交叉编译ROS至aarch64时链接器误找主机库而非目标根文件系统

问题现象 #

交叉编译ROS应用到aarch64系统时，链接器错误地在主机根目录下查找依赖库，而非指定的目标根文件系统（rootfs）。具体错误：

make[2]: *** No rule to make target '/usr/lib/aarch64-linux-gnu/libboost_date_time.so.1.71.0', needed by '~/build/devel/lib/libcv_bridge.so'.  Stop.
make[1]: *** [CMakeFiles/Makefile2:951: src/CMakeFiles/cv_bridge.dir/all] Error 2

实际库文件位于 ${ROOT_PATH}/usr/lib/aarch64-linux-gnu/libboost_date_time.so.1.71.0，但g++尝试在 /usr/lib/aarch64-linux-gnu/ 路径下查找。该问题并非仅针对Boost，rosconsole的liblog4cxx.so也存在同类问题。

已做配置 #

基于NVIDIA提供的交叉编译方案配置了工具链，已检查CMAKE_FIND_ROOT_PATH、CMAKE_FIND_ROOT_PATH_MODE_PROGRAM等变量，当前CMake工具链配置如下：

#----------------------------------------------------------------------------------
# CMake includes and configuration
#----------------------------------------------------------------------------------
SET(CMAKE_SYSTEM_NAME Linux)
SET(CMAKE_SYSTEM_PROCESSOR aarch64)
SET(CMAKE_HOST_SYSTEM_PROCESSOR x86_64)


#----------------------------------------------------------------------------------
# Complier configuration
#----------------------------------------------------------------------------------
SET(CMAKE_LIBRARY_ARCHITECTURE aarch64-linux-gnu) # Below call is necessary to avoid non-RT problem.
SET(CROSSCOMPILE TRUE)

SET(COMPILER_ROOT "$ENV{CROSS_COMPILE}")
SET(TROOT_PATH  $ENV{ROOTFS_ORIN})

# Specify the cross compiler 
set(CMAKE_CXX_COMPILER  ${COMPILER_ROOT}/bin/aarch64-buildroot-linux-gnu-g++)
set(CMAKE_C_COMPILER    ${COMPILER_ROOT}/bin/aarch64-buildroot-linux-gnu-gcc)

#----------------------------------------------------------------------------------
# ROS configuration
#----------------------------------------------------------------------------------
SET(NOETIC_PATH ${ROOT_PATH}/opt/ros/noetic)
SET(CMAKE_CROSS_COMPILE_PREFIX ${NOETIC_PATH})

# Library paths 
set(LD_PATH        ${ROOT_PATH}/usr/lib/aarch64-linux-gnu)
set(LD_PATH_EXTRA  ${ROOT_PATH}/lib/aarch64-linux-gnu)
set(LD_PATH_EXTRA2 ${ROOT_PATH}/lib/)
set(LD_ROS_PATH    ${NOETIC_PATH})
set(CMAKE_PATH     ${LD_PATH}/cmake/)

#----------------------------------------------------------------------------------
# Directory configuration
#----------------------------------------------------------------------------------
SET(CMAKE_PREFIX_PATH ${LD_PATH} ${LD_PATH_EXTRA} ${LD_ROS_PATH} ${CMAKE_PATH})
SET(CMAKE_MODULE_PATH ${LD_PATH} ${LD_PATH_EXTRA} ${LD_ROS_PATH} ${CMAKE_PATH})

# setup compiler for cross-compilation 
SET(CMAKE_SYSROOT           "${ROOT_PATH}" CACHE INTERNAL "" FORCE)
SET(CMAKE_SYSROOT_COMPILE   "${ROOT_PATH}" CACHE INTERNAL "" FORCE)
SET(CMAKE_SYSROOT_LINK      "${ROOT_PATH}" CACHE INTERNAL "" FORCE)

