example : kernel 2.6.34 as example
1. download patch-2.6.34.gz
2. download linux-2.6.34.tar.gz
cp patch-2.6.34.gz to linux-2.6.34
cd linux-2.6.34
gunzip patch-2.6.34.gz (if you download bz2 format ,using bunzip2 command to unzip the patch file)
now you'll get patch file : patch-2.6.34
patch -p0 < patch-2.6.34
