在MacOS NASM 64bit上添加两个数字

Question

我有这段代码：

section .data
x       dw      10
y       dw      10

section .text
        global _main

_main:  xor rax, rax
        mov rax, x
        mov rbx, y
        add rax, rbx
result: nop
exit:   mov rax, 0x2000001      ; System call number for exit = 1
        mov rdi, 0              ; Exit success = 0
        syscall                 ; Invoke the kernel

并尝试编译：

nasm -f macho64 hello.asm
gcc -m64 hello.o -o hello

并使用lldb进行调试

(lldb) r
Process 74574 launched: './hello' (x86_64)
Process 74574 stopped
* thread #1, queue = 'com.apple.main-thread', stop reason = breakpoint 1.1
    frame #0: 0x0000000100000fab hello`result
hello`result:
->  0x100000fab <+0>:  nop

hello`exit:
    0x100000fac <+0>:  movl   $0x2000001, %eax          ; imm = 0x2000001
    0x100000fb1 <+5>:  movl   $0x0, %edi
    0x100000fb6 <+10>: syscall
Target 0: (hello) stopped.
(lldb) register read rax
     rax = 0x0000000200002004

我预计在rax中是0x014，但我有0x0000000200002004，我做错了什么？