[dpdk-dev] Wrong TCP Checkum computed by hardware

[Padam Jeet Singh]

On 28-Oct-2015, at 12:27 pm, Matthew Hall <mhall at mhcomputing.net> wrote:
> 
> On Wed, Oct 28, 2015 at 12:20:22PM +0530, Padam Jeet Singh wrote:
>> Any hint what could I be doing wrong here?
> 
> When this kind of stuff doesn't work it often will depend on the exact version 
> of card, chip, etc. if there are any errata.
> 

82599ES or ixgbe PMD has not had any bug fixes related to offload - not at least what I can see in the git commits.

One important finding: Issue only comes when I do TX VLAN offload using PKT_TX_VLAN_PKT (fill vlan tci, l2_len, l3_len with the VLAN ID, sizeof(struct ether_hdr), sizeof(struct ipv4_hdr) respectively.

So basically VLAN OFFLOAD + IP CSUM OFFLOAD + TCP CSUM OFFLOAD causes the TCP checksum to be computed wrong. VLAN Offload + IP CSUM Offload + TCP CSUM in Software produces correct results. I am suspecting this to be ixgbe driver bug now as nothing in my code can trigger this behaviour.

> So you might want to collect the specifics of the board with lspci -v, 
> ethtool, and pulling it out to check the chip and board revisions.

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

> 
> In addition check over the example apps and see how things work there compared 
> with your own code. Often the DPDK interfaces are kind of complex and small 
> pointer or mbuf manipulation mistakes can cause very odd results.
> 

None of the sample code addresses the scenario which I have = VLAN offload + IP + TCP offload.

> Matthew.

Thanks,
Padam