The initialization phase is executed when an application is started (the CPU is reset) but
before the main function has been entered. The initialization phase can for simplicity be
divided into:
● Hardware initialization, which generally at least initializes the stack pointer.
The hardware initialization is typically performed in the system startup code
cstartup.s and if required, by an extra low-level routine that you provide. It might
include resetting/starting the rest of the hardware, setting up the CPU, etc, in
preparation for the software C/C++ system initialization.
● Software C/C++ system initialization
Typically, this includes assuring that every global (statically linked) C/C++ symbol
receives its proper initialization value before the main function is called.