uImage in RZ/A1H

Hi all,

       I'am working with rz/a1h custom made board using xipImage buildroot environment and everything is working fine, but this only read only file system. I want my file system to be read and write so i tried  UImage, but i dont have complete documents to use UImage i.e how to flash, what command to use while booting.

can anyone please tell or share the complete procedure to use UImage in Renesas Rz/a1H so that the root file system becomes read and write or is there any way that by using XipImage we can make file-system as read and write.   

Thanks

Mahesh R