10. DPAA Poll Mode Driver

The DPAA NIC PMD (librte_pmd_dpaa) provides poll mode driver support for the inbuilt NIC found in the NXP DPAA SoC family.

More information can be found at NXP Official Website.

10.1. NXP DPAA (Data Path Acceleration Architecture - Gen 1)

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

Contents summary

  • DPAA overview
  • DPAA driver architecture overview

10.1.1. DPAA Overview

Reference: FSL DPAA Architecture.

The QorIQ Data Path Acceleration Architecture (DPAA) is a set of hardware components on specific QorIQ series multicore processors. This architecture provides the infrastructure to support simplified sharing of networking interfaces and accelerators by multiple CPU cores, and the accelerators themselves.

DPAA includes:

  • Cores
  • Network and packet I/O
  • Hardware offload accelerators
  • Infrastructure required to facilitate flow of packets between the components above

Infrastructure components are:

  • The Queue Manager (QMan) is a hardware accelerator that manages frame queues. It allows CPUs and other accelerators connected to the SoC datapath to enqueue and dequeue ethernet frames, thus providing the infrastructure for data exchange among CPUs and datapath accelerators.
  • The Buffer Manager (BMan) is a hardware buffer pool management block that allows software and accelerators on the datapath to acquire and release buffers in order to build frames.

Hardware accelerators are:

  • SEC - Cryptographic accelerator
  • PME - Pattern matching engine

The Network and packet I/O component:

  • The Frame Manager (FMan) is a key component in the DPAA and makes use of the DPAA infrastructure (QMan and BMan). FMan is responsible for packet distribution and policing. Each frame can be parsed, classified and results may be attached to the frame. This meta data can be used to select particular QMan queue, which the packet is forwarded to.

10.2. DPAA DPDK - Poll Mode Driver Overview

This section provides an overview of the drivers for DPAA:

  • Bus driver and associated “DPAA infrastructure” drivers
  • Functional object drivers (such as Ethernet).

Brief description of each driver is provided in layout below as well as in the following sections.

                                   +------------+
                                   | DPDK DPAA  |
                                   |    PMD     |
                                   +-----+------+
                                         |
                                   +-----+------+       +---------------+
                                   :  Ethernet  :.......| DPDK DPAA     |
                . . . . . . . . .  :   (FMAN)   :       | Mempool driver|
               .                   +---+---+----+       |  (BMAN)       |
              .                        ^   |            +-----+---------+
             .                         |   |<enqueue,         .
            .                          |   | dequeue>         .
           .                           |   |                  .
          .                        +---+---V----+             .
         .      . . . . . . . . . .: Portal drv :             .
        .      .                   :            :             .
       .      .                    +-----+------+             .
      .      .                     :   QMAN     :             .
     .      .                      :  Driver    :             .
+----+------+-------+              +-----+------+             .
|   DPDK DPAA Bus   |                    |                    .
|   driver          |....................|.....................
|   /bus/dpaa       |                    |
+-------------------+                    |
                                         |
========================== HARDWARE =====|========================
                                        PHY
=========================================|========================

In the above representation, solid lines represent components which interface with DPDK RTE Framework and dotted lines represent DPAA internal components.

10.2.1. DPAA Bus driver

The DPAA bus driver is a rte_bus driver which scans the platform like bus. Key functions include:

  • Scanning and parsing the various objects and adding them to their respective device list.
  • Performing probe for available drivers against each scanned device
  • Creating necessary ethernet instance before passing control to the PMD

10.2.2. DPAA NIC Driver (PMD)

DPAA PMD is traditional DPDK PMD which provides necessary interface between RTE framework and DPAA internal components/drivers.

  • Once devices have been identified by DPAA Bus, each device is associated with the PMD
  • PMD is responsible for implementing necessary glue layer between RTE APIs and lower level QMan and FMan blocks. The Ethernet driver is bound to a FMAN port and implements the interfaces needed to connect the DPAA network interface to the network stack. Each FMAN Port corresponds to a DPDK network interface.

10.2.2.1. Features

Features of the DPAA PMD are:

  • Multiple queues for TX and RX
  • Receive Side Scaling (RSS)
  • Packet type information
  • Checksum offload
  • Promiscuous mode

10.2.3. DPAA Mempool Driver

DPAA has a hardware offloaded buffer pool manager, called BMan, or Buffer Manager.

  • Using standard Mempools operations RTE API, the mempool driver interfaces with RTE to service each mempool creation, deletion, buffer allocation and deallocation requests.
  • Each FMAN instance has a BMan pool attached to it during initialization. Each Tx frame can be automatically released by hardware, if allocated from this pool.

10.3. Supported DPAA SoCs

  • LS1043A/LS1023A
  • LS1046A/LS1026A

10.4. Prerequisites

There are three main pre-requisities for executing DPAA PMD on a DPAA 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 15.10 (Wily) or 16.04 LTS (Xenial) userland which can be obtained from here.

