sysbuild: Add support for snippets

Adds support for sysbuild loading snippets, these can be included
by using e.g.: cmake ... -DSB_SNIPPET=blah for sysbuild
directly or can be used with an application and sysbuild using
-DSNIPPET. Snippets for sysbuild can use SB_EXTRA_CONF_FILE in the
snippet file to specify an extra Kconfig fragment for sysbuild

Signed-off-by: Jamie McCrae <jamie.mccrae@nordicsemi.no>

cmake/modules/root.cmake

@@ -28,6 +28,7 @@ zephyr_get(BOARD_ROOT MERGE SYSBUILD GLOBAL)
 zephyr_get(SOC_ROOT MERGE SYSBUILD GLOBAL)
 zephyr_get(ARCH_ROOT MERGE SYSBUILD GLOBAL)
 zephyr_get(SCA_ROOT MERGE SYSBUILD GLOBAL)
+zephyr_get(SNIPPET_ROOT MERGE SYSBUILD GLOBAL)
 
 # Convert paths to absolute, relative from APPLICATION_SOURCE_DIR
 zephyr_file(APPLICATION_ROOT MODULE_EXT_ROOT)
@@ -35,6 +36,7 @@ zephyr_file(APPLICATION_ROOT BOARD_ROOT)
 zephyr_file(APPLICATION_ROOT SOC_ROOT)
 zephyr_file(APPLICATION_ROOT ARCH_ROOT)
 zephyr_file(APPLICATION_ROOT SCA_ROOT)
+zephyr_file(APPLICATION_ROOT SNIPPET_ROOT)
 
 if(unittest IN_LIST Zephyr_FIND_COMPONENTS)
   # Zephyr used in unittest mode, use dedicated unittest root.

cmake/modules/snippets.cmake

@@ -45,19 +45,23 @@ zephyr_check_cache(SNIPPET WATCH)
 function(zephyr_process_snippets)
   set(snippets_py ${ZEPHYR_BASE}/scripts/snippets.py)
   set(snippets_generated ${CMAKE_BINARY_DIR}/zephyr/snippets_generated.cmake)
+  set_ifndef(SNIPPET_NAMESPACE SNIPPET)
+  set_ifndef(SNIPPET_PYTHON_EXTRA_ARGS "")
+  set_ifndef(SNIPPET_APP_DIR "${APPLICATION_SOURCE_DIR}")
 
   # Set SNIPPET_AS_LIST, removing snippets_generated.cmake if we are
   # running cmake again and snippets are no longer requested.
-  if (NOT DEFINED SNIPPET)
+  if(NOT DEFINED SNIPPET)
     set(SNIPPET_AS_LIST "" PARENT_SCOPE)
     file(REMOVE ${snippets_generated})
   else()
-    string(REPLACE " " ";" SNIPPET_AS_LIST "${SNIPPET}")
+    string(REPLACE " " ";" SNIPPET_AS_LIST "${${SNIPPET_NAMESPACE}}")
     set(SNIPPET_AS_LIST "${SNIPPET_AS_LIST}" PARENT_SCOPE)
   endif()
 
   # Set SNIPPET_ROOT.
-  list(APPEND SNIPPET_ROOT ${APPLICATION_SOURCE_DIR})
+  zephyr_get(SNIPPET_ROOT MERGE SYSBUILD GLOBAL)
+  list(APPEND SNIPPET_ROOT ${SNIPPET_APP_DIR})
   list(APPEND SNIPPET_ROOT ${ZEPHYR_BASE})
   unset(real_snippet_root)
   foreach(snippet_dir ${SNIPPET_ROOT})
@@ -85,6 +89,7 @@ function(zephyr_process_snippets)
     ${snippet_root_args}
     ${requested_snippet_args}
     --cmake-out ${snippets_generated}
+    ${SNIPPET_PYTHON_EXTRA_ARGS}
     OUTPUT_VARIABLE output
     ERROR_VARIABLE output
     RESULT_VARIABLE ret)

scripts/schemas/snippet-schema.yml

@@ -13,6 +13,8 @@ schema;append-schema:
       type: str
     EXTRA_CONF_FILE:
       type: str
+    SB_EXTRA_CONF_FILE:
+      type: str
     DTS_EXTRA_CPPFLAGS:
       type: str
 

scripts/snippets.py

@@ -48,11 +48,11 @@ class Snippet:
     appends: Appends = field(default_factory=_new_append)
     board2appends: Dict[str, Appends] = field(default_factory=_new_board2appends)
 
-    def process_data(self, pathobj: Path, snippet_data: dict):
+    def process_data(self, pathobj: Path, snippet_data: dict, sysbuild: bool):
         '''Process the data in a snippet.yml file, after it is loaded into a
         python object and validated by pykwalify.'''
         def append_value(variable, value):
-            if variable in ('EXTRA_DTC_OVERLAY_FILE', 'EXTRA_CONF_FILE'):
+            if variable in ('SB_EXTRA_CONF_FILE', 'EXTRA_DTC_OVERLAY_FILE', 'EXTRA_CONF_FILE'):
                 path = pathobj.parent / value
                 if not path.is_file():
                     _err(f'snippet file {pathobj}: {variable}: file not found: {path}')
@@ -62,14 +62,18 @@ class Snippet:
             _err(f'unknown append variable: {variable}')
 
