title: How do linux break 64bit virtual address?
body: <p>Assuming a 4-level page-tables, where the first 3 levels are 9-bits and the last one is 12 bits, then shouldn't the maximum virtual address be 3*9+12=39 bits?</p>
  
  <p>Today i have noticed by accident that my addresses where 47 bits long.
  e.g 0x7fb329caa3c0</p>