Subject: Re: [net-next 07/15] i40e/i40evf: Add TX/RX outer UDP checksum support for X722

From: Jesse Brandeburg <[email-masked]>
Date: Wed, 5 Aug 2015 17:38:30 -0700

On Wed, 5 Aug 2015 17:13:21 -0700
Tom Herbert <[email-masked]> wrote:

> On Wed, Aug 5, 2015 at 4:52 PM, Jeff Kirsher
> <[email-masked]> wrote:
> > From: Anjali Singhai Jain <[email-masked]>
> >                 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.