Debugging Assembly (NASM) using gdb

Question

I am trying to debug some Assembly using gdb and I am having some issues. Once I enter gdb, I am unable to add breakpoints, and the file command doesn't seem to work. The exact outputs are at the bottom. I've tried searching for answers but none seem to work. I am running Ubuntu 17.10

main.asm

section .text
global _start
_start:
    mov ecx, string
    call printStr
    exit:
    mov eax, 1
    mov ebx, 0
    int 0x80

    printStr:
    pusha
    cmp byte [ecx], 0
    je breakPrintStr
    mov eax, 4
    mov ebx, 2
    mov edx, 1
    int 0x80
    add ecx, 1
    jmp printStr
    breakPrintStr:
    popa
    ret
section .data
    string db 'Hello, World!',0xa,0

Makefile

file = main
compile: $(file).asm Makefile
    nasm -g -f elf -F dwarf $(file).asm
    ld -m elf_i386 -s -o $(file) $(file).o
    rm $(file).o
    chmod +x $(file)

Then I launch gdb using

gdb main

(gdb) file main

Results in

Reading symbols from main...(no debugging symbols found)...done.

And

(gdb) b _global

Results in

No symbol table is loaded.  Use the "file" command.
Make breakpoint pending on future shared library load? (y or [n])

brenden · Accepted Answer · 2018-02-24 17:57:33Z

2

After searching I finally figured it out. The Corrected makefile is as follows:

file = main
compile: $(file).asm Makefile
    nasm  -g -f elf -F dwarf $(file).asm
    ld -m elf_i386 -o $(file) $(file).o
    rm $(file).o
    chmod +x $(file)

answered Feb 24, 2018 at 17:57

brenden

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