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References: <20210702032943.7865-1-lecopzer.chen@mediatek.com> <20210702032943.7865-3-lecopzer.chen@mediatek.com>
In-Reply-To: <20210702032943.7865-3-lecopzer.chen@mediatek.com>
From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Mon, 5 Jul 2021 11:04:54 +0900
Message-ID: <CAK7LNAR2vSaaCyY9UgjrC10HdbnK7NrtfR5mf1AUf5neEzPhZw@mail.gmail.com>
Subject: Re: [PATCH v3 2/2] Kbuild: lto: add make version checking
To:     Lecopzer Chen <lecopzer.chen@mediatek.com>
Cc:     Nick Desaulniers <ndesaulniers@google.com>,
        Kees Cook <keescook@chromium.org>,
        Sami Tolvanen <samitolvanen@google.com>,
        Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Nathan Chancellor <nathan@kernel.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        yj.chiang@mediatek.com, Michal Marek <michal.lkml@markovi.net>
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On Fri, Jul 2, 2021 at 12:29 PM Lecopzer Chen
<lecopzer.chen@mediatek.com> wrote:
>
> 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.
> and the suitable version should be 4.2(40200) which released in 2016[2].
>
> [1] https://lore.kernel.org/lkml/20210616080252.32046-1-lecopzer.chen@mediatek.com/
> [2] https://ftp.gnu.org/gnu/make/
> Signed-off-by: Lecopzer Chen <lecopzer.chen@mediatek.com>
> ---

NACK for the same reason as 1/2.

We need to write correct code.
If we cannot, we need to add 'depends on BROKEN'.


>  arch/Kconfig | 1 +
>  1 file changed, 1 insertion(+)
>
> diff --git a/arch/Kconfig b/arch/Kconfig
> index 129df498a8e1..beee68149da8 100644
> --- a/arch/Kconfig
> +++ b/arch/Kconfig
> @@ -639,6 +639,7 @@ config HAS_LTO_CLANG
>         def_bool y
>         # Clang >= 11: https://github.com/ClangBuiltLinux/linux/issues/510
>         depends on CC_IS_CLANG && CLANG_VERSION >= 110000 && LD_IS_LLD && AS_IS_LLVM
> +       depends on !MODVERSIONS || MAKE_VERSION >= 40200
>         depends on $(success,$(NM) --help | head -n 1 | grep -qi llvm)
>         depends on $(success,$(AR) --help | head -n 1 | grep -qi llvm)
>         depends on ARCH_SUPPORTS_LTO_CLANG
> --
> 2.18.0
>


-- 
Best Regards
Masahiro Yamada