         for variable, value in snippet_data.get('append', {}).items():
-            self.appends[variable].append(append_value(variable, value))
+            if (sysbuild is True and variable[0:3] == 'SB_') or \
+            (sysbuild is False and variable[0:3] != 'SB_'):
+                self.appends[variable].append(append_value(variable, value))
         for board, settings in snippet_data.get('boards', {}).items():
             if board.startswith('/') and not board.endswith('/'):
                 _err(f"snippet file {pathobj}: board {board} starts with '/', so "
                      "it must end with '/' to use a regular expression")
             for variable, value in settings.get('append', {}).items():
-                self.board2appends[board][variable].append(
-                    append_value(variable, value))
+                if (sysbuild is True and variable[0:3] == 'SB_') or \
+                (sysbuild is False and variable[0:3] != 'SB_'):
+                    self.board2appends[board][variable].append(
+                        append_value(variable, value))
 
 class Snippets(UserDict):
     '''Type for all the information we have discovered about all snippets.
@@ -212,6 +216,8 @@ def parse_args():
     parser.add_argument('--cmake-out', type=Path,
                         help='''file to write cmake output to; include()
                         this file after calling this script''')
+    parser.add_argument('--sysbuild', action="store_true",
+                        help='''set if this is running as sysbuild''')
     return parser.parse_args()
 
 def setup_logging():
@@ -234,7 +240,7 @@ def process_snippets(args: argparse.Namespace) -> Snippets:
     # Process each path in snippet_root in order, adjusting
     # snippets as needed for each one.
     for root in args.snippet_root:
-        process_snippets_in(root, snippets)
+        process_snippets_in(root, snippets, args.sysbuild)
 
     return snippets
 
@@ -250,11 +256,11 @@ def find_snippets_in_roots(requested_snippets, snippet_roots) -> Snippets:
     # Process each path in snippet_root in order, adjusting
     # snippets as needed for each one.
     for root in snippet_roots:
-        process_snippets_in(root, snippets)
+        process_snippets_in(root, snippets, False)
 
     return snippets
 
-def process_snippets_in(root_dir: Path, snippets: Snippets) -> None:
+def process_snippets_in(root_dir: Path, snippets: Snippets, sysbuild: bool) -> None:
     '''Process snippet.yml files in *root_dir*,
     updating *snippets* as needed.'''
 
@@ -276,7 +282,7 @@ def process_snippets_in(root_dir: Path, snippets: Snippets) -> None:
         name = snippet_data['name']
         if name not in snippets:
             snippets[name] = Snippet(name=name)
-        snippets[name].process_data(snippet_yml, snippet_data)
+        snippets[name].process_data(snippet_yml, snippet_data, sysbuild)
         snippets.paths.add(snippet_yml)
 
 def load_snippet_yml(snippet_yml: Path) -> dict:

share/sysbuild/cmake/modules/sysbuild_default.cmake

@@ -15,6 +15,7 @@ include(zephyr_module)
 include(boards)
 include(shields)
 include(hwm_v2)
+include(sysbuild_snippets)
 include(sysbuild_kconfig)
 include(native_simulator_sb_extensions)
 include(sysbuild_images)

share/sysbuild/cmake/modules/sysbuild_kconfig.cmake

@@ -105,6 +105,14 @@ set(KCONFIG_NAMESPACE SB_CONFIG)
 if(EXISTS ${APP_DIR}/Kconfig.sysbuild)
   set(KCONFIG_ROOT ${APP_DIR}/Kconfig.sysbuild)
 endif()
+
+# Apply any EXTRA_CONF_FILE variables from snippets
+if(TARGET snippets_scope)
+  get_property(snippets_EXTRA_CONF_FILE TARGET snippets_scope PROPERTY SB_EXTRA_CONF_FILE)
+  list(APPEND EXTRA_CONF_FILE ${snippets_EXTRA_CONF_FILE})
+endif()
+
 include(${ZEPHYR_BASE}/cmake/modules/kconfig.cmake)
 set(CONF_FILE)
 set(EXTRA_CONF_FILE)
+set(SB_EXTRA_CONF_FILE)

share/sysbuild/cmake/modules/sysbuild_root.cmake

@@ -31,6 +31,7 @@ zephyr_get(BOARD_ROOT MERGE)
 zephyr_get(SOC_ROOT MERGE)
 zephyr_get(ARCH_ROOT MERGE)
 zephyr_get(SCA_ROOT MERGE)
+zephyr_get(SNIPPET_ROOT MERGE)
 
 # Convert paths to absolute, relative from APP_DIR
 zephyr_file(APPLICATION_ROOT MODULE_EXT_ROOT BASE_DIR ${APP_DIR})
@@ -38,6 +39,7 @@ 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})
+zephyr_file(APPLICATION_ROOT SNIPPET_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.
@@ -61,3 +63,7 @@ endif()
 if(DEFINED SCA_ROOT)
   set(SCA_ROOT ${SCA_ROOT} CACHE PATH "Sysbuild adjusted SCA_ROOT" FORCE)
 endif()
+
+if(DEFINED SNIPPET_ROOT)
+  set(SNIPPET_ROOT ${SNIPPET_ROOT} CACHE PATH "Sysbuild adjusted SNIPPET_ROOT" FORCE)
+endif()

share/sysbuild/cmake/modules/sysbuild_snippets.cmake

@@ -0,0 +1,16 @@
+# Copyright (c) 2024 Nordic Semiconductor
+#
+# SPDX-License-Identifier: Apache-2.0
+
+zephyr_get(SB_SNIPPET)
+if(NOT SB_SNIPPET AND SNIPPET)
+  set_ifndef(SB_SNIPPET ${SNIPPET})
+endif()
+set(SNIPPET_NAMESPACE SB_SNIPPET)
+set(SNIPPET_PYTHON_EXTRA_ARGS --sysbuild)
+set(SNIPPET_APP_DIR ${APP_DIR})
+include(${ZEPHYR_BASE}/cmake/modules/snippets.cmake)
+
+set(SNIPPET_NAMESPACE)
+set(SNIPPET_PYTHON_EXTRA_ARGS)
+set(SNIPPET_APP_DIR)