[SLL] root filesystem as a subdirectory of same device

[Jeremy C. Reed]

I want to change the root filesystem to a subdirectory of the only 
device. I want this to happen at boot time.

I am guessing that mount's --rbind (or --bind) could do this.

Any ideas on how to get grub to tell my Linux kernel to change the root 
filesystem to a subdirectory of the existing root file system?

Or maybe use rbind option in fstab and remount / ??

I have changed root file systems by selecting different devices, but never 
a sub directory.

chroot could be used to run init -- but I am not sure easiest way to do 
the chroot before running init.

I also looked at pivot_root and switch_root, but as far as I know they are 
for memory-based file systems only.