text: #include "kernel/types.h"
  #include "user/user.h"
  #include "kernel/fcntl.h"
  
  // print out addresses
  void func();
  
  int a = 20;
  
  int main(int argc, char **argv)
  {
      char buffer[64];
      printf("stack: 0x%x\n", &buffer);
      printf("func addr: 0x%x\n", &func);
      printf("var addr: 0x%x\n", &a);
      exit(0);
  }
  
  void func() {
      printf("func");
  }