linux-kernel - Re: [GIT PULL 2/2] Kconfig updates for v4.18

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Message-ID: <CAK7LNATmdv+n7i0sJTAQMkbRHRVj-mihJs5nS-oi4fUkB8x8qg@mail.gmail.com>
Date:   Sun, 24 Jun 2018 11:36:06 +0900
From:   Masahiro Yamada <yamada.masahiro@...ionext.com>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>
Cc:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Linux Kbuild mailing list <linux-kbuild@...r.kernel.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [GIT PULL 2/2] Kconfig updates for v4.18

Hi.

2018-06-18 22:25 GMT+09:00 Eric W. Biederman <ebiederm@...ssion.com>:
> Masahiro Yamada <yamada.masahiro@...ionext.com> writes:
>
>> - drop CONFIG_CROSS_COMPILE support
>
> aka
>> commit f1089c92da791034af73478159626007cba7f092
>> Author: Masahiro Yamada <yamada.masahiro@...ionext.com>
>> Date:   Mon May 28 18:21:39 2018 +0900
>>
>>     kbuild: remove CONFIG_CROSS_COMPILE support
>>
>>     Kbuild provides a couple of ways to specify CROSS_COMPILE:
>>
>>     [1] Command line
>>     [2] Environment
>>     [3] arch/*/Makefile (only some architectures)
>>     [4] CONFIG_CROSS_COMPILE
>>
>>     [4] is problematic for the compiler capability tests in Kconfig.
>>     CONFIG_CROSS_COMPILE allows users to change the compiler prefix from
>>     'make menuconfig', etc.  It means, the compiler options would have
>>     to be all re-calculated everytime CONFIG_CROSS_COMPILE is changed.
>>
>>     To avoid complexity and performance issues, I'd like to evaluate
>>     the shell commands statically, i.e. only parsing Kconfig files.
>>
>>     I guess the majority is [1] or [2].  Currently, there are only
>>     5 defconfig files that specify CONFIG_CROSS_COMPILE.
>>       arch/arm/configs/lpc18xx_defconfig
>>       arch/hexagon/configs/comet_defconfig
>>       arch/nds32/configs/defconfig
>>       arch/openrisc/configs/or1ksim_defconfig
>>       arch/openrisc/configs/simple_smp_defconfig
>>
>>     Signed-off-by: Masahiro Yamada <yamada.masahiro@...ionext.com>
>>     Reviewed-by: Kees Cook <keescook@...omium.org>
>>
>
> I just started working against 4.18-rc1 and discovered this.
>
> This has broken my setup for building and testing changes on other
> architectures.  I have to put the name of the compiler prefix somewhere.
> The mapping between the prefix to gcc and the linux architecture is
> non-trivial.  Especially with a lot of architectures in the test pool.
>
> I am tired and frustrated this morning as this is going to keep me from
> getting done what I had planned today.
>
> This is a regression pure and simple.  It breaks my workflow.  Please
> fix it.
>
> Eric
>

Sorry, I cannot fix.

As I mentioned in the commit log,
CONFIG_CROSS_COMPILE cannot co-exist with the new Kconfig feature.

Only the possible fix is to revert almost all Kbuild/Kconfig commits
merged in the previous MW, but I do not want to.



-- 
Best Regards
Masahiro Yamada