[PATCH 2/2] release_2_2.rst: add mlx4 and mlx5 known issues

[Olga Shern <olgas@mellanox.com>]

Signed-off-by: Olga Shern <olgas@mellanox.com>
---
 doc/guides/rel_notes/release_2_2.rst |   13 +++++++++++++
 1 files changed, 13 insertions(+), 0 deletions(-)

diff --git a/doc/guides/rel_notes/release_2_2.rst b/doc/guides/rel_notes/release_2_2.rst
index c3ff086..4f393cf 100644
--- a/doc/guides/rel_notes/release_2_2.rst
+++ b/doc/guides/rel_notes/release_2_2.rst
@@ -284,6 +284,19 @@ Known Issues
   As the l3fwd example application requires this info, the i40e vector
   driver must be disabled to benefit of the packet type with i40e.
 
+* **Mellanox PMDs (mlx4 & mlx5):**
+
+  * PMDs do not support DPDK integrated shared library.
+
+  * There is performance degradation for small packets when PMD
+    is compiled with SGE_WR_N = 4 compared to the performance when SGE_WR_N = 1.
+    If scattered packets are not used it is recomended
+    to compile PMD with SGE_WR_N = 1.
+
+  **mlx4:**
+
+  * When a Multicast or Broadcast packet is sent to the SR-IOV VF,
+    it is returned back to the port.
 
 API Changes
 -----------
-- 
1.7.8.2