libcurl是免费的轻量级的客户端网络库，支持DICT, FILE, FTP, FTPS, Gopher, HTTP, HTTPS, IMAP, IMAPS, LDAP, LDAPS,POP3, POP3S, RTMP, RTSP, SCP, SFTP, SMTP, SMTPS, Telnet, TFTP.支持SSL, HTTPPOST,HTTPPUT, FTP上传, HTTP form上传，代理，cookies, 用户名与密码认证。

系统环境：Ubuntu 16.04
源码：curl-7.63.0.tar.gz , 下载地址  https://curl.haxx.se/libcurl/

交叉编译环境：arm-none-linux-gnueabihf

libcurl原代码内包含了CMakeLists.txt和configure，两种方式都可以进行交叉编译

1. toolchain.cmake

#toolchain cmake file 
#cmake -DCMAKE_TOOLCHAIN_FILE=~/toolchain.cmake ../
SET(CMAKE_SYSTEM_NAME Linux)
SET(TOOLCHAIN_DIR "complier_dir")
SET(3RDPART_LIBS_DIR "thirdpart_dir")

#specify the cross compiler
SET(CMAKE_C_COMPILER ${TOOLCHAIN_DIR}/bin/arm-linux-gnueabihf-gcc CACHE FILEPATH "Archiver")
SET(CMAKE_CXX_COMPILER ${TOOLCHAIN_DIR}/bin/arm-linux-gnueabihf-g++ CACHE FILEPATH "Archiver")

#SET(CMAKE_GFORTRAN  ${TOOLCHAIN_DIR}/bin/arm-linux-gnueabihf-gfortran)
SET(CMAKE_AR ${TOOLCHAIN_DIR}/bin/arm-linux-gnueabihf-ar CACHE FILEPATH "Archiver")
SET(CMAKE_AS ${TOOLCHAIN_DIR}/bin/arm-linux-gnueabihf-as CACHE FILEPATH "Archiver")
SET(CMAKE_LD  ${TOOLCHAIN_DIR}/bin/arm-linux-gnueabihf-ld CACHE FILEPATH "Archiver")
SET(CMAKE_NM ${TOOLCHAIN_DIR}/bin/arm-linux-gnueabihf-nm CACHE FILEPATH "Archiver")
SET(CMAKE_STRIP  ${TOOLCHAIN_DIR}/bin/arm-linux-gnueabihf-strip CACHE FILEPATH "Archiver")

# where is the target environment 
SET(CMAKE_FIND_ROOT_PATH  ${TOOLCHAIN_DIR} ${3RDPART_LIBS_DIR})

# search for programs in the build host directories
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)

交叉编译指令

cmake -DCMAKE_TOOLCHAIN_FILE=toochain._dir ../

2. configure

./configure --prefix=install_dir --host=arm-linux/arm-linux-gnueabihf/others CC=arm-linux-gnueabihf-gcc CXX=arm-linux-gnueabihf-g++