[2/2] package/pkg-kconfig.mk: new <pkg>-diff-config target

This patch introduces the new target to compare the current
configuration with the one derived from the defconfig + fragments (if
any). It helps identifying settings not yet inserted to the defconfig
or any fragment.

Signed-off-by: Marcel Patzlaff <m.patzlaff@pilz.de>
---
 package/pkg-kconfig.mk | 36 ++++++++++++++++++++++++++++++------
 1 file changed, 30 insertions(+), 6 deletions(-)

Marcel, All,

On 2018-09-21 15:55 +0200, Marcel Patzlaff spake thusly:
> This patch introduces the new target to compare the current
> configuration with the one derived from the defconfig + fragments (if
> any). It helps identifying settings not yet inserted to the defconfig
> or any fragment.
> 
> Signed-off-by: Marcel Patzlaff <m.patzlaff@pilz.de>

Thanks for this new iteration! :-)

Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Tested-by: "Yann E. MORIN" <yann.morin.1998@free.fr>

Regards,
Yann E. MORIN.

> ---
>  package/pkg-kconfig.mk | 36 ++++++++++++++++++++++++++++++------
>  1 file changed, 30 insertions(+), 6 deletions(-)
> 
> diff --git a/package/pkg-kconfig.mk b/package/pkg-kconfig.mk
> index 5952be5482..b746dc588c 100644
> --- a/package/pkg-kconfig.mk
> +++ b/package/pkg-kconfig.mk
> @@ -49,6 +49,18 @@ define kconfig-package-regen-dot-config
>  			$(Q)(yes "" | $($(1)_KCONFIG_MAKE) oldconfig)))
>  endef
>  
> +# Macro to create a .config file where all given fragments are merged into.
> +# $(1): the name of the package in upper-case letters
> +# $(2): name of the .config file
> +# $(3): fragment files to merge
> +define kconfig-package-merge-config
> +	$(Q)$(if $($(1)_KCONFIG_DEFCONFIG),\
> +		$($(1)_KCONFIG_MAKE) $($(1)_KCONFIG_DEFCONFIG),\
> +		$(INSTALL) -m 0644 -D $($(1)_KCONFIG_FILE) $(2))
> +	$(Q)support/kconfig/merge_config.sh -m -O $(@D) $(2) $(3)
> +	$(call kconfig-package-regen-dot-config,$(1))
> +endef
> +
>  ################################################################################
>  # inner-kconfig-package -- generates the make targets needed to support a
>  # kconfig package
> @@ -121,12 +133,7 @@ $(2)_KCONFIG_RULES = \
>  # Since the file could be a defconfig file it needs to be expanded to a
>  # full .config first.
>  $$($(2)_DIR)/$$($(2)_KCONFIG_DOTCONFIG): $$($(2)_KCONFIG_FILE) $$($(2)_KCONFIG_FRAGMENT_FILES)
> -	$$(Q)$$(if $$($(2)_KCONFIG_DEFCONFIG), \
> -		$$($(2)_KCONFIG_MAKE) $$($(2)_KCONFIG_DEFCONFIG), \
> -		$$(INSTALL) -m 0644 -D $$($(2)_KCONFIG_FILE) $$(@))
> -	$$(Q)support/kconfig/merge_config.sh -m -O $$(@D) \
> -		$$(@) $$($(2)_KCONFIG_FRAGMENT_FILES)
> -	$$(call kconfig-package-regen-dot-config,$(2))
> +	$$(call kconfig-package-merge-config,$(2),$$(@),$$($(2)_KCONFIG_FRAGMENT_FILES))
>  
>  # If _KCONFIG_FILE or _KCONFIG_FRAGMENT_FILES exists, this dependency is
>  # already implied, but if we only have a _KCONFIG_DEFCONFIG we have to add
> @@ -248,11 +255,28 @@ $(1)-update-defconfig: PKG=$(2)
>  $(1)-update-defconfig: $(1)-savedefconfig
>  	$$(call kconfig-package-update-config,defconfig)
>  
> +# Target to output differences between the configuration obtained via the
> +# defconfig + fragments (if any) and the current configuration.
> +# Note: it preserves the timestamp of the current configuration when moving it
> +# around.
> +$(1)-diff-config: $(1)-check-configuration-done
> +	$$(Q)cp -a $$($(2)_DIR)/$$($(2)_KCONFIG_DOTCONFIG) $$($(2)_DIR)/.config.dc.bak
> +	$$(call kconfig-package-merge-config,$(2),$$($(2)_DIR)/$$($(2)_KCONFIG_DOTCONFIG),\
> +		$$($(2)_KCONFIG_FRAGMENT_FILES))
> +	@echo "### start of $$(@) output ###"
> +	@utils/diffconfig $$($(2)_DIR)/$$($(2)_KCONFIG_DOTCONFIG) \
> +		 $$($(2)_DIR)/.config.dc.bak
> +	@echo "### end of $$(@) output ###"
> +	$$(Q)cp -a $$($(2)_DIR)/.config.dc.bak $$($(2)_DIR)/$$($(2)_KCONFIG_DOTCONFIG)
> +	$$(Q)rm -f $$($(2)_DIR)/.config.dc.bak
> +
> +
>  endif # package enabled
>  
>  .PHONY: \
>  	$(1)-update-config \
>  	$(1)-update-defconfig \
> +	$(1)-diff-config \
>  	$(1)-savedefconfig \
>  	$(1)-check-configuration-done \
>  	$$($(2)_DIR)/.kconfig_editor_% \
> -- 
> 2.17.1
> 
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Hello Marcel,

