[U-Boot-Users] Newbie Question on rootfs.ext2.gz.uboot

I have a root file system that I boot over NFS (x86 host, PPC target).

How do I transform that into a root file system of the form rootfs.ext2.gz.uboot so I can load that into flash?

Happy to RTFM if someone can point me to it. And yes, I confess, I'm a newbie to this. :)

Cheers and Thanks!

GS