I'm learning elf file layout, so I'm reading Executable_and_Linkable_Format.
In the beginning, I used `readelf -a` to exmine elf(.o file), but it provided is not my want, so I used hexdump -C to exmined it binaries form.
I used `as -Og -g ... -o ..., ld ... -o ...` and `hexdump -C ...` to...