系統：Ubuntu 14.04 64位
cmake版本：cmake version 3.14.0-rc4
目標:arm板
交叉編譯器：arm-poky-linux-gnueabi-gcc 5.3.0
jsoncpp下載地址：https://github.com/open-source-parsers/jsoncpp/releases
使用版本：jsoncpp-1.8.4.tar.gz
參考cmake官方說明和其他人經驗
https://cmake.org/cmake/help/latest/manual/cmake-toolchains.7.html#cross-compiling-toolchain
https://www.cnblogs.com/rickyk/p/3875334.html
先創建一個用於cmake的交叉編譯器的配置文件，我是在主目錄下創建的一個文件crossCompilingSetting，文件內容如下：
#Cross Compiling for Linux
# configure target system info
SET(CMAKE_SYSTEM_NAME Linux)
set(CMAKE_SYSTEM_PROCESSOR arm)
#sysroot,It can also be set in the compile flag
#For example set(CMAKE_CXX_FLAGS "--sysroot=/opt/fsl-imx-fb/qt5/sysroots/cortexa9hf-neon-poky-linux-gnueabi ${CMAKE_CXX_FLAGS}")
set(CMAKE_SYSROOT /opt/fsl-imx-fb/qt5/sysroots/cortexa9hf-neon-poky-linux-gnueabi)
#The CMAKE_STAGING_PREFIX is also optional. It may be used to specify a path on the host to install to. The CMAKE_INSTALL_PREFIX is always the runtime installation location, even when cross-compiling.
#set(CMAKE_STAGING_PREFIX /home/devel/stage)
# specify the cross compiler
SET(CMAKE_C_COMPILER /opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-gcc)
SET(CMAKE_CXX_COMPILER /opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi/arm-poky-linux-gnueabi-g++)
# set compiler flags
set(CMAKE_C_FLAGS "-march=armv7-a -mfpu=neon -mfloat-abi=hard -mcpu=cortex-a9 ${CMAKE_CXX_FLAGS}")
set(CMAKE_CXX_FLAGS "-march=armv7-a -mfpu=neon -mfloat-abi=hard -mcpu=cortex-a9 ${CMAKE_CXX_FLAGS}")
# where is the target environment
#SET(CMAKE_FIND_ROOT_PATH /opt/fsl-imx-fb/qt5/sysroots/cortexa9hf-neon-poky-linux-gnueabi)
#CMake find_* commands will look in the sysroot, and the CMAKE_FIND_ROOT_PATH entries by default in all cases, as well as looking in the host system root prefix.
# search for programs in the build host directories (not necessary)
SET(CMAKE_FIND_ROOT_PATH_MODE_PROGRAM NEVER)
# for libraries and headers in the target directories
SET(CMAKE_FIND_ROOT_PATH_MODE_LIBRARY ONLY)
SET(CMAKE_FIND_ROOT_PATH_MODE_INCLUDE ONLY)
set(CMAKE_FIND_ROOT_PATH_MODE_PACKAGE ONLY)
# configure Qt
#SET(QT_QMAKE_EXECUTABLE /opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/bin/qt5/qmake)
# configure Boost
#SET(BOOST_ROOT /opt/boost_arm)
然後解壓jsoncpp-1.8.4.tar.gz並修改CMakeLists.txt文件
option(JSONCPP_WITH_TESTS "Compile and (for jsoncpp_check) run JsonCpp test executables" ON)
改爲
option(JSONCPP_WITH_TESTS "Compile and (for jsoncpp_check) run JsonCpp test executables" OFF)
不編譯測試工程，因爲測試工程會編譯失敗，當然庫文件還是會生成的，所以不修改也行
開始編譯
cd jsoncpp-1.8.4/
# 創建一個build目錄，方便編譯後清理
mkdir build
cd build/
# 生成Makefile
cmake -DCMAKE_TOOLCHAIN_FILE=~/crossCompilingSetting -DCMAKE_INSTALL_PREFIX=~/arm/jsoncpp ..
# 編譯，並安裝
make
make install
至此就編譯並安裝完成
除了創建cmake的交叉編譯器的配置文件外，還有種方法可以用，配置編譯環境變量，就像我使用的交叉編譯器，可以直接
source /opt/fsl-imx-fb/qt5/environment-setup-cortexa9hf-neon-poky-linux-gnueabi
配置完所需要的變量，然後不用做其他處理就可以直接 cmake -DCMAKE_INSTALL_PREFIX=~/arm/jsoncpp ..
