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How to enable debug information with nasm?

I have this source code:

; hello.asm a first program for nasm for Linux, Intel, gcc ; ; assemble: nasm -f elf -l hello.lst hello.asm ; link: gcc -o hello hello.o ; run: hello ; output is: Hello World SECTION .data ; data section msg: db "Hello World",10 ; the string to print, 10=cr len: equ $-msg ; "$" means "here" ; len is a value, not an address SECTION .text ; code section global main ; make label available to linker main: ; standard gcc entry point mov edx,len ; arg3, length of string to print mov ecx,msg ; arg2, pointer to string mov ebx,1 ; arg1, where to write, screen mov eax,4 ; write command to int 80 hex int 0x80 ; interrupt 80 hex, call kernel mov ebx,0 ; exit code, 0=normal mov eax,1 ; exit command to kernel int 0x80 ; interrupt 80 hex, call kernel

This code is taken from here .

I am using ubuntu 12.04 32-bit for VirtualBox for training.

Following are the following steps:

  • nasm -f elf -g -F stabs hello.asm
  • ld -o hello hello.o
  • gdb hello -tui

Now when I run hello , it will work fine, but gdb will not be able to show any source code. What for? When I tryp run in gdb, I will see Hello World text just fine, but it does not show the source.

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1 answer

The stabs format doesn't seem to work with GDB, try DWARF instead ( http://en.wikipedia.org/wiki/DWARF )

compile with

nasm -f elf -g -F dwarf hello.asm

something in gdb style

start

then

si

You will see sources with comments and so on. as Korah Tugai said, most likely a mistake in gdb.

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