cmake: version.h generation performed at build time

Fixes: #39503
Fixes: #40167

This commit moves `BUILD_VERSION` CMake variable from a compile
definition to be a define inside version.h.

Besides the benefit of having related settings grouped in a common
header, it also means that an updated `BUILD_VERSION` value does not
need to trigger re-compilation of all source files.

When using compile definitions, CMake cannot tell whether a given source
files uses the definition or not, and hence all sources must be
recompiled to be sure they are up-to-date.

Placing `BUILD_VERSION` in version.h, the source dependencies ensures
that only source files including `version.h` gets recompiled.

As part of this, version.h generation is moved so that it is now done
at build time.
This means that re-generation of version.h is no longer depending on a
CMake re-run but can have it's own dependency in `.git/index` when git
described is used to obtain `BUILD_VERSION` information.

Generation of logging dictionary database has been updated to support
BUILD_VERSION from header file instead of CMake configure time variable.

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

CMakeLists.txt

@@ -145,12 +145,6 @@ if(CONFIG_STACK_CANARIES)
   zephyr_compile_options($<TARGET_PROPERTY:compiler,security_canaries>)
 endif()
 
-if(BUILD_VERSION)
-  zephyr_compile_definitions(
-    BUILD_VERSION=${BUILD_VERSION}
-  )
-endif()
-
 # @Intent: Obtain compiler optimizations flags and store in variables
 # @details:
 #   Kconfig.zephyr "Optimization level" is a kconfig choice, ensuring
@@ -435,7 +429,23 @@ if(NOT EXISTS ${LINKER_SCRIPT})
   message(FATAL_ERROR "Could not find linker script: '${LINKER_SCRIPT}'. Corrupted configuration?")
 endif()
 
-configure_file(version.h.in ${PROJECT_BINARY_DIR}/include/generated/version.h)
+if(DEFINED BUILD_VERSION)
+  set(build_version_argument "-DBUILD_VERSION=${BUILD_VERSION}")
+elseif(EXISTS ${ZEPHYR_BASE}/.git/index)
+  set(git_dependency ${ZEPHYR_BASE}/.git/index)
+else()
+  message(WARNING "ZEPHYR_BASE=${ZEPHYR_BASE} doesn't appear to be a git "
+    "repository, please specify '-DBUILD_VERSION=<version>'")
+endif()
+add_custom_command(
+  OUTPUT ${PROJECT_BINARY_DIR}/include/generated/version.h
+  COMMAND ${CMAKE_COMMAND} -DZEPHYR_BASE=${ZEPHYR_BASE}
+    -DOUT_FILE=${PROJECT_BINARY_DIR}/include/generated/version.h
+    ${build_version_argument}
+    -P ${ZEPHYR_BASE}/cmake/gen_version_h.cmake
+  DEPENDS ${ZEPHYR_BASE}/VERSION ${git_dependency}
+)
+add_custom_target(version_h DEPENDS ${PROJECT_BINARY_DIR}/include/generated/version.h)
 
 # Error-out when the deprecated naming convention is found (until
 # after 1.14.0 has been released)
@@ -705,7 +715,7 @@ gen_kobj(KOBJ_INCLUDE_PATH)
 
 add_custom_target(zephyr_generated_headers)
 add_dependencies(zephyr_generated_headers
-  offsets_h
+  offsets_h version_h
   )
 
 # Generate offsets.c.obj from offsets.c
@@ -1652,7 +1662,7 @@ if(CONFIG_LOG_DICTIONARY_SUPPORT)
     ${ZEPHYR_BASE}/scripts/logging/dictionary/database_gen.py
     ${KERNEL_ELF_NAME}
     ${LOG_DICT_DB_NAME}
-    --build ${BUILD_VERSION}
+    --build-header ${PROJECT_BINARY_DIR}/include/generated/version.h
     )
   list(APPEND
     post_build_byproducts

cmake/app/boilerplate.cmake

@@ -139,7 +139,6 @@ set_property(DIRECTORY APPEND PROPERTY CMAKE_CONFIGURE_DEPENDS ${AUTOCONF_H})
 include(CheckCCompilerFlag)
 include(CheckCXXCompilerFlag)
 include(${ZEPHYR_BASE}/cmake/extensions.cmake)
-include(${ZEPHYR_BASE}/cmake/git.cmake)
 include(${ZEPHYR_BASE}/cmake/version.cmake)  # depends on hex.cmake
 
