【paho-mqtt】关于正点原子交叉编译mqttclient时报错的解决方法

zhoutanooi

[color=rgba(0, 0, 0, 0.75)]环境配置
[color=rgba(0, 0, 0, 0.75)]

操作系统：ubantu16.04
Cmake编译器：3.10.2
Cmake地址：/usr/bin 【直接apt-get安装的】

[color=rgba(0, 0, 0, 0.75)]出现的问题以及解决办法
[color=rgba(0, 0, 0, 0.75)]问题一
[color=rgba(0, 0, 0, 0.75)]ztn@ubuntu:~/QT/mqtt_prj/build$ cmake -DCMAKE_TOOLCHAIN_FILE=../cmake/arm-linux-setup.cmake  -DCMAKE_BUILD_TYPE=Release ..Change Dir: /home/ztn/QT/mqtt_prj/build/CMakeFiles/CMakeTmpRun Build Command:"/usr/bin/make" "cmTC_30da4/fast"/usr/bin/make -f CMakeFiles/cmTC_30da4.dir/build.make CMakeFiles/cmTC_30da4.dir/buildmake[1: 进入目录“/home/ztn/QT/mqtt_prj/build/CMakeFiles/CMakeTmp”Building C object CMakeFiles/cmTC_30da4.dir/testCCompiler.c.o/opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc --sysroot=/opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/cortexa7hf-neon-poky-linux-gnueabi    -o CMakeFiles/cmTC_30da4.dir/testCCompiler.c.o   -c /home/ztn/QT/mqtt_prj/build/CMakeFiles/CMakeTmp/testCCompiler.cLinking C executable cmTC_30da4/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_30da4.dir/link.txt --verbose=1/opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc --sysroot=/opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/cortexa7hf-neon-poky-linux-gnueabi      -rdynamic CMakeFiles/cmTC_30da4.dir/testCCompiler.c.o  -o cmTC_30da4 /opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/real-ld: error: cmTC_30da4 uses VFP register arguments, CMakeFiles/cmTC_30da4.dir/testCCompiler.c.o does not/opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/real-ld: failed to merge target specific data of file CMakeFiles/cmTC_30da4.dir/testCCompiler.c.ocollect2: error: ld returned 1 exit statusCMakeFiles/cmTC_30da4.dir/build.make:97: recipe for target 'cmTC_30da4' failedmake[1: *** [cmTC_30da4 Error 1make[1: 离开目录“/home/ztn/QT/mqtt_prj/build/CMakeFiles/CMakeTmp”Makefile:126: recipe for target 'cmTC_30da4/fast' failedmake: *** [cmTC_30da4/fast Error 2
[color=rgba(0, 0, 0, 0.75)]解决办法
[color=rgba(0, 0, 0, 0.75)]

在您的arm-linux-setup.cmake工具链文件中，明确指定浮点编译选项：

[color=rgba(0, 0, 0, 0.75)]set(CMAKE_C_FLAGS "--sysroot=${SYSROOT} -march=armv7-a -mfpu=neon -mfloat-abi=hard" CACHE STRING "C Flags")set(CMAKE_CXX_FLAGS "--sysroot=${SYSROOT} -march=armv7-a -mfpu=neon -mfloat-abi=hard" CACHE STRING "C++ Flags")
[color=rgba(0, 0, 0, 0.75)]问题二
[color=rgba(0, 0, 0, 0.75)]ztn@ubuntu:~/QT/mqtt_prj/build$ cmake -DCMAKE_TOOLCHAIN_FILE=../cmake/arm-linux-setup.cmake  -DCMAKE_BUILD_TYPE=Release ..-- The C compiler identification is GNU 5.3.0-- Check for working C compiler: /opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc-- Check for working C compiler: /opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc -- works-- Detecting C compiler ABI info-- Detecting C compiler ABI info - done-- Detecting C compile features-- Detecting C compile features - done-- CMake version: 3.10.2-- CMake system name: Linux-- CMake system processor: armCMake Error at CMakeLists.txt:31 (target_link_options):  Unknown CMake command "target_link_options".
[color=rgba(0, 0, 0, 0.75)]解决办法
[color=rgba(0, 0, 0, 0.75)]

