Using SDK 15.0 and FreeRTOS 8.2.1 - stack overflow in Idle task

[Elkana]

Hi, I am using SDK 15.0.0 and FreeRTOS 8.2.1 (from SDK 14.2.0).

I consistently get a stack overflow on the Idle task, caused by PendSVHandler in port.c

This can be easily solved by increasing Idle task stack (configMINIMAL_STACK_SIZE), but I worry why is this happening in the first place?

Just-before screenshot:

just-after screenshot:

FreeRTOSConfig.h:

FreeRTOSConfig.h

[Susheel Nuguru]

not sure if you are doing a lot of processing in idle hook in your app using some stack variables. You can benchmark your stack usage using some external tools. 

[Elkana]

I forgot to mention nothing is done in my vApplicationIdleHook.
I do use vApplicationStackOverflowHook - but this only happens AFTER the stack overflow (and use very little stack).
I am 99% sure idle task is overflowing while running SDK code.

[Susheel Nuguru]

can you try to increase the configMINIMAL_STACK_SIZE in your config file to see if it helps. 

[Elkana]

As mentioned in the original post - increasing configMINIMAL_STACK_SIZE solves the issue.
Nevertheless, the issue is likely in the SDK (as we added no code to Idle task) and it is not very easy to find (as any stack overflow bug)  - so Nordic probably want to fix it

[Susheel Nuguru]

Elkana,

The thing is that i am not getting stack overflow in our examples. I believe you that you have not made any changes to the idle task but still able to trigger the stack overflow, which smells like a bug somewhere. In order for us to be able to fix it, we need to be able to reproduce it. I will send your recommendations to the team so that they also attempt to replicate the bug.