Hi Andrey,
the use of Initrd is highly recommended if you are using a systemd based init system, and it’s not that much overhead. In this case it helps me to boot the rootfs directly from eMMC with a custom partitioning scheme (MBR instead of u-boot).
I’ve seen that you are using the meson64_odroidc2.dtb device tree binary (which belongs to HK 3.14 kernel for the Odroid C2). How good is the HW support for the kvim with this device tree? Did you even succeed to boot a mainline kernel?
Cheers
Uli