sysbuild: Autogenerate secondary slot

Generation of the secendary slot is not trivial if one considers all of
the configuration options available in sysbuild, such as:
 - per-image overrides through variables
 - setting FILE_SUFFIX
 - additional images appearing as a result of enabling SNIPPETs
Achieving this through the regular approach (adding images), requires
enumerating all slotted images in CMake files, applying the same set
of overlays manually, which partially makes the configurability
provided by sysbuild nearly unusable for the secondary slot.

Since sysbuild is an entity that is aware of the images being
built and their configuration parameters, this commit tries to rerun the
image build if the user provides the <image>_slot_b.overlay.
There is no need to add Kconfig overlays as the main point of slotted
images is that exactly two identical configurations are built, with only
one difference - the start address, controlled through the
zephyr,code-partition symbol.

Ref: NCSDK-NONE

Signed-off-by: Tomasz Chyrowicz <[email protected]>

share/sysbuild/cmake/modules/sysbuild_extensions.cmake

@@ -216,7 +216,7 @@ endfunction()
 #                             and debugging.
 #
 function(ExternalZephyrProject_Add)
-  set(app_types MAIN BOOTLOADER)
+  set(app_types MAIN BOOTLOADER SLOT_B)
   cmake_parse_arguments(ZBUILD "" "APPLICATION;BOARD;BOARD_REVISION;SOURCE_DIR;APP_TYPE;BUILD_ONLY" "" ${ARGN})
 
   if(ZBUILD_UNPARSED_ARGUMENTS)
@@ -226,9 +226,15 @@ function(ExternalZephyrProject_Add)
     )
   endif()
 
-  if(TARGET ${ZBUILD_APPLICATION})
+  if("${ZBUILD_APP_TYPE}" STREQUAL "SLOT_B")
+    set(app_target ${ZBUILD_APPLICATION}_slot_b)
+  else()
+    set(app_target ${ZBUILD_APPLICATION})
+  endif()
+
+  if(TARGET ${app_target})
     message(FATAL_ERROR
-      "ExternalZephyrProject_Add(APPLICATION ${ZBUILD_APPLICATION} ...) "
+      "ExternalZephyrProject_Add(APPLICATION ${app_target} ...) "
       "already exists. Application names must be unique."
     )
   endif()
@@ -251,19 +257,58 @@ function(ExternalZephyrProject_Add)
   endif()
   set_property(
     DIRECTORY "${SYSBUILD_CURRENT_SOURCE_DIR}"
-    APPEND PROPERTY sysbuild_images ${ZBUILD_APPLICATION}
+    APPEND PROPERTY sysbuild_images ${app_target}
   )
   set_property(
     GLOBAL
-    APPEND PROPERTY sysbuild_images ${ZBUILD_APPLICATION}
+    APPEND PROPERTY sysbuild_images ${app_target}
   )
 
   set(sysbuild_image_conf_dir ${APP_DIR}/sysbuild)
   set(sysbuild_image_name_conf_dir ${APP_DIR}/sysbuild/${ZBUILD_APPLICATION})
+
+  # There is no need to look for application slot "b" overlays.
+  # It is enough to use values calculated for slot "a".
+  if("${ZBUILD_APP_TYPE}" STREQUAL "SLOT_B")
+    if(EXISTS ${sysbuild_image_name_conf_dir})
+      set(${app_target}_APPLICATION_CONFIG_DIR ${sysbuild_image_name_conf_dir}
+          CACHE INTERNAL "Application configuration dir controlled by sysbuild"
+      )
+    endif()
+
+    if (${ZBUILD_APPLICATION}_EXTRA_CONF_FILE)
+      set(${app_target}_EXTRA_CONF_FILE ${${ZBUILD_APPLICATION}_EXTRA_CONF_FILE}
+          CACHE INTERNAL "Kconfig fragment defined by main application"
+      )
+    endif()
+
+    if (DEFINED ${ZBUILD_APPLICATION}_DTC_OVERLAY_FILE)
+      set(${app_target}_DTC_OVERLAY_FILE "${${ZBUILD_APPLICATION}_DTC_OVERLAY_FILE}"
+          CACHE INTERNAL "devicetree overlay file defined by main application"
+      )
+    endif()
+
+    # Append <ZBUILD_APPLICATION>_slot_b.overlay.
+    set(sysbuild_image_slot_dts_overlay ${sysbuild_image_conf_dir}/${app_target}.overlay)
+    if (NOT EXISTS ${sysbuild_image_slot_dts_overlay})
+      # Slot "b" not configured for the application.
+      return()
+    else()
+      if (DEFINED ${ZBUILD_APPLICATION}_EXTRA_DTC_OVERLAY_FILE)
+        set(${app_target}_EXTRA_DTC_OVERLAY_FILE "${${ZBUILD_APPLICATION}_EXTRA_DTC_OVERLAY_FILE};${sysbuild_image_slot_dts_overlay}"
+          CACHE INTERNAL "additional devicetree overlay file defined by main application"
+      )
+      else()
+        set(${app_target}_EXTRA_DTC_OVERLAY_FILE ${sysbuild_image_slot_dts_overlay}
+          CACHE INTERNAL "additional devicetree overlay file defined by main application"
+      )
+      endif()
+    endif()
+
   # User defined `-D<image>_CONF_FILE=<file.conf>` takes precedence over anything else.
-  if (NOT ${ZBUILD_APPLICATION}_CONF_FILE)
+  elseif (NOT ${ZBUILD_APPLICATION}_CONF_FILE)
     if(EXISTS ${sysbuild_image_name_conf_dir})
-      set(${ZBUILD_APPLICATION}_APPLICATION_CONFIG_DIR ${sysbuild_image_name_conf_dir}
+      set(${app_target}_APPLICATION_CONFIG_DIR ${sysbuild_image_name_conf_dir}
           CACHE INTERNAL "Application configuration dir controlled by sysbuild"
       )
     endif()
@@ -275,18 +320,18 @@ function(ExternalZephyrProject_Add)
                 NAMES ${ZBUILD_APPLICATION}.conf SUFFIX ${FILE_SUFFIX}
     )
 
