This is supposed to be a generic Zynq 7020 TCP server, that receives data from the axi4-stream infrastructure in the FPGA part and uses the TCP stack on Linux running on the ARM core of the Zynq. The FPGA part also provides a packet generation engine, which packs stream of successive 32-bit numbers to packets of various size (depends on Switches). Alternatively, a feedback loop can be used.
Strongly optimized for outgoing direction (S2MM -> TCP), almost no traffic opposite direction. The project consist of following parts:
- VHDL code, that was used as testing environment. It can work either as an echo mode (mm2s->s2mm), or a packet generation mode. PSwitches have a special meaning
- SW0: data production generation enabled
- SW1-4: packet size ("0000" = random size <4 kB, "0001" = 256 Bytes, "0010" = 512 bytes, ... "1101" = 1MBytes)
- SW5: mode of operation ("1" = packet generation, "0" = feadback mode)
- SW6-7: LED status switch
- Linux kernel module, that presents 2 character node in the /dev folder (for reading and writing)
- xldas: a TCP server, that reads from the character device (and writes to)
- TCP receiving application , that checks for the missing data / data corruption checker
VHDL part has to be synthesized via Vivado (version 2018.2 used) Petalinux needs following changes:
- cma=256 parameter to be passed as bootargs. In petalinux: petalinux-config, → DTG Settings → Kernel Bootargs → unset generate boot args automatically, set user set kernel bootargs to "console=ttyPS0,115200 earlyprintk cma=256M"
- create the module: petalinux-create -t modules -n axidmachar --enable
- remove the xilinx dma module: petalinux-config -c kernel #takes a while to start. unset → Device Drivers → DMA Engine support → Xilinx AXI DMAS Engine
- pseudorandom <4kB packets can be received with 72 MBytes/s (555-605 Mbits/s)
- 1MB packets packets can be received with 78 MBytes/s (605-650 Mbits/s)