sysbuild: support sysbuild/CMakeLists.txt as entry point and support APPLICATION_CONFIG_DIR

share/sysbuild-package/cmake/SysbuildConfig.cmake

@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: Apache-2.0
+
+if(Sysbuild_FIND_COMPONENTS)
+  set(Zephyr_FIND_COMPONENTS ${Sysbuild_FIND_COMPONENTS})
+else()
+  set(Zephyr_FIND_COMPONENTS sysbuild_default)
+endif()
+include(${CMAKE_CURRENT_LIST_DIR}/../../zephyr-package/cmake/ZephyrConfig.cmake)
+set(Sysbuild_FOUND True)

share/sysbuild-package/cmake/SysbuildConfigVersion.cmake

@@ -0,0 +1,5 @@
+# SPDX-License-Identifier: Apache-2.0
+
+include(${CMAKE_CURRENT_LIST_DIR}/../../zephyr-package/cmake/ZephyrConfigVersion.cmake)
+list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_LIST_DIR}/../../sysbuild/cmake/modules)
+set(CMAKE_MODULE_PATH ${CMAKE_MODULE_PATH} PARENT_SCOPE)

share/sysbuild/CMakeLists.txt

@@ -12,38 +12,12 @@ endif()
 # If APP_DIR is a relative path, then CMake will adjust to absolute path based
 # on current working dir.
 set(APP_DIR ${APP_DIR} CACHE PATH "Main Application Source Directory")
+set(Sysbuild_DIR ${CMAKE_CURRENT_LIST_DIR}/../sysbuild-package/cmake)
 
-# Add sysbuild/cmake/modules to CMAKE_MODULE_PATH which allows us to integrate
-# sysbuild CMake modules with general Zephyr CMake modules.
-list(APPEND CMAKE_MODULE_PATH ${CMAKE_CURRENT_LIST_DIR}/cmake/modules)
-# List of Zephyr and sysbuild CMake modules we need for sysbuild.
-# Note: sysbuild_kconfig will internally load kconfig CMake module.
-set(zephyr_modules extensions
-    sysbuild_extensions python west root zephyr_module boards shields hwm_v2
-    sysbuild_kconfig native_simulator_sb_extensions
-  )
+project(sysbuild_toplevel LANGUAGES)
 
-find_package(Zephyr REQUIRED HINTS $ENV{ZEPHYR_BASE} COMPONENTS ${zephyr_modules})
-
-project(sysbuild LANGUAGES)
-
-get_filename_component(APP_DIR  ${APP_DIR} ABSOLUTE)
-get_filename_component(app_name ${APP_DIR} NAME)
-set(DEFAULT_IMAGE "${app_name}")
-
-# This is where all Zephyr applications are added to the multi-image build.
-sysbuild_add_subdirectory(images)
-
-get_property(IMAGES GLOBAL PROPERTY sysbuild_images)
-sysbuild_module_call(PRE_CMAKE MODULES ${SYSBUILD_MODULE_NAMES} IMAGES ${IMAGES})
-sysbuild_images_order(IMAGES_CONFIGURATION_ORDER CONFIGURE IMAGES ${IMAGES})
-foreach(image ${IMAGES_CONFIGURATION_ORDER})
-  sysbuild_module_call(PRE_IMAGE_CMAKE MODULES ${SYSBUILD_MODULE_NAMES} IMAGES ${IMAGES} IMAGE ${image})
-  ExternalZephyrProject_Cmake(APPLICATION ${image})
-  sysbuild_module_call(POST_IMAGE_CMAKE MODULES ${SYSBUILD_MODULE_NAMES} IMAGES ${IMAGES} IMAGE ${image})
-endforeach()
-sysbuild_module_call(POST_CMAKE MODULES ${SYSBUILD_MODULE_NAMES} IMAGES ${IMAGES})
-
-sysbuild_module_call(PRE_DOMAINS MODULES ${SYSBUILD_MODULE_NAMES} IMAGES ${IMAGES})
-include(cmake/domains.cmake)
-sysbuild_module_call(POST_DOMAINS MODULES ${SYSBUILD_MODULE_NAMES} IMAGES ${IMAGES})
+if(EXISTS ${APP_DIR}/sysbuild/CMakeLists.txt)
+  add_subdirectory(${APP_DIR}/sysbuild sysbuild/application)
+else()
+  add_subdirectory(template sysbuild/application)
+endif()

