title: Retrieving x64 register values with inline asm
body: <p>I was wondering if there was any way that would allow me to specify anything other than eax, ebx, ecx and edx as output operands.  </p>
  
  <p>Lets say I want to put the content of r8 in a variable, Is it possible to write something like this :</p>
  
  <pre><code>  __asm__ __volatile__ (""  
                          :"=r8"(my_var) 
                          : /* no input */                             
                          );            
  </code></pre>