> > 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 forward > > engine. > > > > The main changes in mbuf are as follows, in place of removing > > PKT_TX_VXLAN_CKSUM, we introduce 4 new flags: > > PKT_TX_OUTER_IP_CKSUM, PKT_TX_OUTER_IPV4, PKT_TX_OUTER_IPV6 and > > PKT_TX_UDP_TUNNEL_PKT. Replace the inner_l2_len > > and the inner_l3_len field with the outer_l2_len and outer_l3_len field. > > > > Let's use a few examples to demonstrate how to use these new flags and > > existing flags in rte_mbuf.h > > Let say we have a tunnel packet: > > eth_hdr_out/ipv4_hdr_out/udp_hdr_out/vxlan_hdr/ehtr_hdr_in/ipv4_hdr_in/tcp_hdr_in. > > There > > could be several scenarios: > > > > A) User requests HW offload for ipv4_hdr_out checksum. > > He doesn't care is it a tunnelled packet or not. So he sets: > > > > mb->l2_len = eth_hdr_out; > > mb->l3_len = ipv4_hdr_out; > > mb->ol_flags |= PKT_TX_IPV4_CSUM; > > > > B) User is aware that it is a tunnelled packet and requests HW offload for > > ipv4_hdr_in and tcp_hdr_in *only*. > > He doesn't care about outer IP checksum offload. In that case, for FVL he > > has 2 choices: > > 1. Treat that packet as a 'proper' tunnelled packet, and fill all the > > fields: > > mb->l2_len = udp_hdr_out + vxlan_hdr +eth_hdr_in; > > mb->l3_len = ipv4_hdr_in; > > mb->outer_l2_len = eth_hdr_out; > > mb->outer_l3_len = ipv4_hdr_out; > > mb->ol_flags |= PKT_TX_UDP_TUNNEL_PKT | PKT_TX_IP_CKSUM | > > PKT_TX_TCP_CKSUM; > > > > 2. As user doesn't care about outer IP hdr checksum, he can treat > > everything before ipv4_hdr_in as L2 header. > > So he knows, that it is a tunnelled packet, but makes HW to treat it as > > ordinary (non-tunnelled) packet: > > mb->l2_len = eth_hdr_out + ipv4_hdr_out + udp_hdr_out + vxlan_hdr + > > ehtr_hdr_in; > > mb->l3_len = ipv4_hdr_in; > > mb->ol_flags |= PKT_TX_IP_CKSUM | PKT_TX_TCP_CKSUM; > > > > i40e PMD will support both B.1 and B.2, but ixgbe/igb/em PMD supports only > > B.2. > > if HW supports both - it will be up to user app which method to choose. > > tespmd will support both methods, and it should be configurable by user > > which approach to use (cmdline parameter). > > So the user can try/test both methods and select an appropriate for him. > > > > C) User knows that is a tunnelled packet, and wants HW offload for all 3 > > checksums: outer IP hdr checksum, inner IP checksum, inner > > TCP checksum. > > Then he has to setup all TX checksum fields: > > mb->l2_len = udp_hdr_out + vxlan_hdr +eth_hdr_in;; > > mb->l3_len = ipv4_hdr_in; > > mb->outer_l2_len = eth_hdr_out; > > mb->outer_l3_len = ipv4_hdr_out; > > mb->ol_flags |= PKT_TX_OUT_IP_CKSUM | PKT_TX_UDP_TUNNEL_PKT | > > PKT_TX_IP_CKSUM | PKT_TX_TCP_CKSUM; > > > > Change notes: > > v2 changes: > > remove PKT_TX_IP_CKSUM alias. > > add PKT_TX_OUT_IP_CKSUM and PKT_TX_OUTER_IPV6 in > > rte_get_tx_ol_flag_name. > > spliting mbuf changes into two patches. > > fix MACLEN caculation issue in i40e driver > > fix some issues in csumonly.c > > change cover letter. > > v3 changes: > > fix MACLEN caculation issue in i40e driver when non-tunneling packet > > v4 changes: > > reorganize patches to avoid compilation to be broken between patches. > > remove l4_tun_len from mbuf structure. > > add PKT_TX_OUTER_IPV4 to indicate no IP checksum offload requirement > > for tunneling packet. > > change i40e PMD and csum engine due to above changes. > > > > v5 changes: > > according to Konstantin's comments, optimize process_outer_cksums() in > > order to avoid setting PKT_TX_OUTER_IPV4 flags for the > > case when user didn't enable TESTPMD_TX_OFFLOAD_VXLAN_CKSUM > > > > Jijiang Liu (3): > > Redefine PKT_TX_IPV4, PKT_TX_IPV6 and PKT_TX_VLAN_PKT; > > Replace PKT_TX_VXLAN_CKSUM with PKT_TX_UDP_TUNNEL_PKT, and add 3 TX > > flags, which are PKT_TX_OUTER_IP_CKSUM, > > PKT_TX_OUTER_IPV4 and PKT_TX_OUTER_IPV6,and rework csum forward engine and > > i40e pmd due to these changes; > > Replace the inner_l2_len and the inner_l3_len field with the outer_l2_len > > and outer_l3_len field, and rework csum forward engine > > and i40e pmd due to these changes; > > Acked-by: Konstantin Ananyev <konstantin.ananyev at intel.com>
Applied with small comments changes suggested by Olivier. Thanks everyone for finding a consensus. It's not easy to accept different of views but we finally did it! Lesson learned: every details of an API must be explicited with clear and short sentences. Thanks -- Thomas
