[yocto] initramfs in rootfs included

[Alexander Stein]

Hello,

is it possible to include an initramfs image in the rootfs? If so, how can I do that?
I want to create a single image including everything: kernel, device tree, rootfs and initramfs.
The initramfs shall contain a custom startup to mount / using overlayfs before calling pivot_root.
A single image is important in order to ease the usage of rauc for updates.
I know about INITRAMFS_IMAGE_BUNDLE which includes the initramfs into the kernel.
This would be great too and creates an kernel containing the initramfs, but unfortunately
this kernel is _not_ included in the rootfs, only the kernel without initramfs.
I tried creating a custom image, based on core-image-minimal-initramfs, but failed at some
point as do_image depends on do_rootfs which depends on do_package. AFAIK the files to install
for a package are installed during do_install which come before do_package, so this does not work.

So I'm wondering how to get an initramfs image into the rootfs.

Best regards,
Alexander