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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Tue, 19 Jul 2022 18:15:32 +0900
Message-ID: <CAK7LNAQa0QqEG1PLY3nr_ajP59d9cNU-0FBq2WGKnvEnZGJ1MA@mail.gmail.com>
Subject: Re: [PATCH v2 1/2] kbuild: pass jobserver to cmd_ld_vmlinux.o
To:     Jiri Slaby <jslaby@suse.cz>
Cc:     Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        Sedat Dilek <sedat.dilek@gmail.com>,
        Michal Marek <michal.lkml@markovi.net>,
        Nick Desaulniers <ndesaulniers@google.com>,
        "Signed-off-by : Martin Liska" <mliska@suse.cz>
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On Tue, Jul 19, 2022 at 5:41 PM Jiri Slaby <jslaby@suse.cz> wrote:
>
> Until the link-vmlinux.sh split (cf. the commit below), the linker was
> run with jobserver set in MAKEFLAGS. After the split, the command in
> Makefile.vmlinux_o is not prefixed by "+" anymore, so this information
> is lost.
>
> Restore it as linkers working in parallel (esp. the LTO ones) make a use
> of it. In this case, it is gcc producing this warning otherwise:
> lto-wrapper: warning: jobserver is not available: =E2=80=98--jobserver-au=
th=3D=E2=80=99 is not present in =E2=80=98MAKEFLAGS=E2=80=99
>
> Cc: Sedat Dilek <sedat.dilek@gmail.com>
> Cc: Masahiro Yamada <masahiroy@kernel.org>
> Cc: Michal Marek <michal.lkml@markovi.net>
> Cc: Nick Desaulniers <ndesaulniers@google.com>
> Cc: Signed-off-by: Martin Liska <mliska@suse.cz>
> Fixes: 5d45950dfbb1 (kbuild: move vmlinux.o link to scripts/Makefile.vmli=
nux_o)
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> ---
>
> Notes:
>     [v2] only commit message updated


Did you read my previous email?

https://lore.kernel.org/linux-kbuild/CAK7LNAS46hrVh3FNiHHL8_Hqp85VgWnsHyjQ4=
t-TFH_H344NOg@mail.gmail.com/


>
>  scripts/Makefile.vmlinux_o | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/scripts/Makefile.vmlinux_o b/scripts/Makefile.vmlinux_o
> index 84019814f33f..886db0659d9c 100644
> --- a/scripts/Makefile.vmlinux_o
> +++ b/scripts/Makefile.vmlinux_o
> @@ -65,7 +65,7 @@ define rule_ld_vmlinux.o
>  endef
>
>  vmlinux.o: $(initcalls-lds) $(KBUILD_VMLINUX_OBJS) $(KBUILD_VMLINUX_LIBS=
) FORCE
> -       $(call if_changed_rule,ld_vmlinux.o)
> +       +$(call if_changed_rule,ld_vmlinux.o)
>
>  targets +=3D vmlinux.o
>
> --
> 2.37.1
>


--=20
Best Regards
Masahiro Yamada