+LBK HW Access
+-------------
+
+Loopback HW Unit (LBK) receives packets from NIX-RX and sends packets back to NIX-TX.
+The loopback block has N channels and contains data buffering that is shared across
+all channels. The LBK HW Unit is abstracted using ethdev subsystem, Where PF0's
+VFs are exposed as ethdev device and odd-even pairs of VFs are tied together,
+that is, packets sent on odd VF end up received on even VF and vice versa.
+This would enable HW accelerated means of communication between two domains
+where even VF bound to the first domain and odd VF bound to the second domain.
+
+Typical application usage models are,
+
+#. Communication between the Linux kernel and DPDK application.
+#. Exception path to Linux kernel from DPDK application as SW ``KNI`` replacement.
+#. Communication between two different DPDK applications.
+
+SDP interface
+-------------
+
+System DPI Packet Interface unit(SDP) provides PCIe endpoint support for remote host
+to DMA packets into and out of OCTEON TX2 SoC. SDP interface comes in to live only when
+OCTEON TX2 SoC is connected in PCIe endpoint mode. It can be used to send/receive
+packets to/from remote host machine using input/output queue pairs exposed to it.
+SDP interface receives input packets from remote host from NIX-RX and sends packets
+to remote host using NIX-TX. Remote host machine need to use corresponding driver
+(kernel/user mode) to communicate with SDP interface on OCTEON TX2 SoC. SDP supports
+single PCIe SRIOV physical function(PF) and multiple virtual functions(VF's). Users
+can bind PF or VF to use SDP interface and it will be enumerated as ethdev ports.
+
+The primary use case for SDP is to enable the smart NIC use case. Typical usage models are,
+
+#. Communication channel between remote host and OCTEON TX2 SoC over PCIe.
+#. Transfer packets received from network interface to remote host over PCIe and
+ vice-versa.
+