kconfig: Remove assignments to CONFIG_<arch> syms and hide them

All board defconfig files currently set the architecture in addition to
the board and the SoC, by setting e.g. CONFIG_ARM=y. This spams up
defconfig files.

CONFIG_<arch> symbols currently being set in configuration files also
means that they are configurable (can be changed in menuconfig and in
configuration files), even though changing the architecture won't work,
since other things get set from -DBOARD=<board>. Many boards also allow
changing the architecture symbols independently from the SoC symbols,
which doesn't make sense.

Get rid of all assignments to CONFIG_<arch> symbols and clean up the
relationships between symbols and the configuration interface, like
this:

1. Remove the choice with the CONFIG_<arch> symbols in arch/Kconfig and
   turn the CONFIG_<arch> symbols into invisible
   (promptless/nonconfigurable) symbols instead.

   Getting rid of the choice allows the symbols to be 'select'ed (choice
   symbols don't support 'select').

2. Select the right CONFIG_<arch> symbol from the SOC_SERIES_* symbols.
   This makes sense since you know the architecture if you know the SoC.

   Put the select on the SOC_* symbol instead for boards that don't have
   a SOC_SERIES_*.

3. Remove all assignments to CONFIG_<arch> symbols. The assignments
   would generate errors now, since the symbols are promptless.

The change was done by grepping for assignments to CONFIG_<arch>
symbols, finding the SOC_SERIES_* (or SOC_*) symbol being set in the
same defconfig file, and putting a 'select' on it instead.

See
https://github.com/ulfalizer/zephyr/commits/hide-arch-syms-unsquashed
for a split-up version of this commit, which will make it easier to see
how stuff was done. This needs to go in as one commit though.

This change is safer than it might seem re. outstanding PRs, because any
assignment to CONFIG_<arch> symbols generates an error now, making
outdated stuff easy to catch.

Signed-off-by: Ulf Magnusson <[email protected]>

Author: ulfalizer

arch/Kconfig

@@ -11,50 +11,62 @@
 # Note: $ARCH might be a glob pattern
 source "$(ARCH_DIR)/$(ARCH)/Kconfig"
 
-choice ARCH_CHOICE
-	prompt "Architecture"
-	default X86
+# Architecture symbols
+#
+# Should be 'select'ed by low-level symbols like SOC_SERIES_* or, lacking that,
+# by SOC_*.
 
 config ARC
-	bool "ARC architecture"
+	bool
 	select HAS_DTS
+	help
+	  ARC architecture
 
 config ARM
-	bool "ARM architecture"
+	bool
 	select HAS_DTS
+	help
+	  ARM architecture
 
 config X86
-	bool "x86 architecture"
+	bool
 	select ATOMIC_OPERATIONS_BUILTIN
 	select HAS_DTS
+	help
+	  x86 architecture
 
 config NIOS2
-	bool "Nios II Gen 2 architecture"
+	bool
 	select ATOMIC_OPERATIONS_C
 	select HAS_DTS
+	help
+	  Nios II Gen 2 architecture
 
 config RISCV
-	bool "RISCV architecture"
+	bool
 	select HAS_DTS
+	help
+	  RISCV architecture
 
 config XTENSA
-	bool "Xtensa architecture"
+	bool
 	select HAS_DTS
 	select USE_SWITCH
 	select USE_SWITCH_SUPPORTED
 	select XTENSA_HAL if "$(ZEPHYR_TOOLCHAIN_VARIANT)" != "xcc"
+	help
+	  Xtensa architecture
 
 config ARCH_POSIX
-	bool "POSIX (native) architecture"
+	bool
 	select ATOMIC_OPERATIONS_BUILTIN
 	select ARCH_HAS_CUSTOM_SWAP_TO_MAIN
 	select ARCH_HAS_CUSTOM_BUSY_WAIT
 	select ARCH_HAS_THREAD_ABORT
 	select NATIVE_APPLICATION
 	select HAS_COVERAGE_SUPPORT
-
-endchoice
-
+	help
+	  POSIX (native) architecture
 
 menu "General Architecture Options"
 

boards/arc/em_starterkit/em_starterkit_defconfig

@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_ARC=y
 CONFIG_CPU_ARCEM=y
 CONFIG_SOC_EMSK=y
 CONFIG_SOC_EMSK_EM9D=y

boards/arc/em_starterkit/em_starterkit_em11d_defconfig

@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_ARC=y
 CONFIG_CPU_ARCEM=y
 CONFIG_SOC_EMSK=y
 CONFIG_SOC_EMSK_EM11D=y

boards/arc/em_starterkit/em_starterkit_em7d_defconfig

@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_ARC=y
 CONFIG_CPU_ARCEM=y
 CONFIG_SOC_EMSK=y
 CONFIG_SOC_EMSK_EM7D=y

boards/arc/em_starterkit/em_starterkit_em7d_normal_defconfig

@@ -1,4 +1,3 @@
-CONFIG_ARC=y
 CONFIG_SOC_EMSK=y
 CONFIG_SOC_EMSK_EM7D=y
 CONFIG_BOARD_EM_STARTERKIT=y

boards/arc/em_starterkit/em_starterkit_em7d_v22_defconfig

@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_ARC=y
 CONFIG_CPU_ARCEM=y
 CONFIG_SOC_EMSK=y
 CONFIG_SOC_EMSK_EM7D=y

boards/arc/emsdp/emsdp_defconfig

@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_ARC=y
 CONFIG_CPU_ARCEM=y
 CONFIG_SOC_ARC_EMSDP=y
 CONFIG_SOC_EMSDP_EM11D=y

boards/arc/emsdp/emsdp_em4_defconfig

@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_ARC=y
 CONFIG_CPU_ARCEM=y
 CONFIG_SOC_ARC_EMSDP=y
 CONFIG_SOC_EMSDP_EM4=y

boards/arc/emsdp/emsdp_em5d_defconfig

@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_ARC=y
 CONFIG_CPU_ARCEM=y
 CONFIG_SOC_ARC_EMSDP=y
 CONFIG_SOC_EMSDP_EM5D=y

boards/arc/emsdp/emsdp_em6_defconfig

@@ -1,6 +1,5 @@
 # SPDX-License-Identifier: Apache-2.0
 
-CONFIG_ARC=y
 CONFIG_CPU_ARCEM=y
 CONFIG_SOC_ARC_EMSDP=y
 CONFIG_SOC_EMSDP_EM6=y