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Thread-Aware Debugging

Debug RTOS-based applications with full thread awareness in J-Link GDB Server

  • View all RTOS threads and tasks
  • Inspect registers and call stacks for individual tasks
  • Extend RTOS support through a flexible plugin system
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SEGGER Debug & Trace Probes
  1. 1.What is Thread-Aware Debugging?
  2. 2.The GDB Server plugin interface
  3. 3.Which IDEs are supported for thread-aware debugging?
  4. 4.What RTOSes are supported?
  5. 5.How to add support for additional RTOSes?

What is Thread-Aware Debugging?

GDBServer_RTOSPlugin_Screenshot

By default, when a target system is halted in the debugger, the current CPU registers, such as the program counter and stack pointer, as well as the current call stack are displayed. In an RTOS-based application, however, the system is often executing the idle task when it is halted. In this case, the current registers and call stack provide little information about the state of other tasks in the system.

Thread-aware debugging enables the debugger to display all RTOS threads and tasks when the target system is halted. Developers can select any task in the IDE, regardless of whether it is currently active or suspended, and inspect its CPU registers and call stack. This provides insight into the state of individual tasks and makes it easier to analyze RTOS-based applications.

GDBServer_RTOSPlugin_Concept

The GDB Server plugin interface

By default, J-Link GDB Server has no information about the RTOS running on the target system and therefore cannot provide the thread-specific information required for thread-aware debugging.

To enable thread-aware debugging, an optional plugin for the respective RTOS can be loaded when starting J-Link GDB Server. The plugin is provided as a DLL on Windows or as a shared library on Linux and macOS.

When the target system is halted, the GDB-based development environment requests information about the existing threads. Since the plugin understands the internal structure of the RTOS, it can retrieve this information and pass it to J-Link GDB Server, which then makes it available to the development environment.

Which IDEs are supported for thread-aware debugging?

In general, thread-aware debugging should work with any Eclipse + GDB-based environment that uses J-Link GDB Server for debugging. So far, it has been tested with the following IDEs:

  • NXP Kinetis Design Studio
  • Atollic TrueSTUDIO
  • ARM DS-5 Development Studio

What RTOSes are supported?

Currently, SEGGER provides plugins for thread-aware debugging for Cortex-M architecture and the following RTOSes:

  • SEGGER embOS (V4.20 or newer)
  • FreeRTOS (V8.0.0 or newer)

The plugins are part of the J-Link Software and Documentation pack. For more information on how to use a plugin, please refer to UM08001, chapter "J-Link GDB Server".

How to add support for additional RTOSes?

Support for additional RTOSes can be added by creating a dedicated plugin using the J-Link GDB Server RTOS Plugin SDK, available from SEGGER upon request.

The SDK includes a plugin source template, the source code of the embOS plugin as a reference implementation, and documentation for the J-Link GDB Server Plugin API.