-    if (NOT (${ZBUILD_APPLICATION}_OVERLAY_CONFIG OR ${ZBUILD_APPLICATION}_EXTRA_CONF_FILE)
+    if (NOT (${app_target}_OVERLAY_CONFIG OR ${app_target}_EXTRA_CONF_FILE)
         AND EXISTS ${sysbuild_image_conf_fragment}
     )
-      set(${ZBUILD_APPLICATION}_EXTRA_CONF_FILE ${sysbuild_image_conf_fragment}
+      set(${app_target}_EXTRA_CONF_FILE ${sysbuild_image_conf_fragment}
           CACHE INTERNAL "Kconfig fragment defined by main application"
       )
     endif()
 
     # Check for overlay named <ZBUILD_APPLICATION>.overlay.
     set(sysbuild_image_dts_overlay ${sysbuild_image_conf_dir}/${ZBUILD_APPLICATION}.overlay)
-    if (NOT ${ZBUILD_APPLICATION}_DTC_OVERLAY_FILE AND EXISTS ${sysbuild_image_dts_overlay})
-      set(${ZBUILD_APPLICATION}_DTC_OVERLAY_FILE ${sysbuild_image_dts_overlay}
+    if (NOT ${app_target}_DTC_OVERLAY_FILE AND EXISTS ${sysbuild_image_dts_overlay})
+      set(${app_target}_DTC_OVERLAY_FILE ${sysbuild_image_dts_overlay}
           CACHE INTERNAL "devicetree overlay file defined by main application"
       )
     endif()
@@ -295,10 +340,16 @@ function(ExternalZephyrProject_Add)
   # Update ROOT variables with relative paths to use absolute paths based on
   # the source application directory.
   foreach(type MODULE_EXT BOARD SOC ARCH SCA)
-    if(DEFINED CACHE{${ZBUILD_APPLICATION}_${type}_ROOT} AND NOT IS_ABSOLUTE $CACHE{${ZBUILD_APPLICATION}_${type}_ROOT})
-      set(rel_path $CACHE{${ZBUILD_APPLICATION}_${type}_ROOT})
-      cmake_path(ABSOLUTE_PATH rel_path BASE_DIRECTORY "${ZBUILD_SOURCE_DIR}" NORMALIZE OUTPUT_VARIABLE abs_path)
-      set(${ZBUILD_APPLICATION}_${type}_ROOT ${abs_path} CACHE PATH "Sysbuild adjusted absolute path" FORCE)
+    if("${ZBUILD_APP_TYPE}" STREQUAL "SLOT_B")
+      if(DEFINED CACHE{${ZBUILD_APPLICATION}_${type}_ROOT})
+        set(${app_target}_${type}_ROOT $CACHE{${ZBUILD_APPLICATION}_${type}_ROOT} CACHE PATH "Sysbuild adjusted absolute path" FORCE)
+      endif()
+    else()
+      if(DEFINED CACHE{${app_target}_${type}_ROOT} AND NOT IS_ABSOLUTE $CACHE{${app_target}_${type}_ROOT})
+        set(rel_path $CACHE{${app_target}_${type}_ROOT})
+            cmake_path(ABSOLUTE_PATH rel_path BASE_DIRECTORY "${ZBUILD_SOURCE_DIR}" NORMALIZE OUTPUT_VARIABLE abs_path)
+        set(${app_target}_${type}_ROOT ${abs_path} CACHE PATH "Sysbuild adjusted absolute path" FORCE)
+      endif()
     endif()
   endforeach()
 
