[dpdk-dev] Wrong TCP Checkum computed by hardware

[Padam Jeet Singh]

>> 
> Yes, you are correct, I just noticed you declare  it is static, If possible, send more codes to me, I can help you with this.
>>> 
>>>> Thanks,
>>>> Padam
> 


I have the following code:


mbuf->ol_flags = (uint16_t) (mbuf->ol_flags &
			(~PKT_TX_OFFLOAD_MASK));
mbuf->ol_flags |= PKT_TX_IP_CKSUM;
ipv4hdr->hdr_checksum = 0;
tcphdr = (struct tcp_hdr *)(pkt + sizeof(struct ether_hdr) +
						sizeof(struct ipv4_hdr));
#ifdef L4CSUM_SW

tcphdr->cksum = 0;
tcphdr->cksum = get_ipv4_udptcp_checksum(ipv4hdr,	(uint16_t*)tcphdr);

#else

mbuf->ol_flags |= PKT_TX_TCP_CKSUM;
if(!(mbuf->ol_flags & PKT_TX_IPV4))
	mbuf->ol_flags |= PKT_TX_IPV4;
tcphdr->cksum = 0;
tcphdr->cksum = rte_ipv4_phdr_cksum(ipv4hdr);

#endif

mbuf->pkt.vlan_macip.f.vlan_tci = 100;
mbuf->ol_flags |= PKT_TX_VLAN_PKT;

I have added a macro called L4CSUM_SW, if enabled does L4 Checksum computation in software. When I enable this, the packet received has the correct TCP checksum. It is important to note that the checksum is being computed, but is being computed wrong when TX_VLAN, IP_CKSUM and TCP_CKSUM are enabled.

When I do the same test with VLAN removed from the setup, the TCP checksum computation is correct. 

The system exhibiting this issue is a  Intel(R) Xeon(R) CPU E5-2620 v3 @ 2.40GHz X 2, with 2 X 82599ES on a PCIe3 bus:
02:00.0 Ethernet controller: Intel Corporation 82599ES 10-Gigabit SFI/SFP+ Network Connection (rev 01)
	Flags: bus master, fast devsel, latency 0, IRQ 32
	Memory at c7d20000 (64-bit, non-prefetchable) [size=128K]
	Memory at c7d44000 (64-bit, non-prefetchable) [size=16K]
	Capabilities: [40] Power Management version 3
	Capabilities: [50] MSI: Enable- Count=1/1 Maskable+ 64bit+
	Capabilities: [70] MSI-X: Enable+ Count=64 Masked-
	Capabilities: [a0] Express Endpoint, MSI 00
	Capabilities: [e0] Vital Product Data
	Capabilities: [100] Advanced Error Reporting
	Capabilities: [140] Device Serial Number 00-90-0b-ff-ff-3f-19-d0
	Capabilities: [150] Alternative Routing-ID Interpretation (ARI)
	Capabilities: [160] Single Root I/O Virtualization (SR-IOV)
	Kernel driver in use: igb_uio
	Kernel modules: ixgbe