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From:   Michael Ellerman <mpe@ellerman.id.au>
To:     Mathieu Malaterre <malat@debian.org>
Cc:     Masahiro Yamada <yamada.masahiro@socionext.com>,
        linuxppc-dev <linuxppc-dev@lists.ozlabs.org>,
        Paul Mackerras <paulus@samba.org>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] powerpc: use $(origin ARCH) to select KBUILD_DEFCONFIG
In-Reply-To: <CA+7wUsxruu0GdyRGJ3vsjRvSBAptMn8_f5BmeMo=-E3zbhGGxQ@mail.gmail.com>
References: <1550223519-18290-1-git-send-email-yamada.masahiro@socionext.com> <CA+7wUswJ5+nb3OdZYrx6++batRMUcnje3jLTgdN4zAQo=--xBg@mail.gmail.com> <CAK7LNAQUEivnhFnmkP+5uCHRJcYWDtK_fm2gB0rsbzGv1taBCg@mail.gmail.com> <CA+7wUsxruu0GdyRGJ3vsjRvSBAptMn8_f5BmeMo=-E3zbhGGxQ@mail.gmail.com>
Date:   Thu, 14 Mar 2019 13:24:03 +1100
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Mathieu Malaterre <malat@debian.org> writes:
> On Sat, Feb 16, 2019 at 3:26 AM Masahiro Yamada
> <yamada.masahiro@socionext.com> wrote:
>>
>> On Sat, Feb 16, 2019 at 1:11 AM Mathieu Malaterre <malat@debian.org> wrote:
>> >
>> > 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/
>>
>> I did not know that because I do not subscribe to ppc ML.
>>
>> Michael's patch looks good to me.
>
> OK
>
>>
>> If you mimic x86, the following will work:
>>
>
> Nice! Michael do you have a preference ?

Yeah I don't like playing games with ARCH. Doing so means auto builders
and other build scripts need to learn about the special rules for ARCH,
which is a pain.

So I'll merge my patch, which I think will also work for Masahiro's
case.

cheers