From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: [PATCH net] gso: do GSO for local skb with size bigger than MTU
Date: Tue, 02 Dec 2014 20:35:11 -0800 (PST)
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From: "Du, Fan" <fan.du@intel.com>
Date: Wed, 3 Dec 2014 03:32:46 +0000

>>If guest sees a 1500 byte MTU, that's it's link layer MTU and it had better be able to
>>send 1500 byte packets onto the "wire".
> 
> This patch makes it happens exactly as you putted.
> 
>>If you cannot properly propagate the vxlan encapsulation overhead back into the
>>guest's MTU you must hide this problem from the rest of our stack somehow.
> 
> Again, this patch hide this problem to make Guest feel it can send packet with MTU as 1500 bytes.

I said make the guest see the real MTU, not hide the real MTU by
fragmenting or spitting ICMP PMTU messages back.