43. PFE Poll Mode Driver

The PFE NIC PMD (librte_net_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:

  1. ARM 64 Tool Chain

    For example, the *aarch64* Linaro Toolchain.

  2. Linux Kernel

    It can be obtained from NXP’s Github hosting.

  3. 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.

  4. 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.