share/sysbuild/cmake/modules/sysbuild_default.cmake

@@ -0,0 +1,19 @@
+# Copyright (c) 2024 Nordic Semiconductor
+#
+# SPDX-License-Identifier: Apache-2.0
+
+#
+# Sysbuild default list of CMake modules to include in a regular sysbuild session.
+#
+include(extensions)
+include(sysbuild_extensions)
+include(python)
+include(west)
+include(root)
+include(zephyr_module)
+include(boards)
+include(shields)
+include(hwm_v2)
+include(sysbuild_kconfig)
+include(native_simulator_sb_extensions)
+include(sysbuild_images)

share/sysbuild/cmake/modules/sysbuild_extensions.cmake

@@ -661,7 +661,7 @@ function(sysbuild_add_subdirectory source_dir)
       " (expected at most 2, got ${ARGC})"
     )
   endif()
-  set(binary_dir ${ARGV1})
+  set(binary_dir ${ARGN})
 
   # Update SYSBUILD_CURRENT_SOURCE_DIR in this scope, to support nesting
   # of sysbuild_add_subdirectory() and even regular add_subdirectory().

share/sysbuild/cmake/modules/sysbuild_images.cmake

@@ -0,0 +1,27 @@
+# Copyright (c) 2024 Nordic Semiconductor
+#
+# SPDX-License-Identifier: Apache-2.0
+
+# This module is responsible for including images into sysbuild and to call
+# pre and post hooks.
+
+get_filename_component(APP_DIR  ${APP_DIR} ABSOLUTE)
+get_filename_component(app_name ${APP_DIR} NAME)
+set(DEFAULT_IMAGE "${app_name}")
+
+# This is where all Zephyr applications are added to the multi-image build.
+sysbuild_add_subdirectory(${sysbuild_toplevel_SOURCE_DIR}/images sysbuild/images)
+
+get_property(IMAGES GLOBAL PROPERTY sysbuild_images)
+sysbuild_module_call(PRE_CMAKE MODULES ${SYSBUILD_MODULE_NAMES} IMAGES ${IMAGES})
+sysbuild_images_order(IMAGES_CONFIGURATION_ORDER CONFIGURE IMAGES ${IMAGES})
+foreach(image ${IMAGES_CONFIGURATION_ORDER})
+  sysbuild_module_call(PRE_IMAGE_CMAKE MODULES ${SYSBUILD_MODULE_NAMES} IMAGES ${IMAGES} IMAGE ${image})
+  ExternalZephyrProject_Cmake(APPLICATION ${image})
+  sysbuild_module_call(POST_IMAGE_CMAKE MODULES ${SYSBUILD_MODULE_NAMES} IMAGES ${IMAGES} IMAGE ${image})
+endforeach()
+sysbuild_module_call(POST_CMAKE MODULES ${SYSBUILD_MODULE_NAMES} IMAGES ${IMAGES})
+
+sysbuild_module_call(PRE_DOMAINS MODULES ${SYSBUILD_MODULE_NAMES} IMAGES ${IMAGES})
+include(${sysbuild_toplevel_SOURCE_DIR}/cmake/domains.cmake)
+sysbuild_module_call(POST_DOMAINS MODULES ${SYSBUILD_MODULE_NAMES} IMAGES ${IMAGES})

share/sysbuild/cmake/modules/sysbuild_kconfig.cmake

@@ -13,13 +13,37 @@ set(EXTRA_KCONFIG_TARGET_COMMAND_FOR_sysbuild_guiconfig
 set(KCONFIG_TARGETS sysbuild_menuconfig sysbuild_guiconfig)
 list(TRANSFORM EXTRA_KCONFIG_TARGETS PREPEND "sysbuild_")
 
