XDMA repository

What does this repo contain ?

This repository contains two things : first one is the Vivado 2018.1 project with a customized DMA/PCIe Xilinx IP and an example app (https://www.xilinx.com/support/documentation/ip_documentation/xdma/v4_1/pg195-pcie-dma.pdf). The second one is a fork of Xilinx DMA IP Drivers (https://github.com/Xilinx/dma_ip_drivers) which I modified alongside the Vivado project. These two parts are designed to work together, however each part can be used independantly and serve as a working base for further improvements.

Xilinx DMA/IP Subsystem (/xdma_0_ex)

The project has been built under Vivado 2018.1. It's based on the "example project" of the Xilinx DMA Subsystem for PCIe. For now, the configuration has the following properties :

• PCIe Gen3.0 x8
• NetFPGA SUME constraints file (Virtex-7)
• Vendor ID : 10EE, Device ID : 7038
• PCIe to AXI Lite Master interface (PCIe to AXI offset : 0x00000000, size : 1Mio)
• PCIe to DMA Interface
• 1 DMA read channel
• 1 DMA write channel

These options are easily customizable by opening the project and recustomizaing the IP. The project hasn't been tested on other Vivado version nor FPGA devices yet.

Xilinx DMA IP driver (/XDMA)

For more information, see : https://www.xilinx.com/Attachment/Xilinx_Answer_71435_XDMA_Debug_Guide.pdf

This is a fork of the original Xilinx DMA IP driver. It's currently being tested under Linux kernel v5.3. Some modifications were brought to the original driver :

• Supports for 2 (and only 2) DMA channel (modification in xdma/xdma_cdev.c:624 : xdma_threads_create(82); )
• Makefile modification according to Xilinx/dma_ip_drivers#44 (comment)

IMPORTANT

This section contains some important things I've noticed/done in order to make everything work.

• For the Xilinx driver : loading the driver will cause the devices to be part of the "root" group. A solution is to create a udev rule :

sudo groupadd xdma
sudo usermod -a -G xdma $USERNAME
sudo echo '"SUBSYSTEM=="xdma", GROUP="xdma", MODE="0660"' > /etc/udev/rules.d/29-xdma.rules
sudo chown root:root /etc/udev/rules.d/29-xdma.rules
sudo chmod 0644 /etc/udev/rules.d/29-xdma.rules

This will create a "xdma" group for the XDMA channels/devices and add yourself in this group. This way, you don't need to run every script accessing the devices as root. Maybe another solution could be found ?

• There is a driver signature issue, someone offered a solution in Xilinx/dma_ip_drivers#39 (comment)