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Dear Sir
I don't uderstand the meaning of stack size in the startup assembler code (stm32),what is for ? I have some confusion because the file is talking about stack tailor :
Amount of memory (in bytes) allocated for Stack Tailor this value to your application needs Stack Configuration
In the case we have FreeRTOS running on ,where the memory of freertos is allocated ,it is depending on the stack tailor size?
Same questions about the heap size(in the startup file)
Thank you
Tailoring = customizing.
So the startup file says that you, as developer, should adjust the size of the stack based on how much you need.
And the processor needs a stack before it starts the RTOS. The RTOS would then have own methods to define the stack size (and mapping them to a memory pool or explicitly allocated buffers) for the individual threads.
Thanks you for the answer
what do you mean by "How much you need", the confusion for me is that I have in the startup file a definition of stack_size smaller than the space reserved for the freeRTOS and it works ,so I try to understand the relation between these two parameters.?
The startup file defines the stack space of the processor. The operating systems allocates a stack per task, but not from the processor stack (mostly from internal/external RAM). Processor stack might still be used to handle interrupts or failures - but task use their own stack allocated by the OS.
So what is the stack space for the processor?where is located and what is the difference between it and the RAM space ,that's mean that the location space for the OS is not a part of the stack processor?right?
Processor stack is allocated from RAM, just like tasks stacks.
Here is what I can understand:
1- RAM=Stack+heap So in the startup file we reserve space for stack and heap. then freertos reserve his own stack but this time where this is done in the stack part of the RAM or the heap? 2-
RAM=Stack+Heap+memory for freertos
so in this case is logic for me.
So what is a stack processor in this case?
Which scenario is correct?
Your chip has volatile memory (RAM). Some of it is allocated for processor stack. Some of it is allocated for processor heap. Some of it is allocated for operating system stacks. This is merely memory which is not related to the previous two items.
This is merely memory which is not related to the previous two items.
Unless, in the case of FreeRTOS, a memory manager is used that allocates memory from the heap or processor stack. But usually this is not the case.
So,
RAM = processor stack + processor heap + memory for FreeRTOS + more unused RAM (optional).
Wrong.
Stack is stored in RAM. Heap is stored in RAM. Read/Write variables (global, local and parameters) are stored in RAM. ...
A program may use the CRTL (C Runtime Library) heap functions for memory allocation. Or a program may use own code. And that own code may not use any heap declared in the startup file but instead make use of one or more large array variables.
Read this, regarding memory allocations in FreeRTOS.