linux-kernel - Re: [PATCH v3 1/2] Kbuild: lto: add CONFIG_MAKE

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Date:   Mon, 5 Jul 2021 11:02:42 +0900
From:   Masahiro Yamada <masahiroy@...nel.org>
To:     Lecopzer Chen <lecopzer.chen@...iatek.com>
Cc:     Nick Desaulniers <ndesaulniers@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Sami Tolvanen <samitolvanen@...gle.com>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Nathan Chancellor <nathan@...nel.org>,
        clang-built-linux <clang-built-linux@...glegroups.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        yj.chiang@...iatek.com, Michal Marek <michal.lkml@...kovi.net>
Subject: Re: [PATCH v3 1/2] Kbuild: lto: add CONFIG_MAKE_VERSION

On Fri, Jul 2, 2021 at 12:29 PM Lecopzer Chen
<lecopzer.chen@...iatek.com> wrote:
>
> To check the GNU make version. Used by the LTO Kconfig.
>
> LTO with MODVERSIONS will fail in generating correct CRC because
> the makefile rule doesn't work for make with version 3.8X.[1]
>
> Thus we need to check make version during selecting on LTO Kconfig.
> Add CONFIG_MAKE_VERSION which means MAKE_VERSION in canonical digits
> for arithmetic comparisons.
>
> [1] https://lore.kernel.org/lkml/20210616080252.32046-1-lecopzer.chen@mediatek.com/
> Signed-off-by: Lecopzer Chen <lecopzer.chen@...iatek.com>
> ---


NACK.

"Let's add MAKE_VERSION >= 40200 restriction
just because I cannot write correct code that
works for older Make" is a horrible idea.

Also, Kconfig is supposed to check the compiler
(or toolchains) capability, not host tool versions.







>  Makefile                |  2 +-
>  init/Kconfig            |  4 ++++
>  scripts/make-version.sh | 13 +++++++++++++
>  3 files changed, 18 insertions(+), 1 deletion(-)
>  create mode 100755 scripts/make-version.sh
>
> diff --git a/Makefile b/Makefile
> index 88888fff4c62..2402745b2ba9 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -516,7 +516,7 @@ CLANG_FLAGS :=
>
>  export ARCH SRCARCH CONFIG_SHELL BASH HOSTCC KBUILD_HOSTCFLAGS CROSS_COMPILE LD CC
>  export CPP AR NM STRIP OBJCOPY OBJDUMP READELF PAHOLE RESOLVE_BTFIDS LEX YACC AWK INSTALLKERNEL
> -export PERL PYTHON3 CHECK CHECKFLAGS MAKE UTS_MACHINE HOSTCXX
> +export PERL PYTHON3 CHECK CHECKFLAGS MAKE MAKE_VERSION UTS_MACHINE HOSTCXX
>  export KGZIP KBZIP2 KLZOP LZMA LZ4 XZ ZSTD
>  export KBUILD_HOSTCXXFLAGS KBUILD_HOSTLDFLAGS KBUILD_HOSTLDLIBS LDFLAGS_MODULE
>
> diff --git a/init/Kconfig b/init/Kconfig
> index 55f9f7738ebb..ecc110504f87 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -86,6 +86,10 @@ config CC_HAS_ASM_INLINE
>  config CC_HAS_NO_PROFILE_FN_ATTR
>         def_bool $(success,echo '__attribute__((no_profile_instrument_function)) int x();' | $(CC) -x c - -c -o /dev/null -Werror)
>
> +config MAKE_VERSION
> +       int
> +       default $(shell,$(srctree)/scripts/make-version.sh $(MAKE_VERSION))
> +
>  config CONSTRUCTORS
>         bool
>
> diff --git a/scripts/make-version.sh b/scripts/make-version.sh
> new file mode 100755
> index 000000000000..3a451db3c067
> --- /dev/null
> +++ b/scripts/make-version.sh
> @@ -0,0 +1,13 @@
> +#!/bin/sh
> +# SPDX-License-Identifier: GPL-2.0
> +#
> +# Print the GNU make version in a 5 or 6-digit form.
> +
> +set -e
> +
> +# Convert the version string x.y.z to a canonical 5 or 6-digit form.
> +IFS=.
> +set -- $1
> +
> +# If the 2nd or 3rd field is missing, fill it with a zero.
> +echo $((10000 * $1 + 100 * ${2:-0} + ${3:-0}))
> --
> 2.18.0
>


--
Best Regards
Masahiro Yamada