cmake: Allow selecting toolchain file based on config

Refactor IDF "project" functionality under a wrapping of the default
"project" command, so we can tweak it a bit...

Will need more testing in other environments.

components/bootloader/project_include.cmake

@@ -1,4 +1,4 @@
-if(IS_BOOTLOADER_BUILD)
+if(BOOTLOADER_BUILD)
   return()  # don't keep recursing!
 endif()
 

components/bootloader/subproject/CMakeLists.txt

@@ -1,20 +1,17 @@
 cmake_minimum_required(VERSION 3.5)
-set(CMAKE_TOOLCHAIN_FILE $ENV{IDF_PATH}/toolchain.cmake)
 
 if(NOT SDKCONFIG)
   message(FATAL_ERROR "Bootloader subproject expects the SDKCONFIG variable to be passed in by the parent build process.")
 endif()
 
-project(bootloader ASM C CXX)
-
 set(COMPONENTS bootloader esptool_py esp32 soc bootloader_support log spi_flash micro-ecc soc)
 set(BOOTLOADER_BUILD 1)
-set(IS_BOOTLOADER_BUILD 1)  # deprecated, use BOOTLOADER_BUILD
 add_definitions(-DBOOTLOADER_BUILD=1)
 
 set(MAIN_SRCS main/bootloader_start.c)
 
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(bootloader)
 
 target_link_libraries(bootloader.elf "-L ${CMAKE_CURRENT_SOURCE_DIR}/main")
 target_link_libraries(bootloader.elf "-T esp32.bootloader.ld")

examples/get-started/hello_world/CMakeLists.txt

@@ -1,10 +1,8 @@
 # The following five lines of boilerplate have to be in your project's CMakeLists
 # in this exact order for cmake to work correctly
 cmake_minimum_required(VERSION 3.5)
-set(CMAKE_TOOLCHAIN_FILE $ENV{IDF_PATH}/toolchain.cmake)
-
-project(hello-world ASM C CXX)
 
 set(MAIN_SRCS main/hello_world_main.c)
 
 include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(hello-world)

tools/cmake/idf_functions.cmake

@@ -2,6 +2,12 @@
 
 include(crosstool_version_check)
 
+#
+# Set some variables used by rest of the build
+#
+# Note at the time this macro is expanded, the config is not yet
+# loaded and the toolchain and project are not yet set
+#
 macro(idf_set_global_variables)
   # Note that CONFIG_xxx is not available when this function is called
 
@@ -22,9 +28,6 @@ macro(idf_set_global_variables)
   # Tell cmake to drop executables in the top-level build dir
   set(EXECUTABLE_OUTPUT_PATH "${CMAKE_BINARY_DIR}")
 
-  # cmake cross-toolchain doesn't include any gcc binutils names
-  set(CMAKE_OBJCOPY xtensa-esp32-elf-objcopy)
-
   # path to idf.py tool
   set(IDFTOOL ${PYTHON} "${IDF_PATH}/tools/idf.py")
 
@@ -93,20 +96,18 @@ endfunction(idf_set_global_compiler_options)
 function(idf_verify_environment)
 
   if(NOT CMAKE_PROJECT_NAME)
-    message(FATAL_ERROR "Project top-level CMakeLists.txt file must call project() before including project.cmake")
+    message(FATAL_ERROR "Internal error, IDF project.cmake should have set this variable already")
   endif()
 
   # Check toolchain is configured properly in cmake
   if(NOT ( ${CMAKE_SYSTEM_NAME} STREQUAL "Generic" AND ${CMAKE_C_COMPILER} MATCHES xtensa))
-    message(FATAL_ERROR "Project top-level CMakeLists.txt file needs to set CMAKE_TOOLCHAIN_FILE "
-      "before including project.cmake.\n"
-      "Update CMakeLists.txt to match the template project and delete CMakeCache.txt before "
-      "re-running cmake.")
+    message(FATAL_ERROR "Internal error, toolchain has not been set correctly by project")
   endif()
 
   #
   # Warn if the toolchain version doesn't match
   #
+  # TODO: make these platform-specific for diff toolchains
   gcc_version_check("5.2.0")
   crosstool_version_check("1.22.0-80-g6c4433a")
 

tools/cmake/project.cmake

@@ -24,55 +24,79 @@ include(idf_functions)
 
 set_default(PYTHON "python")
 
