[Buildroot] [PATCH v2 1/5] Add support for merged defconfigs

Tue Jun 21 22:09:14 UTC 2016

Hi Sam, All,

Thanks for this new series!

I tested it by merging qemu_arm_vexpress_defconfig as base configuration file
with a arm_toolchain.config and efl.config partial configuration files.
The merged defconfig is named efl_on_arm_defconfig.

I think it's a "must have" for 2016.08.

Some comments bellow.

Le 21/06/2016 à 06:56, Sam Bobroff a écrit :
> Signed-off-by: Sam Bobroff <sam.bobroff at au1.ibm.com>
> ---
>  Makefile                             | 38 +++++++++++++++++++++++
>  docs/manual/adding-board-support.txt |  3 ++
>  docs/manual/appendix.txt             |  1 +
>  docs/manual/merged-defconfigs.txt    | 60 ++++++++++++++++++++++++++++++++++++
>  4 files changed, 102 insertions(+)
>  create mode 100644 docs/manual/merged-defconfigs.txt

I would be good to split in two commits the Makefile changes and the documentation.

> 
> diff --git a/Makefile b/Makefile
> index 78b44c5..9f3fc92 100644
> --- a/Makefile
> +++ b/Makefile
> @@ -858,6 +858,44 @@ savedefconfig: $(BUILD_DIR)/buildroot-config/conf outputmakefile
>  
>  .PHONY: defconfig savedefconfig
>  
> +# Find the path of a config file that may be either in TOPDIR or BR2_EXTERNAL.
> +# Missing or duplicate matches must be checked for elsewhere.
> +define FIND_CONFIG_FILE =
> +$(foreach d,$(TOPDIR)/configs $(BR2_EXTERNAL)/configs,$(wildcard $(d)/$(1)))
> +endef
> +
> +define CONFIG_FILE_LIST =
> +$(foreach f,$1,$(call FIND_CONFIG_FILE,$f))
> +endef
> +
> +# Check that each config file is found once and only once.
> +define CHECK_CONFIG_FILE_LIST =
> +$(foreach f,$(1),
> +ifeq "$(words $(call FIND_CONFIG_FILE,$(f)))" "0"
> +$$(error ERROR: Missing input file: $(f))
> +else
> +ifneq "$(words $(call FIND_CONFIG_FILE,$(f)))" "1"
> +$$(error ERROR: Duplicate input file: $(f))
> +endif
> +endif
> +)
> +endef
> +
> +# To be called by configuration fragments (*.mk) to set up defconfigs built
> +# by merge_config.sh, via the include that follows:
> +define merge_config =
> +$(call CHECK_CONFIG_FILE_LIST,$2 $3)
> +$(1): $$(BUILD_DIR)/buildroot-config/conf $(call CONFIG_FILE_LIST,$2 $3) outputmakefile
> +	@mkdir $$(CONFIG_DIR)/.merge_config
> +	@$$(TOPDIR)/support/kconfig/merge_config.sh -m -O $$(CONFIG_DIR)/.merge_config \
> +		$(call CONFIG_FILE_LIST,$2 $3)
> +	@$$(COMMON_CONFIG_ENV) BR2_DEFCONFIG=$$(CONFIG_DIR)/.merge_config/.config \
> +		$$< --defconfig=$$(CONFIG_DIR)/.merge_config/.config $$(CONFIG_CONFIG_IN)
> +	@rm -rf $$(CONFIG_DIR)/.merge_config
> +endef

There is a problem here with make savedefconfig since BR2_DEFCONFIG =
$$(CONFIG_DIR)/.merge_config/.config and .merge_config directory is removed with
the last command.

I get:
*** Error while saving defconfig to: test/efl-1.17.1-merged/.merge_config/.config

BR2_DEFCONFIG should be set to configs/efl_on_arm_defconfig

I need more time to continue the review and testing.

