43. PFE Poll Mode Driver

The PFE NIC PMD (librte_pmd_pfe) provides poll mode driver support for the inbuilt NIC found in the NXP LS1012 SoC.

More information can be found at NXP Official Website.

43.1. PFE

This section provides an overview of the NXP PFE and how it is integrated into the DPDK.

Contents summary

PFE overview
PFE features
Supported PFE SoCs
Prerequisites
Driver compilation and testing
Limitations

43.1.1. PFE Overview

PFE is a hardware programmable packet forwarding engine to provide high performance Ethernet interfaces. The diagram below shows a system level overview of PFE:

====================================================+===============
US   +-----------------------------------------+    | Kernel Space
     |                                         |    |
     |           PFE Ethernet Driver           |    |
     +-----------------------------------------+    |
               ^   |          ^     |               |
PFE         RXQ|   |TXQ    RXQ|     |TXQ            |
PMD            |   |          |     |               |
               |   v          |     v               |   +----------+
            +---------+     +----------+            |   | pfe.ko   |
            | net_pfe0|     | net_pfe1 |            |   +----------+
            +---------+     +----------+            |
               ^   |          ^     |               |
            TXQ|   |RXQ    TXQ|     |RXQ            |
               |   |          |     |               |
               |   v          |     v               |
              +------------------------+            |
              |                        |            |
              |      PFE HIF driver    |            |
              +------------------------+            |
                    ^         |                     |
                 RX |      TX |                     |
                RING|     RING|                     |
                    |         v                     |
                  +--------------+                  |
                  |              |                  |
==================|    HIF       |==================+===============
      +-----------+              +--------------+
      |           |              |              |        HW
      |  PFE      +--------------+              |
      |       +-----+                +-----+    |
      |       | MAC |                | MAC |    |
      |       |     |                |     |    |
      +-------+-----+----------------+-----+----+
              | PHY |                | PHY |
              +-----+                +-----+

The HIF, PFE, MAC and PHY are the hardware blocks, the pfe.ko is a kernel module, the PFE HIF driver and the PFE ethernet driver combined represent as DPDK PFE poll mode driver are running in the userspace.

The PFE hardware supports one HIF (host interface) RX ring and one TX ring to send and receive packets through packet forwarding engine. Both network interface traffic is multiplexed and send over HIF queue.

net_pfe0 and net_pfe1 are logical ethernet interfaces, created by HIF client driver. HIF driver is responsible for send and receive packets between host interface and these logical interfaces. PFE ethernet driver is a hardware independent and register with the HIF client driver to transmit and receive packets from HIF via logical interfaces.

pfe.ko is required for PHY initialisation and also responsible for creating the character device “pfe_us_cdev” which will be used for interacting with the kernel layer for link status.

43.1.2. PFE Features

L3/L4 checksum offload
Packet type parsing
Basic stats
MTU update
Promiscuous mode
Allmulticast mode
Link status
ARMv8

43.1.3. Supported PFE SoCs

LS1012

43.1.4. Prerequisites

Below are some pre-requisites for executing PFE PMD on a PFE compatible board:

ARM 64 Tool Chain

For example, the *aarch64* Linaro Toolchain.
Linux Kernel

It can be obtained from NXP’s Github hosting.
Rootfile system

Any aarch64 supporting filesystem can be used. For example, Ubuntu 16.04 LTS (Xenial) or 18.04 (Bionic) userland which can be obtained from here.
The ethernet device will be registered as virtual device, so pfe has dependency on rte_bus_vdev library and it is mandatory to use –vdev with value net_pfe to run DPDK application.

The following dependencies are not part of DPDK and must be installed separately:

NXP Linux LSDK

NXP Layerscape software development kit (LSDK) includes support for family of QorIQ® ARM-Architecture-based system on chip (SoC) processors and corresponding boards.

It includes the Linux board support packages (BSPs) for NXP SoCs, a fully operational tool chain, kernel and board specific modules.

LSDK and related information can be obtained from: LSDK
pfe kernel module

pfe kernel module can be obtained from NXP Layerscape software development kit at location /lib/modules/<kernel version>/kernel/drivers/staging/fsl_ppfe in rootfs. Module should be loaded using below command:
```
insmod pfe.ko us=1
```

43.1.5. Driver compilation and testing

Follow instructions available in the document compiling and testing a PMD for a NIC to launch testpmd

Additionally, PFE driver needs –vdev as an input with value net_pfe to execute DPDK application. There is an optional parameter intf available to specify port ID. PFE driver supports only two interfaces, so valid values for intf are 0 and 1. see the command below:

<dpdk app> <EAL args> --vdev="net_pfe0,intf=0" --vdev="net_pfe1,intf=1" -- ...

43.1.6. Limitations

Multi buffer pool cannot be supported.