@@ -311,7 +362,7 @@ function(ExternalZephyrProject_Add)
     CMAKE_VERBOSE_MAKEFILE
   )
 
-  set(sysbuild_cache_file ${CMAKE_BINARY_DIR}/${ZBUILD_APPLICATION}_sysbuild_cache.txt)
+  set(sysbuild_cache_file ${CMAKE_BINARY_DIR}/${app_target}_sysbuild_cache.txt)
 
   set(shared_cmake_vars_argument)
   foreach(shared_var ${shared_cmake_variables_list})
@@ -328,37 +379,43 @@ function(ExternalZephyrProject_Add)
     endif()
   endforeach()
 
-  foreach(kconfig_target
-      menuconfig
-      hardenconfig
-      guiconfig
-      $CACHE{EXTRA_KCONFIG_TARGETS}
-      )
+  if("${ZBUILD_APP_TYPE}" STREQUAL "SLOT_B")
+    # There is no need for Kconfig targets in slot "b".
+    # Kconfigs should be configured in slot "a".
+    set(image_extra_kconfig_targets )
+  else()
+    foreach(kconfig_target
+        menuconfig
+        hardenconfig
+        guiconfig
+        $CACHE{EXTRA_KCONFIG_TARGETS}
+        )
 
-    if(NOT ZBUILD_APP_TYPE STREQUAL "MAIN")
-      set(image_prefix "${ZBUILD_APPLICATION}_")
-    endif()
+      if(NOT ZBUILD_APP_TYPE STREQUAL "MAIN")
+        set(image_prefix "${ZBUILD_APPLICATION}_")
+      endif()
 
-    add_custom_target(${image_prefix}${kconfig_target}
-      ${CMAKE_MAKE_PROGRAM} ${kconfig_target}
-      WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/${ZBUILD_APPLICATION}
-      USES_TERMINAL
-      )
-  endforeach()
+      add_custom_target(${image_prefix}${kconfig_target}
+        ${CMAKE_MAKE_PROGRAM} ${kconfig_target}
+        WORKING_DIRECTORY ${CMAKE_BINARY_DIR}/${ZBUILD_APPLICATION}
+        USES_TERMINAL
+        )
+    endforeach()
 
-  set(list_separator ",")
-  set(image_extra_kconfig_targets "-DEXTRA_KCONFIG_TARGETS=$CACHE{EXTRA_KCONFIG_TARGETS}")
-  string(REPLACE ";" "${list_separator}" image_extra_kconfig_targets "${image_extra_kconfig_targets}")
-  foreach(target $CACHE{EXTRA_KCONFIG_TARGETS})
-    list(APPEND image_extra_kconfig_targets
-         -DEXTRA_KCONFIG_TARGET_COMMAND_FOR_${target}=$CACHE{EXTRA_KCONFIG_TARGET_COMMAND_FOR_${target}}
-    )
-  endforeach()
+    set(list_separator ",")
+    set(image_extra_kconfig_targets "-DEXTRA_KCONFIG_TARGETS=$CACHE{EXTRA_KCONFIG_TARGETS}")
+    string(REPLACE ";" "${list_separator}" image_extra_kconfig_targets "${image_extra_kconfig_targets}")
+    foreach(target $CACHE{EXTRA_KCONFIG_TARGETS})
+      list(APPEND image_extra_kconfig_targets
+           -DEXTRA_KCONFIG_TARGET_COMMAND_FOR_${target}=$CACHE{EXTRA_KCONFIG_TARGET_COMMAND_FOR_${target}}
+      )
+    endforeach()
+  endif()
 
