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Shiina
Associate III
April 11, 2024
Solved

What does malloc() do in an STM32 MCU run without an OS ?

How does STM32 dynamically allocate memory ?

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Andrew Neil
Andrew NeilBest answer
Super User
April 11, 2024

https://stackoverflow.com/questions/77829982/how-does-arm-none-eabi-gcc-9-2-implement-malloc-free

 

EDIT

You didn't state what compiler you're asking about.

The above relates to the GCC/ARM compiler, as used in the STM32CubeIDE, using the newlib library.

Other compilers & libraries are available; eg,

https://developer.arm.com/documentation/dui0067/d/the-c-and-c---libraries/tailoring-storage-management/support-for-malloc

 

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
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4 replies

Andrew Neil
Andrew NeilBest answer
Super User
April 11, 2024

https://stackoverflow.com/questions/77829982/how-does-arm-none-eabi-gcc-9-2-implement-malloc-free

 

EDIT

You didn't state what compiler you're asking about.

The above relates to the GCC/ARM compiler, as used in the STM32CubeIDE, using the newlib library.

Other compilers & libraries are available; eg,

https://developer.arm.com/documentation/dui0067/d/the-c-and-c---libraries/tailoring-storage-management/support-for-malloc

 

A complex system that works is invariably found to have evolved from a simple system that worked.A complex system designed from scratch never works and cannot be patched up to make it work.
    ShiinaAuthor
    Associate III
    April 13, 2024

    thanks

    Tesla DeLorean
    Tesla DeLorean
    Guru
    April 11, 2024

    It allocates memory from the heap. In the GNU/GCC sense this is from the top of the statics to the bottom of the stack via sbrk().

    On Keil/IAR it would be a section of heap memory of defined size that the linker places after the statics. 

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      mƎALLEm
      mƎALLEm
      ST Technical Moderator
      April 11, 2024

      From the title I understand: in which situation the dynamic allocation is used if no rtos is used, but in the text I understand something else. Need to be concise.

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