7. Intel® vRAN Boost Poll Mode Driver (PMD)

The Intel® vRAN Boost integrated accelerator enables cost-effective 4G and 5G next-generation virtualized Radio Access Network (vRAN) solutions. The Intel vRAN Boost v1.0 (VRB1 in the code) is specifically integrated on the 4th Gen Intel® Xeon® Scalable processor with Intel® vRAN Boost, also known as Sapphire Rapids Edge Enhanced (SPR-EE).

7.1. Features

Intel vRAN Boost v1.0 includes a 5G Low Density Parity Check (LDPC) encoder/decoder, rate match/dematch, Hybrid Automatic Repeat Request (HARQ) with access to DDR memory for buffer management, a 4G Turbo encoder/decoder, a Fast Fourier Transform (FFT) block providing DFT/iDFT processing offload for the 5G Sounding Reference Signal (SRS), a Queue Manager (QMGR), and a DMA subsystem. There is no dedicated on-card memory for HARQ, the coherent memory on the CPU side is being used.

These hardware blocks provide the following features exposed by the PMD:

  • LDPC Encode in the Downlink (5GNR)

  • LDPC Decode in the Uplink (5GNR)

  • Turbo Encode in the Downlink (4G)

  • Turbo Decode in the Uplink (4G)

  • FFT processing

  • Single Root I/O Virtualization (SR-IOV) with 16 Virtual Functions (VFs) per Physical Function (PF)

  • Maximum of 256 queues per VF

The Intel vRAN Boost v1.0 PMD supports the following bbdev capabilities:

  • For the LDPC encode operation:

    • RTE_BBDEV_LDPC_CRC_24B_ATTACH: set to attach CRC24B to CB(s).

    • RTE_BBDEV_LDPC_RATE_MATCH: if set then do not do Rate Match bypass.

    • RTE_BBDEV_LDPC_INTERLEAVER_BYPASS: if set then bypass interleaver.

  • For the LDPC decode operation:

    • RTE_BBDEV_LDPC_CRC_TYPE_24B_CHECK: check CRC24B from CB(s).

    • RTE_BBDEV_LDPC_CRC_TYPE_24B_DROP: drops CRC24B bits appended while decoding.

    • RTE_BBDEV_LDPC_CRC_TYPE_24A_CHECK: check CRC24A from CB(s).

    • RTE_BBDEV_LDPC_CRC_TYPE_16_CHECK: check CRC16 from CB(s).

    • RTE_BBDEV_LDPC_HQ_COMBINE_IN_ENABLE: provides an input for HARQ combining.

    • RTE_BBDEV_LDPC_HQ_COMBINE_OUT_ENABLE: provides an input for HARQ combining.

    • RTE_BBDEV_LDPC_ITERATION_STOP_ENABLE: disable early termination.

    • RTE_BBDEV_LDPC_DEC_SCATTER_GATHER: supports scatter-gather for input/output data.

    • RTE_BBDEV_LDPC_HARQ_6BIT_COMPRESSION: supports compression of the HARQ input/output.

    • RTE_BBDEV_LDPC_LLR_COMPRESSION: supports LLR input compression.

  • For the turbo encode operation:

    • RTE_BBDEV_TURBO_CRC_24B_ATTACH: set to attach CRC24B to CB(s).

    • RTE_BBDEV_TURBO_RATE_MATCH: if set then do not do Rate Match bypass.

    • RTE_BBDEV_TURBO_RV_INDEX_BYPASS: set to bypass RV index.

    • RTE_BBDEV_TURBO_ENC_SCATTER_GATHER: supports scatter-gather for input/output data.

  • For the turbo decode operation:

    • RTE_BBDEV_TURBO_CRC_TYPE_24B: check CRC24B from CB(s).

    • RTE_BBDEV_TURBO_SUBBLOCK_DEINTERLEAVE: perform subblock de-interleave.

    • RTE_BBDEV_TURBO_NEG_LLR_1_BIT_IN: set if negative LLR input is supported.

