Hello World in x86 Assembly (AT&T)

hello.s

# .data stores variables
.data
    hello: .string "Hello world\n"

# .text stores the code
.text
.globl _start # makes _start the entry point of the program
_start:
    # call write(fd, buf, size)
    movl $4, %eax # write = 4 
    movl $1, %ebx
    movl $hello, %ecx
    movl $12, %edx 
    int $0x80 # calls the kernel and the kernel runs the system call

    # exit(0)
    # needs to exit so the CPU stops execution 
    # otherwise it segfaults
    movl $1, %eax 
    movl $0, %ebx
    int  $0x80