fix(build): add kconfig support for fortified toolchains

CMakeLists.txt

@@ -240,8 +240,15 @@ if(NOT CMAKE_BUILD_TYPE)
 	set(CMAKE_BUILD_TYPE ${PX4_BUILD_TYPE} CACHE STRING "Build type" FORCE)
 endif()
 
+if(CONFIG_BOARD_SUPPORT_FORTIFIED_TOOLCHAIN)
+	set(PX4_DEBUG_OPT_LEVEL -Og)
+	message(STATUS "fortified toolchain support enabled: PX4_DEBUG_OPT_LEVEL=${PX4_DEBUG_OPT_LEVEL}")
+else()
+	set(PX4_DEBUG_OPT_LEVEL -O0)
+endif()
+
 if((CMAKE_BUILD_TYPE STREQUAL "Debug") OR (CMAKE_BUILD_TYPE STREQUAL "Coverage"))
-	set(MAX_CUSTOM_OPT_LEVEL -O0)
+	set(MAX_CUSTOM_OPT_LEVEL ${PX4_DEBUG_OPT_LEVEL})
 elseif(CMAKE_BUILD_TYPE MATCHES "Sanitizer")
 	set(MAX_CUSTOM_OPT_LEVEL -O1)
 elseif(CMAKE_BUILD_TYPE MATCHES "Release")

Kconfig

@@ -67,6 +67,16 @@ menu "Toolchain"
         help
             Enables Cmake Release for -O3 optimization
 
+    config BOARD_SUPPORT_FORTIFIED_TOOLCHAIN
+        bool "Fortified toolchain support"
+        default n
+        help
+            Enable compatibility with toolchains that define
+            _FORTIFY_SOURCE.
+
+            This switches PX4_DEBUG_OPT_LEVEL from -O0 to -Og. Keep this
+            disabled unless the fortified toolchain requires optimization.
+
     config BOARD_ROMFSROOT
         string "ROMFSROOT"
         default "px4fmu_common"

cmake/coverage.cmake

@@ -52,10 +52,10 @@ endif()
 
 # add code coverage build type
 if (("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang") OR ("${CMAKE_CXX_COMPILER_ID}" MATCHES "AppleClang"))
-	set(CMAKE_C_FLAGS_COVERAGE "--coverage -ftest-coverage -fdiagnostics-absolute-paths -O0 -fprofile-arcs -fno-inline-functions"
+	set(CMAKE_C_FLAGS_COVERAGE "--coverage -ftest-coverage -fdiagnostics-absolute-paths ${PX4_DEBUG_OPT_LEVEL} -fprofile-arcs -fno-inline-functions"
 		CACHE STRING "Flags used by the C compiler during coverage builds" FORCE)
 
-	set(CMAKE_CXX_FLAGS_COVERAGE "--coverage -ftest-coverage -fdiagnostics-absolute-paths -O0-fprofile-arcs -fno-inline-functions -fno-elide-constructors"
+	set(CMAKE_CXX_FLAGS_COVERAGE "--coverage -ftest-coverage -fdiagnostics-absolute-paths ${PX4_DEBUG_OPT_LEVEL} -fprofile-arcs -fno-inline-functions -fno-elide-constructors"
 		CACHE STRING "Flags used by the C++ compiler during coverage builds" FORCE)
 
 	set(CMAKE_EXE_LINKER_FLAGS_COVERAGE "-ftest-coverage -fdiagnostics-absolute-paths"
@@ -63,11 +63,11 @@ if (("${CMAKE_CXX_COMPILER_ID}" MATCHES "Clang") OR ("${CMAKE_CXX_COMPILER_ID}"
 
 else()
 	# Add  -fprofile-abs-path for GCC v8/9 later on
-	set(CMAKE_C_FLAGS_COVERAGE "--coverage -ftest-coverage -fprofile-arcs -O0 -fno-default-inline -fno-inline"
+	set(CMAKE_C_FLAGS_COVERAGE "--coverage -ftest-coverage -fprofile-arcs ${PX4_DEBUG_OPT_LEVEL} -fno-default-inline -fno-inline"
 		CACHE STRING "Flags used by the C compiler during coverage builds" FORCE)
 
 	# Add  -fprofile-abs-path for GCC v8/9 later on
-	set(CMAKE_CXX_FLAGS_COVERAGE "--coverage -ftest-coverage -fprofile-arcs -O0 -fno-default-inline -fno-inline -fno-elide-constructors"
+	set(CMAKE_CXX_FLAGS_COVERAGE "--coverage -ftest-coverage -fprofile-arcs ${PX4_DEBUG_OPT_LEVEL} -fno-default-inline -fno-inline -fno-elide-constructors"
 		CACHE STRING "Flags used by the C++ compiler during coverage builds" FORCE)
 
 	set(CMAKE_EXE_LINKER_FLAGS_COVERAGE "--coverage -ftest-coverage -lgcov"

docs/en/hardware/porting_guide_config.md

@@ -70,3 +70,19 @@ The command line and GUI interfaces are shown below.
 ### menuconfig Command Line Interface
 
 ![menuconfig command line interface](../../assets/hardware/kconfig-guiconfig.png)
+
+## Fortified Toolchain Compatibility
+
+Some toolchains define `_FORTIFY_SOURCE` by default. Those toolchains generally require some optimization, which means PX4 configurations that use `-O0` may fail.
+
+PX4 keeps the default debug optimization unchanged unless you explicitly opt in. To switch `PX4_DEBUG_OPT_LEVEL` from `-O0` to `-Og`, enable:
+
+- `Toolchain > Fortified toolchain support`
+
+This is the Kconfig symbol:
+
+```sh
+CONFIG_BOARD_SUPPORT_FORTIFIED_TOOLCHAIN=y
+```
+
+You can set it either in `boardconfig`/`boardguiconfig` or directly in your board's `*.px4board` file.

src/drivers/cyphal/CMakeLists.txt

@@ -109,7 +109,7 @@ px4_add_module(
 	COMPILE_FLAGS
 		#-DCANARD_ASSERT
 		-DUINT32_C\(x\)=__UINT32_C\(x\)
-		-O0
+		${PX4_DEBUG_OPT_LEVEL}
 		${DRIVERS_CYPHAL_OPTIONS}
 	INCLUDES
 		${LIBCANARD_DIR}/libcanard/

src/lib/world_magnetic_model/CMakeLists.txt

@@ -57,5 +57,5 @@ target_compile_options(world_magnetic_model PRIVATE ${MAX_CUSTOM_OPT_LEVEL})
 
 if(BUILD_TESTING)
 	px4_add_unit_gtest(SRC test_geo_lookup.cpp LINKLIBS world_magnetic_model)
-	target_compile_options(unit-test_geo_lookup PRIVATE -O0 -Wno-double-promotion)
+	target_compile_options(unit-test_geo_lookup PRIVATE ${PX4_DEBUG_OPT_LEVEL} -Wno-double-promotion)
 endif()