Foro de elhacker.net

section	.text
    global _start			;must be declared for linker (ld)
 
_start:					;tell linker entry point
 
	mov	edx,len	;message length
	mov	ecx,msg	;message to write
	mov	ebx,1	;file descriptor (stdout)
	mov	eax,4	;system call number (sys_write)
	int	0x80	;call kernel
 
	mov	eax,1	;system call number (sys_exit)
	int	0x80	;call kernel
 
section	.data
 
msg	db	'Hello, world!',0xa	;our dear string
len	equ	$ - msg			;length of our dear string

debci@debci-laptop:~$ nasm -f elf test.asm
debci@debci-laptop:~$ ld test.o -o test
debci@debci-laptop:~$ gcc test.o -o test
test.o: In function `_start':
test.asm:(.text+0x0): multiple definition of `_start'
/usr/lib/gcc/i486-linux-gnu/4.3.3/../../../../lib/crt1.o:/build/buildd/glibc-2.9/csu/../sysdeps/i386/elf/start.S:65: first defined here
/usr/lib/gcc/i486-linux-gnu/4.3.3/../../../../lib/crt1.o: In function `_start':
(.text+0x18): undefined reference to `main'
collect2: ld devolvió el estado de salida 1
debci@debci-laptop:~$ ./test
bash: ./test: No existe el fichero ó directorio
debci@debci-laptop:~$ gcc test.o -o test
test.o: In function `_start':
test.asm:(.text+0x0): multiple definition of `_start'
/usr/lib/gcc/i486-linux-gnu/4.3.3/../../../../lib/crt1.o:/build/buildd/glibc-2.9/csu/../sysdeps/i386/elf/start.S:65: first defined here
/usr/lib/gcc/i486-linux-gnu/4.3.3/../../../../lib/crt1.o: In function `_start':
(.text+0x18): undefined reference to `main'
collect2: ld devolvió el estado de salida 1
debci@debci-laptop:~$