hssi_loopback - Software utility to run HSSI loopback tests on FPGA


hssi_loopback [[--bus|-b <bus number>] [--device | -d <device number>] [--function | -f <function number>]]|[--socket-id <socket-id>]       [--mode|-m auto|e40|e10]        [send [<source port> [<destination port>] [--packet-count|-c <count>] [--packet-delay|-d <delay>] [--packet-length|-l <length>]] |status [clear] | stop | readmacs


The hssi_loopback utility works in conjunction with a packet generator accelerator function unit (AFU) to test high-speed serial interface (HSSI) cards. The hssi_loopback utility tests both external and internal loopbacks. hssi_loopback runs an external loopback test when the command line arguments include both source and destination ports. hssi_loopback runs an internal loopback test when command line arguments include a single port. hssi_loopback only runs on the Intel Xeon with Arria 10 FPGA. You cannot run it on Intel FPGA PACs.

NOTE: The following limitations apply to the current version of hssi_loopback:

  • For the external loopback the two port arguments can be the same. For the e10 design, the ports should be the same.
  • The hssi_loopback test supports only the e40 and e10 E2E AFUs. The e10 E2E AFU tests HSSI with a retimer card.
  • The hssi_loopback test uses the control and status registers (CSRs) defined in the AFU.


-S SOCKET_ID, --socket-id SOCKET_ID

Socket ID FPGA resource.

-B BUS, --bus BUS

Bus ID of FPGA resource.

-D DEVICE, --device DEVICE

Device ID of FPGA resource.


Function ID of FPGA resource.

-G, --guid

Specifies guid for the AFC enumeration.

-m, --mode

One of the following: [auto, e40, e10] auto is the default and indicates that the software runs the mode based on the first accelerator functional context (AFC) it enumerates.

-t, --timeout

Timeout (in seconds) before the application terminates in continuous mode. Continuous mode is the default when you do not specify the number of packets.

-y, --delay

Delay (in seconds) between printing out a simple status line. Default is 0.100 seconds (100 milliseconds).

-c, --packet-count

The number of packets to send.

-d, --packet-delay

The delay in between packets. This delay is the number of 100 MHz clock cycles, roughly 10 nanoseconds.

-s, --packet-size

The packet size to send. The minimum is 46 bytes and the maximum is 1500 bytes. The default is 46 bytes.


send <source port> [<destination port>] [--packet-count|-c <count>] [--packet-delay|-d <delay>] [--packet-length|-l <length>]

Send packets from one port to the other. If the command line does not specify a destination port, the test runs an internal loopback. Otherwise, the test runs an external loopback from the source port to the destination port.

status [clear]

Read and interpret the status registers and print to the screen. clear clears the status registers.


Issue a stop command to all Ethernet controllers in the AFU.


Read and display the port MAC addresses. An EEPROM stores the MAC addresses.


0 Success - Number of packets received are equal to the number of packets sent and no errors are reported.

-1 Loopback failure - Either number of packets does not match or the test detected errors.

-2 Errors parsing arguments.


Read the MAC addresses of the AFU loaded on bus 0x5e:

>sudo hssi_loopback readmacs -B 0x5e

Run an external loopback, sending 100 packets from port 0 to port 1. The AFU is on bus 0x5e:

>sudo hssi_loopback -B 0x5e send 0 1 -c 100

Run an internal loopback until a timeout of 5 seconds is reached. The AFU is on bus 0x5e:

>sudo hssi_loopback -B 0x5e send 0 -t 5

Revision History

Document Version Changes
2019.05.13 No change from the previous release.
2018.05.21 Corrected typos.