   include(ExternalProject)
-  set(application_binary_dir ${CMAKE_BINARY_DIR}/${ZBUILD_APPLICATION})
+  set(application_binary_dir ${CMAKE_BINARY_DIR}/${app_target})
   ExternalProject_Add(
-    ${ZBUILD_APPLICATION}
+    ${app_target}
     SOURCE_DIR ${ZBUILD_SOURCE_DIR}
     BINARY_DIR ${application_binary_dir}
     CONFIGURE_COMMAND ""
@@ -372,25 +429,25 @@ function(ExternalZephyrProject_Add)
     BUILD_ALWAYS True
     USES_TERMINAL_BUILD True
   )
-  set_property(TARGET ${ZBUILD_APPLICATION} PROPERTY APP_TYPE ${ZBUILD_APP_TYPE})
-  set_property(TARGET ${ZBUILD_APPLICATION} PROPERTY CONFIG
+  set_property(TARGET ${app_target} PROPERTY APP_TYPE ${ZBUILD_APP_TYPE})
+  set_property(TARGET ${app_target} PROPERTY CONFIG
                "# sysbuild controlled configuration settings\n"
   )
-  set_target_properties(${ZBUILD_APPLICATION} PROPERTIES CACHE_FILE ${sysbuild_cache_file})
-  set_target_properties(${ZBUILD_APPLICATION} PROPERTIES KCONFIG_BINARY_DIR
+  set_target_properties(${app_target} PROPERTIES CACHE_FILE ${sysbuild_cache_file})
+  set_target_properties(${app_target} PROPERTIES KCONFIG_BINARY_DIR
                         ${application_binary_dir}/Kconfig
   )
   if("${ZBUILD_APP_TYPE}" STREQUAL "MAIN")
-    set_target_properties(${ZBUILD_APPLICATION} PROPERTIES MAIN_APP True)
+    set_target_properties(${app_target} PROPERTIES MAIN_APP True)
   endif()
 
   set(image_default "${CMAKE_SOURCE_DIR}/image_configurations/ALL_image_default.cmake")
 
-  if(DEFINED ZBUILD_APP_TYPE)
+  if(DEFINED ZBUILD_APP_TYPE AND NOT ZBUILD_APP_TYPE STREQUAL "SLOT_B")
     list(APPEND image_default "${CMAKE_SOURCE_DIR}/image_configurations/${ZBUILD_APP_TYPE}_image_default.cmake")
   endif()
 
-  set_target_properties(${ZBUILD_APPLICATION} PROPERTIES IMAGE_CONF_SCRIPT "${image_default}")
+  set_target_properties(${app_target} PROPERTIES IMAGE_CONF_SCRIPT "${image_default}")
 
   if(DEFINED ZBUILD_BOARD)
     # Only set image specific board if provided.
@@ -407,15 +464,15 @@ function(ExternalZephyrProject_Add)
         list(REMOVE_AT split_board_qualifiers 0)
         list(PREPEND split_board_qualifiers ${target_board})
         string(REPLACE ";" "/" board_qualifiers "${split_board_qualifiers}")
-        set_target_properties(${ZBUILD_APPLICATION} PROPERTIES BOARD ${board_qualifiers})
+        set_target_properties(${app_target} PROPERTIES BOARD ${board_qualifiers})
         set(split_board_qualifiers)
         set(board_qualifiers)
       else()
         # Legacy HWMv1 support, version goes at end
-        set_target_properties(${ZBUILD_APPLICATION} PROPERTIES BOARD ${ZBUILD_BOARD}@${ZBUILD_BOARD_REVISION})
+        set_target_properties(${app_target} PROPERTIES BOARD ${ZBUILD_BOARD}@${ZBUILD_BOARD_REVISION})
       endif()
     else()
-      set_target_properties(${ZBUILD_APPLICATION} PROPERTIES BOARD ${ZBUILD_BOARD})
+      set_target_properties(${app_target} PROPERTIES BOARD ${ZBUILD_BOARD})
     endif()
   elseif(DEFINED ZBUILD_BOARD_REVISION)
     message(FATAL_ERROR
@@ -425,7 +482,19 @@ function(ExternalZephyrProject_Add)
   endif()
 
   if(DEFINED ZBUILD_BUILD_ONLY)
-    set_target_properties(${ZBUILD_APPLICATION} PROPERTIES BUILD_ONLY ${ZBUILD_BUILD_ONLY})
+    set_target_properties(${app_target} PROPERTIES BUILD_ONLY ${ZBUILD_BUILD_ONLY})
+  endif()
+
+  set(sysbuild_image_slot_b_dts_overlay ${sysbuild_image_conf_dir}/${ZBUILD_APPLICATION}_slot_b.overlay)
+  if (EXISTS ${sysbuild_image_slot_b_dts_overlay} AND NOT "${ZBUILD_APP_TYPE}" STREQUAL "SLOT_B")
+    ExternalZephyrProject_Add(
+      APPLICATION ${ZBUILD_APPLICATION}
+      BOARD ${ZBUILD_BOARD}
+      BOARD_REVISION ${ZBUILD_BOARD_REVISION}
+      SOURCE_DIR ${ZBUILD_SOURCE_DIR}
+      APP_TYPE "SLOT_B"
+      BUILD_ONLY ${ZBUILD_BUILD_ONLY}
+    )
   endif()
 endfunction()