title: What are the calling conventions for UNIX & Linux system calls (and user-space functions) on i386 and x86-64
body: <p>Following links explain x86-32 system call conventions for both UNIX (BSD flavor) &amp; Linux:</p>
  
  <ul>
  <li><p><a href="http://www.int80h.org/bsdasm/#system-calls" rel="noreferrer">http://www.int80h.org/bsdasm/#system-calls</a></p></li>
  <li><p><a href="http://www.freebsd.org/doc/en/books/developers-handbook/x86-system-calls.html" rel="noreferrer">http://www.freebsd.org/doc/en/books/developers-handbook/x86-system-calls.html</a></p></li>
  </ul>
  
  <p>But what are the x86-64 system call conventions on both UNIX &amp; Linux?</p>