For kernel:
1.	enable kernel config  
		Device Drivers  ---> 
			Network device support  --->
				<*>   PPP (point-to-point protocol) support                                              
 		    	<*>     PPP support for async serial ports                                             
 		    	<*>     PPP support for sync tty ports                                                 
 		    	<*>     PPP Deflate compression                                                        
 		    	<*>     PPP BSD-Compress compression                                                   
 		    	<*>     PPP MPPE compression (encryption) (EXPERIMENTAL)                               
			Character devices  --->
				[*] Unix98 PTY support
2.	patch kernel
		1. copy pptp.c from accel-pptp-0.8.5/kernel/driver/pptp.c and fixed compile error
 		2. patch /include/linux/if_pppox.h from accel-pptp-0.8.5/kernel/driver/if_pppox.h
		3. patch accel-pptp-0.8.5/patch/patch-2.6.18 
				/drivers/net/Kconfig
				/drivers/net/Makefile
		4. patch accel-pptp-0.8.5/patch/ppp-generic-smp-2.6.28.patch 
				/drivers/net/ppp_generic.c
3. enable kernel config
		Device Drivers  ---> 
			Network device support  --->
				<*>   PPP (point-to-point protocol) support                                              
 		    	<*>     PPTP (Point-to-Point Tunneling Protocol) (EXPERIMENTAL)			

4. build codes


For user space apps:
1. set PATH to the path of cross complier

2. go to pppd_plugin and run "./configure --host=mipsel-linux-uclibc --disable-dependency-tracking"

3. modify Makefile and libtool, config.h ,config.status
config.h & config.status:
		#define KERNELVERSION "2.6.31"
		#define PPPD_VERSION "2.4.3"

4. build codes and create pptp.so