git clone https://github.com/friendlyarm/kernel-rockchip --depth 1 -b nanopi4-linux-v4.4.y kernel-rockchip
cd kernel-rockchip
make ARCH=arm64 nanopi4_linux_defconfig
export PATH=/opt/FriendlyARM/toolchain/6.4-aarch64/bin/:$PATH
make ARCH=arm64 nanopi4-images
After compilation is done a kernel.img and a resource.img will be generated. You can simply copy them to replace the existing files in your eflasher SD card. We assume your SD card's FRIENDLYARM partition is mounted at the FRIENDLYARM directory and you can run the following commands to update system:
ShellAlbert
commented
5 years ago 
http://wiki.friendlyarm.com/wiki/index.php/NanoPC-T4#Compile_FriendlyCore.2FFriendlyDesktop.2FLubuntu.2FEFlasher_Kernel_Source_Code
14.5 Compile FriendlyCore/FriendlyDesktop/Lubuntu/EFlasher Kernel Source Code
git clone https://github.com/friendlyarm/kernel-rockchip --depth 1 -b nanopi4-linux-v4.4.y kernel-rockchip cd kernel-rockchip make ARCH=arm64 nanopi4_linux_defconfig export PATH=/opt/FriendlyARM/toolchain/6.4-aarch64/bin/:$PATH make ARCH=arm64 nanopi4-images
After compilation is done a kernel.img and a resource.img will be generated. You can simply copy them to replace the existing files in your eflasher SD card. We assume your SD card's FRIENDLYARM partition is mounted at the FRIENDLYARM directory and you can run the following commands to update system:
for Lubuntu
cp kernel.img resource.img /media/FRIENDLYARM/lubuntu/
for FriendlyCore
cp kernel.img resource.img /media/FRIENDLYARM/friendlycore-arm64/
for FriendlyDesktop
cp kernel.img resource.img /media/FRIENDLYARM/friendlydesktop-arm64/
Or you can use a USB Type-C cable and the Linux_Upgrade_Tool utility to update system.