127-byte Tiny Teensy x86_64 compliant ELF64 using standard tools

tiny.asm

; tiny.asm
; 127-byte fully compliant X86-64 ELF64 binary
; Inspired by:
; - https://www.muppetlabs.com/~breadbox/software/tiny/
; - https://ech0.re/building-the-smallest-elf-program/
; - https://nullprogram.com/blog/2016/11/17/
; Restrictions:
; - True x86_64 ELF64 binary, not 32bit-binary-on-64bit-platform
; - No handcrafting ELF headers in ASM
; - No hex editing or directly manipulating binaries
; - Only standard GNU tools (nasm, ld, gcc, etc)
; To "compile":
; - nasm -f elf64 tiny.asm  # tiny.o, 576 bytes
; - ld -s -no-pie -z noseparate-code tiny.o -o tiny  # tiny, 336 bytes
;   (~13K without the flags!!!)
; - strip --strip-section-headers tiny  # 127 bytes
BITS 64
SECTION .text align=1
GLOBAL _start
_start:
	; _exit(42)
	; all registers zeroed by Linux ABI at start, so safe to use al/dil
	mov       al, 60  ; Select the _exit syscall (60 in Linux ABI)
	mov      dil, 42  ; Set the exit code argument for _exit
	syscall           ; Perform the selected syscall