> -----Original Message----- > From: Olivier MATZ [mailto:olivier.matz at 6wind.com] > Sent: Thursday, November 27, 2014 6:13 PM > To: Liu, Jijiang; dev at dpdk.org > Subject: Re: [dpdk-dev] [PATCH 0/3] i40e VXLAN TX checksum rework > > > >> We have got some feedback about backward compatibility of VXLAN TX > >> checksum offload API with 1G/10G NIC after the i40e VXLAN TX checksum > >> codes were applied, so we have to rework the APIs on i40e, including > >> the changes of mbuf, i40e PMD and csum engine. > >> > >> The main changes in mbuf are as follows, In place of removing > >> PKT_TX_VXLAN_CKSUM, we introducing 2 new flags: > >> PKT_TX_OUT_IP_CKSUM, PKT_TX_UDP_TUNNEL_PKT, and a new field: > l4_tun_len. > > > > What about PKT_TX_OUT_UDP_CKSUM instead of > PKT_TX_UDP_TUNNEL_PKT? It's > > maybe more coherent with the other names. > > oh I just realized that the flag is not for asking to the hardware to > calculate the > outer UDP checksum. > So why does the hardware need this information?
As I said before, this flag is used to tell FVL that the transmit packet is a UDP tunneling packet. In FVL, there is a register need to configured, see below. L4 Tunneling Type (Teredo / GRE header / VXLAN header) indication: 00b - No UDP / GRE tunneling (field must be set to zero if EIPT equals to zero) 01b - UDP tunneling header (Any UDP tunneling, VxLAN and Geneve) 10b - GRE tunneling header Else - reserved
