 2005, Mike Silbersack wrote:

>
> On Tue, 3 May 2005, Sten Spans wrote:
>
>> For the if_tap case fixing the driver ( or rather changing m_uiotombuf )
>> is definately the correct solution. No sensible person would say otherwise.
>> Once the if_tap change is properly tested and signed off it should
>> make it into the tree.
>
> Yes, that makes sense.
>
>> But on the proposed alignment changes:
>> 
>> If you would look at the netbsd url (
>> http://mail-index.netbsd.org/source-changes/2002/07/01/0001.html )
>
> As I said above, just leave the IP stack alone and put the (conditional on 
> non-i386) code around line 731 of if_ethersubr.c:
>
>        /* If the CRC is still on the packet, trim it off. */
>        if (m->m_flags & M_HASFCS) {
>                m_adj(m, -ETHER_CRC_LEN);
>                m->m_flags &= ~M_HASFCS;
>        }
> <-- here
>        switch (ether_type) {
> #ifdef INET
>        case ETHERTYPE_IP:
>
> Then you cover all the protocols at once.

Well it's pretty hard to only align the l3 protocol
header in the ethernet code ...

-- 
Sten Spans

"There is a crack in everything, that's how the light gets in."
Leonard Cohen - Anthem