修改 CMakeLists.txt

[color=rgba(0, 0, 0, 0.75)]# 删除或注释以下行：# target_link_options(mqttClient PRIVATE "--sysroot=${CMAKE_SYSROOT}")# 改为通过全局链接器标志传递 sysroot（适用于交叉编译）set(CMAKE_EXE_LINKER_FLAGS "--sysroot=${CMAKE_SYSROOT} ${CMAKE_EXE_LINKER_FLAGS}")
[color=rgba(0, 0, 0, 0.75)]问题三
[color=rgba(0, 0, 0, 0.75)]ztn@ubuntu:~/QT/mqtt_prj/build$ make Scanning dependencies of target mqttClient[ 50% Building C object CMakeFiles/mqttClient.dir/mqttClient.c.o[100% Linking C executable bin/mqttClient/opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/real-ld: cannot find -lpaho-mqtt3ccollect2: error: ld returned 1 exit statusCMakeFiles/mqttClient.dir/build.make:94: recipe for target 'bin/mqttClient' failedmake[2: *** [bin/mqttClient Error 1CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/mqttClient.dir/all' failedmake[1: *** [CMakeFiles/mqttClient.dir/all Error 2Makefile:83: recipe for target 'all' failedmake: *** [all Error 2
[color=rgba(0, 0, 0, 0.75)]解决办法
[color=rgba(0, 0, 0, 0.75)]

在 CMakeLists.txt 中直接使用绝对路径链接库：

[color=rgba(0, 0, 0, 0.75)]target_link_libraries(mqttClient PRIVATE    /home/ztn/tools/paho.mqtt.c-1.3.8/install/lib/libpaho-mqtt3c.so)
[color=rgba(0, 0, 0, 0.75)]完整的文件如下
[color=rgba(0, 0, 0, 0.75)]

CMakeLists.txt

[color=rgba(0, 0, 0, 0.75)]cmake_minimum_required(VERSION 2.8.12)project(MQTTClient C)message(STATUS "CMake version: " ${CMAKE_VERSION})message(STATUS "CMake system name: " ${CMAKE_SYSTEM_NAME})message(STATUS "CMake system processor: " ${CMAKE_SYSTEM_PROCESSOR})# 设置可执行文件输出路径set(EXECUTABLE_OUTPUT_PATH ${PROJECT_BINARY_DIR}/bin)# 定义可执行文件目标add_executable(mqttClient mqttClient.c)# 指定头文件路径target_include_directories(mqttClient PRIVATE    /home/ztn/tools/paho.mqtt.c-1.3.8/install/include)# 指定库路径link_directories(/home/ztn/tools/paho.mqtt.c-1.3.8/install/lib)# 链接库target_link_libraries(mqttClient PRIVATE    paho-mqtt3c)# 添加链接器选项（兼容旧版 CMake）set(CMAKE_EXE_LINKER_FLAGS    "${CMAKE_EXE_LINKER_FLAGS} -L/home/ztn/tools/paho.mqtt.c-1.3.8/install/lib -Wl,-rpath-link,/home/ztn/tools/paho.mqtt.c-1.3.8/install/lib")# 交叉编译兼容性：通过全局标志传递 sysrootif(CMAKE_CROSSCOMPILING)    set(CMAKE_EXE_LINKER_FLAGS "--sysroot=${CMAKE_SYSROOT} ${CMAKE_EXE_LINKER_FLAGS}")endif()
[color=rgba(0, 0, 0, 0.75)]

arm-linux-setup.cmake

[color=rgba(0, 0, 0, 0.75)]# arm-linux-setup.cmakeset(CMAKE_CROSSCOMPILING TRUE)set(CMAKE_SYSTEM_NAME Linux)set(CMAKE_SYSTEM_PROCESSOR arm)# 指定编译器的sysroot路径set(TOOLCHAIN_DIR /opt/fsl-imx-x11/4.1.15-2.1.0/sysroots)set(CMAKE_SYSROOT ${TOOLCHAIN_DIR}/cortexa7hf-neon-poky-linux-gnueabi)# 指定交叉编译器arm-linux-gccset(CMAKE_C_COMPILER ${TOOLCHAIN_DIR}/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc)# 添加编译和链接参数set(CMAKE_C_FLAGS "-march=armv7ve -mfpu=neon -mfloat-abi=hard -mcpu=cortex-a7")set(CMAKE_CXX_FLAGS "${CMAKE_C_FLAGS}")set(CMAKE_EXE_LINKER_FLAGS "-march=armv7ve -mfpu=neon -mfloat-abi=hard")# 设置编译器标志set(CMAKE_C_FLAGS "--sysroot=${SYSROOT} -march=armv7-a -mfpu=neon -mfloat-abi=hard" CACHE STRING "C Flags")set(CMAKE_CXX_FLAGS "--sysroot=${SYSROOT} -march=armv7-a -mfpu=neon -mfloat-abi=hard" CACHE STRING "C++ Flags")# 强制隔离交叉编译环境set(CMAKE_FIND_ROOT_PATH ${CMAKE_SYSROOT})set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
[color=rgba(0, 0, 0, 0.75)]

