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In-Reply-To: <20190921064954.11196-1-yamada.masahiro@socionext.com>
From:   Nick Desaulniers <ndesaulniers@google.com>
Date:   Tue, 24 Sep 2019 09:47:36 -0700
Message-ID: <CAKwvOdnmYCbZiFKrvzwjJWmhzn5X+rKSs2GQZC4Dy-7VmKyntw@mail.gmail.com>
Subject: Re: [PATCH] kbuild: remove ar-option and KBUILD_ARFLAGS
To:     Masahiro Yamada <yamada.masahiro@socionext.com>
Cc:     Linux Kbuild mailing list <linux-kbuild@vger.kernel.org>,
        Benjamin Herrenschmidt <benh@kernel.crashing.org>,
        Jonathan Corbet <corbet@lwn.net>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Michal Marek <michal.lkml@markovi.net>,
        Paul Mackerras <paulus@samba.org>,
        clang-built-linux <clang-built-linux@googlegroups.com>,
        linux-doc@vger.kernel.org, LKML <linux-kernel@vger.kernel.org>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>
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On Tue, Sep 24, 2019 at 9:38 AM Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> Commit 40df759e2b9e ("kbuild: Fix build with binutils <= 2.19")
> introduced ar-option and KBUILD_ARFLAGS to cope with old binutils.
>
> According to Documentation/process/changes.rst, the current minimal
> supported version of binutils is 2.21 so you can assume the 'D' option
> is always supported. Not only GNU ar but also llvm-ar supports it.

Yep, a nice cleanup. Thanks for the patch and I appreciate checking llvm-ar.
Reviewed-by: Nick Desaulniers <ndesaulniers@google.com>
Tested-by: Nick Desaulniers <ndesaulniers@google.com>

>
> With the 'D' option hard-coded, there is no more user of ar-option
> or KBUILD_ARFLAGS.
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
>
>  Documentation/kbuild/makefiles.rst | 5 -----
>  Makefile                           | 4 ----
>  arch/powerpc/boot/Makefile         | 2 +-
>  scripts/Kbuild.include             | 5 -----
>  scripts/Makefile.build             | 2 +-
>  scripts/Makefile.lib               | 2 +-
>  6 files changed, 3 insertions(+), 17 deletions(-)
>
> diff --git a/Documentation/kbuild/makefiles.rst b/Documentation/kbuild/makefiles.rst
> index 6ba9d5365ff3..b89c88168d6a 100644
> --- a/Documentation/kbuild/makefiles.rst
> +++ b/Documentation/kbuild/makefiles.rst
> @@ -954,11 +954,6 @@ When kbuild executes, the following steps are followed (roughly):
>
>         From commandline LDFLAGS_MODULE shall be used (see kbuild.txt).
>
> -    KBUILD_ARFLAGS   Options for $(AR) when creating archives
> -
> -       $(KBUILD_ARFLAGS) set by the top level Makefile to "D" (deterministic
> -       mode) if this option is supported by $(AR).
> -
>      KBUILD_LDS
>
>         The linker script with full path. Assigned by the top-level Makefile.
> diff --git a/Makefile b/Makefile
> index 656a8c95789d..88b180b2cb64 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -498,7 +498,6 @@ export CFLAGS_KASAN CFLAGS_KASAN_NOSANITIZE CFLAGS_UBSAN
>  export KBUILD_AFLAGS AFLAGS_KERNEL AFLAGS_MODULE
>  export KBUILD_AFLAGS_MODULE KBUILD_CFLAGS_MODULE KBUILD_LDFLAGS_MODULE
>  export KBUILD_AFLAGS_KERNEL KBUILD_CFLAGS_KERNEL
> -export KBUILD_ARFLAGS
>
>  # Files to ignore in find ... statements
>
> @@ -914,9 +913,6 @@ ifdef CONFIG_RETPOLINE
>  KBUILD_CFLAGS += $(call cc-option,-fcf-protection=none)
>  endif
>
> -# use the deterministic mode of AR if available
> -KBUILD_ARFLAGS := $(call ar-option,D)
> -
>  include scripts/Makefile.kasan
>  include scripts/Makefile.extrawarn
>  include scripts/Makefile.ubsan
> diff --git a/arch/powerpc/boot/Makefile b/arch/powerpc/boot/Makefile
> index 6841bd52738b..dfbd7f22eef5 100644
> --- a/arch/powerpc/boot/Makefile
> +++ b/arch/powerpc/boot/Makefile
> @@ -50,7 +50,7 @@ endif
>
>  BOOTAFLAGS     := -D__ASSEMBLY__ $(BOOTCFLAGS) -nostdinc
>
> -BOOTARFLAGS    := -cr$(KBUILD_ARFLAGS)
> +BOOTARFLAGS    := -crD
>
>  ifdef CONFIG_CC_IS_CLANG
>  BOOTCFLAGS += $(CLANG_FLAGS)
> diff --git a/scripts/Kbuild.include b/scripts/Kbuild.include
> index e31fd6a8b2a3..956668239ef5 100644
> --- a/scripts/Kbuild.include
> +++ b/scripts/Kbuild.include
> @@ -143,11 +143,6 @@ cc-ifversion = $(shell [ $(CONFIG_GCC_VERSION)0 $(1) $(2)000 ] && echo $(3) || e
>  # Usage: KBUILD_LDFLAGS += $(call ld-option, -X, -Y)
>  ld-option = $(call try-run, $(LD) $(KBUILD_LDFLAGS) $(1) -v,$(1),$(2),$(3))
>
> -# ar-option
> -# Usage: KBUILD_ARFLAGS := $(call ar-option,D)
> -# Important: no spaces around options
> -ar-option = $(call try-run, $(AR) rc$(1) "$$TMP",$(1),$(2))
> -
>  # ld-version
>  # Note this is mainly for HJ Lu's 3 number binutil versions
>  ld-version = $(shell $(LD) --version | $(srctree)/scripts/ld-version.sh)
> diff --git a/scripts/Makefile.build b/scripts/Makefile.build
> index 611bda95ac5e..f199341f04eb 100644
> --- a/scripts/Makefile.build
> +++ b/scripts/Makefile.build
> @@ -395,7 +395,7 @@ $(sort $(subdir-obj-y)): $(subdir-ym) ;
>  ifdef builtin-target
>
>  quiet_cmd_ar_builtin = AR      $@
> -      cmd_ar_builtin = rm -f $@; $(AR) rcSTP$(KBUILD_ARFLAGS) $@ $(real-prereqs)
> +      cmd_ar_builtin = rm -f $@; $(AR) cDPrST $@ $(real-prereqs)
>
>  $(builtin-target): $(real-obj-y) FORCE
>         $(call if_changed,ar_builtin)
> diff --git a/scripts/Makefile.lib b/scripts/Makefile.lib
> index 23e524027740..15895fd4ef9f 100644
> --- a/scripts/Makefile.lib
> +++ b/scripts/Makefile.lib
> @@ -238,7 +238,7 @@ quiet_cmd_ld = LD      $@
>  # ---------------------------------------------------------------------------
>
>  quiet_cmd_ar = AR      $@
> -      cmd_ar = rm -f $@; $(AR) rcsTP$(KBUILD_ARFLAGS) $@ $(real-prereqs)
> +      cmd_ar = rm -f $@; $(AR) cDPrsT $@ $(real-prereqs)
>
>  # Objcopy
>  # ---------------------------------------------------------------------------
> --
> 2.17.1
>
> --
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-- 
Thanks,
~Nick Desaulniers