Why uxTaskGetStackHighWaterMark can be higher than main task stack size?

[Ragtime]

Hi,

does anyone know why the return value of `uxTaskGetStackHighWaterMark()` for main task can be higher than the "Main task stack size" set in sdkconfig?

In my `sdkconfig`:
Common ESP-related -> Main task stack size: 20000

Here is my `main.c`:

Code: [Select all] [Expand/Collapse]

1. #include <stdio.h>
2. #include "freertos/FreeRTOS.h"
3. #include "freertos/task.h"
4. #include "esp_system.h"
5. #include "esp_spi_flash.h"
6.  
7.  
8.  
9. void app_main()
10. {
11.     printf("stackHWM: %d\n", uxTaskGetStackHighWaterMark(NULL)); // in console: stackHWM: 20024
12.  
13. }

GeSHi © Codebox Plus Extension

I expect the stackHighWaterMark to be no more than 20000, but it's actually 24 bytes higher than that.

The value is even higher if the "Optimization Level" is set to `Debug (-Og)`.

idf version: 4.0

[WiFive]

https://github.com/espressif/esp-idf/bl ... task.h#L57

[Ragtime]

https://github.com/espressif/esp-idf/bl ... task.h#L57

Great! Thank you!