Re: [PATCH 10/11] lib: consolidate the GENERIC_HWEIGHT symbol

Masahiro Yamada
2019-02-18T03:06:26Z

On Thu, Feb 14, 2019 at 2:41 AM Christoph Hellwig <hch@lst.de> wrote:
>
> Introduce a new ARCH_HAS_HWEIGHT symbol for alpha and ia64,

I think this is really confusing.

"ARCH has its own optimized hweight implementation"

is not equivalent to

"ARCH does not need generic hweight at all".

For example, see

arch/powerpc/lib/hweight_64.S

As far as I understood the code,
it will fallback to generic lib/hweight.c
if it turns out the optimized one is not available.

Thanks.

> and just
> default to the generic version otherwise.
>
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
> arch/alpha/Kconfig | 5 +----
> arch/arc/Kconfig | 3 ---
> arch/arm/Kconfig | 4 ----
> arch/arm64/Kconfig | 3 ---
> arch/c6x/Kconfig | 3 ---
> arch/csky/Kconfig | 3 ---
> arch/h8300/Kconfig | 3 ---
> arch/hexagon/Kconfig | 3 ---
> arch/ia64/Kconfig | 1 +
> arch/m68k/Kconfig | 4 ----
> arch/microblaze/Kconfig | 3 ---
> arch/mips/Kconfig | 4 ----
> arch/nds32/Kconfig | 3 ---
> arch/nios2/Kconfig | 3 ---
> arch/openrisc/Kconfig | 3 ---
> arch/parisc/Kconfig | 4 ----
> arch/powerpc/Kconfig | 4 ----
> arch/riscv/Kconfig | 3 ---
> arch/s390/Kconfig | 3 ---
> arch/sh/Kconfig | 3 ---
> arch/sparc/Kconfig | 4 ----
> arch/unicore32/Kconfig | 3 ---
> arch/x86/Kconfig | 3 ---
> arch/x86/um/Kconfig | 3 ---
> arch/xtensa/Kconfig | 3 ---
> lib/Kconfig | 7 +++++++
> 26 files changed, 9 insertions(+), 79 deletions(-)
>
> diff --git a/arch/alpha/Kconfig b/arch/alpha/Kconfig
> index 65b5514e5a7f..a549c53563e8 100644
> --- a/arch/alpha/Kconfig
> +++ b/arch/alpha/Kconfig
> @@ -2,6 +2,7 @@
> config ALPHA
> bool
> default y
> + select ARCH_HAS_HWEIGHT if ALPHA_EV67
> select ARCH_MIGHT_HAVE_PC_PARPORT
> select ARCH_MIGHT_HAVE_PC_SERIO
> select ARCH_NO_PREEMPT
> @@ -446,10 +447,6 @@ config ALPHA_IRONGATE
> depends on ALPHA_NAUTILUS
> default y
>
> -config GENERIC_HWEIGHT
> - bool
> - default y if !ALPHA_EV67
> -
> config ALPHA_AVANTI
> bool
> depends on ALPHA_XL || ALPHA_AVANTI_CH
> diff --git a/arch/arc/Kconfig b/arch/arc/Kconfig
> index 6476404b98b8..8bf4c0f7cc1d 100644
> --- a/arch/arc/Kconfig
> +++ b/arch/arc/Kconfig
> @@ -72,9 +72,6 @@ config MMU
> config NO_IOPORT_MAP
> def_bool y
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> config HAVE_ARCH_TRANSPARENT_HUGEPAGE
> def_bool y
> depends on ARC_MMU_V4
> diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
> index c230fb1e09ba..b47825767e3d 100644
> --- a/arch/arm/Kconfig
> +++ b/arch/arm/Kconfig
> @@ -182,10 +182,6 @@ config ARCH_HAS_BANDGAP
> config FIX_EARLYCON_MEM
> def_bool y if MMU
>
> -config GENERIC_HWEIGHT
> - bool
> - default y
> -
> config ARCH_MAY_HAVE_PC_FDC
> bool
>
> diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
> index 7cc3334aba29..98c3776ccf6b 100644
> --- a/arch/arm64/Kconfig
> +++ b/arch/arm64/Kconfig
> @@ -237,9 +237,6 @@ config ILLEGAL_POINTER_VALUE
> hex
> default 0xdead000000000000
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> config ZONE_DMA32
> def_bool y
>
> diff --git a/arch/c6x/Kconfig b/arch/c6x/Kconfig
> index 19b145ef7d92..c439d2f46af0 100644
> --- a/arch/c6x/Kconfig
> +++ b/arch/c6x/Kconfig
> @@ -28,9 +28,6 @@ config MMU
> config FPU
> def_bool n
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> config C6X_BIG_KERNEL
> bool "Build a big kernel"
> help
> diff --git a/arch/csky/Kconfig b/arch/csky/Kconfig
> index c0a49cbd3df0..14a9905e99a4 100644
> --- a/arch/csky/Kconfig
> +++ b/arch/csky/Kconfig
> @@ -84,9 +84,6 @@ config CPU_NO_USER_BKPT
