linux-kernel - Re: [PATCH 2/2] x86: disable CONFIG_GENERIC_HWEIGHT and remove __HAVE_ARCH_SW

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Date:   Tue, 19 Feb 2019 10:16:01 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        Borislav Petkov <bp@...en8.de>,
        "H . Peter Anvin" <hpa@...or.com>, X86 ML <x86@...nel.org>
Cc:     Kalle Valo <kvalo@...eaurora.org>, linux-wireless@...r.kernel.org,
        Christoph Hellwig <hch@....de>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 2/2] x86: disable CONFIG_GENERIC_HWEIGHT and remove __HAVE_ARCH_SW_HWEIGHT

On Mon, Feb 18, 2019 at 3:09 PM Masahiro Yamada
<yamada.masahiro@...ionext.com> wrote:
>
> arch/x86/include/asm/arch_hweight.h uses __sw_hweight{32,64} as
> alternatives, but they are implemented in arch/x86/lib/hweight.S
>
> x86 does not rely on the generic C implementation lib/hweight.c
> at all, so CONFIG_GENERIC_HWEIGHT should be disabled.
>
> __HAVE_ARCH_SW_HWEIGHT was unneeded in the first place.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>


Maintainers,

As I replied to 1/2,
please ignore this for now.


I will resend this later,
hopefully in the next development cycle.


> ---
>
>  arch/x86/Kconfig                    | 3 ---
>  arch/x86/include/asm/arch_hweight.h | 2 --
>  lib/hweight.c                       | 4 ----
>  3 files changed, 9 deletions(-)
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index 6826143..c2813af 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -262,9 +262,6 @@ config GENERIC_BUG
>  config GENERIC_BUG_RELATIVE_POINTERS
>         bool
>
> -config GENERIC_HWEIGHT
> -       def_bool y
> -
>  config ARCH_MAY_HAVE_PC_FDC
>         def_bool y
>         depends on ISA_DMA_API
> diff --git a/arch/x86/include/asm/arch_hweight.h b/arch/x86/include/asm/arch_hweight.h
> index fc06935..ba88edd 100644
> --- a/arch/x86/include/asm/arch_hweight.h
> +++ b/arch/x86/include/asm/arch_hweight.h
> @@ -12,8 +12,6 @@
>  #define REG_OUT "a"
>  #endif
>
> -#define __HAVE_ARCH_SW_HWEIGHT
> -
>  static __always_inline unsigned int __arch_hweight32(unsigned int w)
>  {
>         unsigned int res;
> diff --git a/lib/hweight.c b/lib/hweight.c
> index 7660d88..c94586b 100644
> --- a/lib/hweight.c
> +++ b/lib/hweight.c
> @@ -10,7 +10,6 @@
>   * The Hamming Weight of a number is the total number of bits set in it.
>   */
>
> -#ifndef __HAVE_ARCH_SW_HWEIGHT
>  unsigned int __sw_hweight32(unsigned int w)
>  {
>  #ifdef CONFIG_ARCH_HAS_FAST_MULTIPLIER
> @@ -27,7 +26,6 @@ unsigned int __sw_hweight32(unsigned int w)
>  #endif
>  }
>  EXPORT_SYMBOL(__sw_hweight32);
> -#endif
>
>  unsigned int __sw_hweight16(unsigned int w)
>  {
> @@ -46,7 +44,6 @@ unsigned int __sw_hweight8(unsigned int w)
>  }
>  EXPORT_SYMBOL(__sw_hweight8);
>
> -#ifndef __HAVE_ARCH_SW_HWEIGHT
>  unsigned long __sw_hweight64(__u64 w)
>  {
>  #if BITS_PER_LONG == 32
> @@ -69,4 +66,3 @@ unsigned long __sw_hweight64(__u64 w)
>  #endif
>  }
>  EXPORT_SYMBOL(__sw_hweight64);
> -#endif
> --
> 2.7.4
>


-- 
Best Regards
Masahiro Yamada