netdev - Re: [PATCH 0/2] net: Set maximum receive packet size on veth interfaces

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Message-ID: <20170509084928.4cfcbda5@xeon-e3>
Date:   Tue, 9 May 2017 08:49:28 -0700
From:   Stephen Hemminger <stephen@...workplumber.org>
To:     Fredrik Markstrom <fredrik.markstrom@...il.com>
Cc:     Eric Dumazet <eric.dumazet@...il.com>,
        "David S. Miller" <davem@...emloft.net>,
        Alexei Starovoitov <ast@...nel.org>,
        Daniel Borkmann <daniel@...earbox.net>, netdev@...r.kernel.org,
        linux-kernel@...r.kernel.org, bridge@...ts.linux-foundation.org
Subject: Re: [PATCH 0/2] net: Set maximum receive packet size on veth
 interfaces

On Tue,  9 May 2017 14:44:36 +0200
Fredrik Markstrom <fredrik.markstrom@...il.com> wrote:

> Currently veth drops all packets larger then the mtu set on the receiving
> end of the pair. This is inconsistent with most hardware ethernet drivers.

There is no guarantee that packets larger than MTU + VLAN tag will be received
by hardware drivers. So why is this necessary for veth? What is your special
use case which makes this necessary?