12. CNXK Poll Mode driver

The CNXK ETHDEV PMD (librte_net_cnxk) provides poll mode ethdev driver support for the inbuilt network device found in Marvell OCTEON CN9K/CN10K SoC family as well as for their virtual functions (VF) in SR-IOV context.

More information can be found at Marvell Official Website.

12.1. Features

Features of the CNXK Ethdev PMD are:

  • Packet type information
  • Promiscuous mode
  • Jumbo frames
  • Lock-free Tx queue
  • Multiple queues for TX and RX
  • Receiver Side Scaling (RSS)
  • MAC filtering
  • Generic flow API
  • Inner and Outer Checksum offload
  • Port hardware statistics
  • Link state information
  • Link flow control
  • MTU update
  • Scatter-Gather IO support
  • Vector Poll mode driver
  • Debug utilities - Context dump and error interrupt support
  • Support Rx interrupt

12.2. Prerequisites

See Marvell cnxk platform guide for setup information.

12.3. 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:

    ./<build_dir>/app/dpdk-testpmd -c 0xc -a 0002:02:00.0 -- --portmask=0x1 --nb-cores=1 --port-topology=loop --rxq=1 --txq=1
    EAL: Detected 4 lcore(s)
    EAL: Detected 1 NUMA nodes
    EAL: Multi-process socket /var/run/dpdk/rte/mp_socket
    EAL: Selected IOVA mode 'VA'
    EAL: No available hugepages reported in hugepages-16777216kB
    EAL: No available hugepages reported in hugepages-2048kB
    EAL: Probing VFIO support...
    EAL: VFIO support initialized
    EAL:   using IOMMU type 1 (Type 1)
    [ 2003.202721] vfio-pci 0002:02:00.0: vfio_cap_init: hiding cap 0x14@0x98
    EAL: Probe PCI driver: net_cn10k (177d:a063) device: 0002:02:00.0 (socket 0)
    PMD: RoC Model: cn10k
    EAL: No legacy callbacks, legacy socket not created
    testpmd: create a new mbuf pool <mb_pool_0>: n=155456, size=2176, socket=0
    testpmd: preferred mempool ops selected: cn10k_mempool_ops
    Configuring Port 0 (socket 0)
    PMD: Port 0: Link Up - speed 25000 Mbps - full-duplex
    Port 0: link state change event
    Port 0: 96:D4:99:72:A5:BF
    Checking link statuses...
    No commandline core given, start packet forwarding
    io packet forwarding - ports=1 - cores=1 - streams=1 - NUMA support enabled, MP allocation mode: native
    Logical Core 3 (socket 0) forwards packets on 1 streams:
      RX P=0/Q=0 (socket 0) -> TX P=0/Q=0 (socket 0) peer=02:00:00:00:00:00
      io packet forwarding packets/burst=32
      nb forwarding cores=1 - nb forwarding ports=1
      port 0: RX queue number: 1 Tx queue number: 1
        Rx offloads=0x0 Tx offloads=0x10000
        RX queue: 0
          RX desc=4096 - RX free threshold=0
          RX threshold registers: pthresh=0 hthresh=0  wthresh=0
          RX Offloads=0x0
        TX queue: 0
          TX desc=512 - TX free threshold=0
          TX threshold registers: pthresh=0 hthresh=0  wthresh=0
          TX offloads=0x0 - TX RS bit threshold=0
    Press enter to exit

12.4. Runtime Config Options

  • Rx&Tx scalar mode enable (default 0)

    PMD supports both scalar and vector mode, it may be selected at runtime using scalar_enable devargs parameter.

  • RSS reta size (default 64)

    RSS redirection table size may be configured during runtime using reta_size devargs parameter.

    For example:

    -a 0002:02:00.0,reta_size=256

    With the above configuration, reta table of size 256 is populated.

  • Flow priority levels (default 3)

    RTE Flow priority levels can be configured during runtime using flow_max_priority devargs parameter.

