linux-kernel - Re: [PATCH] vmxnet3: Use correct minimum MTU value

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Message-Id: <20171020.071548.524144466372098011.davem@davemloft.net>
Date:   Fri, 20 Oct 2017 07:15:48 +0100 (WEST)
From:   David Miller <davem@...emloft.net>
To:     mgamal@...hat.com
Cc:     netdev@...r.kernel.org, skhare@...are.com, pv-drivers@...are.com,
        linux-kernel@...r.kernel.org, cavery@...hat.com, otubo@...hat.com,
        vkuznets@...hat.com
Subject: Re: [PATCH] vmxnet3: Use correct minimum MTU value

From: Mohammed Gamal <mgamal@...hat.com>
Date: Tue, 17 Oct 2017 16:33:43 +0200

> Currently the vmxnet3 driver has a minimum MTU value of 60. Which
> goes against the RFC791 spec which specifies it at 68.
> 
> Setting MTU to values between 60 <= MTU <= 67 causes the network
> interface to lose its IP, and it fails to restart.
> 
> This sets the minimum value to ETH_MIN_MTU (68) which is compatible
> with is according to spec.
> 
> Reported-by: Bo Yang <boyang@...hat.com>
> Signed-off-by: Mohammed Gamal <mgamal@...hat.com>

There are protocols other than IPv4, and as Andrew mentioned
the ipv4 stack does the right thing by disabling ipv4 on
an interface when the MTU is too small.