-# Verify the environment is configured correctly
-idf_verify_environment()
-
-# Set global variables used by rest of the build
-idf_set_global_variables()
-
-# Search COMPONENT_DIRS for COMPONENTS, make a list of full paths to each component in COMPONENT_PATHS
-components_find_all("${COMPONENT_DIRS}" "${COMPONENTS}" COMPONENT_PATHS COMPONENTS)
-
-kconfig_set_variables()
-
-kconfig_process_config()
-
-# Include sdkconfig.cmake so rest of the build knows the configuration
-include(${SDKCONFIG_CMAKE})
-
-# Add some idf-wide definitions
-idf_set_global_compiler_options()
-
-# Check git version (may trigger reruns of cmake)
-# & set GIT_REVISION/IDF_VER variable
-git_describe(GIT_REVISION)
-add_definitions(-DIDF_VER=\"${GIT_REVISION}\")
-git_submodule_check("${IDF_PATH}")
-
-# Include any top-level project_include.cmake files from components
-foreach(component ${COMPONENT_PATHS})
-  include_if_exists("${component}/project_include.cmake")
-endforeach()
-
+# project
 #
-# Add each component to the build as a library
+# This macro wraps the cmake 'project' command to add
+# all of the IDF-specific functionality required
 #
-foreach(component ${COMPONENT_PATHS})
-  get_filename_component(component_name ${component} NAME)
-  add_subdirectory(${component} ${component_name})
-endforeach()
+# Implementation Note: This macro wraps 'project' on purpose, because cmake has some
+# backwards-compatible magic where if you don't call "project" in the top-level
+# CMakeLists file, it will call it implicitly. However, the implict project will not
+# have CMAKE_TOOLCHAIN_FILE set and therefore tries to create a native build project.
+#
+# Therefore, to keep all the IDF "build magic", the cleanest way is to keep the
+# top-level "project" call but customize it to do what we want in the IDF build...
+#
+macro(project name)
+  # Set global variables used by rest of the build
+  idf_set_global_variables()
 
-#
-# Add the app executable to the build (has name of PROJECT.elf)
-#
-idf_add_executable()
+  # Search COMPONENT_DIRS for COMPONENTS, make a list of full paths to each component in COMPONENT_PATHS
+  components_find_all("${COMPONENT_DIRS}" "${COMPONENTS}" COMPONENT_PATHS COMPONENTS)
 
-# Write project description JSON file
-configure_file("${CMAKE_CURRENT_LIST_DIR}/project_description.json.in"
-  "${CMAKE_BINARY_DIR}/project_description.json")
+  kconfig_set_variables()
 
-#
-# Finish component registration (add cross-dependencies, make
-# executable dependent on all components)
-#
-components_finish_registration()
+  kconfig_process_config()
+
+  # Include sdkconfig.cmake so rest of the build knows the configuration
+  include(${SDKCONFIG_CMAKE})
+
+  # Now the configuration is loaded, set the toolchain appropriately
+  #
+  # TODO: support more toolchains than just ESP32
+  set(CMAKE_TOOLCHAIN_FILE $ENV{IDF_PATH}/tools/cmake/toolchain-esp32.cmake)
+
+  # Declare the actual cmake-level project
+  _project(${name} ASM C CXX)
+
+  # Verify the environment is configured correctly
+  idf_verify_environment()
+
+  # Add some idf-wide definitions
+  idf_set_global_compiler_options()
+
+  # Check git version (may trigger reruns of cmake)
+  # & set GIT_REVISION/IDF_VER variable
+  git_describe(GIT_REVISION)
+  add_definitions(-DIDF_VER=\"${GIT_REVISION}\")
+  git_submodule_check("${IDF_PATH}")
+
+  # Include any top-level project_include.cmake files from components
+  foreach(component ${COMPONENT_PATHS})
+    include_if_exists("${component}/project_include.cmake")
+  endforeach()
+
+  #
+  # Add each component to the build as a library
+  #
+  foreach(component ${COMPONENT_PATHS})
+    get_filename_component(component_name ${component} NAME)
+    add_subdirectory(${component} ${component_name})
+  endforeach()
+
+  #
+  # Add the app executable to the build (has name of PROJECT.elf)
+  #
+  idf_add_executable()
+
+  # Write project description JSON file
+  configure_file("${IDF_PATH}/tools/cmake/project_description.json.in"
+    "${CMAKE_BINARY_DIR}/project_description.json")
+
+  #
+  # Finish component registration (add cross-dependencies, make
+  # executable dependent on all components)
+  #
+  components_finish_registration()
+
+endmacro(project)