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Troubleshooting target connection issues

You might have problems when trying to start a capture session, for instance by pressing the Start capture button. Use these solutions to solve common target connection issues.



Error message generated:

Unable to connect to the gator daemon at target_address.

Please verify that the target is reachable and that you are running gator daemon v17 or later. Installation instructions can be found in: streamline/gator/

If connecting over WiFi, please try again or use a wired connection.

Make sure gatord is running on your target. Enter the following command in the shell of your target:

ps ax | grep gatord

If this command returns no results, gatord is not active. Start it by navigating to the directory that contains gatord and entering the following command:

sudo ./gatord &

Try connecting to the target again.

If gatord is active and you still receive this error message, try disabling any firewalls on your host machine that might be interfering with communication between it and the target.

In addition, if you are running Android on your target, make sure the ports are accessible by using the adb forward command, for example:

adb forward tcp:8080 tcp:8080

Error message generated:

Unknown host

Make sure that you have correctly entered the name or IP address of the target in Address field. If you have entered a name, try an IP address instead.

When using event-based sampling, Arm Streamline fails to find the PMU.

The PMU on your hardware might not be correctly configured to allow the processor interrupts necessary for Arm Streamline to use event-based sampling. Test on alternate hardware or disable event-based sampling in the Counter Configuration dialog box.

The target is running a firewall, which prevents Arm Streamline from connecting to gatord.

There are several possible ways to resolve this issue:

  • Update the firewall to allow connections to gatord, which defaults to using port 8080.

  • Use local captures.

  • If the target accepts SSH connections, you can establish an SSH tunnel by using the ssh command on the host. For example:

    ssh user@target -L 8080:localhost:8080 -N

    In this example, replace user with the username to log in as and target with the hostname of the target. On the target, use localhost as the hostname.


    An SSH tunnel requires additional processing on the target.
  • Reverse SSH tunnels are also possible by running ssh from the target to the host. For example:

    ssh user@host -R 8080:localhost:8080 -N

Delay between clicking the Capture button and the Live view displaying data.

Use the gator.ko kernel module.

Setting ftrace to use a different clock can also help. Use one of the following commands:

Linux kernel 4.2 or later
echo mono_raw > /sys/kernel/debug/tracing/trace_clock
Older Linux kernel versions
echo perf > /sys/kernel/debug/tracing/trace_clock