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From:   Mathieu Malaterre <malat@debian.org>
Date:   Fri, 15 Feb 2019 12:00:04 +0100
Message-ID: <CA+7wUswJ5+nb3OdZYrx6++batRMUcnje3jLTgdN4zAQo=--xBg@mail.gmail.com>
Subject: Re: [PATCH] powerpc: use $(origin ARCH) to select KBUILD_DEFCONFIG
To:     Masahiro Yamada <yamada.masahiro@socionext.com>
Cc:     linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        Michael Ellerman <mpe@ellerman.id.au>,
        Paul Mackerras <paulus@samba.org>,
        LKML <linux-kernel@vger.kernel.org>
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On Fri, Feb 15, 2019 at 10:41 AM Masahiro Yamada
<yamada.masahiro@socionext.com> wrote:
>
> I often test all Kconfig commands for all architectures. To ease my
> workflow, I want 'make defconfig' at least working without any cross
> compiler.
>
> Currently, arch/powerpc/Makefile checks CROSS_COMPILE to decide the
> default defconfig source.
>
> If CROSS_COMPILE is unset, it is likely to be the native build, so
> 'uname -m' is useful to choose the defconfig. If CROSS_COMPILE is set,
> the user is cross-building (i.e. 'uname -m' is probably x86_64), so
> it falls back to ppc64_defconfig. Yup, make sense.
>
> However, I want to run 'make ARCH=* defconfig' without setting
> CROSS_COMPILE for each architecture.
>
> My suggestion is to check $(origin ARCH).
>
> When you cross-compile the kernel, you need to set ARCH from your
> environment or from the command line.
>
> For the native build, you do not need to set ARCH. The default in
> the top Makefile is used:
>
>   ARCH            ?= $(SUBARCH)
>
> Hence, $(origin ARCH) returns 'file'.
>
> Before this commit, 'make ARCH=powerpc defconfig' failed:

In case you have not seen it, please check:

http://patchwork.ozlabs.org/patch/1037835/

>   $ make ARCH=powerpc defconfig
>   *** Default configuration is based on target 'x86_64_defconfig'
>   ***
>   *** Can't find default configuration "arch/powerpc/configs/x86_64_defconfig"!
>   ***
>
> After this commit, it will succeed:
>
>   $ make ARCH=powerpc defconfig
>   *** Default configuration is based on 'ppc64_defconfig'
>   #
>   # configuration written to .config
>   #
>
> Signed-off-by: Masahiro Yamada <yamada.masahiro@socionext.com>
> ---
>
>  arch/powerpc/Makefile | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
>
> diff --git a/arch/powerpc/Makefile b/arch/powerpc/Makefile
> index ac03334..f989979 100644
> --- a/arch/powerpc/Makefile
> +++ b/arch/powerpc/Makefile
> @@ -34,7 +34,7 @@ ifdef CONFIG_PPC_BOOK3S_32
>  KBUILD_CFLAGS          += -mcpu=powerpc
>  endif
>
> -ifeq ($(CROSS_COMPILE),)
> +ifeq ($(origin ARCH), file)
>  KBUILD_DEFCONFIG := $(shell uname -m)_defconfig
>  else
>  KBUILD_DEFCONFIG := ppc64_defconfig
> --
> 2.7.4
>