"Hello World!", x86-64 assembly for Linux

a/assembler_nasm_linux64.asm

@@ -0,0 +1,20 @@
+section	.text
+    global _start			;must be declared for linker (ld)
+
+_start:					;tell linker entry point
+
+	xor	eax,eax	; eax:=0
+	lea	edx,[rax+len]	;message length
+	mov	esi,msg	;message to write
+	lea	edi,[rax+1];file descriptor (stdout)
+	mov	al,1	;system call number (sys_write)
+	syscall		;call kernel
+	
+;	xor	eax, eax
+	mov	al,60	;system call number (sys_exit)
+	syscall		;call kernel
+
+section	.data
+
+msg	db	'Hello, world!',0xa	;our string
+len	equ	$ - msg			;length of our string