corundum/README.md

Corundum Readme

GitHub repository: https://github.com/ucsdsysnet/corundum

Introduction

Corundum is an open-source, high-performance FPGA-based NIC. Features include a high performance datapath (256 bit AXI), 10G Ethernet, PCI express gen 3, a custom, high performance, tightly-integrated PCIe DMA engine, many (1000+) transmit, receive, completion, and event queues, MSI interrupts, multiple interfaces, multiple ports per interface, per-port transmit scheduling including high precision TDMA, checksum offloading, and native IEEE 1588 PTP timestamping. A Linux driver is included that integrates with the Linux networking stack. Development and debugging is facilitated by an extensive simulation framwork that covers the entire system from a simulation model of the driver and PCI express interface on one side to the Ethernet interfaces on the other side.

Corundum has several unique architectural features. First, transmit, receive, completion, and event queue states are stored efficiently in block RAM or ultra RAM, enabling support for thousands of individually-controllable queues. These queues are associated with interfaces, and each interface can have multiple ports, each with its own independent scheduler. This enables extremely fine-grained control over packet transmission. Coupled with PTP time synchronization, this enables high precision TDMA.

Corundum currently supports Xilinx Ultrascale and Ultrascale Plus series devices. Desgins are included for the following FPGA boards:

• Alpha Data ADM-PCIE-9V3 (Xilinx Virtex Ultrascale Plus XCVU3P)
• Exablaze ExaNIC X10 (Xilinx Kintex Ultrascale XCKU035)
• Xilinx VCU108 (Xilinx Virtex Ultrascale XCVU095)
• Xilinx VCU118 (Xilinx Virtex Ultrascale Plus XCVU9P)

Documentation

Modules

cpl_queue_manager module

Completion queue manager module. Stores device to host queue state in block RAM or ultra RAM.

event_mux module

Event mux module. Enables multiple event sources to feed the same event queue.

event_queue module

Event queue module. Responsible for writing event queue entries into host memory.

interface module

Interface module. Contains the event queues, interface queues, and ports.

port module

Port module. Contains the transmit and receive engines

queue_manager module

Queue manager module. Stores host to device queue state in block RAM or ultra RAM.

rx_checksum module

Receive checksum computation module. Computes 16 bit checksum of Ethernet frame payload to aid in IP checksum offloading.

rx_engine module

Receive engine. Manages receive descriptor dequeue and fetch via DMA, packet reception, data writeback via DMA, and completion enqueue and writeback via DMA. Handles PTP timestamps for inclusion in completion records.

tdma_ber_ch module

TDMA bit error ratio test channel module. Controls PRBS logic in Ethernet PHY and accumulates bit errors. Can be configured to bin error counts by TDMA timeslot.

tdma_ber module

TDMA bit error ratio test module. Wrapper for a tdma_scheduler and multiple instances of tdma_ber_ch.

tdma_scheduler module

TDMA scheduler module. Generates TDMA timeslot index and timing signals from PTP time.

tx_checksum module

Transmit checksum computation and insertion module. Computes 16 bit checksum of frame data with specified start offset, then inserts computed checksum at the specified position.

tx_engine module

Transmit engine. Manages receive descriptor dequeue and fetch via DMA, packet data fetch via DMA, packet transmission, and completion enqueue and writeback via DMA. Handles PTP timestamps for inclusion in completion records.

tx_scheduler_rr module

Round-robin transmit scheduler. Determines which queues from which to send packets.

tx_scheduler_tdma_rr module

Round-robin TDMA transmit scheduler. Determines which queues from which to send packets. Contains a tdma_scheduler instance to control configuration based on PTP time.

Source Files

cpl_queue_manager.v      : Completion queue manager
event_mux.v              : Event mux
event_queue.v            : Event queue
interface.v              : Interface
port.v                   : Port
queue_manager.v          : Queue manager
rx_checksum.v            : Receive checksum offload
rx_engine.v              : Receive engine
tdma_ber_ch.v            : TDMA BER channel
tdma_ber.v               : TDMA BER
tdma_scheduler.v         : TDMA scheduler
tx_checksum.v            : Transmit checksum offload
tx_engine.v              : Transmit engine
tx_scheduler_rr.v        : Round robin transmit scheduler
tx_scheduler_tdma_rr.v   : Round robin TDMA transmit scheduler

Testing

Running the included testbenches requires MyHDL and Icarus Verilog. Make sure that myhdl.vpi is installed properly for cosimulation to work correctly. The testbenches can be run with a Python test runner like nose or py.test, or the individual test scripts can be run with python directly.

Testbench Files

tb/axi.py            : MyHDL AXI4 master and memory BFM
tb/axil.py           : MyHDL AXI4 lite master and memory BFM
tb/axis_ep.py        : MyHDL AXI Stream endpoints
tb/eth_ep.py         : MyHDL Ethernet frame endpoints
tb/ip_ep.py          : MyHDL IP frame endpoints
tb/mqnic.py          : MyHDL mqnic driver model
tb/pcie.py           : MyHDL PCI Express BFM
tb/pcie_us.py        : MyHDL Xilinx Ultrascale PCIe core model
tb/pcie_usp.py       : MyHDL Xilinx Ultrascale Plus PCIe core model
tb/ptp.py            : MyHDL PTP clock model
tb/udp_ep.py         : MyHDL UDP frame endpoints
tb/xgmii_ep.py       : MyHDL XGMII endpoints

Dependencies

Corundum internally uses the following libraries:

• https://github.com/alexforencich/verilog-axi
• https://github.com/alexforencich/verilog-axis
• https://github.com/alexforencich/verilog-ethernet
• https://github.com/alexforencich/verilog-pcie
• https://github.com/solemnwarning/timespec