Hello, x86_64!

Your First x86_64 Program

x86_64 (also called AMD64) is the dominant desktop and server processor architecture. It powers nearly every laptop, desktop, and cloud server you use. Learning x86_64 assembly gives you a direct view into how your computer really works.

Program Structure

An x86_64 assembly program in Intel syntax has two main sections:

section .data -- holds your data (strings, numbers, buffers)
section .text -- holds your code (instructions)

The _start label marks where execution begins. The global _start directive makes it visible to the system.

Registers

x86_64 has 16 general-purpose 64-bit registers:

Register	Typical Use
`rax`	Return value, syscall number
`rbx`	Callee-saved general purpose
`rcx`	Counter for loops
`rdx`	Syscall arg 3, I/O
`rsi`	Syscall arg 2 (source index)
`rdi`	Syscall arg 1 (destination index)
`rsp`	Stack pointer
`rbp`	Base pointer (frame pointer)
`r8`-`r15`	Additional general purpose

Linux x86_64 Syscalls

On Linux x86_64, you invoke a syscall by:

Setting rax to the syscall number
Setting arguments in rdi, rsi, rdx, r10, r8, r9
Executing the syscall instruction

For sys_write (syscall 1):

rdi = file descriptor (1 = stdout)
rsi = pointer to the string in memory
rdx = length of the string

For sys_exit (syscall 60):

rdi = exit code

Loading Addresses

To load the address of a data label into a register, use lea (load effective address):

lea rsi, [msg]    ; rsi now holds the address of msg

Your Task

Write a program that prints exactly Hello, x86_64!\n (15 characters) to stdout using the write syscall, then exits with code 0.

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x86_64 runtime loading...

Click "Run" to execute your code.