linux-kernel - Re: building in 32bit chroot on x86

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Date:   Tue, 5 Jun 2018 21:50:56 +0259
From:   Thomas Backlund <tmb@...eia.org>
To:     Linus Torvalds <torvalds@...ux-foundation.org>
CC:     Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: building in 32bit chroot on x86_64 host broken


Den 2018-06-05 kl. 21:38, skrev Linus Torvalds:
> On Tue, Jun 5, 2018 at 11:23 AM Thomas Backlund <tmb@...eia.org> wrote:
>>    #
>> -# CONFIG_64BIT is not set
>>
>> So something _does_ strip away the needed config bit
> Why do you need it?
>
> I get
>
>    CONFIG_X86_32=y
>    CONFIG_X86=y
>
> and CONFIG_64BIT never gets set.
>
> It is true that I don't get the
>
>    # CONFIG_64BIT is not set
>
> line, but why do you care?
>
>              Linus

Because without it running the build in the 32bit chroot will get the 
initial reported issue:


$ uname -m
i686
$ make oldconfig
scripts/kconfig/conf  --oldconfig Kconfig
*
* Restart config...
*
*
* Linux/x86 4.17.0 Kernel Configuration
*
64-bit kernel (64BIT) [Y/n/?] (NEW)


which breaks our buildbots running in chroots...


Now I can work around it by adding the config bit myself, but I'd like 
to understand what changed and why...

--
Thomas