dracut rootfs overlayfs module
Make any rootfs ro, but writable via overlayfs. This is convenient, if for example using an ro-nfs-mount.
Add the parameter "rootovl" to the kernel, to activate this feature
This happens pre-pivot. Therefore the final root file system is already mounted. It will be set ro, and turned into an overlayfs mount with an underlying tmpfs.
The original root and the tmpfs will be mounted at /live/image and /live/cow in the final rootfs.
The module is derived from the FAI (Fully automatic Installation) project by Thomas Lange, https://fai-project.org/ and licensed under GNU GPL license.