I am trying to make a C++ application using C++ wrapper from michaelbecker/freertos-addons (see on github), but there was a problem with local variables of the Thread class in main function. After running the scheduler prvPortStartFirstTask function updates the stack pointer to its initial value and…

FreeRTOS, in many ports, reuses the main stack as the interrupt stack, and as such any data place on that stack might not be still available after the schedule starts. This has not been considered a bug. The key is that you don’t want to create the objects on the main function stack, but either on …

But this feature is not mentioned anywhere)

except for a negligible perceived 1 Million places on the internet: <a href="https://www.google.de/search?q=freertos+startup+stack+reuse&sca_esv=fe9f719d59c6d571&source=hp&ei=3h6MZ7_DAfmSxc8PxL_PsQE&iflsig=AL9hbdgAAAAAZ4ws7pxjoyzZL2MXV5xZE7Dm0ntQPDYT&ved=0ahUKEwi_qv2PnYCLAxV5SfEDHcTfMxYQ4dUDCBA&uact=5&oq=freertos+startup+stack+reuse&gs_lp=Egdnd3Mtd2l6IhxmcmVlcnRvcyBzdGFydHVwIHN0YWNrIHJldXNlMgUQABjvBTIFEAAY7wUyBRAAGO8FMgUQABjvBTIFEAAY7wVI81xQwARY1VlwAHgAkAEAmAGtAaABphyqAQQyLjI3uAEDyAEA-AEBmAIcoALRHqgCAMICCxAuGIAEGNEDGMcBwgIFEAAYgATCAggQLhiABBjUAsICBRAuGIAEwgILEC4YgAQYxwEYrwHCAgYQABgWGB7CAgsQABiABBiGAxiKBcICCBAAGIAEGKIEwgIHECEYoAEYCsICBRAhGJ8FwgIFECEYoAGYA5AB8QUpRsy1Z0bH2ZIHBDAuMjigB5PAAQ&sclient=gws-wiz" rel="noopener nofollow ugc">freertos startup stack reuse - Google Search

I agree that the mention isn’t very obvious, but I thought it was mentioned in the port file itself. You are not the first person to have this problem, but as I remember, it is considered an intentional limitation (to save memory) and not a “bug”. I agree that it would sometimes be nice to have th…

well yes and no. It is a design decision made for resource usage efficiency. One of the things that enables FreeRTOS to run on even very tiny platforms. The pros and cons have been discussed here many many times. Of course you are free to change it if it offends you, FreeRTOS being open source.

A big benefit of this somewhat special approach is that one can always rely on having the full specified main stack as ISR stack independent of any user code in main. I consider main as just the FreeRTOS bootloader not being part of the FreeRTOS application itself because the runtime environment re…

I do not think that this is possible because the decision how this is done is eventually made by the port - some ports may already use a disjoint interrupt stack, so a global configuration would be meaningless for such ports.

It is described here - Before the FAQ... - FreeRTOS™ . @AlexaderM does moving your objects out of main solve your problem?

Yes. Thank you all for your answers.

Freertos c++ prvPortStartFirstTask damage stack

Kernel

AlexaderM (alexader_m) January 18, 2025, 10:14pm 8

Maybe the community add a definition to FreeRTOSConfig?

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Main stack pointer reset when starting the scheduler Kernel	17	951	June 30, 2015
Restoring MSP in vPortStartFirstTask Kernel	5	694	December 16, 2020
Hardfault During Interrupt Kernel	6	297	May 28, 2024
Passing parameter from main to various tasks Kernel	3	317	September 21, 2019
Passing auto variables defined in main as task parameters Kernel	5	2995	May 19, 2022

Freertos c++ prvPortStartFirstTask damage stack

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