在使用ARM工具链链接CMake项目时，多个未定义的引用

Question

我正在使用CMake开发一个构建系统，使用arm-none-eabi工具链构建应用程序。这是我的文件夹结构:

project/
├── apps/
│   ├── test_app
│   │   ├── inc/
│   │   ├── src/
│   │   ├── CMakeLists.txt
├── arch/
│   ├── CMSIS/
│   ├── include/
│   ├── startup/
│   ├── CMakeLists.txt
├── cmake/
│   ├── toolchain-samd51.cmake
├── CMakeLists.txt

这是我的顶层CMakeLists.txt:

cmake_minimum_required(VERSION 3.17)
project(SMALL-FW LANGUAGES C)
add_subdirectory(arch)
add_subdirectory(apps/test_app)

这是工具链cmake文件:

# Set target architecture
set(CMAKE_SYSTEM_NAME Generic)
set(CMAKE_SYSTEM_PROCESSOR arm)
# Set compiler to use
set(CMAKE_C_COMPILER "arm-none-eabi-gcc")
#set(CMAKE_LINKER "arm-none-eabi-ld")
# Clear default compiler and linker flags.
set(CMAKE_C_FLAGS "")
set(CMAKE_C_LINK_FLAGS "")
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
# FIX - Bypass compiler check
set(CMAKE_C_COMPILER_FORCED TRUE)
# Define common compiler and linker flags
set(ARM_OPTIONS 
-mthumb
-mabi=aapcs-linux
-mcpu=cortex-m4
-mfpu=fpv4-sp-d16
-mfloat-abi=softfp
--specs=nano.specs
-mlong-calls
-DSAMD51
)
# Define compiler specific flags
add_compile_options(
${ARM_OPTIONS}
-D__SAMD51J19A__
-ffunction-sections
-Wall
)
# Define linker specific flags
add_link_options(
${ARM_OPTIONS}
#--specs=nano.specs
LINKER:--gc-sections
)

这是位于arch文件夹中的CMakeList.txt文件:

add_library(asf OBJECT
startup/startup_samd51.c
startup/system_samd51.c
)
# Every target that links against asf needs to know where the ASF headers are.
target_include_directories(asf PUBLIC
${CMAKE_CURRENT_SOURCE_DIR}/CMSIS/Include
${CMAKE_CURRENT_SOURCE_DIR}/include
)
# Use the custom linker script provided with ASF.
target_link_options(asf PUBLIC
-T${CMAKE_CURRENT_SOURCE_DIR}/startup/samd51j19a_flash.ld
)

这是应用程序cmakelists。txt:

add_executable(APP)
target_sources(APP PRIVATE src/main.c src/module.c)
target_include_directories(APP PRIVATE inc/)
target_link_libraries(APP asf)

当CMAKE_C_COMPILER_FORCED选项设置为true时，CMake运行良好，但当我试图使项目失败时，会出现多个未定义的引用错误，如下一个:

/build/arm-none-eabi-newlib/src/build-nano/arm-none-eabi/thumb/v7e-m+fp/softfp/newlib/libc/reent/../../../../../../../../newlib-4.2.0.20211231/newlib/libc/reent/sbrkr.c:51: undefined reference to_sbrk' '

我已经尝试使用nosys.specs标志，但发生类似的错误。

Answer 1

试试这个，它看起来像typo

# Define linker specific flags
add_link_options(
${ARM_OPTIONS}
--specs=nano.specs
--gc-sections
)