---

[color=rgba(0, 0, 0, 0.75)]如果该文章有帮助到你，麻烦关注我的公众号：代码随心敲。 在这里，可以联系到我，无偿分享技术知识。

zhoutanooi

## 环境配置
操作系统：ubantu16.04
Cmake编译器：3.10.2
Cmake地址：/usr/bin 【直接apt-get安装的】


## 出现的问题以及解决办法
#### 问题一

```bash
ztn@ubuntu:~/QT/mqtt_prj/build$ cmake -DCMAKE_TOOLCHAIN_FILE=../cmake/arm-linux-setup.cmake  -DCMAKE_BUILD_TYPE=Release ..

Change Dir: /home/ztn/QT/mqtt_prj/build/CMakeFiles/CMakeTmp
Run Build Command:"/usr/bin/make" "cmTC_30da4/fast"
/usr/bin/make -f CMakeFiles/cmTC_30da4.dir/build.make CMakeFiles/cmTC_30da4.dir/build
make[1]: 进入目录“/home/ztn/QT/mqtt_prj/build/CMakeFiles/CMakeTmp”
Building C object CMakeFiles/cmTC_30da4.dir/testCCompiler.c.o
/opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc --sysroot=/opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/cortexa7hf-neon-poky-linux-gnueabi    -o CMakeFiles/cmTC_30da4.dir/testCCompiler.c.o   -c /home/ztn/QT/mqtt_prj/build/CMakeFiles/CMakeTmp/testCCompiler.c
Linking C executable cmTC_30da4
/usr/bin/cmake -E cmake_link_script CMakeFiles/cmTC_30da4.dir/link.txt --verbose=1
/opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc --sysroot=/opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/cortexa7hf-neon-poky-linux-gnueabi      -rdynamic CMakeFiles/cmTC_30da4.dir/testCCompiler.c.o  -o cmTC_30da4
/opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/real-ld: error: cmTC_30da4 uses VFP register arguments, CMakeFiles/cmTC_30da4.dir/testCCompiler.c.o does not
/opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/real-ld: failed to merge target specific data of file CMakeFiles/cmTC_30da4.dir/testCCompiler.c.o
collect2: error: ld returned 1 exit status
CMakeFiles/cmTC_30da4.dir/build.make:97: recipe for target 'cmTC_30da4' failed
make[1]: *** [cmTC_30da4] Error 1
make[1]: 离开目录“/home/ztn/QT/mqtt_prj/build/CMakeFiles/CMakeTmp”
Makefile:126: recipe for target 'cmTC_30da4/fast' failed
make: *** [cmTC_30da4/fast] Error 2
```
#### 解决办法
在您的arm-linux-setup.cmake工具链文件中，明确指定浮点编译选项：
```bash
set(CMAKE_C_FLAGS "--sysroot=${SYSROOT} -march=armv7-a -mfpu=neon -mfloat-abi=hard" CACHE STRING "C Flags")
set(CMAKE_CXX_FLAGS "--sysroot=${SYSROOT} -march=armv7-a -mfpu=neon -mfloat-abi=hard" CACHE STRING "C++ Flags")
```
#### 问题二
```bash
ztn@ubuntu:~/QT/mqtt_prj/build$ cmake -DCMAKE_TOOLCHAIN_FILE=../cmake/arm-linux-setup.cmake  -DCMAKE_BUILD_TYPE=Release ..

-- The C compiler identification is GNU 5.3.0
-- Check for working C compiler: /opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc
-- Check for working C compiler: /opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc -- works
-- Detecting C compiler ABI info
-- Detecting C compiler ABI info - done
-- Detecting C compile features
-- Detecting C compile features - done
-- CMake version: 3.10.2
-- CMake system name: Linux
-- CMake system processor: arm
CMake Error at CMakeLists.txt:31 (target_link_options):
  Unknown CMake command "target_link_options".
```
#### 解决办法
修改 CMakeLists.txt
```bash
# 删除或注释以下行：
# target_link_options(mqttClient PRIVATE "--sysroot=${CMAKE_SYSROOT}")

# 改为通过全局链接器标志传递 sysroot（适用于交叉编译）
set(CMAKE_EXE_LINKER_FLAGS "--sysroot=${CMAKE_SYSROOT} ${CMAKE_EXE_LINKER_FLAGS}")
```


