Assembly example (nasm) for amd64 in NetBSD

[Rocky Hotas <rockyhotas%firemail.cc@localhost>]

Hello!
I was looking for a simple assembly code, a `Hello world' for example,
which runs on NetBSD, written and compiled with nasm.
I tried a code to print the CPU vendor string through cpuid: the entire
code is copied after the text of this e-mail. It works on FreeBSD. On
NetBSD 9.0 I built it with

nasm -f elf64 -o testcpu.o testcpu.s
ld -s -o testcpu testcpu.o

This gives no error, however the file can not execute. If I try to run
the file, I obtain:

/bin/sh: Cannot execute ELF binary ./testcpu

The only example I found is

 https://wiki.netbsd.org/examples/netbsd_assembly/

However, it is quite confusing and it is for i386, while I would like to
use amd64.
I can't understand if the error is due to a bad linking or building, or
if the code itself has some wrong instruction.
Is there a NetBSD nasm amd64 example? Or some hints that I should follow?
Bye!

Rocky


Here is my code, that is the contents of file testcpu.s:


section .bss

    buff resb 12

section .text
global _start

_start:
  
    mov eax, 0
    cpuid

    mov dword [buff+0], ebx     
    mov dword [buff+4], edx     
    mov dword [buff+8], ecx     

    mov rax, 4
    mov rdi, 1
    mov rsi, buff
    mov rdx, 12
    syscall

    mov rax, 1
    mov rbx, 0
    syscall