20. ENETFEC Poll Mode Driver

The ENETFEC NIC PMD (librte_net_enetfec) provides poll mode driver support for the inbuilt NIC found in the ** NXP i.MX 8M Mini** SoC.

More information can be found at NXP Official Website <https://www.nxp.com/products/processors-and-microcontrollers/arm-processors/i-mx-applications-processors/i-mx-8-processors/i-mx-8m-mini-arm-cortex-a53-cortex-m4-audio-voice-video:i.MX8MMINI>

This section provides an overview of the NXP ENETFEC and how it is integrated into the DPDK. Driver is taken as experimental as driver depends on a Linux kernel module ‘enetfec-uio’, which is not upstreamed yet.

Contents summary

  • ENETFEC overview

  • Supported ENETFEC SoCs

  • ENETFEC features

  • Prerequisites

  • Driver compilation and testing

  • Limitations

20.1. ENETFEC Overview

The i.MX 8M Mini Media Applications Processor is built to achieve both high performance and low power consumption. ENETFEC PMD is a hardware programmable packet forwarding engine to provide high performance Ethernet interface. It has only 1 GB Ethernet interface with RJ45 connector.

The diagram below shows a system level overview of ENETFEC:

=====================================================
Userspace
     +-----------------------------------------+
     |             ENETFEC Driver              |
     |        +-------------------------+      |
     |        | virtual ethernet device |      |
     +-----------------------------------------+
                       ^   |
                       |   |
                       |   |
                  RXQ  |   | TXQ
                       |   |
                       |   v
=====================================================
Kernel Space
                    +---------+
                    | fec-uio |
====================+=========+======================
Hardware
     +-----------------------------------------+
     |           i.MX 8M MINI EVK              |
     |               +-----+                   |
     |               | MAC |                   |
     +---------------+-----+-------------------+
                     | PHY |
                     +-----+

ENETFEC Ethernet driver is traditional DPDK PMD running in userspace. ‘fec-uio’ is the kernel driver. The MAC and PHY are the hardware blocks. ENETFEC PMD uses standard UIO interface to access kernel for PHY initialisation and for mapping the allocated memory of register & buffer descriptor with DPDK which gives access to non-cacheable memory for buffer descriptor. net_enetfec is logical Ethernet interface, created by ENETFEC driver.

  • ENETFEC driver registers the device in virtual device driver.

  • RTE framework scans and will invoke the probe function of ENETFEC driver.

  • The probe function will set the basic device registers and also setups BD rings.

  • On packet Rx the respective BD Ring status bit is set which is then used for packet processing.

  • Then Tx is done first followed by Rx via logical interfaces.

20.2. Supported ENETFEC SoCs

  • i.MX 8M Mini

20.3. ENETFEC Features

  • Basic stats

  • Promiscuous

  • VLAN offload

  • L3/L4 checksum offload

  • Linux

  • ARMv8

20.4. Prerequisites

There are three main pre-requisites for executing ENETFEC PMD on a i.MX 8M Mini 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.

    Note

    Branch is ‘lf-5.10.y’

  3. Rootfile system

    Any aarch64 supporting filesystem can be used. For example, Ubuntu 18.04 LTS (Bionic) or 20.04 LTS(Focal) userland which can be obtained from here.

  4. The Ethernet device will be registered as virtual device, so ENETFEC has dependency on rte_bus_vdev library and it is mandatory to use –vdev with value net_enetfec to run DPDK application.

20.5. Driver compilation and testing

Follow instructions available in the document Compiling and testing a PMD for a NIC to launch dpdk-testpmd.

20.6. Limitations

  • Multi queue is not supported.