Which init system intigrates read-only rootfs features into image?

as mentioned in below link sysvinit requried for read only rootfs
poky - Poky Build Tool and Metadata.
But image init system is systemd.
How can i go forward for read-only rootfs feature to add in image.
Please suggest anyone correct way of building read-only rootfs image ??

hello siva

What is your application? What do you want to build?