23/09/2021 13:20, Ivan Malov:

In 2019, commit [1] announced changes in DEV_RX_OFFLOAD namespace
intending to add new flags, RSS_HASH and FLOW_MARK. Since then,
only the former has been added. The problem hasn't been solved.
Applications still assume that no efforts are needed to enable
flow mark and similar meta data delivery.

The team behind net/sfc driver has to take over the efforts since
the problem has started impacting us. Riverhead, a cutting edge
Xilinx smart NIC family, has two Rx prefix types. Rx meta data
is available only from long Rx prefix. Switching between the
prefix formats can't happen in started state. Hence, we run
into the same problem which [1] was aiming to solve.

Sorry I don't understand what is Rx prefix?

Rx meta data (mark, flag, tunnel ID) delivery is not an offload
on its own since the corresponding flows must be active to set
the data in the first place. Hence, adding offload flags
similar to RSS_HASH is not a good idea.

What means "active" here?

Patch [1/5] of this series adds a generic API to let applications
negotiate delivery of Rx meta data during initialisation period.
This way, an application knows right from the start which parts
of Rx meta data won't be delivered. Hence, no necessity to try
inserting flows requesting such data and handle the failures.

Sorry I don't understand the problem you want to solve.
And sorry for not noticing earlier.