Re: [PATCH] kbuild: use KBUILD_DEFCONFIG as the fallback for DEFCONFIG_LIST

[Masahiro Yamada <masahiroy@kernel.org>]

On Fri, Feb 28, 2020 at 12:47 PM Masahiro Yamada <masahiroy@kernel.org> wrote:
>
> Most of the Kconfig commands (except defconfig and all*config) read
> the .config file as a base set of CONFIG options.
>
> When it does not exist, the files in DEFCONFIG_LIST are searched in
> this order and loaded if found.
>
> I do not see much sense in the last two lines in DEFCONFIG_LIST.
>
> [1] ARCH_DEFCONFIG
>
> The entry for DEFCONFIG_LIST is guarded by 'depends on !UML'. So, the
> ARCH_DEFCONFIG definition in arch/x86/um/Kconfig is meaningless.
>
> arch/{sh,sparc,x86}/Kconfig define ARCH_DEFCONFIG depending on 32 or
> 64 bit variant symbols. This is a little bit strange; ARCH_DEFCONFIG
> should be a fixed string because the base config file is loaded before
> the symbol evaluation stage.
>
> Using KBUILD_DEFCONFIG makes more sense because it is fixed before
> Kconfig is invoked. Fortunately, arch/{sh,sparc,x86}/Makefile define it
> in the same way, and it works as expected. Hence, replace ARCH_DEFCONFIG
> with "arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)".
>
> [2] arch/$(ARCH)/defconfig
>
> This file path is no longer valid. The defconfig files are always located
> in the arch configs/ directories.
>
>   $ find arch -name defconfig | sort
>   arch/alpha/configs/defconfig
>   arch/arm64/configs/defconfig
>   arch/csky/configs/defconfig
>   arch/nds32/configs/defconfig
>   arch/riscv/configs/defconfig
>   arch/s390/configs/defconfig
>   arch/unicore32/configs/defconfig
>
> The path arch/*/configs/defconfig is already covered by
> "arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)". So, this file path is
> not necessary.
>
> I moved the default KBUILD_DEFCONFIG to the top Makefile. Otherwise,
> the 7 architectures listed above would end up with endless loop of
> syncconfig.
>
> Signed-off-by: Masahiro Yamada <masahiroy@kernel.org>


I forgot to say this.
This is v2.

Changes in v2:
  - Move KBUILD_DEFCONFIG to fix endless loop of syncconfig


> ---
>
>  Makefile                 | 3 +++
>  arch/sh/Kconfig          | 5 -----
>  arch/sparc/Kconfig       | 5 -----
>  arch/x86/Kconfig         | 5 -----
>  arch/x86/um/Kconfig      | 5 -----
>  init/Kconfig             | 3 +--
>  scripts/kconfig/Makefile | 4 ----
>  7 files changed, 4 insertions(+), 26 deletions(-)
>
> diff --git a/Makefile b/Makefile
> index 81d130ad9534..17cc09304561 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -388,6 +388,9 @@ endif
>  KCONFIG_CONFIG ?= .config
>  export KCONFIG_CONFIG
>
> +# Default file for 'make defconfig'. This may be overridden by arch-Makefile.
> +export KBUILD_DEFCONFIG := defconfig
> +
>  # SHELL used by kbuild
>  CONFIG_SHELL := sh
>
> diff --git a/arch/sh/Kconfig b/arch/sh/Kconfig
> index 9ece111b0254..b4f0e37b83eb 100644
> --- a/arch/sh/Kconfig
> +++ b/arch/sh/Kconfig
> @@ -87,11 +87,6 @@ config SUPERH64
>         select HAVE_EXIT_THREAD
>         select KALLSYMS
>
> -config ARCH_DEFCONFIG
> -       string
> -       default "arch/sh/configs/shx3_defconfig" if SUPERH32
> -       default "arch/sh/configs/cayman_defconfig" if SUPERH64
> -
>  config GENERIC_BUG
>         def_bool y
>         depends on BUG && SUPERH32
> diff --git a/arch/sparc/Kconfig b/arch/sparc/Kconfig
> index c1dd6dd642f4..0de15380d1fc 100644
> --- a/arch/sparc/Kconfig
> +++ b/arch/sparc/Kconfig
> @@ -95,11 +95,6 @@ config SPARC64
>         select PCI_DOMAINS if PCI
>         select ARCH_HAS_GIGANTIC_PAGE
>
> -config ARCH_DEFCONFIG
> -       string
> -       default "arch/sparc/configs/sparc32_defconfig" if SPARC32
> -       default "arch/sparc/configs/sparc64_defconfig" if SPARC64
> -
>  config ARCH_PROC_KCORE_TEXT
>         def_bool y
>
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index beea77046f9b..98935f4387f9 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -240,11 +240,6 @@ config OUTPUT_FORMAT
>         default "elf32-i386" if X86_32
>         default "elf64-x86-64" if X86_64
>
> -config ARCH_DEFCONFIG
> -       string
> -       default "arch/x86/configs/i386_defconfig" if X86_32
> -       default "arch/x86/configs/x86_64_defconfig" if X86_64
> -
>  config LOCKDEP_SUPPORT
>         def_bool y
>
> diff --git a/arch/x86/um/Kconfig b/arch/x86/um/Kconfig
> index a8985e1f7432..95d26a69088b 100644
> --- a/arch/x86/um/Kconfig
> +++ b/arch/x86/um/Kconfig
> @@ -27,11 +27,6 @@ config X86_64
>         def_bool 64BIT
>         select MODULES_USE_ELF_RELA
>
> -config ARCH_DEFCONFIG
> -       string
> -       default "arch/um/configs/i386_defconfig" if X86_32
> -       default "arch/um/configs/x86_64_defconfig" if X86_64
> -
>  config 3_LEVEL_PGTABLES
>         bool "Three-level pagetables" if !64BIT
>         default 64BIT
> diff --git a/init/Kconfig b/init/Kconfig
> index 20a6ac33761c..240c1ed15c69 100644
> --- a/init/Kconfig
> +++ b/init/Kconfig
> @@ -6,8 +6,7 @@ config DEFCONFIG_LIST
>         default "/lib/modules/$(shell,uname -r)/.config"
>         default "/etc/kernel-config"
>         default "/boot/config-$(shell,uname -r)"
> -       default ARCH_DEFCONFIG
> -       default "arch/$(ARCH)/defconfig"
> +       default "arch/$(SRCARCH)/configs/$(KBUILD_DEFCONFIG)"
>
>  config CC_IS_GCC
>         def_bool $(success,$(CC) --version | head -n 1 | grep -q gcc)
> diff --git a/scripts/kconfig/Makefile b/scripts/kconfig/Makefile
> index 5887ceb6229e..c9d0a4a8efb3 100644
> --- a/scripts/kconfig/Makefile
> +++ b/scripts/kconfig/Makefile
> @@ -12,10 +12,6 @@ else
>  Kconfig := Kconfig
>  endif
>
> -ifndef KBUILD_DEFCONFIG
> -KBUILD_DEFCONFIG := defconfig
> -endif
> -
>  ifeq ($(quiet),silent_)
>  silent := -s
>  endif
> --
> 2.17.1
>


-- 
Best Regards
Masahiro Yamada