A simple "Hello, world !" (debuggable) program for NASM with Linux

helloWorld.asm

; Copyright (c) 1999 Konstantin Boldyshev <konst@linuxassembly.org>
;
; Reviewed by HorlogeSkynet (12/09/16)
;
; "Hello, world !" in assembly language for Linux

; To compile:             nasm -f elf64 -g helloWorld.asm
; To link the executable: ld -m elf_x86_64 -g -o helloWorld helloWorld.o
; To run the program:     ./helloWorld
; To debug the program:   gdb ./helloWorld


section	.data

	msg	db  'Hello, world !', 0xa  ; Our dear string
	len	equ $ - msg                ; Length of our dear string


section	.text

	global _start  ; Must be declared for linker (ld)

_start:                ; Tell linker entry point

	mov edx, len   ; Message length
	mov ecx, msg   ; Message to write

	mov ebx, 1     ; File descriptor (stdout)
	mov eax, 4     ; System call number (sys_write)
	int 0x80       ; Call kernel

	mov eax, 1     ; System call number (sys_exit)
	mov ebx, 0     ; Set the returned value
	int 0x80       ; Call kernel