GNU Linker Map File Giving Unexpected Load Addresses

Question

I\'m working on an embedded program where I have a custom linker script. The program works, but I have noticed that there is possibly something amiss with how the linker is

Answer 1

You are looking for NOLOAD. See Gnu LD output section type. I read your whole post now and I see you postulated about NOLOAD. With NOLOAD, all of the addresses are defined. If you use them within your 'C' code, they will load from that address. You must provide some start-up code, usually in assembler that clears the BSS area. Usually, you don't expect your stack to be initialized.

A NOLOAD section is like a compile/link time malloc(). You get the memory to use, just don't expect anything there. For BSS you define __bss_start__ and __bss_end__ in your linker script and write a short initialization routine to clear this memory using those variables/addresses.

Note: everything shows up in the map file. It won't show up in a generated binary or have data in an ELF. Just the section meta information will be held in the ELF.

Edit: The load address in the map file is like a location counter for loading. The load address is where ld is set to put stuff. ld is not really putting things there if they take zero size. The map output is not linguistically un-ambiguious; I can see how it is confusing, but ld does things correctly in creating the output binary. BSS is normally marked NOLOAD by gcc in the object files, so in the example only the stack section would need NOLOAD. For a something like stack, a section is not really needed and just a set of symbols declarations would work.