environment-setup-cortexa9hf-neon-poky-linux-gnueabi文件內容如下，用參考：
export SDKTARGETSYSROOT=/opt/fsl-imx-fb/qt5/sysroots/cortexa9hf-neon-poky-linux-gnueabi
export PATH=/opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/bin:/opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/sbin:/opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/bin:/opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/sbin:/opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/bin/../x86_64-pokysdk-linux/bin:/opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi:/opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-uclibc:/opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-musl:$PATH
export CCACHE_PATH=/opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/bin:/opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/bin/../x86_64-pokysdk-linux/bin:/opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-gnueabi:/opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-uclibc:/opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/bin/arm-poky-linux-musl:$CCACHE_PATH
export PKG_CONFIG_SYSROOT_DIR=$SDKTARGETSYSROOT
export PKG_CONFIG_PATH=$SDKTARGETSYSROOT/usr/lib/pkgconfig
export CONFIG_SITE=/opt/fsl-imx-fb/qt5/site-config-cortexa9hf-neon-poky-linux-gnueabi
export OECORE_NATIVE_SYSROOT="/opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux"
export OECORE_TARGET_SYSROOT="$SDKTARGETSYSROOT"
export OECORE_ACLOCAL_OPTS="-I /opt/fsl-imx-fb/qt5/sysroots/x86_64-pokysdk-linux/usr/share/aclocal"
unset command_not_found_handle
export CC="arm-poky-linux-gnueabi-gcc -march=armv7-a -mfpu=neon -mfloat-abi=hard -mcpu=cortex-a9 --sysroot=$SDKTARGETSYSROOT"
export CXX="arm-poky-linux-gnueabi-g++ -march=armv7-a -mfpu=neon -mfloat-abi=hard -mcpu=cortex-a9 --sysroot=$SDKTARGETSYSROOT"
export CPP="arm-poky-linux-gnueabi-gcc -E -march=armv7-a -mfpu=neon -mfloat-abi=hard -mcpu=cortex-a9 --sysroot=$SDKTARGETSYSROOT"
export AS="arm-poky-linux-gnueabi-as "
export LD="arm-poky-linux-gnueabi-ld --sysroot=$SDKTARGETSYSROOT"
export GDB=arm-poky-linux-gnueabi-gdb
export STRIP=arm-poky-linux-gnueabi-strip
export RANLIB=arm-poky-linux-gnueabi-ranlib
export OBJCOPY=arm-poky-linux-gnueabi-objcopy
export OBJDUMP=arm-poky-linux-gnueabi-objdump
export AR=arm-poky-linux-gnueabi-ar
export NM=arm-poky-linux-gnueabi-nm
export M4=m4
export TARGET_PREFIX=arm-poky-linux-gnueabi-
export CONFIGURE_FLAGS="--target=arm-poky-linux-gnueabi --host=arm-poky-linux-gnueabi --build=x86_64-linux --with-libtool-sysroot=$SDKTARGETSYSROOT"
export CFLAGS=" -O2 -pipe -g -feliminate-unused-debug-types -fdebug-prefix-map=/home2/zhengsh/linux/yocto/build/tmp/work/x86_64-nativesdk-pokysdk-linux/meta-environment-imx6qsabresd/1.0-r8=/usr/src/debug/meta-environment-imx6qsabresd/1.0-r8 -fdebug-prefix-map=/home2/zhengsh/linux/yocto/build/tmp/sysroots/x86_64-linux= -fdebug-prefix-map=/home2/zhengsh/linux/yocto/build/tmp/sysroots/x86_64-nativesdk-pokysdk-linux= "
export CXXFLAGS=" -O2 -pipe -g -feliminate-unused-debug-types -fdebug-prefix-map=/home2/zhengsh/linux/yocto/build/tmp/work/x86_64-nativesdk-pokysdk-linux/meta-environment-imx6qsabresd/1.0-r8=/usr/src/debug/meta-environment-imx6qsabresd/1.0-r8 -fdebug-prefix-map=/home2/zhengsh/linux/yocto/build/tmp/sysroots/x86_64-linux= -fdebug-prefix-map=/home2/zhengsh/linux/yocto/build/tmp/sysroots/x86_64-nativesdk-pokysdk-linux= "
export LDFLAGS="-Wl,-O1 -Wl,--hash-style=gnu -Wl,--as-needed"
export CPPFLAGS=""
export KCFLAGS="--sysroot=$SDKTARGETSYSROOT"
export OECORE_DISTRO_VERSION="4.1.15-2.0.0"
export OECORE_SDK_VERSION="4.1.15-2.0.0"
export ARCH=arm
export CROSS_COMPILE=arm-poky-linux-gnueabi-
# Append environment subscripts
if [ -d "$OECORE_TARGET_SYSROOT/environment-setup.d" ]; then
for envfile in $OECORE_TARGET_SYSROOT/environment-setup.d/*.sh; do
. $envfile
done
fi
if [ -d "$OECORE_NATIVE_SYSROOT/environment-setup.d" ]; then
for envfile in $OECORE_NATIVE_SYSROOT/environment-setup.d/*.sh; do
. $envfile
done
fi