From mboxrd@z Thu Jan  1 00:00:00 1970
From: David Miller <davem@davemloft.net>
Subject: Re: ipv4 gro receive IHL
Date: Tue, 23 Oct 2012 02:27:13 -0400 (EDT)
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From: Eric Dumazet <eric.dumazet@gmail.com>
Date: Tue, 23 Oct 2012 08:01:34 +0200

> GRO on IPv4 only supports ihl = 5, this is tested in :
> 
> if (*(u8 *)iph != 0x45)
>     goto out_unlock;
> 
> I also was planning to add some code to ip_fast_csum(addr, X) to have a
> fast path (no conditional jump) for the case where X is the constant 5

Oh indeed, thanks for clearing that up.