Hi Thomas, > -----Original Message----- > From: Liu, Jijiang > Sent: Friday, November 28, 2014 12:32 AM > To: Olivier MATZ > Cc: Ananyev, Konstantin; dev at dpdk.org > Subject: RE: [dpdk-dev] [PATCH 0/3] i40e VXLAN TX checksum rework > > > > > -----Original Message----- > > From: Ananyev, Konstantin > > Sent: Thursday, November 27, 2014 11:30 PM > > To: Olivier MATZ; Liu, Jijiang; dev at dpdk.org > > Subject: RE: [dpdk-dev] [PATCH 0/3] i40e VXLAN TX checksum rework > > > > Hi Oliver, > > > > > -----Original Message----- > > > From: dev [mailto:dev-bounces at dpdk.org] On Behalf Of Olivier MATZ > > > Sent: Thursday, November 27, 2014 9:45 AM > > > To: Liu, Jijiang; dev at dpdk.org > > > Subject: Re: [dpdk-dev] [PATCH 0/3] i40e VXLAN TX checksum rework > > > > > > Hi Jijiang, > > > > > > Please find below some comments about the specifications. The global > > > picture looks fine to me. > > > > > > I've not reviewed the patch right now, but it's in the pipe. > > > > > > On 11/27/2014 09:18 AM, Jijiang Liu wrote: > > > > 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. > > > > FVL HW don't support outer L4 checksum offload. > > But to calculate inner checksums correctly, it needs a hint from SW > > about L4 Tunnelling Type. > > > > > > > > > > > > Replace the inner_l2_len and the inner_l3_len field with the > > > > outer_l2_len and > > outer_l3_len field. > > > > > > > > The existing flags are listed below, > > > > PKT_TX_IP_CKSUM: HW IPv4 checksum for non-tunnelling packet/ HW > > inner IPv4 checksum for tunnelling packet > > > > PKT_TX_TCP_CKSUM: HW TCP checksum for non-tunnelling packet/ HW > > inner TCP checksum for tunnelling packet > > > > PKT_TX_SCTP_CKSUM: HW SCTP checksum for non-tunnelling packet/ HW > > inner SCTP checksum for tunnelling packet > > > > PKT_TX_UDP_CKSUM: HW SCTP checksum for non-tunnelling packet/ HW > > inner SCTP checksum for tunnelling packet > > > > PKT_TX_IPV4: IPv4 with no HW checksum offload for non-tunnelling > > packet/inner IPv4 with no HW checksum offload for > > > tunnelling packet > > > > PKT_TX_IPV6: IPv6 non-tunnelling packet/ inner IPv6 with no HW > > checksum offload for tunnelling packet > > > > > > As I suggested in the TSO thread, I think the following semantics is > > > easier to understand for the user: > > > > > > - PKT_TX_IP_CKSUM: tell the NIC to compute IP cksum > > > > > > - PKT_TX_IPV4: tell the NIC it's an IPv4 packet. Required for L4 > > > checksum offload or TSO. > > > > > > - PKT_TX_IPV6: tell the NIC it's an IPv6 packet. Required for L4 > > > checksum offload or TSO. > > > > > > I think it won't make a big difference in the FVL driver. > > > > No, no big difference here, but I still think it will be a bit cleaner > > if all 3 flags would be nutually exclusive. > > In fact, we can unite all 3 of them them into 2 bits, same as we doing > > for L4 > > checksum flags. > > > > > > > > > > > > let's use a few examples to demonstrate how to use these flags: > > > > Let say we have a tunnel packet: > > > > eth_hdr_out/ipv4_hdr_out/udp_hdr_out/vxlan_hdr/ehtr_hdr_in/ipv4_hd > > > > r_ > > > > 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 = eth_hdr_in; > > > > mb->l3_len = ipv4_hdr_in; > > > > mb->outer_l2_len = eth_hdr_out; > > > > mb->outer_l3_len = ipv4_hdr_out; > > > > mb->l4tun_len = vxlan_hdr; > > > > 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. > > > > ixgbe/igb/em PMD supports only B.2. > > > > if HW supports both - it will be up to user app which method to choose. > > > > > > I think we should have a flag to advertise outer ip and outer udp > > > checksum offload support, so the application knows which mode can be > > > used. > > > > You mean a new DEV_TX_OFFLOAD_* value, right? > > Something like: DEV_TX_OFFLOAD_UDP_TUNNEL? > > And make i40e_dev_info_get() to return it? > > Yes, forgot about it, sounds like a proper thing to do.
> Yes, makes sense, I will send a separate patch(bug fixing) to do this. Thanks > . I'm preparing this patch, and will send it out soon, I hope this patch also can be included in DPDK1.8 Thanks. > > Konstantin > > > > > > > > > > > Regards, > > > Olivier