  nr  and sys  are the two common prefixes for the userspace constants for system calls i forget which is sysv and which is the other one so you need to grep your linux kernel tree for clone or read  man clone  or whatever what s happening here is that other than  flags  and  fn  being the wrong way round bionic clone s arguments are the same as the kernel s syscall  that is handled in the next block  up here  we are stashing the two arguments that bionic clone entry will need later i d like to reorder to remove the need for the later block  but some   retard   made this public abi  so i worry i would break something i d also like to kill pthread clone and just use this more general form  but since we probably have to keep this for abi compatibility anyway  it s worth thinking about simplifying all this for the bit architectures though 