Preparations:
- $ git clone git://git.openwrt.org/openwrt.git
- $ git log --grep=r39286
- $ cd openwrt
- $ wget https://sites.google.com/site/variousopenwrt/rpi-patch/openwrt-rpi-kernel-3.12.7y.patch
- $ patch -p1 < openwrt-rpi-kernel-3.12.7y.patch
- $ scripts/feeds update
- $ scripts/feeds install -a