cpu/cortexm: Use DEVELHELP to add stack guard

Kconfig

@@ -50,3 +50,10 @@ config TEST_KCONFIG
         This is used during the Kconfig migration to test the module dependency
         modelling. Don't change the default value unless you know what you are
         doing.
+
+config DEVELHELP
+    bool "Development Help"
+    help
+        Set to enable code in RIOT that does safety checking which might not be
+        needed in a production environment but helps in the development
+        process.

cpu/cortexm_common/Kconfig

@@ -124,10 +124,20 @@ config HAS_CORTEXM_SVC
     help
         Indicates that ARM Cortex-M Supervisor Calls are available.
 
+menu "Cortex-M"
+    depends on TEST_KCONFIG
+    depends on CPU_CORE_CORTEX_M
+
 config MODULE_CORTEXM_FPU
     bool "Cortex-M Floating Point Unit (FPU) support"
     default y
     depends on HAS_CORTEXM_FPU
-    depends on TEST_KCONFIG
+
+config MODULE_MPU_STACK_GUARD
+    bool "Memory Protection Unit (MPU) stack guard"
+    default y if DEVELHELP
+    depends on HAS_CORTEXM_MPU
+
+endmenu # Cortex-M
 
 rsource "periph/Kconfig"

makefiles/kconfig.mk

@@ -112,6 +112,11 @@ ifeq (1,$(TEST_KCONFIG))
   SHOULD_RUN_KCONFIG := 1
 endif
 
+# Expose DEVELHELP to kconfig
+ifeq (1,$(DEVELHELP))
+  RIOT_CONFIG_DEVELHELP ?= y
+endif
+
 # export variable to make it visible in other Makefiles
 export SHOULD_RUN_KCONFIG