rootfs from kernel ubuntu

I am wondering that creating a rootfs from kernel is possible? I
downloaded a kernel and i changed some drivers on that for
touchscreen. And then i compiled it. After it created a uImage. But
when i use this uImage with different rootfs, it cant found /lib/
modules/<kernel version>.

For that situation first of all i did some things. in kernel path ;

# make modules
# make INSTALL_MOD_PATH=<rootfs path> modules_install
# cd /home/user/target/lib/modules
# arm-none-linux-gnueabi-strip `find . –name “*.ko”`


and then after this operation i realized that rootfs' size is ~1gb. So
i used it and this time it did not error about founding libs but i
did not work.
i took init(45) init (72) lines lastly and then serial terminal

How can i create a rootfs from kernel? thank you