  4. FMC Tool

    Before any DPDK application can be executed, the Frame Manager Configuration Tool (FMC) need to be executed to set the configurations of the queues. This includes the queue state, RSS and other policies. This tool can be obtained from NXP (Freescale) Public Git Repository.

    This tool needs configuration files which are available in the DPDK Extra Scripts, described below for DPDK usages.

As an alternative method, DPAA PMD can also be executed using images provided as part of SDK from NXP. The SDK includes all the above prerequisites necessary to bring up a DPAA board.

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

  • NXP Linux SDK

    NXP Linux software development kit (SDK) 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.

    SDK and related information can be obtained from: NXP QorIQ SDK.

  • DPDK Extra Scripts

    DPAA based resources can be configured easily with the help of ready scripts as provided in the DPDK Extra repository.

    DPDK Extras Scripts.

Currently supported by DPDK:

Note

Some part of dpaa bus code (qbman and fman - library) routines are dual licensed (BSD & GPLv2), however they are used as BSD in DPDK in userspace.

10.5. Pre-Installation Configuration

10.5.1. Config File Options

The following options can be modified in the config file. Please note that enabling debugging options may affect system performance.

  • CONFIG_RTE_LIBRTE_DPAA_BUS (default n)

    By default it is enabled only for defconfig_arm64-dpaa-* config. Toggle compilation of the librte_bus_dpaa driver.

  • CONFIG_RTE_LIBRTE_DPAA_PMD (default n)

    By default it is enabled only for defconfig_arm64-dpaa-* config. Toggle compilation of the librte_pmd_dpaa driver.

  • CONFIG_RTE_LIBRTE_DPAA_DEBUG_DRIVER (default n)

    Toggles display of bus configurations and enables a debugging queue to fetch error (Rx/Tx) packets to driver. By default, packets with errors (like wrong checksum) are dropped by the hardware.

  • CONFIG_RTE_LIBRTE_DPAA_HWDEBUG (default n)

    Enables debugging of the Queue and Buffer Manager layer which interacts with the DPAA hardware.

  • CONFIG_RTE_MBUF_DEFAULT_MEMPOOL_OPS (default dpaa)

    This is not a DPAA specific configuration - it is a generic RTE config. For optimal performance and hardware utilization, it is expected that DPAA Mempool driver is used for mempools. For that, this configuration needs to enabled.

10.5.2. Environment Variables

DPAA drivers uses the following environment variables to configure its state during application initialization:

  • DPAA_NUM_RX_QUEUES (default 1)

    This defines the number of Rx queues configured for an application, per port. Hardware would distribute across these many number of queues on Rx of packets. In case the application is configured to use lesser number of queues than configured above, it might result in packet loss (because of distribution).

  • DPAA_PUSH_QUEUES_NUMBER (default 4)

    This defines the number of High performance queues to be used for ethdev Rx. These queues use one private HW portal per queue configured, so they are limited in the system. The first configured ethdev queues will be automatically be assigned from the these high perf PUSH queues. Any queue configuration beyond that will be standard Rx queues. The application can choose to change their number if HW portals are limited. The valid values are from ‘0’ to ‘4’. The valuse shall be set to ‘0’ if the application want to use eventdev with DPAA device.

10.6. Driver compilation and testing

Refer to the document compiling and testing a PMD for a NIC for details.

  1. Running testpmd:

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

    Example output:

    ./arm64-dpaa-linuxapp-gcc/testpmd -c 0xff -n 1 \
      -- -i --portmask=0x3 --nb-cores=1 --no-flush-rx
    
    .....
    EAL: Registered [pci] bus.
    EAL: Registered [dpaa] bus.
    EAL: Detected 4 lcore(s)
    .....
    EAL: dpaa: Bus scan completed
    .....
    Configuring Port 0 (socket 0)
    Port 0: 00:00:00:00:00:01
    Configuring Port 1 (socket 0)
    Port 1: 00:00:00:00:00:02
    .....
    Checking link statuses...
    Port 0 Link Up - speed 10000 Mbps - full-duplex
    Port 1 Link Up - speed 10000 Mbps - full-duplex
    Done
    testpmd>
    

10.7. Limitations

10.7.1. Platform Requirement

DPAA drivers for DPDK can only work on NXP SoCs as listed in the Supported DPAA SoCs.

10.7.2. Maximum packet length

The DPAA SoC family support a maximum of a 10240 jumbo frame. The value is fixed and cannot be changed. So, even when the rxmode.max_rx_pkt_len member of struct rte_eth_conf is set to a value lower than 10240, frames up to 10240 bytes can still reach the host interface.

10.7.3. Multiprocess Support

Current version of DPAA driver doesn’t support multi-process applications where I/O is performed using secondary processes. This feature would be implemented in subsequent versions.