doc: update flow mark action in mlx5 guide

There some limitations added for the MARK action value range.

Fixes: 2d241515ebaf ("net/mlx5: add devarg for extensive metadata support")
Cc: stable@dpdk.org
Signed-off-by: Viacheslav Ovsiienko <viacheslavo@nvidia.com>

diff --git a/doc/guides/nics/mlx5.rst b/doc/guides/nics/mlx5.rst
index 1765952..13fd1d8 100644 (file)
--- a/doc/guides/nics/mlx5.rst
+++ b/doc/guides/nics/mlx5.rst
@@ -840,7 +840,7 @@ Driver options
   +------+-----------+-----------+-------------+-------------+
   | 1    | 24 bits   | vary 0-32 | 32 bits     | yes         |
   +------+-----------+-----------+-------------+-------------+
-  | 2    | vary 0-32 | 32 bits   | 32 bits     | yes         |
+  | 2    | vary 0-24 | 32 bits   | 32 bits     | yes         |
   +------+-----------+-----------+-------------+-------------+
 
   If there is no E-Switch configuration the ``dv_xmeta_en`` parameter is
@@ -852,6 +852,15 @@ Driver options
   of the extensive metadata features. The legacy Verbs supports FLAG and
   MARK metadata actions over NIC Rx steering domain only.
 
+  The setting MARK or META value to zero means there is no item provided and
+  receiving datapath will not report in mbufs these items are present.
+
+  For the MARK action the last 16 values in the full range are reserved for
+  internal PMD purposes (to emulate FLAG action). The valid range for the
+  MARK action values is 0-0xFFEF for the 16-bit mode and 0-xFFFFEF
+  for the 24-bit mode, the flows with the MARK action value outside
+  the specified range will be rejected.
+
 - ``dv_flow_en`` parameter [int]
 
   A nonzero value enables the DV flow steering assuming it is supported