Buildroot rootfs-overlay

rootfs-overly is a pretty good feature, it can overwrite the specified file to a directory after the target filesystem is compiled. In this way, we can easily add or modify some files to the root filesystem.

Suppose we want to add the file overlay-test under the /etc/ directory of the root filesystem, we can do as follows:

• Set rootfs-overlay root directory

Open the configuration menu make menuconfig, and add the root directory for coverage by setting the BR2_ROOTFS_OVERLAY option. For RK3568, the directory board/rockchip/rk356x/fs-overlay/ has been added by default.

• Add files to the coverage directory

cd buildroot/board/rockchip/rk356x/fs-overlay/
mkdir etc/
touch etc/overlay-test

• Compile

make

• Download the root filesystem

Download the compiled root filesystem output/rockchip_rk3568/images/rootfs.ext2 to the device. Start the device, you can see that the file /etc/overlay-test has been added.

You can also check the target/ directory to verify whether the addition is successful:

ls buildroot/output/rockchip_rk3568/target/etc/overlay-test