Can't link assembly and c -

i have problems linking c , assembly code. tried search solutions, none of found worked me.

c file "l3.c" looks this:

#include <stdio.h> #include <stdlib.h>  const int inp_size = 100;  extern int mult(int c1, int c2);  int main() {     char number[inp_size];      scanf("%s",number);     printf("you typed: %s \n",number);      int j=2;     int k=5;     j = mult(j,k); #here problem     printf("%d",j);      scanf("%s",number);     return 0; } 

and asembly "mult.s" this:

.type mult, @function mult: push %rbp mov %rsp, %rbp mov 8(%rbp), %rbx mov 12(%rbp), %rcx  mov $0, %rax add %rbx, %rax; add %rcx, %rax;  mov %rbp, %rsp pop %rbp ret 

in makefile got following lines(most recent solution googled):

l3:     -g -o mult.o mult.s     gcc -o l3.o -c l3.c     gcc l3.o mult.o 

when type make in console throwing: undefined reference 'mult' when comment //j = mult(j,k); program works fine. how should link this?

it looks you're not exporting mult symbol, linker can't find later on. how correctly depends on assembler you're using. since you're using at&t syntax, i'm going guess gnu - in case add .global mult @ top of assembly file.