recompile kernel

1.install kernel source code
#sysinstall/configure/distribution/src/sys

2.cp GENERIC to new kernel
#cd /usr/src/sys/i386/conf
#cp GENERIC /root/NEWKERNEL
#ln -s /root/NEWKERNEL

3.modify kernel setting
#ee NEWKERNEL

4.compile and install new kernel
#make cleandepend && make depend

5.if error occurs,please follow step2
#make && make install

6.reboot system to check new keneral
#reboot