importing linker addresses in c

July 31, 2024

I want to use an address named _end from the linker.ld file in main.c.
I know this address to be atleast 0x80000000. But when importing it like this extern char _end; in main.c and printing it I only get 17.
The linker.ld file is something like this :

SECTIONS {
    . = 0x80000000; 

/*some more code and sections (doesnt matter)*/

    _end = .;
}

Does anyone why this is happening or how I should import _end?
Thx in advance, jip.

>Solution :

It is a symbol only. You can only get its reference. You do not "import it"

extern char _end;

void foo(void)
{
     printf("%u", (unsigned)&_end);
}

extern char _end[];

void foo(void)
{
     printf("%u", (unsigned)_end);
}

For those who will complain about format and conversion. It is likely to be STM32 and nano library for this MCU does not support %zu and %p and sizeof(int) == sizeof(char *)