35. SZEDATA2 poll mode driver library
The SZEDATA2 poll mode driver library implements support for the Netcope FPGA Boards (NFB-*), FPGA-based programmable NICs. The SZEDATA2 PMD uses interface provided by the libsze2 library to communicate with the NFB cards over the sze2 layer.
This driver has external dependencies.
Therefore it is disabled in default configuration files.
It can be enabled by setting
Currently the driver is supported only on x86_64 architectures. Only x86_64 versions of the external libraries are provided.
This PMD requires kernel modules which are responsible for initialization and allocation of resources needed for sze2 layer function. Communication between PMD and kernel modules is mediated by libsze2 library. These kernel modules and library are not part of DPDK and must be installed separately:
The library provides API for initialization of sze2 transfers, receiving and transmitting data segments.
- szedata2_cv3 or szedata2_cv3_fdt
Kernel modules manage initialization of hardware, allocation and sharing of resources for user space applications.
Information about getting the dependencies can be found here.
35.1.1. Versions of the packages
The minimum version of the provided packages:
- for DPDK from 18.05: 4.4.1
- for DPDK up to 18.02 (including): 3.0.5
These configuration options can be modified before compilation in the
CONFIG_RTE_LIBRTE_PMD_SZEDATA2default value: n
Value y enables compilation of szedata2 PMD.
35.3. Using the SZEDATA2 PMD
From DPDK version 16.04 the type of SZEDATA2 PMD is changed to PMD_PDEV. SZEDATA2 device is automatically recognized during EAL initialization. No special command line options are needed.
Kernel modules have to be loaded before running the DPDK application.
35.4. 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 were historically represented in DPDK as a single port.
However, the new 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).
Since each slot may be connected to a different CPU and therefore to a different NUMA node, the card is represented as two ports in DPDK (each with half of the queues), which allows DPDK to work with data from the individual queues on the right NUMA node.
The SZEDATA2 PMD does not support operations related to Ethernet ports (link_up, link_down, set_mac_address, etc.).
NFB cards employ multiple Ethernet ports. Until now, Ethernet port-related operations were performed on all of them (since the whole card was represented as a single port). With NFB-200G2QL card, this is no longer viable (see above).
Since there is no fixed mapping between the queues and Ethernet ports, and since a single card can be represented as two ports in DPDK, there is no way of telling which (if any) physical ports should be associated with individual ports in DPDK.
35.6. Example of usage
Read packets from 0. and 1. receive channel and write them to 0. and 1. transmit channel:
$RTE_TARGET/app/testpmd -l 0-3 -n 2 \ -- --port-topology=chained --rxq=2 --txq=2 --nb-cores=2 -i -a
[...] EAL: PCI device 0000:06:00.0 on NUMA socket -1 EAL: probe driver: 1b26:c1c1 rte_szedata2_pmd PMD: Initializing szedata2 device (0000:06:00.0) PMD: SZEDATA2 path: /dev/szedataII0 PMD: Available DMA channels RX: 8 TX: 8 PMD: resource0 phys_addr = 0xe8000000 len = 134217728 virt addr = 7f48f8000000 PMD: szedata2 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>