[Unionfs] UnionFS as root filesystem

[Francesco Carsana]

Francis Galiegue wrote:
> Erm, you should at least create /dev/console...

I know that, infact I think the kernel mounts hda2 as root filesystem,
but I don't know why the init process doesn't start!!
Why the kernel remount the filesystem? How can I use my UnionFS as root 
filesystem?

I've read in a previous post that it's not possible create a union between
two block devices, like hda1 and hda2, and use it as root filesystem... 
Is it right?
In this case I can't solve my problem... :-(