09-07-2013, 10:37 AM
8.1 x64 drops A64 and 90nm P4 support. A64 lacks CMPXCHG16 which is why Windows is limited to 8TB of address space. NSA couldn't wait for Win9 so we get that breaking change now⸮ The P4 is more interesting though. MS's 64bit compiler emits a 3DNow! instruction. MS had to trap this instruction for Intel. Cedar Mill NOPs it and Broadwell will support it.