Re: [PATCH 2/5] x86_64, -march=native: POPCNT support

[Peter Zijlstra]

On Mon, Jul 22, 2019 at 11:27:20PM +0300, Alexey Dobriyan wrote:
> Detect POPCNT instruction support and inline hweigth*() functions
> if it is supported by CPU.
> 
> Detect POPCNT at boot time and conditionally refuse to boot.
> 
> Signed-off-by: Alexey Dobriyan <adobriyan@xxxxxxxxx>
> ---
>  arch/x86/include/asm/arch_hweight.h           | 24 +++++++++++++++++++
>  arch/x86/include/asm/segment.h                |  1 +
>  arch/x86/kernel/verify_cpu.S                  |  8 +++++++
>  arch/x86/lib/Makefile                         |  5 +++-
>  .../drm/i915/display/intel_display_power.c    |  2 +-
>  drivers/misc/sgi-gru/grumain.c                |  2 +-
>  fs/btrfs/tree-checker.c                       |  4 ++--
>  include/linux/bitops.h                        |  2 ++
>  lib/Makefile                                  |  2 ++
>  scripts/kconfig/cpuid.c                       |  7 ++++++
>  scripts/march-native.sh                       |  2 ++
>  11 files changed, 54 insertions(+), 5 deletions(-)

*WHY* ?

AFAICT this just adds lines and complexity and wins aboslutely nothing.