kconfig/cmake: Check that one of the CONFIG_<arch> symbols is set

All SoCs must now 'select' one of the CONFIG_<arch> symbols. Add an
ARCH_IS_SET helper symbol that's selected by the arch symbols and
checked in CMake, printing a warning otherwise.

Might save people some time until they're used to the new scheme.

Signed-off-by: Ulf Magnusson <Ulf.Magnusson@nordicsemi.no>

CMakeLists.txt

@@ -142,6 +142,13 @@ else()
   assert(0 "Unreachable code. Expected optimization level to have been chosen. See Kconfig.zephyr")
 endif()
 
+if(NOT CONFIG_ARCH_IS_SET)
+  message(WARNING "\
+None of the CONFIG_<arch> (e.g. CONFIG_X86) symbols are set. \
+Select one of them from the SOC_SERIES_* symbol or, lacking that, from the \
+SOC_* symbol.")
+endif()
+
 # Apply the final optimization flag(s)
 zephyr_compile_options(${OPTIMIZATION_FLAG})
 

arch/Kconfig

@@ -18,18 +18,21 @@ source "$(ARCH_DIR)/$(ARCH)/Kconfig"
 
 config ARC
 	bool
+	select ARCH_IS_SET
 	select HAS_DTS
 	help
 	  ARC architecture
 
 config ARM
 	bool
+	select ARCH_IS_SET
 	select HAS_DTS
 	help
 	  ARM architecture
 
 config X86
 	bool
+	select ARCH_IS_SET
 	select ATOMIC_OPERATIONS_BUILTIN
 	select HAS_DTS
 	help
@@ -37,6 +40,7 @@ config X86
 
 config NIOS2
 	bool
+	select ARCH_IS_SET
 	select ATOMIC_OPERATIONS_C
 	select HAS_DTS
 	help
@@ -44,12 +48,14 @@ config NIOS2
 
 config RISCV
 	bool
+	select ARCH_IS_SET
 	select HAS_DTS
 	help
 	  RISCV architecture
 
 config XTENSA
 	bool
+	select ARCH_IS_SET
 	select HAS_DTS
 	select USE_SWITCH
 	select USE_SWITCH_SUPPORTED
@@ -59,6 +65,7 @@ config XTENSA
 
 config ARCH_POSIX
 	bool
+	select ARCH_IS_SET
 	select ATOMIC_OPERATIONS_BUILTIN
 	select ARCH_HAS_CUSTOM_SWAP_TO_MAIN
 	select ARCH_HAS_CUSTOM_BUSY_WAIT
@@ -68,6 +75,12 @@ config ARCH_POSIX
 	help
 	  POSIX (native) architecture
 
+config ARCH_IS_SET
+	bool
+	help
+	  Helper symbol to detect SoCs forgetting to select one of the arch
+	  symbols above. See the top-level CMakeLists.txt.
+
 menu "General Architecture Options"
 
 module = ARCH