Hello world Assembly i386 (Linux)

; Hello world program
; Language: x86 (i386) Assembly
; Library: Linux system calls

global _start

section .text
_start:
    mov edx, message_length
    mov ecx, message
    mov ebx, 1
    mov eax, 4
    int 0x80
    xor ebx, ebx
    mov eax, 1
    int 0x80

section .data
    message db 'Hello world!', 0xA
    message_length equ $ - message