> instruction exception.
> In kernel we parse the *regs->pc to determine whether to send SIGTRAP or not.
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> config MMU
> def_bool y
>
> diff --git a/arch/h8300/Kconfig b/arch/h8300/Kconfig
> index 4f5a1efab822..77ce104bb42e 100644
> --- a/arch/h8300/Kconfig
> +++ b/arch/h8300/Kconfig
> @@ -27,9 +27,6 @@ config H8300
> config CPU_BIG_ENDIAN
> def_bool y
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> config NO_IOPORT_MAP
> def_bool y
>
> diff --git a/arch/hexagon/Kconfig b/arch/hexagon/Kconfig
> index 7a01f4c5a4f6..fb2996063d5a 100644
> --- a/arch/hexagon/Kconfig
> +++ b/arch/hexagon/Kconfig
> @@ -61,9 +61,6 @@ config MMU
> config GENERIC_IRQ_PROBE
> def_bool y
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> menu "Machine selection"
>
> choice
> diff --git a/arch/ia64/Kconfig b/arch/ia64/Kconfig
> index fc44c046953e..c9eb106b1f4c 100644
> --- a/arch/ia64/Kconfig
> +++ b/arch/ia64/Kconfig
> @@ -8,6 +8,7 @@ menu "Processor type and features"
>
> config IA64
> bool
> + select ARCH_HAS_HWEIGHT
> select ARCH_MIGHT_HAVE_PC_PARPORT
> select ARCH_MIGHT_HAVE_PC_SERIO
> select ACPI if (!IA64_HP_SIM)
> diff --git a/arch/m68k/Kconfig b/arch/m68k/Kconfig
> index 1bf6abaea604..91b150b6572c 100644
> --- a/arch/m68k/Kconfig
> +++ b/arch/m68k/Kconfig
> @@ -38,10 +38,6 @@ config ARCH_HAS_ILOG2_U32
> config ARCH_HAS_ILOG2_U64
> bool
>
> -config GENERIC_HWEIGHT
> - bool
> - default y
> -
> config TIME_LOW_RES
> bool
> default y
> diff --git a/arch/microblaze/Kconfig b/arch/microblaze/Kconfig
> index d8907d6f969c..0185ac1f0268 100644
> --- a/arch/microblaze/Kconfig
> +++ b/arch/microblaze/Kconfig
> @@ -71,9 +71,6 @@ config ARCH_HAS_ILOG2_U32
> config ARCH_HAS_ILOG2_U64
> def_bool n
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> source "arch/microblaze/Kconfig.platform"
>
> menu "Processor type and features"
> diff --git a/arch/mips/Kconfig b/arch/mips/Kconfig
> index bd0c9be7e7cf..04e041cac595 100644
> --- a/arch/mips/Kconfig
> +++ b/arch/mips/Kconfig
> @@ -1042,10 +1042,6 @@ source "arch/mips/paravirt/Kconfig"
>
> endmenu
>
> -config GENERIC_HWEIGHT
> - bool
> - default y
> -
> config SCHED_OMIT_FRAME_POINTER
> bool
> default y
> diff --git a/arch/nds32/Kconfig b/arch/nds32/Kconfig
> index 7b3a36705aa8..979661f0ab51 100644
> --- a/arch/nds32/Kconfig
> +++ b/arch/nds32/Kconfig
> @@ -50,9 +50,6 @@ config NDS32
> help
> Andes(nds32) Linux support.
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> config GENERIC_LOCKBREAK
> def_bool y
> depends on PREEMPT
> diff --git a/arch/nios2/Kconfig b/arch/nios2/Kconfig
> index 11ef63217ebe..a0485f5f0db0 100644
> --- a/arch/nios2/Kconfig
> +++ b/arch/nios2/Kconfig
> @@ -27,9 +27,6 @@ config NIOS2
> select CPU_NO_EFFICIENT_FFS
> select ARCH_DISCARD_MEMBLOCK
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> config NO_IOPORT_MAP
> def_bool y
>
> diff --git a/arch/openrisc/Kconfig b/arch/openrisc/Kconfig
> index 15d7df402c19..dc026973e6f6 100644
> --- a/arch/openrisc/Kconfig
> +++ b/arch/openrisc/Kconfig
> @@ -46,9 +46,6 @@ config CPU_BIG_ENDIAN
> config MMU
> def_bool y
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> config NO_IOPORT_MAP
> def_bool y
>
> diff --git a/arch/parisc/Kconfig b/arch/parisc/Kconfig
> index 42282b8e086d..7d5ded83c180 100644
> --- a/arch/parisc/Kconfig
> +++ b/arch/parisc/Kconfig
> @@ -86,10 +86,6 @@ config ARCH_HAS_ILOG2_U64
> bool
> default n
>
> -config GENERIC_HWEIGHT
> - bool
> - default y
> -
> config TIME_LOW_RES
> bool
> depends on SMP
