[dpdk-users] Why flow can not be created?

[Adrien Mazarguil]

On Fri, Aug 02, 2019 at 03:06:19PM +0900, Hideyuki Yamashita wrote:
> Helllo Experts,

I think most of them are on vacation :)

> Q1. Are there any NICs which supports entag/detag VLAN?
> I searched source DPDK source code with keyword "OF_POP_VLAN" or "OF_POP_VLAN"
> and found some codes within mlx5_flow_tcf.c and cxgbe_flow.c.

Indeed only those two seem to implement that. However depending on what
you're trying to achieve, there could be a workaround as many drivers
provide support for VLAN entag/detag outside rte_flow.

For Rx, you can dedicate queues to perform VLAN stripping through
rte_eth_dev_set_vlan_strip_on_queue(), and use rte_flow to redirect traffic
of interest to these queues after matching specific VLANs and other
properties for instance.

If you don't care about specific VLANs or queues, you can request VLAN
stripping globally using ETH_VLAN_STRIP_OFFLOAD with
rte_eth_dev_set_vlan_offload(), then rely on mbuf->ol_flags & PKT_RX_VLAN to
retrieve it from mbuf->vlan_tci.

On the Tx side you simply have to request mbuf->ol_flags | PKT_TX_VLAN while
doing Tx. As for Rx, make sure DEV_TX_OFFLOAD_VLAN_INSERT is among the Tx
offloads requested during setup (rte_eth_conf->txmode.offloads).

> Q2. Are there any plans in DPDK community to update document about 
> NIC to update support of rte_flow?
> I have heard the situation about document form Adrien, and to be honest
> I felt it is very hard to take try and error with testpmd for every NIC.

This was discussed in the past, however so far no action was taken.

I think we cannot summarize all supported combinations for each NIC while
covering their specific quirks efficiently. For instance, two NICs may
support a given pattern item, but not necessarily at the same position in
the pattern. Likewise for pattern item fields, they may not support the same
masks.

The most sensible approach is perhaps to provide a list of popular flow
rules tagged with the NICs supporting them.

Anyway since it's not a huge priority at the moment, you should start a
discussion on that topic on the dev at dpdk.org mailing list. Without noise,
nothing will happen :) As usual contributions are always welcome!

-- 
Adrien Mazarguil
6WIND