    For example:

    -a 0002:02:00.0,flow_max_priority=10

    With the above configuration, priority level was set to 10 (0-9). Max priority level supported is 32.

  • Reserve Flow entries (default 8)

    RTE flow entries can be pre allocated and the size of pre allocation can be selected runtime using flow_prealloc_size devargs parameter.

    For example:

    -a 0002:02:00.0,flow_prealloc_size=4

    With the above configuration, pre alloc size was set to 4. Max pre alloc size supported is 32.

  • Max SQB buffer count (default 512)

    Send queue descriptor buffer count may be limited during runtime using max_sqb_count devargs parameter.

    For example:

    -a 0002:02:00.0,max_sqb_count=64

    With the above configuration, each send queue’s descriptor buffer count is limited to a maximum of 64 buffers.

  • Switch header enable (default none)

    A port can be configured to a specific switch header type by using switch_header devargs parameter.

    For example:

    -a 0002:02:00.0,switch_header="higig2"

    With the above configuration, higig2 will be enabled on that port and the traffic on this port should be higig2 traffic only. Supported switch header types are “chlen24b”, “chlen90b”, “dsa”, “exdsa”, “higig2” and “vlan_exdsa”.

  • RSS tag as XOR (default 0)

    The HW gives two options to configure the RSS adder i.e

    • rss_adder<7:0> = flow_tag<7:0> ^ flow_tag<15:8> ^ flow_tag<23:16> ^ flow_tag<31:24>
    • rss_adder<7:0> = flow_tag<7:0>

    Latter one aligns with standard NIC behavior vs former one is a legacy RSS adder scheme used in OCTEON TX2 products.

    By default, the driver runs in the latter mode. Setting this flag to 1 to select the legacy mode.

    For example to select the legacy mode(RSS tag adder as XOR):

    -a 0002:02:00.0,tag_as_xor=1


Above devarg parameters are configurable per device, user needs to pass the parameters to all the PCIe devices if application requires to configure on all the ethdev ports.

12.5. Limitations

12.5.1. mempool_cnxk external mempool handler dependency

The OCTEON CN9K/CN10K SoC family NIC has inbuilt HW assisted external mempool manager. net_cnxk pmd only works with mempool_cnxk mempool handler as it is performance wise most effective way for packet allocation and Tx buffer recycling on OCTEON TX2 SoC platform.

12.5.2. CRC stripping

The OCTEON CN9K/CN10K SoC family NICs strip the CRC for every packet being received by the host interface irrespective of the offload configuration.

12.5.3. RTE flow GRE support

  • RTE_FLOW_ITEM_TYPE_GRE_KEY works only when checksum and routing bits in the GRE header are equal to 0.

12.5.4. Custom protocols supported in RTE Flow

The RTE_FLOW_ITEM_TYPE_RAW can be used to parse the below custom protocols.

  • vlan_exdsa and exdsa can be parsed at L2 level.
  • NGIO can be parsed at L3 level.

For vlan_exdsa and exdsa, the port has to be configured with the respective switch header.

For example:

-a 0002:02:00.0,switch_header="vlan_exdsa"

The below fields of struct rte_flow_item_raw shall be used to specify the pattern.

  • relative Selects the layer at which parsing is done.
    • 0 for exdsa and vlan_exdsa.
    • 1 for NGIO.
  • offset The offset in the header where the pattern should be matched.
  • length Length of the pattern.
  • pattern Pattern as a byte string.

Example usage in testpmd:

./dpdk-testpmd -c 3 -w 0002:02:00.0,switch_header=exdsa -- -i \
               --rx-offloads=0x00080000 --rxq 8 --txq 8
testpmd> flow create 0 ingress pattern eth / raw relative is 0 pattern \
       spec ab pattern mask ab offset is 4 / end actions queue index 1 / end

12.6. Debugging Options

Table 12.96 cnxk ethdev debug options
# Component EAL log command
1 NIX –log-level=’pmd.net.cnxk,8’
2 NPC –log-level=’pmd.net.cnxk.flow,8’