> diff --git a/arch/powerpc/Kconfig b/arch/powerpc/Kconfig
> index a0e9207893c8..8dd4d2b24fdb 100644
> --- a/arch/powerpc/Kconfig
> +++ b/arch/powerpc/Kconfig
> @@ -96,10 +96,6 @@ config GENERIC_LOCKBREAK
> default y
> depends on SMP && PREEMPT
>
> -config GENERIC_HWEIGHT
> - bool
> - default y
> -
> config ARCH_HAS_DMA_SET_COHERENT_MASK
> bool
>
> diff --git a/arch/riscv/Kconfig b/arch/riscv/Kconfig
> index 2b173a48bdbc..0acdd7aaaaea 100644
> --- a/arch/riscv/Kconfig
> +++ b/arch/riscv/Kconfig
> @@ -69,9 +69,6 @@ config PAGE_OFFSET
> default 0xffffffff80000000 if 64BIT && MAXPHYSMEM_2GB
> default 0xffffffe000000000 if 64BIT && MAXPHYSMEM_128GB
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> config PGTABLE_LEVELS
> int
> default 3 if 64BIT
> diff --git a/arch/s390/Kconfig b/arch/s390/Kconfig
> index 2a5c12be633e..9a25e19364f5 100644
> --- a/arch/s390/Kconfig
> +++ b/arch/s390/Kconfig
> @@ -14,9 +14,6 @@ config ARCH_HAS_ILOG2_U32
> config ARCH_HAS_ILOG2_U64
> def_bool n
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> config GENERIC_LOCKBREAK
> def_bool y if SMP && PREEMPT
>
> diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
> index 3d0bd7fbe11a..af6a40af1702 100644
> --- a/arch/sh/Kconfig
> +++ b/arch/sh/Kconfig
> @@ -94,9 +94,6 @@ config ARCH_DEFCONFIG
> default "arch/sh/configs/shx3_defconfig" if SUPERH32
> default "arch/sh/configs/cayman_defconfig" if SUPERH64
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> config GENERIC_LOCKBREAK
> def_bool y
> depends on SMP && PREEMPT
> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> index 58270c021b01..78135ac357ed 100644
> --- a/arch/sparc/Kconfig
> +++ b/arch/sparc/Kconfig
> @@ -187,10 +187,6 @@ config NR_CPUS
>
> source "kernel/Kconfig.hz"
>
> -config GENERIC_HWEIGHT
> - bool
> - default y
> -
> config ARCH_MAY_HAVE_PC_FDC
> bool
> default y
> diff --git a/arch/unicore32/Kconfig b/arch/unicore32/Kconfig
> index 9de1d983a99a..e69a8c3232e1 100644
> --- a/arch/unicore32/Kconfig
> +++ b/arch/unicore32/Kconfig
> @@ -38,9 +38,6 @@ config ARCH_HAS_ILOG2_U32
> config ARCH_HAS_ILOG2_U64
> bool
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> config ARCH_MAY_HAVE_PC_FDC
> bool
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index f4cb31174e1b..7a9347c7448e 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -255,9 +255,6 @@ config GENERIC_ISA_DMA
> def_bool y
> depends on ISA_DMA_API
>
> -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/um/Kconfig b/arch/x86/um/Kconfig
> index f5a8cded3ca4..1628a54af003 100644
> --- a/arch/x86/um/Kconfig
> +++ b/arch/x86/um/Kconfig
> @@ -49,6 +49,3 @@ config ARCH_HAS_SC_SIGNALS
>
> config ARCH_REUSE_HOST_VSYSCALL_AREA
> def_bool !64BIT
> -
> -config GENERIC_HWEIGHT
> - def_bool y
> diff --git a/arch/xtensa/Kconfig b/arch/xtensa/Kconfig
> index d02c25184ca0..ff57afdeda04 100644
> --- a/arch/xtensa/Kconfig
> +++ b/arch/xtensa/Kconfig
> @@ -47,9 +47,6 @@ config XTENSA
> with reasonable minimum requirements. The Xtensa Linux project has
> a home page at <http://www.linux-xtensa.org/>.
>
> -config GENERIC_HWEIGHT
> - def_bool y
> -
> config ARCH_HAS_ILOG2_U32
> def_bool n
>
> diff --git a/lib/Kconfig b/lib/Kconfig
> index bd2e7e74c321..91019f26d0a8 100644
> --- a/lib/Kconfig
> +++ b/lib/Kconfig
> @@ -35,6 +35,13 @@ config RATIONAL
> config GENERIC_CSUM
> bool
>
> +config ARCH_HAS_HWEIGHT
> + bool
> +
> +config GENERIC_HWEIGHT
> + default y if !ARCH_HAS_HWEIGHT
> + bool
> +
> config GENERIC_STRNCPY_FROM_USER
> bool
>
> --
> 2.20.1
>
>
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--
Best Regards
Masahiro Yamada