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From:   Masahiro Yamada <masahiroy@kernel.org>
Date:   Tue, 15 Nov 2022 02:57:16 +0900
Message-ID: <CAK7LNASUb0PLiZahw46c0qBUn_caMWm2SrtY1Hb8Vd7RzsAwzg@mail.gmail.com>
Subject: Re: [PATCH 02/46] kbuild: pass jobserver to cmd_ld_vmlinux.o
To:     "Jiri Slaby (SUSE)" <jirislaby@kernel.org>
Cc:     linux-kernel@vger.kernel.org, Jiri Slaby <jslaby@suse.cz>,
        Sedat Dilek <sedat.dilek@gmail.com>,
        Michal Marek <michal.lkml@markovi.net>,
        Nick Desaulniers <ndesaulniers@google.com>,
        Martin Liska <mliska@suse.cz>
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On Mon, Nov 14, 2022 at 8:44 PM Jiri Slaby (SUSE) <jirislaby@kernel.org> wrote:
>
> From: Jiri Slaby <jslaby@suse.cz>
>
> 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 (namely gcc LTO) make a use of
> it. Actually, they complain, if jobserver is not set:
>   lto-wrapper: warning: jobserver is not available: '--jobserver-auth=' is not present in 'MAKEFLAGS'
>
> Fixes: 5d45950dfbb1 (kbuild: move vmlinux.o link to scripts/Makefile.vmlinux_o)


This Fixes is wrong since GCC LTO is not in upstream code.


> 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: Martin Liska <mliska@suse.cz>
> Signed-off-by: Jiri Slaby <jslaby@suse.cz>
> ---
>  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 0edfdb40364b..1c86895cfcf8 100644
> --- a/scripts/Makefile.vmlinux_o
> +++ b/scripts/Makefile.vmlinux_o
> @@ -58,7 +58,7 @@ define rule_ld_vmlinux.o
>  endef
>
>  vmlinux.o: $(initcalls-lds) vmlinux.a $(KBUILD_VMLINUX_LIBS) FORCE
> -       $(call if_changed_rule,ld_vmlinux.o)
> +       +$(call if_changed_rule,ld_vmlinux.o)
>
>  targets += vmlinux.o
>
> --
> 2.38.1
>


-- 
Best Regards
Masahiro Yamada