make menuconfig -> Device Drivers -> Network device support -> PPP (point-to-point protocol) 中，选中所有ppp选项。退出，保存配置，修改Makefile重新执行make zImage. 将arch/mips/boot/下的zImage下载到开发板上重启系统。
tar -zxvf ppp-2.4.5.tar.gz
cd ppp-2.4.5
[root@root ppp-2.4.5 ]# ./configure CC=mipsel-linux-gcc AR=mipsel-linux-ar BANLIB=mipsel-linux-ranlib --host=mipsel
Configuring for Linux
Creating Makefiles.
Makefile <= linux/Makefile.top
pppd/Makefile <= pppd/Makefile.linux
pppstats/Makefile <= pppstats/Makefile.linux
chat/Makefile <= chat/Makefile.linux
pppdump/Makefile <= pppdump/Makefile.linux
pppd/plugins/Makefile <= pppd/plugins/Makefile.linux
pppd/plugins/rp-pppoe/Makefile <= pppd/plugins/rp-pppoe/Makefile.linux
pppd/plugins/radius/Makefile <= pppd/plugins/radius/Makefile.linux
pppd/plugins/pppoatm/Makefile <= pppd/plugins/pppoatm/Makefile.linux
pppd/plugins/pppol2tp/Makefile <= pppd/plugins/pppol2tp/Makefile.linux