#### 问题三

```bash
ztn@ubuntu:~/QT/mqtt_prj/build$ make
Scanning dependencies of target mqttClient
[ 50%] Building C object CMakeFiles/mqttClient.dir/mqttClient.c.o
[100%] Linking C executable bin/mqttClient
/opt/fsl-imx-x11/4.1.15-2.1.0/sysroots/x86_64-pokysdk-linux/usr/libexec/arm-poky-linux-gnueabi/gcc/arm-poky-linux-gnueabi/5.3.0/real-ld: cannot find -lpaho-mqtt3c
collect2: error: ld returned 1 exit status
CMakeFiles/mqttClient.dir/build.make:94: recipe for target 'bin/mqttClient' failed
make[2]: *** [bin/mqttClient] Error 1
CMakeFiles/Makefile2:67: recipe for target 'CMakeFiles/mqttClient.dir/all' failed
make[1]: *** [CMakeFiles/mqttClient.dir/all] Error 2
Makefile:83: recipe for target 'all' failed
make: *** [all] Error 2
```

#### 解决办法
在 CMakeLists.txt 中直接使用绝对路径链接库：

```bash
target_link_libraries(mqttClient PRIVATE
    /home/ztn/tools/paho.mqtt.c-1.3.8/install/lib/libpaho-mqtt3c.so
)
```


## 完整的文件如下
**CMakeLists.txt**
```bash
cmake_minimum_required(VERSION 2.8.12)
project(MQTTClient C)

message(STATUS "CMake version: " ${CMAKE_VERSION})
message(STATUS "CMake system name: " ${CMAKE_SYSTEM_NAME})
message(STATUS "CMake system processor: " ${CMAKE_SYSTEM_PROCESSOR})

# 设置可执行文件输出路径
set(EXECUTABLE_OUTPUT_PATH ${PROJECT_BINARY_DIR}/bin)

# 定义可执行文件目标
add_executable(mqttClient mqttClient.c)

# 指定头文件路径
target_include_directories(mqttClient PRIVATE
    /home/ztn/tools/paho.mqtt.c-1.3.8/install/include
)

# 指定库路径
link_directories(/home/ztn/tools/paho.mqtt.c-1.3.8/install/lib)

# 链接库
target_link_libraries(mqttClient PRIVATE
    paho-mqtt3c
)
# 添加链接器选项（兼容旧版 CMake）
set(CMAKE_EXE_LINKER_FLAGS
    "${CMAKE_EXE_LINKER_FLAGS} -L/home/ztn/tools/paho.mqtt.c-1.3.8/install/lib -Wl,-rpath-link,/home/ztn/tools/paho.mqtt.c-1.3.8/install/lib"
)

# 交叉编译兼容性：通过全局标志传递 sysroot
if(CMAKE_CROSSCOMPILING)
    set(CMAKE_EXE_LINKER_FLAGS "--sysroot=${CMAKE_SYSROOT} ${CMAKE_EXE_LINKER_FLAGS}")
endif()
```

**arm-linux-setup.cmake**

```bash
# arm-linux-setup.cmake
set(CMAKE_CROSSCOMPILING TRUE)
set(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR arm)

# 指定编译器的sysroot路径
set(TOOLCHAIN_DIR /opt/fsl-imx-x11/4.1.15-2.1.0/sysroots)
set(CMAKE_SYSROOT ${TOOLCHAIN_DIR}/cortexa7hf-neon-poky-linux-gnueabi)

# 指定交叉编译器arm-linux-gcc
set(CMAKE_C_COMPILER ${TOOLCHAIN_DIR}/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc)

# 添加编译和链接参数
set(CMAKE_C_FLAGS "-march=armv7ve -mfpu=neon -mfloat-abi=hard -mcpu=cortex-a7")
set(CMAKE_CXX_FLAGS "${CMAKE_C_FLAGS}")
set(CMAKE_EXE_LINKER_FLAGS "-march=armv7ve -mfpu=neon -mfloat-abi=hard")

# 设置编译器标志
set(CMAKE_C_FLAGS "--sysroot=${SYSROOT} -march=armv7-a -mfpu=neon -mfloat-abi=hard" CACHE STRING "C Flags")
set(CMAKE_CXX_FLAGS "--sysroot=${SYSROOT} -march=armv7-a -mfpu=neon -mfloat-abi=hard" CACHE STRING "C++ Flags")

# 强制隔离交叉编译环境
set(CMAKE_FIND_ROOT_PATH ${CMAKE_SYSROOT})
set(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
set(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
```


***

## 如果该文章有帮助到你，麻烦关注我的公众号：代码随心敲。 在这里，可以联系到我，无偿分享技术知识。

***

zhoutanooi

本人用markdown格式写的懒得改了，兄弟们将就着看吧