Best regards,
Romain Naour

> +
> +$(foreach d,$(TOPDIR)/configs $(BR2_EXTERNAL)/configs,$(eval -include $(d)/*.mk))
> +
>  ################################################################################
>  #
>  # Cleanup and misc junk
> diff --git a/docs/manual/adding-board-support.txt b/docs/manual/adding-board-support.txt
> index f6d74ae..086a67e 100644
> --- a/docs/manual/adding-board-support.txt
> +++ b/docs/manual/adding-board-support.txt
> @@ -24,6 +24,9 @@ savedefconfig+. This will generate a minimal +defconfig+ file at the
>  root of the Buildroot source tree. Move this file into the +configs/+
>  directory, and rename it +<boardname>_defconfig+.
>  
> +It is also possible to create configurations by specifying differences from
> +an existing configuration. See xref:merged-defconfigs[].
> +
>  It is recommended to use as much as possible upstream versions of the
>  Linux kernel and bootloaders, and to use as much as possible default
>  kernel and bootloader configurations. If they are incorrect for your
> diff --git a/docs/manual/appendix.txt b/docs/manual/appendix.txt
> index 87a20bd..9abc37e 100644
> --- a/docs/manual/appendix.txt
> +++ b/docs/manual/appendix.txt
> @@ -3,6 +3,7 @@
>  
>  include::makedev-syntax.txt[]
>  include::makeusers-syntax.txt[]
> +include::merged-defconfigs.txt[]
>  
>  
>  // Automatically generated lists:
> diff --git a/docs/manual/merged-defconfigs.txt b/docs/manual/merged-defconfigs.txt
> new file mode 100644
> index 0000000..e1f50fd
> --- /dev/null
> +++ b/docs/manual/merged-defconfigs.txt
> @@ -0,0 +1,60 @@
> +// -*- mode:doc -*- ;
> +// vim: set syntax=asciidoc:
> +
> +[[merged-defconfigs]]
> +== Merged configurations
> +
> +Buildroot supports the use of the Linux kernel's +merge_config.sh+ script to
> +create configurations by merging a set of partial configurations (or overlays)
> +on top of a base configuration. This may be useful when there are several
> +configurations that are specializations of a single generic configuration.
> +
> +Files in the +configs/+ directory with the extension
> ++.mk+ will be read by the top level Makefile and the Make function
> ++merge_config+ can be used within them to define new merged configurations.
> +
> +The merge_config function takes three parameters: the first is the name of the
> +new configuration (which should end with +_defconfig+), the second is the name
> +of the base configuration file and the third is a space separated list of the
> +partial configuration files to merge from the +configs/+ directory. All files
> +should be specified relative to the +configs/+ directory and the name of the
> +Make fragment file should match the name of the configuration it creates.
> +
> +The new configuration can be selected as if it were a normal configuration, i.e. with
> ++make foo_defconfig+.
> +
> +Partial configurations have the same format as full configuration
> +files except that they contain only a subset of values. They can be created by
> +starting with a normal configuration file and deleting lines as appropriate.
> +
> +External configuration files from the +$(BR2_EXTERNAL)/configs+ directory are fully
> +supported, and merge configurations may freely refer to files from either
> +location.
> +
> +Example:
> +
> +If configs/foo_defconfig contains:
> +-----
> +BR2_TARGET_GENERIC_HOSTNAME="buildroot"
> +-----
> +
> +And configs/bar_defconfig.mk contains:
> +-----
> +$(eval $(call merge_config,bar_defconfig,foo_defconfig,b.config))
> +-----
> +
> +And configs/b.config contains:
> +-----
> +BR2_TARGET_GENERIC_ISSUE="Welcome to BAR"
> +-----
> +
> +After running the command:
> +-----
> +make bar_defconfig
> +-----
> +
> +The resulting .config file would contain:
> +-----
> +BR2_TARGET_GENERIC_HOSTNAME="buildroot"
> +BR2_TARGET_GENERIC_ISSUE="Welcome to BAR"
> +-----
> 