    • RTE_BBDEV_TURBO_DEC_TB_CRC_24B_KEEP: keep CRC24B bits appended while decoding.

    • RTE_BBDEV_TURBO_DEC_CRC_24B_DROP: option to drop the code block CRC after decoding.

    • RTE_BBDEV_TURBO_EARLY_TERMINATION: set early termination feature.

    • RTE_BBDEV_TURBO_DEC_SCATTER_GATHER: supports scatter-gather for input/output data.

    • RTE_BBDEV_TURBO_HALF_ITERATION_EVEN: set half iteration granularity.

    • RTE_BBDEV_TURBO_CONTINUE_CRC_MATCH: set to run an extra odd iteration after CRC match.

    • RTE_BBDEV_TURBO_MAP_DEC: supports flexible parallel MAP engine decoding.

  • For the FFT operation:

    • RTE_BBDEV_FFT_WINDOWING: flexible windowing capability.

    • RTE_BBDEV_FFT_CS_ADJUSTMENT: flexible adjustment of Cyclic Shift time offset.

    • RTE_BBDEV_FFT_DFT_BYPASS: set for bypass the DFT and get directly into iDFT input.

    • RTE_BBDEV_FFT_IDFT_BYPASS: set for bypass the IDFT and get directly the DFT output.

    • RTE_BBDEV_FFT_WINDOWING_BYPASS: set for bypass time domain windowing.

7.2. Installation

Section 3 of the DPDK manual provides instructions on installing and compiling DPDK.

DPDK requires hugepages to be configured as detailed in section 2 of the DPDK manual. The bbdev test application has been tested with a configuration 40 x 1GB hugepages. The hugepage configuration of a server may be examined using:

grep Huge* /proc/meminfo

7.3. Initialization

When the device first powers up, its PCI Physical Functions (PF) can be listed through these commands for Intel vRAN Boost v1:

sudo lspci -vd8086:57c0

The physical and virtual functions are compatible with Linux UIO drivers: vfio_pci and igb_uio. However, in order to work the 5G/4G FEC device first needs to be bound to one of these Linux drivers through DPDK.

For more details on how to bind the PF device and create VF devices, see Binding and Unbinding Network Ports to/from the Kernel Modules.

7.3.1. Configure the VFs through PF

The PCI virtual functions must be configured before working or getting assigned to VMs/Containers. The configuration involves allocating the number of hardware queues, priorities, load balance, bandwidth and other settings necessary for the device to perform FEC functions.

This configuration needs to be executed at least once after reboot or PCI FLR and can be achieved by using the functions rte_acc200_configure(), which sets up the parameters defined in the compatible acc200_conf structure.

7.4. Test Application

BBDEV provides a test application, test-bbdev.py and range of test data for testing the functionality of the device, depending on the device’s capabilities.

For more details on how to use the test application, see dpdk-test-bbdev Application.

7.4.1. Test Vectors

In addition to the simple LDPC decoder and LDPC encoder tests, bbdev also provides a range of additional tests under the test_vectors folder, which may be useful. The results of these tests will depend on the device capabilities which may cause some test cases to be skipped, but no failure should be reported.

7.4.2. Alternate Baseband Device configuration tool

On top of the embedded configuration feature supported in test-bbdev using “- -init-device” option mentioned above, there is also a tool available to perform that device configuration using a companion application. The pf_bb_config application notably enables then to run bbdev-test from the VF and not only limited to the PF as captured above.

See for more details: https://github.com/intel/pf-bb-config

Specifically for the bbdev Intel vRAN Boost v1 PMD, the command below can be used (note that ACC200 was used previously to refer to VRB1):

pf_bb_config ACC200 -c ./acc200/acc200_config_vf_5g.cfg
test-bbdev.py -e="-c 0xff0 -a${VF_PCI_ADDR}" -c validation -n 64 -b 64 -l 1 -v ./ldpc_dec_default.data