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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Sat, 17 Dec 2022 16:59:41 +0900
Message-ID: <CAK7LNASM6KsrXHXLykaQ=rJ3YZ5OA+7im4=g=3Ob3EPt97n_HQ@mail.gmail.com>
Subject: Re: [PATCH] kbuild: Fix compilation error
To:     Rong Tao <rtoax@foxmail.com>
Cc:     linux-kbuild@vger.kernel.org, Rong Tao <rongtao@cestc.cn>,
        Nathan Chancellor <nathan@kernel.org>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Nicolas Schier <nicolas@fjasle.eu>,
        open list <linux-kernel@vger.kernel.org>,
        "open list:BPF [MISC]" <bpf@vger.kernel.org>
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On Sat, Dec 17, 2022 at 4:07 PM Rong Tao <rtoax@foxmail.com> wrote:
>
> From: Rong Tao <rongtao@cestc.cn>
>
> In the absence of a CONFIG_FUNCTION_ALIGNMENT defined,

Does it happen in the mainline kernel?


CONFIG_FUNCTION_ALIGNMENT is always defined
as far as I understood arch/Kconfig.


> -falign-functions=3D
> will be given a null value, which results in a compilation error, as
> follows:
>
>     $ make -C samples/bpf/
>     ...
>     CC      /home/sdb/Git/linux/samples/bpf/syscall_nrs.s
>     gcc: error: missing argument to =E2=80=98-falign-functions=3D=E2=80=
=99
>     make[2]: *** [scripts/Makefile.build:118: /home/sdb/Git/linux/samples
>         /bpf/syscall_nrs.s] Error 1
>     make[1]: *** [Makefile:1996: /home/sdb/Git/linux/samples/bpf] Error 2
>     make[1]: Leaving directory '/home/sdb/Git/linux'
>     make: *** [Makefile:269: all] Error 2
>
> Signed-off-by: Rong Tao <rongtao@cestc.cn>
> ---
>  Makefile | 2 ++
>  1 file changed, 2 insertions(+)
>
> diff --git a/Makefile b/Makefile
> index 6aa709df6bde..57cce4c8f8a2 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -1006,9 +1006,11 @@ KBUILD_CFLAGS    +=3D $(CC_FLAGS_CFI)
>  export CC_FLAGS_CFI
>  endif
>
> +ifdef CONFIG_FUNCTION_ALIGNMENT
>  ifneq ($(CONFIG_FUNCTION_ALIGNMENT),0)
>  KBUILD_CFLAGS +=3D -falign-functions=3D$(CONFIG_FUNCTION_ALIGNMENT)
>  endif
> +endif
>
>  # arch Makefile may override CC so keep this after arch Makefile is incl=
uded
>  NOSTDINC_FLAGS +=3D -nostdinc
> --
> 2.38.1
>


--=20
Best Regards
Masahiro Yamada