STM32链接器脚本初始化部分，使用C时需要吗？

Question

As far as I know, sections like.init, .preinit_array, .init_array, .finit, .fini_array... found in STM32CubeIDE linkerscripts are used in C++ for calling the static objects' constructors that need to be executed before main (and the fini versions for the destructors).

My assumption is that these sections are used by functions called implicitly by the compiler and the C/C++ runtime libraries, but if your firmware is written in C, are all these sections really needed? What does the compiler do behind the scenes?

Answer 1

You can live without many of them.

Other than C++, some of them may initialize things required by the standard library. If you only call pure functions from the standard library and you only have code in C or assembly then you could try taking them out.

If you are trying to do this as a learning exercise, then take them out and just see what doesn't work. Also search on google, there are loads of sites that explain this sort of thing in a way that is far too long to reproduce here.

If you are just trying to get your project finished, then leave them alone. They only add a tiny amount to your program size and it isn't worth your time to fight with them.

Answer 2

are used in C++ for calling the static objects' constructors that need to be executed before main (and the fini versions for the destructors).

It is not 100% truth. cubeIDE uses gcc based ARM toolchain which has some extensions which may use some of those sections. For example, you can use use attributes to make functions which will be executed before main and/or called after the main function return.

void __attribute__((constructor)) called_before_main(void)
{
   /* some code */
}

void __attribute__((destructor)) called_after_main(void)
{
   /* some code */
}

If you even not use any of those, external libraries may use them. Even if you do not use external libraries keeping those sections does not hurt as they will be discarded if they are empty.