Hi Konstantin,

-----Original Message-----
From: Ananyev, Konstantin
Sent: Monday, February 15, 2016 9:16 PM
To: Thomas Monjalon; Lu, Wenzhuo
Cc: dev@dpdk.org
Subject: RE: [dpdk-dev] [PATCH v2 5/6] ixgbe: support VxLAN & NVGRE TX
checksum off-load

Hi lads,

quoted

-----Original Message-----
From: Thomas Monjalon [mailto:thomas.monjalon@6wind.com]
Sent: Monday, February 15, 2016 10:03 AM
To: Lu, Wenzhuo
Cc: dev@dpdk.org; Ananyev, Konstantin
Subject: Re: [dpdk-dev] [PATCH v2 5/6] ixgbe: support VxLAN & NVGRE TX
checksum off-load

2016-02-15 05:32, Lu, Wenzhuo:

quoted

From: Ananyev, Konstantin

quoted

From reading X550 spec, I don't really understand what for we need
to specify is it GRE or VXLAN packet, so probably we don't need that flag

for now at all?

quoted

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The reason is we need to set the tunnel type in the Advanced Transmit Data

Descriptor.

Yes, I saw that in x550 spec, though I really doubt it is needed to calculate etiher
outer IP, or inner IP/L4 checksum.
After all TUNNELLEN includes all tunnel headers plus inner L2 length.
The only reason I can think it might be useful for  HW is when packets are sent
from one VF to another.
In that case, HW probably would try to avoid extra packet scanning and rely on
information from SW.
As mentioned in x550 spec, section's  note:
"...In virtualization mode, packets might be received from other local VMs. The
X550 does not check the L5 header for these packets and does not report NFS
header. If such packets carry IP tunneling (IPv4 - IPv6), they are reported as
IPV4E. The packets received from local VM are indicated by the LB bit in the
status field. To be identified, the CC bit in the transmit descriptor must be set
and if it is a tunnel packet, the TUNNEL.OUTERIPCS must be set also."
Though I am not sure we do need to support that case.
That's why probably the easiest way would be to avoid setting 'Tunnel Type' field
at all.

Many thanks for your suggestion. I think you're right.
For outer IP header checksum offload, we need not to set the tunnel type bit. I'll choose this option and remove this vxlan ol_flag.

quoted

Why don't we use packet type?

Yes, that's probably another possible way, if we really decide to setup this info
at TX descriptor.

BTW, reading x550 spec, I think ixgbe RX code that setups packet_type need to
be updated too.
Right now it can't handle vxlan/gre tunnelling case.

Konstantin

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If we really do, might bw worth to organise it like KT_TX_L4_CKSUM
(as enum) and reserve few values for future expansion (2 or 3 bits?).

Now there're only VxLAN and NVGRE supported. So, only 1 bit is
occupied for that. Not sure if more types will be supported in the

future. Any suggestions? Thanks.

Yes there can be a lot of tunnel types.
Please check RTE_PTYPE_TUNNEL_*