doc: add sample flow limitation in mlx5 guide

Add description about the sample flow limitation.
Sample Flow supports in NIC-Rx and E-Switch domains.
Due to Metadata register c0 is deleted while doing the loopback,
so that only support forward the sampling packet into
E-Switch manager port, no additional action support in sample flow.

Add the offloads minimum versions for new sampling feature.

Signed-off-by: Jiawei Wang <jiaweiw@nvidia.com>
Acked-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>

diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index a174cdd..a071db2 100644 (file)
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst
@@ -311,6 +311,12 @@ Limitations
     for some NICs (such as ConnectX-6 Dx and BlueField 2).
     The capability bit ``scatter_fcs_w_decap_disable`` shows NIC support.
 
+- Sample flow:
+
+  - Supports ``RTE_FLOW_ACTION_TYPE_SAMPLE`` action only within NIC Rx and E-Switch steering domain.
+  - The E-Switch Sample flow must have the eswitch_manager VPORT destination (PF or ECPF) and no additional actions.
+  - For ConnectX-5, the ``RTE_FLOW_ACTION_TYPE_SAMPLE`` is typically used as first action in the E-Switch egress flow if with header modify or encapsulation actions.
+
 Statistics
 ----------
 
@@ -1452,6 +1458,11 @@ Supported hardware offloads
    |                       | |  rdma-core 26 | | rdma-core 26  |
    |                       | |  ConnectX-5   | | ConnectX-5    |
    +-----------------------+-----------------+-----------------+
+   | Sampling              | |  DPDK 20.11   | | DPDK 20.11    |
+   |                       | |  OFED 5.2     | | OFED 5.2      |
+   |                       | |  rdma-core 32 | | rdma-core 32  |
+   |                       | |  ConnectX-5   | | ConnectX-5    |
+   +-----------------------+-----------------+-----------------+
 
 Notes for metadata
 ------------------