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

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Date:   Sat, 23 Jun 2018 09:54:43 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     "Eric W. Biederman" <ebiederm@...ssion.com>,
        Masahiro Yamada <yamada.masahiro@...ionext.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>,
        masahiroy@...nel.org
Subject: Re: [GIT PULL 2/2] Kconfig updates for v4.18

On 06/18/2018 06:25 AM, Eric W. Biederman wrote:
> 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.

Hi Eric,

I haven't seen any replies to your email.

FWIW, every bump in kernel major version number breaks my scripts, and I just
update them.


Anyway, I can offer you my cross-build scripts if you want them.
Then are named xbuild_$(ARCH).sh (well, mostly) and they (mostly) replace
and work like "make".  E.g. this is how I use one of them:
$ xbuild_arm.sh allmodconfig
$ xbuild_arm.sh all >armall.out 2>&1

I used Arnd's crosstool builds from https://cdn.kernel.org/pub/tools/crosstool/.


Or you could check out the kbuild test robot make.cross script that is
mentioned in every build-errors report:

        wget https://raw.githubusercontent.com/intel/lkp-tests/master/sbin/make.cross -O ~/bin/make.cross
        chmod +x ~/bin/make.cross
        git checkout ee076e81fc14ca79334d02970cea66604f183a14
        # save the attached .config to linux build tree
        GCC_VERSION=8.1.0 make.cross ARCH=sparc


-- 
~Randy