On Fri, 21 Sep 2018 15:55:21 +0200
Marcel Patzlaff <m.patzlaff@pilz.de> wrote:

> This patch introduces the new target to compare the current
> configuration with the one derived from the defconfig + fragments (if
> any). It helps identifying settings not yet inserted to the defconfig
> or any fragment.
> 
> Signed-off-by: Marcel Patzlaff <m.patzlaff@pilz.de>
> ---
>  package/pkg-kconfig.mk | 36 ++++++++++++++++++++++++++++++------
>  1 file changed, 30 insertions(+), 6 deletions(-)
> 
> diff --git a/package/pkg-kconfig.mk b/package/pkg-kconfig.mk
> index 5952be5482..b746dc588c 100644
> --- a/package/pkg-kconfig.mk
> +++ b/package/pkg-kconfig.mk
> @@ -49,6 +49,18 @@ define kconfig-package-regen-dot-config
>  			$(Q)(yes "" | $($(1)_KCONFIG_MAKE) oldconfig)))
>  endef
>  
> +# Macro to create a .config file where all given fragments are merged into.
> +# $(1): the name of the package in upper-case letters
> +# $(2): name of the .config file
> +# $(3): fragment files to merge
> +define kconfig-package-merge-config
> +	$(Q)$(if $($(1)_KCONFIG_DEFCONFIG),\
> +		$($(1)_KCONFIG_MAKE) $($(1)_KCONFIG_DEFCONFIG),\
> +		$(INSTALL) -m 0644 -D $($(1)_KCONFIG_FILE) $(2))
> +	$(Q)support/kconfig/merge_config.sh -m -O $(@D) $(2) $(3)

This $(@D) here cannot work. It works when this macro is called in the
context of the $$($(2)_DIR)/$$($(2)_KCONFIG_DOTCONFIG) rule, because
$(@D) makes sense. But when it's called inside the $(1)-diff-config
rule, $(@D) doesn't make sense, and evaluates to ".". Due to this,
when building in-tree, kconfig-package-merge-config overwrites the
Buildroot .config file!

I fixed this by using $(dir $(2)) instead of $(@D).

> +$(1)-diff-config: $(1)-check-configuration-done
> +	$$(Q)cp -a $$($(2)_DIR)/$$($(2)_KCONFIG_DOTCONFIG) $$($(2)_DIR)/.config.dc.bak
> +	$$(call kconfig-package-merge-config,$(2),$$($(2)_DIR)/$$($(2)_KCONFIG_DOTCONFIG),\
> +		$$($(2)_KCONFIG_FRAGMENT_FILES))
> +	@echo "### start of $$(@) output ###"
> +	@utils/diffconfig $$($(2)_DIR)/$$($(2)_KCONFIG_DOTCONFIG) \
> +		 $$($(2)_DIR)/.config.dc.bak

Changed @utils/diffconfig to $$(Q)utils/diffconfig

> +	@echo "### end of $$(@) output ###"

Both Yann and me found that the start/end messages were not really
needed. It would be nice if the output was less verbose, and really
only contained the output of utils/diffconfig, but we didn't find that
the start/end marker were making things any better.

I've applied with the above changes. Thanks a lot for this contribution!

Could you prepare an addition to the Buildroot manual to document this
new feature ?

Thanks!

Thomas