title: Return value size or type of a system call in Linux
body: <p>I understand, from looking at kernel code, the linux system call return type is long int and the size is effectively <code>32-bit</code>. </p>
  
  <p>Is it possible to have a linux system call return a <code>64-bit</code> value (of type, say, <code>long long int</code>)? </p>
  
  <p>I understand that changing the size makes no sense but I am interested in learning the limitations if there are any or if this is just a matter of preference.</p>