linux-kernel - Re: [PATCH 11/13] kconfig: do not use allnoconfig

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Message-ID: <20210331171238.GA141362@roeck-us.net>
Date:   Wed, 31 Mar 2021 10:12:38 -0700
From:   Guenter Roeck <linux@...ck-us.net>
To:     Masahiro Yamada <masahiroy@...nel.org>
Cc:     linux-kbuild@...r.kernel.org,
        Andrew Morton <akpm@...ux-foundation.org>,
        David Howells <dhowells@...hat.com>,
        Johannes Weiner <hannes@...xchg.org>,
        KP Singh <kpsingh@...gle.com>,
        Kees Cook <keescook@...omium.org>,
        Nathan Chancellor <nathan@...nel.org>,
        Nick Desaulniers <ndesaulniers@...gle.com>,
        Nick Terrell <terrelln@...com>,
        Valentin Schneider <valentin.schneider@....com>,
        Vlastimil Babka <vbabka@...e.cz>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 11/13] kconfig: do not use allnoconfig_y option

On Sun, Mar 14, 2021 at 04:48:34AM +0900, Masahiro Yamada wrote:
> allnoconfig_y is a bad hack that sets a symbol to 'y' by allnoconfig.
> 
> allnoconfig does not mean a minimum set of CONFIG options because a
> bunch of prompts are hidden by 'if EMBEDDED' or 'if EXPERT', but I do
> not like to do a workaround this way.
> 
> Use the pre-existing feature, KCONFIG_ALLCONFIG, to provide a one
> liner config fragment. CONFIG_EMBEDDED=y is still forced under
> allnoconfig.
> 
> No change in the .config file produced by 'make tinyconfig'.
> 
> The output of 'make allnoconfig' will be changed; we will get
> CONFIG_EMBEDDED=n because allnoconfig literally sets all symbols to n.
> 
> Signed-off-by: Masahiro Yamada <masahiroy@...nel.org>

With this patch in place, mips:allnoconfig fails to build with
the following error.

Error log:
WARNING: modpost: vmlinux.o(.text+0x9c70): Section mismatch in reference from the function reserve_exception_space() to the function .meminit.text:memblock_reserve()
The function reserve_exception_space() references
the function __meminit memblock_reserve().
This is often because reserve_exception_space lacks a __meminit
annotation or the annotation of memblock_reserve is wrong.
ERROR: modpost: Section mismatches detected.
Set CONFIG_SECTION_MISMATCH_WARN_ONLY=y to allow them.
make[2]: *** [scripts/Makefile.modpost:62: vmlinux.symvers] Error 1
make[2]: *** Deleting file 'vmlinux.symvers'
make[1]: *** [Makefile:1292: vmlinux] Error 2
make: *** [Makefile:222: __sub-make] Error 2

Guenter

> ---
> 
>  init/Kconfig                    | 1 -
>  kernel/configs/tiny-base.config | 1 +
>  scripts/kconfig/Makefile        | 3 ++-
>  3 files changed, 3 insertions(+), 2 deletions(-)
>  create mode 100644 kernel/configs/tiny-base.config
> 
> diff --git a/init/Kconfig b/init/Kconfig
> index 46b87ad73f6a..beb8314fdf96 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -1769,7 +1769,6 @@ config DEBUG_RSEQ
>  
>  config EMBEDDED
>  	bool "Embedded system"
> -	option allnoconfig_y
>  	select EXPERT
>  	help
>  	  This option should be enabled if compiling the kernel for
> diff --git a/kernel/configs/tiny-base.config b/kernel/configs/tiny-base.config
> new file mode 100644
> index 000000000000..2f0e6bf6db2c
> --- /dev/null
> +++ b/kernel/configs/tiny-base.config
> @@ -0,0 +1 @@
> +CONFIG_EMBEDDED=y
> diff --git a/scripts/kconfig/Makefile b/scripts/kconfig/Makefile
> index 7df3c0e4c52e..46f2465177f0 100644
> --- a/scripts/kconfig/Makefile
> +++ b/scripts/kconfig/Makefile
> @@ -102,7 +102,8 @@ configfiles=$(wildcard $(srctree)/kernel/configs/$@ $(srctree)/arch/$(SRCARCH)/c
>  
>  PHONY += tinyconfig
>  tinyconfig:
> -	$(Q)$(MAKE) -f $(srctree)/Makefile allnoconfig tiny.config
> +	$(Q)KCONFIG_ALLCONFIG=kernel/configs/tiny-base.config $(MAKE) -f $(srctree)/Makefile allnoconfig
> +	$(Q)$(MAKE) -f $(srctree)/Makefile tiny.config
>  
>  # CHECK: -o cache_dir=<path> working?
>  PHONY += testconfig
> -- 
> 2.27.0
>