+X550 does not support legacy interrupt mode
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+Description
+^^^^^^^^^^^
+X550 cannot get interrupts if using ``uio_pci_generic`` module or using legacy
+interrupt mode of ``igb_uio`` or ``vfio``. Because the errata of X550 states
+that the Interrupt Status bit is not implemented. The errata is the item #22
+from `X550 spec update <https://www.intel.com/content/dam/www/public/us/en/
+documents/specification-updates/ethernet-x550-spec-update.pdf>`_
+
+Implication
+^^^^^^^^^^^
+When using ``uio_pci_generic`` module or using legacy interrupt mode of
+``igb_uio`` or ``vfio``, the Interrupt Status bit would be checked if the
+interrupt is coming. Since the bit is not implemented in X550, the irq cannot
+be handled correctly and cannot report the event fd to DPDK apps. Then apps
+cannot get interrupts and ``dmesg`` will show messages like ``irq #No.: ``
+``nobody cared.``
+
+Workaround
+^^^^^^^^^^
+Do not bind the ``uio_pci_generic`` module in X550 NICs.
+Do not bind ``igb_uio`` with legacy mode in X550 NICs.
+Before binding ``vfio`` with legacy mode in X550 NICs, use ``modprobe vfio ``
+``nointxmask=1`` to load ``vfio`` module if the intx is not shared with other
+devices.
+
+Inline crypto processing support
+--------------------------------
+
+Inline IPsec processing is supported for ``RTE_SECURITY_ACTION_TYPE_INLINE_CRYPTO``
+mode for ESP packets only:
+
+- ESP authentication only: AES-128-GMAC (128-bit key)
+- ESP encryption and authentication: AES-128-GCM (128-bit key)
+
+IPsec Security Gateway Sample Application supports inline IPsec processing for
+ixgbe PMD.
+
+For more details see the IPsec Security Gateway Sample Application and Security
+library documentation.
+
+
+Virtual Function Port Representors
+----------------------------------
+The IXGBE PF PMD supports the creation of VF port representors for the control
+and monitoring of IXGBE virtual function devices. Each port representor
+corresponds to a single virtual function of that device. Using the ``devargs``
+option ``representor`` the user can specify which virtual functions to create
+port representors for on initialization of the PF PMD by passing the VF IDs of
+the VFs which are required.::
+
+ -w DBDF,representor=[0,1,4]
+
+Currently hot-plugging of representor ports is not supported so all required
+representors must be specified on the creation of the PF.