+if(DEFINED APPLICATION_CONFIG_DIR AND NOT DEFINED CACHE{APPLICATION_CONFIG_DIR})
+  set(APPLICATION_CONFIG_DIR "${APPLICATION_CONFIG_DIR}" CACHE INTERNAL "Application config dir")
+elseif(DEFINED CACHE{APPLICATION_CONFIG_DIR} AND
+       NOT (APPLICATION_CONFIG_DIR STREQUAL "$CACHE{APPLICATION_CONFIG_DIR}"))
+  message(WARNING
+          "Sysbuild scoped APPLICATION_CONFIG_DIR and cached APPLICATION_CONFIG_DIR differs.\n"
+          "Setting value used internally by Sysbuild (sysbuild scoped):\n"
+	  " - ${APPLICATION_CONFIG_DIR}\n"
+	  "Setting value used by images (cached):\n"
+	  " - $CACHE{APPLICATION_CONFIG_DIR}\n"
+  )
+endif()
+
+# If there is a dedicated SB_APPLICATION_CONFIG_DIR, then create a local
+# scoped APPLICATION_CONFIG_DIR hiding any cache variant.
+# The cache setting is the setting passed to sysbuild image cache files
+if(DEFINED SB_APPLICATION_CONFIG_DIR)
+  set(APPLICATION_CONFIG_DIR ${SB_APPLICATION_CONFIG_DIR})
+elseif(NOT DEFINED APPLICATION_CONFIG_DIR)
+  get_filename_component(APP_DIR  ${APP_DIR} ABSOLUTE)
+  set(APPLICATION_CONFIG_DIR ${APP_DIR})
+endif()
+string(CONFIGURE ${APPLICATION_CONFIG_DIR} APPLICATION_CONFIG_DIR)
+
 if(DEFINED SB_CONF_FILE)
   # SB_CONF_FILE already set so nothing to do.
 elseif(DEFINED ENV{SB_CONF_FILE})
   set(SB_CONF_FILE $ENV{SB_CONF_FILE})
 else()
   # sysbuild.conf is an optional file, because sysbuild is an opt-in feature.
-  zephyr_file(CONF_FILES ${APP_DIR} KCONF SB_CONF_FILE NAMES "sysbuild.conf" SUFFIX ${FILE_SUFFIX})
+  zephyr_file(CONF_FILES ${APPLICATION_CONFIG_DIR} KCONF SB_CONF_FILE NAMES "sysbuild.conf" SUFFIX ${FILE_SUFFIX})
 endif()
 
 if(NOT DEFINED SB_EXTRA_CONF_FILE AND DEFINED SB_OVERLAY_CONFIG)
@@ -56,7 +80,7 @@ endif()
 
 # Empty files to make kconfig.py happy.
 file(TOUCH ${CMAKE_CURRENT_BINARY_DIR}/empty.conf)
-set(APPLICATION_SOURCE_DIR ${CMAKE_CURRENT_SOURCE_DIR})
+set(APPLICATION_SOURCE_DIR ${sysbuild_toplevel_SOURCE_DIR})
 set(AUTOCONF_H             ${CMAKE_CURRENT_BINARY_DIR}/autoconf.h)
 set(CONF_FILE              ${SB_CONF_FILE})
 set(EXTRA_CONF_FILE        "${SB_EXTRA_CONF_FILE}")

share/sysbuild/template/CMakeLists.txt

@@ -0,0 +1,12 @@
+# Copyright (c) 2024 Nordic Semiconductor
+#
+# SPDX-License-Identifier: Apache-2.0
+
+# Generic sysbuild CMakeLists.txt file used as sysbuild entry point for multi-image builds.
+#
+# Applications which requires custom handling when built using sysbuild may copy this
+# file to the folder `<app-dir>/sysbuild` and use as a template and extend as needed.
+
+find_package(Sysbuild REQUIRED HINTS $ENV{ZEPHYR_BASE})
+
+project(sysbuild LANGUAGES)