linux-kernel - Re: make defconfig (Re: + x86-defconfigs-explicitly-unset-config_64bit-in-i386

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Message-ID: <CA+icZUVPjw_JMXFA9Y=wUewq6Bi0ATFOX-4dce3mOpVbv9SHXw@mail.gmail.com>
Date:   Fri, 21 Aug 2020 20:52:17 +0200
From:   Sedat Dilek <sedat.dilek@...il.com>
To:     Randy Dunlap <rdunlap@...radead.org>
Cc:     Alexey Dobriyan <adobriyan@...il.com>,
        linux-kernel@...r.kernel.org, daniel.diaz@...aro.org
Subject: Re: make defconfig (Re: + x86-defconfigs-explicitly-unset-config_64bit-in-i386_defconfig.patch
 added to -mm tree)

On Fri, Aug 21, 2020 at 7:27 PM Randy Dunlap <rdunlap@...radead.org> wrote:
>
> On 8/21/20 10:22 AM, Alexey Dobriyan wrote:
> > On Thu, Aug 20, 2020 at 02:29:40PM -0700, akpm@...ux-foundation.org wrote:
> >> Subject: x86/defconfigs: Explicitly unset CONFIG_64BIT in i386_defconfig
> >>
> >> A recent refresh of the defconfigs got rid of the following (unset)
> >> config:
> >>
> >>   # CONFIG_64BIT is not set
> >>
> >> Innocuous as it seems, when the config file is saved again the
> >> behavior is changed so that CONFIG_64BIT=y.
> >>
> >> Currently,
> >>
> >>   $ make i386_defconfig
> >>   $ grep CONFIG_64BIT .config
> >>   CONFIG_64BIT=y
> >>
> >> whereas previously (and with this patch):
> >>
> >>   $ make i386_defconfig
> >>   $ grep CONFIG_64BIT .config
> >>   # CONFIG_64BIT is not set
> >
> > It is highly, highly, highly advisable to always pass ARCH when dealing
> > with 32/64-bit archs:
> >
> >       +---------------------------------------+
> >       |       make ARCH=x86_64 defconfig      |
> >       |       make ARCH=i386 defconfig        |
> >       +---------------------------------------+
>
> I certainly always do that and I also avoid
> ARCH=x86
> although it is supported/allowed.
>

Unsure, if this already documented - if not - might be good to document it.

While playing with ClangBuiltLinux issue #194 this was not clear to me.

- Sedat -

[1] https://github.com/ClangBuiltLinux/linux/issues/194
[2] https://github.com/ClangBuiltLinux/linux/issues/194#issuecomment-662433916
[3] https://github.com/ClangBuiltLinux/linux/issues/194#issuecomment-662613396
[4] https://github.com/ClangBuiltLinux/linux/issues/194#issuecomment-662620461