Rita,
I'm using fsl-community-bsp 2.2 (Morty). My rootfs is 46MB in size so I believe it will fit in the 64MB I have. u-boot, zImage, and dtb files add about 8MB to that number for a total of 54MB excluding any memory alignment overhead.
There are two main things I'm trying to figure out:
1. How can I get mfgtool to flash the rootfs into SPI NOR flash.
2. How can I configure u-boot to use it.
Thanks,
Neil