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Start the Fuchsia debugger

The ffx debug connect command starts the Fuchsia debugger (which is called zxdb) for debugging Fuchsia components on a device.


zxdb is Fuchsia’s own debugger that allows you to attach a Fuchsia component running on a device. Once a component is attached to zxdb, you can perform interactive debugging operations, such as adding breakpoints, stepping through code, and inspecting stack traces and variables of the component.

For zxdb to understand and unpack the code of a Fuchsia component, the component's debug symbols must be available in your development environment. (For more information on debug symbols, see Register debug symbols.)

When you run the ffx debug connect command, it establishes a connection to the Fuchsia device and starts the zxdb terminal on the host machine. In this terminal, you can use the zxdb commands to interactively debug Fuchsia components running on the device.

Run the Fuchsia debugger

To start the Fuchsia debugger, run the following command:

ffx debug connect

Once successfully connected to a Fuchsia device, this command starts the zxdb terminal, for example:

$ ffx debug connect
Connecting (use "disconnect" to cancel)...
Connected successfully.
👉 To get started, try "status" or "help".

In the zxdb terminal, you can start performing interactive debugging operations. The example below shows that zxdb is attached to the memory_monitor component and a breakpoint is created at the component's main function:

[zxdb] attach
Waiting for process matching "".
Type "filter" to see the current filters.
Attached Process 1 state=Running koid=47467
[zxdb] process
  # State    Koid Name
▶ 1 Running 47467
[zxdb] break $main
Created Breakpoint 1 @ $main
 ◉ 49 int main(int argc, const char** argv) {
   50   auto command_line = fxl::CommandLineFromArgcArgv(argc, argv);

To exit the zxdb terminal, type exit or press Ctrl-D.

For more information on usages and best practices on zxdb, see the zxdb user guide.