sysbuild: introduce sysbuild_root for root adjustment

Fixes: #73066

Introduce sysbuild_root CMake module similar to the Zephyr root CMake
module. The sysbuild_root CMake module works similar to existing root
module, but with the difference that root paths are adjusted relative to
APP_DIR which is the main image, instead of relative to sysbuild.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>

share/sysbuild/cmake/modules/sysbuild_default.cmake

@@ -9,7 +9,7 @@ include(extensions)
 include(sysbuild_extensions)
 include(python)
 include(west)
-include(root)
+include(sysbuild_root)
 include(zephyr_module)
 include(boards)
 include(shields)

share/sysbuild/cmake/modules/sysbuild_extensions.cmake

@@ -460,16 +460,6 @@ function(ExternalZephyrProject_Cmake)
                PROPERTY IMAGE_CONF_SCRIPT
   )
 
-  # 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{${type}_ROOT} AND NOT IS_ABSOLUTE $CACHE{${type}_ROOT})
-      set(rel_path $CACHE{${type}_ROOT})
-      cmake_path(ABSOLUTE_PATH rel_path BASE_DIRECTORY "${APP_DIR}" NORMALIZE OUTPUT_VARIABLE abs_path)
-      set(${type}_ROOT ${abs_path} CACHE PATH "Sysbuild adjusted absolute path" FORCE)
-    endif()
-  endforeach()
-
   sysbuild_cache(CREATE APPLICATION ${ZCMAKE_APPLICATION})
 
   foreach(script ${${ZCMAKE_APPLICATION}_CONF_SCRIPT})

share/sysbuild/cmake/modules/sysbuild_root.cmake

@@ -0,0 +1,63 @@
+# SPDX-License-Identifier: Apache-2.0
+#
+# Copyright (c) 2024, Nordic Semiconductor ASA
+
+# Convert Zephyr roots to absolute paths to be used by sysbuild.
+#
+# This CMake module will convert all relative paths in existing ROOT lists to
+# absolute path relative from APP_DIR.
+#
+# Optional variables:
+# - ARCH_ROOT:       CMake list of arch roots containing arch implementations
+# - SOC_ROOT:        CMake list of SoC roots containing SoC implementations
+# - BOARD_ROOT:      CMake list of board roots containing board and shield implementations
+# - MODULE_EXT_ROOT: CMake list of module external roots containing module glue code
+# - SCA_ROOT:        CMake list of SCA roots containing static code analysis integration code
+#
+# If a root is defined it will check the list of paths in the root and convert
+# any relative path to absolute path and update the root list.
+# If a root is undefined it will still be undefined when this module has loaded.
+#
+# Converted paths are placed in the CMake cache so that they are propagated
+# correctly to image builds.
+
+include_guard(GLOBAL)
+
+include(extensions)
+
+# Merge in variables from other sources
+zephyr_get(MODULE_EXT_ROOT MERGE)
+zephyr_get(BOARD_ROOT MERGE)
+zephyr_get(SOC_ROOT MERGE)
+zephyr_get(ARCH_ROOT MERGE)
+zephyr_get(SCA_ROOT MERGE)
+
+# Convert paths to absolute, relative from APP_DIR
+zephyr_file(APPLICATION_ROOT MODULE_EXT_ROOT BASE_DIR ${APP_DIR})
+zephyr_file(APPLICATION_ROOT BOARD_ROOT BASE_DIR ${APP_DIR})
+zephyr_file(APPLICATION_ROOT SOC_ROOT BASE_DIR ${APP_DIR})
+zephyr_file(APPLICATION_ROOT ARCH_ROOT BASE_DIR ${APP_DIR})
+zephyr_file(APPLICATION_ROOT SCA_ROOT BASE_DIR ${APP_DIR})
+
+# Sysbuild must ensure any locally defined variables in sysbuild/CMakeLists.txt
+# have been added to the cache in order for the settings to propagate to images.
+# note: zephyr_file has removed any list duplicates
+if(DEFINED MODULE_EXT_ROOT)
+  set(MODULE_EXT_ROOT ${MODULE_EXT_ROOT} CACHE PATH "Sysbuild adjusted MODULE_EXT_ROOT" FORCE)
+endif()
+
+if(DEFINED BOARD_ROOT)
+  set(BOARD_ROOT ${BOARD_ROOT} CACHE PATH "Sysbuild adjusted BOARD_ROOT" FORCE)
+endif()
+
+if(DEFINED SOC_ROOT)
+  set(SOC_ROOT ${SOC_ROOT} CACHE PATH "Sysbuild adjusted SOC_ROOT" FORCE)
+endif()
+
+if(DEFINED ARCH_ROOT)
+  set(ARCH_ROOT ${ARCH_ROOT} CACHE PATH "Sysbuild adjusted ARCH_ROOT" FORCE)
+endif()
+
+if(DEFINED SCA_ROOT)
+  set(SCA_ROOT ${SCA_ROOT} CACHE PATH "Sysbuild adjusted SCA_ROOT" FORCE)
+endif()