38. NFB poll mode driver library

The NFB poll mode driver library implements support for the Netcope FPGA Boards (NFB-40G2, NFB-100G2, NFB-200G2QL) and Silicom FB2CGG3 card, FPGA-based programmable NICs. The NFB PMD uses interface provided by the libnfb library to communicate with these cards over the nfb layer.

More information about the NFB cards and used technology (Netcope Development Kit) can be found on the Netcope Technologies website.

Note

This driver has external dependencies. Therefore it is disabled in default configuration files. It can be enabled by setting CONFIG_RTE_LIBRTE_NFB_PMD=y and recompiling.

Note

Currently the driver is supported only on x86_64 architectures. Only x86_64 versions of the external libraries are provided.

38.1. Prerequisites

This PMD requires kernel modules which are responsible for initialization and allocation of resources needed for nfb layer function. Communication between PMD and kernel modules is mediated by libnfb library. These kernel modules and library are not part of DPDK and must be installed separately:

• libnfb library

  The library provides API for initialization of nfb transfers, receiving and transmitting data segments.

• Kernel modules

  • nfb

  Kernel modules manage initialization of hardware, allocation and sharing of resources for user space applications.

Dependencies can be found here: Netcope common.

38.1.1. Versions of the packages

The minimum version of the provided packages:

• for DPDK from 19.05

38.2. Configuration

These configuration options can be modified before compilation in the .config file:

• CONFIG_RTE_LIBRTE_NFB_PMD default value: n

  Value y enables compilation of nfb PMD.

Timestamps

The PMD supports hardware timestamps of frame receipt on physical network interface. In order to use the timestamps, the hardware timestamping unit must be enabled (follow the documentation of the NFB products) and the device argument timestamp=1 must be used.

$RTE_TARGET/app/testpmd -w b3:00.0,timestamp=1 <other EAL params> -- <testpmd params>

When the timestamps are enabled with the devarg, a timestamp validity flag is set in the MBUFs containing received frames and timestamp is inserted into the rte_mbuf struct.

The timestamp is an uint64_t field. Its lower 32 bits represent seconds portion of the timestamp (number of seconds elapsed since 1.1.1970 00:00:00 UTC) and its higher 32 bits represent nanosecond portion of the timestamp (number of nanoseconds elapsed since the beginning of the second in the seconds portion.

38.3. Using the NFB PMD

Kernel modules have to be loaded before running the DPDK application.

38.4. NFB card architecture

The NFB cards are multi-port multi-queue cards, where (generally) data from any Ethernet port may be sent to any queue. They are represented in DPDK as a single port.

NFB-200G2QL card employs an add-on cable which allows to connect it to two physical PCI-E slots at the same time (see the diagram below). This is done to allow 200 Gbps of traffic to be transferred through the PCI-E bus (note that a single PCI-E 3.0 x16 slot provides only 125 Gbps theoretical throughput).

Although each slot may be connected to a different CPU and therefore to a different NUMA node, the card is represented as a single port in DPDK. To work with data from the individual queues on the right NUMA node, connection of NUMA nodes on first and last queue (each NUMA node has half of the queues) need to be checked.

Fig. 38.1 NFB-200G2QL high-level diagram

38.5. Limitations

Driver is usable only on Linux architecture, namely on CentOS.

Since a card is always represented as a single port, but can be connected to two NUMA nodes, there is need for manual check where master/slave is connected.

38.6. Example of usage

Read packets from 0. and 1. receive queue and write them to 0. and 1. transmit queue:

$RTE_TARGET/app/testpmd -l 0-3 -n 2 \
-- --port-topology=chained --rxq=2 --txq=2 --nb-cores=2 -i -a

Example output:

[...]
EAL: PCI device 0000:06:00.0 on NUMA socket -1
EAL:   probe driver: 1b26:c1c1 net_nfb
PMD: Initializing NFB device (0000:06:00.0)
PMD: Available DMA queues RX: 8 TX: 8
PMD: NFB device (0000:06:00.0) successfully initialized
Interactive-mode selected
Auto-start selected
Configuring Port 0 (socket 0)
Port 0: 00:11:17:00:00:00
Checking link statuses...
Port 0 Link Up - speed 10000 Mbps - full-duplex
Done
Start automatic packet forwarding
  io packet forwarding - CRC stripping disabled - packets/burst=32
  nb forwarding cores=2 - nb forwarding ports=1
  RX queues=2 - RX desc=128 - RX free threshold=0
  RX threshold registers: pthresh=0 hthresh=0 wthresh=0
  TX queues=2 - TX desc=512 - TX free threshold=0
  TX threshold registers: pthresh=0 hthresh=0 wthresh=0
  TX RS bit threshold=0 - TXQ flags=0x0
testpmd>