SET(CMAKE_C_FLAGS   "${CMAKE_CXX_FLAGS} -L${LD_PATH} -L${LD_PATH_EXTRA} -L ${LD_ROS_PATH}")
SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -L${LD_PATH} -L${LD_PATH_EXTRA} -L ${LD_ROS_PATH}")


set(CMAKE_EXPORT_COMPILE_COMMANDS=ON)
set(CMAKE_FIND_ROOT_PATH ${ROOT_PATH} ${NOETIC_PATH})
SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
SET(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)

# Set compiler flags 
set(CMAKE_SHARED_LINKER_FLAGS   "-L${LD_PATH} -L${LD_PATH_EXTRA} -L ${LD_ROS_PATH} -Wl,-rpath,${LD_PATH} -Wl,-rpath,${LD_PATH_EXTRA} -Wl,-rpath,${LD_PATH_EXTRA} -Wl,-rpath,${LD_ROS_PATH} ${CMAKE_SHARED_LINKER_FLAGS}")
set(CMAKE_MODULE_LINKER_FLAGS   "-L${LD_PATH} -L${LD_PATH_EXTRA} -L ${LD_ROS_PATH} -Wl,-rpath,${LD_PATH} -Wl,-rpath,${LD_PATH_EXTRA} -Wl,-rpath,${LD_PATH_EXTRA} -Wl,-rpath,${LD_ROS_PATH} ${CMAKE_MODULE_LINKER_FLAGS}")
set(CMAKE_EXE_LINKER_FLAGS      "-L${LD_PATH} -L${LD_PATH_EXTRA} -L ${LD_ROS_PATH} -Wl,-rpath,${LD_PATH} -Wl,-rpath,${LD_PATH_EXTRA} -Wl,-rpath,${LD_PATH_EXTRA} -Wl,-rpath,${LD_ROS_PATH} ${CMAKE_EXE_LINKER_FLAGS}")

#----------------------------------------------------------------------------------
# Library Versions
#----------------------------------------------------------------------------------

SET(OPENCV_VERSION 4.5)
SET(BOOST_VERSION  1.71.0)
SET(PKG_CONFIG_EXECUTABLE /usr/bin/pkg-config)
SET(PYTHON_EXECUTABLE /usr/bin/python3.8)

# Flags for libraries
include_directories(BEFORE SYSTEM ${ROOT_PATH}/usr/include)
include_directories("${ROOT_PATH}/usr/include/aarch64-linux-gnu")

解决方案 #

1. 修复PKG_CONFIG配置 #

当前使用主机的pkg-config会读取主机库配置，需指定目标rootfs的工具并设置相关路径：

SET(PKG_CONFIG_EXECUTABLE ${ROOT_PATH}/usr/bin/pkg-config)
SET(PKG_CONFIG_SYSROOT_DIR ${ROOT_PATH})
SET(PKG_CONFIG_LIBDIR ${ROOT_PATH}/usr/lib/aarch64-linux-gnu/pkgconfig:${ROOT_PATH}/usr/share/pkgconfig:${NOETIC_PATH}/lib/pkgconfig)

2. 修正变量引用错误 #

工具链中TROOT_PATH定义为$ENV{ROOTFS_ORIN}，但后续使用${ROOT_PATH}，变量名不匹配，统一修正：

# 将TROOT_PATH改为ROOT_PATH
SET(ROOT_PATH $ENV{ROOTFS_ORIN})

3. 修复链接器路径空格问题 #

CMAKE_C_FLAGS和链接器flags中-L ${LD_ROS_PATH}的空格会导致路径解析错误，改为：

SET(CMAKE_C_FLAGS   "${CMAKE_CXX_FLAGS} -L${LD_PATH} -L${LD_PATH_EXTRA} -L${LD_ROS_PATH}")
SET(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -L${LD_PATH} -L${LD_PATH_EXTRA} -L${LD_ROS_PATH}")

链接器flags中的-L 空格也同步去掉。

4. 强制指定Boost根目录 #

若问题仍存在，手动指定Boost路径强制从目标rootfs查找：

SET(BOOST_ROOT ${ROOT_PATH}/usr)
SET(Boost_NO_SYSTEM_PATHS ON)
find_package(Boost ${BOOST_VERSION} REQUIRED COMPONENTS date_time)

内容的提问来源于stack exchange，提问作者matialmar