From mboxrd@z Thu Jan  1 00:00:00 1970
From: Jesse Brandeburg <jesse.brandeburg@intel.com>
Subject: Re: [net-next 07/15] i40e/i40evf: Add TX/RX outer UDP checksum
 support for X722
Date: Wed, 5 Aug 2015 17:38:30 -0700
Message-ID: <20150805173830.00001a1c@unknown>
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Cc: Jeff Kirsher <jeffrey.t.kirsher@intel.com>,
	"David S. Miller" <davem@davemloft.net>,
	Anjali Singhai Jain <anjali.singhai@intel.com>,
	Linux Kernel Network Developers <netdev@vger.kernel.org>,
	<nhorman@redhat.com>, <sassmann@redhat.com>, <jogreene@redhat.com>,
	Catherine Sullivan <catherine.sullivan@intel.com>,
	jesse.brandeburg@intel.com
To: Tom Herbert <tom@herbertland.com>
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On Wed, 5 Aug 2015 17:13:21 -0700
Tom Herbert <tom@herbertland.com> wrote:

> On Wed, Aug 5, 2015 at 4:52 PM, Jeff Kirsher
> <jeffrey.t.kirsher@intel.com> wrote:
> > From: Anjali Singhai Jain <anjali.singhai@intel.com>
> >                 if (vsi->back->flags & I40E_FLAG_WB_ON_ITR_CAPABLE)
> >                         tx_ring->flags = I40E_TXR_FLAGS_WB_ON_ITR;
> > +               if (vsi->back->flags & I40E_FLAG_OUTER_UDP_CSUM_CAPABLE)
> > +                       tx_ring->flags |= I40E_TXR_FLAGS_OUTER_UDP_CSUM;
> 
> Just curious... is there a difference between enabling the outer UDP
> checksum (of a tunnel) and just enabling checksum offload for UDP
> packets?

Yes, the hardware knows the difference (or we actually tell it
the difference) between a UDP packet and a tunnel inside a UDP
packet.