Merge pull request #16052 from miri64/dist/enh/genconfig-env

makefiles/kconfig.mk: generate config file from RIOT_CONFIG_% environment variables

dist/tools/buildsystem_sanity_check/check.sh

@@ -334,6 +334,20 @@ check_no_pkg_source_local() {
         | error_with_message "Don't push PKG_SOURCE_LOCAL definitions upstream"
 }
 
+check_no_riot_config() {
+    local patterns=()
+    local pathspec=()
+
+    patterns+=(-e 'RIOT_CONFIG_.*')
+
+    pathspec+=('Makefile*')
+    pathspec+=('**/Makefile*')
+    pathspec+=('**/*.mk')
+    pathspec+=(':!makefiles/kconfig.mk')
+    git -C "${RIOTBASE}" grep -n "${patterns[@]}" -- "${pathspec[@]}" \
+        | error_with_message "Don't push RIOT_CONFIG_* definitions upstream. Rather define configuration via Kconfig"
+}
+
 error_on_input() {
     ! grep ''
 }
@@ -353,6 +367,7 @@ all_checks() {
     check_no_pseudomodules_in_makefile_dep
     check_no_usemodules_in_makefile_include
     check_no_pkg_source_local
+    check_no_riot_config
 }
 
 main() {

doc/doxygen/src/kconfig/kconfig.md

@@ -86,6 +86,23 @@ be placed in the application's folder. For an example of this you can check
 the [tests/kconfig](https://github.com/RIOT-OS/RIOT/tree/master/tests/kconfig)
 application.
 
+## Configuration via environment variables                {#env-config-kconfig}
+For easy debugging of configuration or testing new modules by compiling them
+into existing applications, one can also use environment variables prefixed by
+`RIOT_CONFIG_`. To achieve the same configuration exemplified in
+@ref configure-using-files, e.g., you could also use
+
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ {.sh}
+RIOT_CONFIG_KCONFIG_MODULE_SOCK_UTIL=1 \
+RIOT_CONFIG_SOCK_UTIL_SCHEME_MAXLEN=24 \
+    make
+~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
+
+All the checks that apply for `.config` files also are done with this approach.
+
+Mind that this is only meant to be used during development. In production,
+please set the configuration via `.config` files.
+
 ## A note on the usage of CFLAGS
 When a certain module is being configured via Kconfig the configuration macro
 will not longer be overridable by means of CFLAGS (e.g. set on the

makefiles/kconfig.mk

@@ -42,6 +42,11 @@ endif
 # Default and user overwritten configurations
 KCONFIG_USER_CONFIG = $(APPDIR)/user.config
 
+# This file will contain configuration using the `RIOT_CONFIG_<CONFIG>`
+# environment variables. Used to enforce a rerun of GENCONFIG when environment
+# changes.
+KCONFIG_GENERATED_ENV_CONFIG = $(GENERATED_DIR)/env.config
+
 # This is the output of the generated configuration. It always mirrors the
 # content of KCONFIG_GENERATED_AUTOCONF_HEADER_C, and it is used to load
 # configuration symbols to the build system.
@@ -63,6 +68,7 @@ KCONFIG_OUT_DEP = $(KCONFIG_OUT_CONFIG).d
 MERGE_SOURCES += $(KCONFIG_ADD_CONFIG)
 MERGE_SOURCES += $(wildcard $(KCONFIG_APP_CONFIG))
 MERGE_SOURCES += $(wildcard $(KCONFIG_USER_CONFIG))
+MERGE_SOURCES += $(KCONFIG_GENERATED_ENV_CONFIG)
 
 # Create directory to place generated files
 $(GENERATED_DIR): $(if $(MAKE_RESTARTS),,$(CLEAN))
@@ -155,6 +161,14 @@ $(KCONFIG_GENERATED_DEPENDENCIES): FORCE | $(GENERATED_DIR)
 	      printf "config %s\n\tbool\n\tdefault y\n", toupper($$0)}' \
 	  | $(LAZYSPONGE) $(LAZYSPONGE_FLAGS) $@
 
+KCONFIG_ENV_CONFIG = $(patsubst RIOT_%,%,$(foreach v,$(filter RIOT_CONFIG_%,$(.VARIABLES)),$(v)=$($(v))))
+
+# Build an intermediate file based on the `RIOT_CONFIG_<CONFIG>` environment
+# variables
+$(KCONFIG_GENERATED_ENV_CONFIG): FORCE | $(GENERATED_DIR)
+	$(Q)printf "%s\n" $(KCONFIG_ENV_CONFIG) \
+	  | $(LAZYSPONGE) $(LAZYSPONGE_FLAGS) $@
+
 # All directories in EXTERNAL_MODULES_PATHS which have a Kconfig file
 EXTERNAL_MODULE_KCONFIGS ?= $(sort $(foreach dir,$(EXTERNAL_MODULE_PATHS),\
                               $(wildcard $(dir)/Kconfig)))