readme.md

Arty-A7

To test and debug hBPF this folder contains a simple design which instantiates a hBPF CPU, connects its status signals to some LEDs and creates a serial Wishbone Bridge and LiteScope Debugger as shown in the following overview picture. It also connects to the Ethernet port of the Arty-A7 by using LiteETH.

The bitstream includes a sample hBPF program which looks for IP4 or IPv6 ICMP(6) Echo Requests (Pings) to detect possible missing sequence numbers. Its a simple program which does not provide any type of IP4 ARP or IPv6 ND, does not send Echo responses back, and which does not care about which host send the pings.

To try it out, the following testbed could be used:

Connect a host either directly using a crossover cable or by using a switch to the Arty. Then use the sc_setup.sh script to configure the host interface with IP addresses and a permanent neighbour cache entry to reach the Arty. Later this can be undone with sc_clean.sh.

Next try to ping the Arty under the IP address you configured in the script (e.g. 10.0.10.50 or 2001:db9:10::50). You should see the blue Network Activity LED blink each time a ping was received. Try using different ping speeds, see also send_pings.sh script.

Whenever the hBPF program detects a missed ping (missing sequence number), it sets the blue Network Error LED high. This can be simulated for example by a short network cable disconnect.

Each time a new ping test is started, the Network Error LED is reset.

To debug (e.g. show a received packet) do the following:

• Run server-start.sh to start the wishbone bridge.
• Run dump.sh which waits til a network packet is completely received and then creates a *.vcd capture file on the host.
• Send exactly one packet from host with ping -c 1 10.0.10.50.
• This should trigger a capture on the target. Wait til dump file is completely received on host.
• Use gtkwave dump.vcd dump.gtkw to display the capture file.

The physical connections on the Arty:

Build report for the included bitstream can be found here.