 #

cmake/gen_version_h.cmake

@@ -0,0 +1,26 @@
+# SPDX-License-Identifier: Apache-2.0
+
+cmake_minimum_required(VERSION 3.20.0)
+
+if(NOT DEFINED BUILD_VERSION)
+  find_package(Git QUIET)
+  if(GIT_FOUND)
+    execute_process(
+      COMMAND ${GIT_EXECUTABLE} describe --abbrev=12 --always
+      WORKING_DIRECTORY                ${ZEPHYR_BASE}
+      OUTPUT_VARIABLE                  BUILD_VERSION
+      OUTPUT_STRIP_TRAILING_WHITESPACE
+      ERROR_STRIP_TRAILING_WHITESPACE
+      ERROR_VARIABLE                   stderr
+      RESULT_VARIABLE                  return_code
+    )
+    if(return_code)
+      message(STATUS "git describe failed: ${stderr}")
+    elseif(NOT "${stderr}" STREQUAL "")
+      message(STATUS "git describe warned: ${stderr}")
+    endif()
+  endif()
+endif()
+
+include(${ZEPHYR_BASE}/cmake/version.cmake)
+configure_file(${ZEPHYR_BASE}/version.h.in ${OUT_FILE})

scripts/logging/dictionary/database_gen.py

@@ -15,6 +15,7 @@
 import argparse
 import logging
 import os
+import re
 import struct
 import sys
 
@@ -47,6 +48,8 @@ def parse_args():
     argparser.add_argument("elffile", help="Zephyr ELF binary")
     argparser.add_argument("dbfile", help="Dictionary Logging Database file")
     argparser.add_argument("--build", help="Build ID")
+    argparser.add_argument("--build-header",
+                           help="Header file containing BUILD_VERSION define")
     argparser.add_argument("--debug", action="store_true",
                            help="Print extra debugging information")
     argparser.add_argument("-v", "--verbose", action="store_true",
@@ -264,6 +267,14 @@ def main():
 
     database = LogDatabase()
 
+    if args.build_header:
+        with open(args.build_header) as f:
+            for l in f:
+                match = re.match(r'\s*#define\s+BUILD_VERSION\s+(.*)', l)
+                if match:
+                    database.set_build_id(match.group(1))
+                    break
+
     if args.build:
         database.set_build_id(args.build)
         logger.info("Build ID: %s", args.build)

version.h.in

@@ -1,7 +1,9 @@
 #ifndef _KERNEL_VERSION_H_
 #define _KERNEL_VERSION_H_
 
-/* @templates@ values come from cmake/version.cmake */
+/* KERNEL and ZEPHYR_VERSION @templates@ values come from cmake/version.cmake
+ * BUILD_VERSION @template@ will be 'git describe', alternatively user defined BUILD_VERSION.
+ */
 
 #cmakedefine ZEPHYR_VERSION_CODE @ZEPHYR_VERSION_CODE@
 #define ZEPHYR_VERSION(a,b,c) (((a) << 16) + ((b) << 8) + (c))
@@ -13,4 +15,6 @@
 #define KERNEL_PATCHLEVEL      @KERNEL_PATCHLEVEL@
 #define KERNEL_VERSION_STRING  @KERNEL_VERSION_STRING@
 
+#define BUILD_VERSION          @BUILD_VERSION@
+
 #endif /* _KERNEL_VERSION_H_ */