推荐订阅源

首先找交叉编译工具（ toolchain ）

Development Snapshots

http://downloads.openwrt.org/snapshots/trunk/

我需要的版本是 m7620 

http://downloads.openwrt.org/snapshots/trunk/ramips/mt7620/ 

下载文件  OpenWrt-Toolchain-ramips-mt7620_gcc-5.3.0_musl-1.1.15.Linux-x86_64.tar.bz2 

[root@VM_129_51_centos openwrt]# wget http://downloads.openwrt.org/snapshots/trunk/ramips/mt7620/OpenWrt-Toolchain-ramips-mt7620_gcc-5.3.0_musl-1.1.15.Linux-x86_64.tar.bz2
[root@VM_129_51_centos openwrt]# tar -jxf OpenWrt-Toolchain-ramips-mt7620_gcc-5.3.0_musl-1.1.15.Linux-x86_64.tar.bz2
[root@VM_129_51_centos openwrt]# mv OpenWrt-Toolchain-ramips-mt7620_gcc-5.3.0_musl-1.1.15.Linux-x86_64 toolchain
[root@VM_129_51_centos openwrt]# wget http://downloads.openwrt.org/chaos_calmer/15.05.1/ramips/mt7620/OpenWrt-SDK-15.05.1-ramips-mt7620_gcc-4.8-linaro_uClibc-0.9.33.2.Linux-x86_64.tar.bz2
[root@VM_129_51_centos openwrt]# tar -jxf OpenWrt-SDK-15.05.1-ramips-mt7620_gcc-4.8-linaro_uClibc-0.9.33.2.Linux-x86_64.tar.bz2
[root@VM_129_51_centos openwrt]# mv OpenWrt-SDK-15.05.1-ramips-mt7620_gcc-4.8-linaro_uClibc-0.9.33.2.Linux-x86_64 SDK
[root@VM_129_51_centos openwrt]# find / -name staging_dir
/root/openwrt/SDK/staging_dir
[root@VM_129_51_centos bin]# export STAGING_DIR='/root/openwrt/SDK/staging_dir'
[root@VM_129_51_centos bin]# export CC=/root/openwrt/toolchain/toolchain-mipsel_24kec+dsp_gcc-5.3.0_musl-1.1.15/bin/mipsel-openwrt-linux-musl-g++

[root@VM_129_51_centos bin]# export CPLUS_INCLUDE_PATH=/root/openwrt/SDK/build_dir/target-mipsel_24kec+dsp_uClibc-0.9.33.2/linux-ramips_mt7620/linux-3.18.23/include/uapi/linux/can/

[root@VM_129_51_centos bin]# export LD_FLAGS=-L/root/openwrt/toolchain/toolchain-mipsel_24kec+dsp_gcc-5.3.0_musl-1.1.15/lib/  -static-libstdc++ -static-libgcc -lgcc_s

-static-libstdc++ -static-libgcc

两个选项必须同时使用。相关的介绍请参照：http://blog.csdn.net/kissnsms/article/details/17142149

交叉工具链没有ldd,因此无法查找库依赖关系,可以用以下替代解决方案

readelf -a filename|grep "Shared library"