calling libc functions on OS X x64

cpuid2.s

# cpuid2.s
# calling libc functions on OS X x64
#
# $ as -g -o cpuid2.o cpuid2.s 
# $ ld -o cpuid2 -lc cpuid2.o
# $ ./cpuid2
# Vendor ID: GenuineIntel
# $

.data
_output:
	.asciz	"Vendor ID: %s\n"

	.lcomm	_vendor, 12

.text
.globl		start

start:
	xorq	%rbp, %rbp
	pushq	%rbp

	xorq	%rax, %rax
	cpuid

	leaq	_vendor(%rip), %rsi
	movl	%ebx, (%esi)
	movl	%edx, 4(%esi)
	movl	%ecx, 8(%esi)

	# leaq	_vendor(%rip), %rsi
	leaq	_output(%rip), %rdi
	xorq	%rax, %rax
	callq	_printf

	xorq	%rdi, %rdi
	callq	_exit

	hlt