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RTOS Threads Analysis

Memfault automatically detects what RTOS your system is running. For uploaded coredumps, it will attempt to extract backtraces for all threads in the system and optionally determine what state each thread is in and the stack usage high water mark.

In order for this to work correctly, the coredump must capture the RTOS' thread state variables, all thread control blocks as well as the stack memory of each thread. The following sections list for each RTOS what needs to be captured. See the documentation on Coredump Collection for details on how to set up additional coredump capturing regions.

FreeRTOS​

Required​

These variables must be captured in the coredump. On top of this, the memory of all task control blocks (TCB_t) must be captured. Because FreeRTOS TCBs double as linked list nodes, all TCBs must be captured.

  • uxCurrentNumberOfTasks
  • pxCurrentTCB
  • pxReadyTasksLists
  • xDelayedTaskList1
  • xDelayedTaskList2
  • xPendingReadyList
  • uxTopReadyPriority
  • xSchedulerRunning
note

There were several releases of FreeRTOS that did not include uxTopUsedPriority, see this GitHub issue:

https://github.com/FreeRTOS/FreeRTOS-Kernel/issues/33#issue-583304006

If the version of FreeRTOS in use doesn't include the fix, add the sample file (for example, this copy) and relevant linker flags.

Optional​

  • xTasksWaitingTermination
  • xSuspendedTaskList

To enable stack usage high water marking, the configCHECK_FOR_STACK_OVERFLOW configuration option must be enabled and the full stacks for each thread must be captured as well.

Zephyr​

Required​

These variables must be captured in the coredump:

  • _kernel
  • _kernel_openocd_offsets
  • _kernel_openocd_size_t_size

Other RTOSes​

Memfault also supports these other RTOSes: Argon, ChibiOS, Mynewt, NuttX, Quantum Platform, Keil RTX5 / ARM mbedOS, ThreadX and TI RTOS.