mqttsn with openthread and freertos

RE: mqttsn with openthread and freertos

EdgarGrimberg — Thu, 10 Sep 2020 17:44:15 GMT

OK, I think I got it. I was single stepping through the mqttsn code, when stack overflow handler kicked. Really lucky here!

Here's what the current TCB was showing:

So it was the timer task that was running low on stack. The solution, of course, was to increase the task size for the timer task.

In FreeRTOSConfig.h, I bumped the timer task stack depth to 160:

#define configTIMER_TASK_STACK_DEPTH  ( 160 )

And it all went fine from there.

Thanks for pointing me into the right direction, really appreciate the support!

Regards,

Edgar

RE: mqttsn with openthread and freertos

EdgarGrimberg — Thu, 10 Sep 2020 16:44:29 GMT

Hi Jørgen.

Thanks for the suggestions. Here's what I did:

- Double the heap in freeRTOS:

#define configTOTAL_HEAP_SIZE ( 1024 * 64 )

- Increase the stack sizes for: * my state machine twice as I had, still crashes:

#define CSM_STACK_TASK_STACK_SIZE     (( 1024 * 16 ) / sizeof(StackType_t))   /**< FreeRTOS task stack size is determined in multiples of StackType_t. */

* the openthread task, increased with (1024 * 2) / sizeof(StackType_t), still crashes. increased even with (1024 * 4) / sizeof(StackType_t), the same result:

#define THREAD_STACK_TASK_STACK_SIZE     (( 1024 * 12 ) / sizeof(StackType_t))

Even more, I've added the hard fault handlers from the SDK, and here's the log:

00> <info> app: Succesfully send the search for gate<error> hardfault: HARD FAULT at 0x00008D52
00>
00> <error> hardfault:   R0:  0x20040000  R1:  0x00000000  R2:  0x00000000  R3:  0x20015410
00>
00> <error> hardfault:   R12: 0x20020BD0  LR:  0x00008D45  PSR: 0x4100000E
00>
00> <error> hardfault: Cause: Data bus error (PC value stacked for the exception return points to the instruction that caused the fault).
00>
00> <error> hardfault: Bus Fault Address: 0x20040000

Setting a breakpoint here, I can see the following variables:and Still chasing a memory corruption, I've enabled more debugging from freeRTOS:

#define configCHECK_FOR_STACK_OVERFLOW                                            1
#define configUSE_MALLOC_FAILED_HOOK                                              1

and implemented my hooks:

void vApplicationMallocFailedHook( void )
{
    NRF_LOG_ERROR("malloc failed");
    while(1);
}

void vApplicationStackOverflowHook( void )
{
    NRF_LOG_ERROR("stack overflow");
    while(1);
}

but I never reach the infinite loops, only the hard faultThanks,Edgar

RE: mqttsn with openthread and freertos

Jørgen Holmefjord — Thu, 10 Sep 2020 11:44:35 GMT

Hi,

It looks like the hardfault happens when xPortPendSVHandler is executing. This will attempt to pop the current TCB value from the stack, but if the stack or stack pointer is corrupted at this point, it could lead to hardfault. First step is to increase the heap size in FreeRTOSConfig.h file and increase the default task stack size

You can try the following as a starting point:

#define configMINIMAL_STACK_SIZE ( 400 )
#define configTOTAL_HEAP_SIZE ( 1024 * 40 )

If this does not work, try to increase the stack size in 200 byte steps, and heap size in 1-2 kB steps. This can be fine-tuned at a later point once you get everything working correctly.

Best regards,
Jørgen

RE: mqttsn with openthread and freertos

EdgarGrimberg — Wed, 09 Sep 2020 11:53:59 GMT

Forgot to mention, the same build environment minus freeRTOS and re-arranged code to look more like the example code works fine.