Re: [RFC, PATCHv1 15/28] x86: detect 5-level paging support

From: hpa
Date: Thu Dec 15 2016 - 15:53:46 EST

On December 15, 2016 11:20:17 AM PST, Andi Kleen <ak@xxxxxxxxxxxxxxx> wrote:
>The code is not calling CPUID in any performance critical path, only
>at initialization. So any discussion about saving a few instructions
>is a complete waste of time.

Sort of. The BIOS boot code is very space-constrained for certain legacy bootloaders to continue to work. The BIOS boot code proper does not need PIC.

However, the existing .ifnc solution already takes care of it, so it doesn't matter.
Sent from my Android device with K-9 Mail. Please excuse my brevity.