To format an sd card for booting linux on the ZYBO-Z7 board WITH a root filesystem under LINUX. 

NOTE: The root filesystem is persistent, so you can copy files to the root partition (see below) using your 
laptop, and then plug the card into the ZYBO board, boot and those files will be available.

1) Mount the disk (plug it in) and note device name, e.g., /dev/sdc1. 
   ***** WARNING: DO NOT PROCEED UNLESS YOU ARE CERTAIN OF THE DEVICE NAME for your SD card
   In the following, I assume the sd card is given the device names /dev/sdc and /dev/sdc1

2) Unmount
   umount /dev/sdc1

3) Create the boot and root partitions. 
   WARNING: BE VERY CAREFUL WITH THIS COMMAND. BE SURE YOU CHOOSE THE SD CARD device in /dev, e.g., /dev/sdc
   NOTE: USE /dev/sdc and NOT /dev/sdc1
   fdisk /dev/sdc 
      p (prints the partition table -- probably none at this point)
      n, p, 1, 2048, +1G (create a 1 GB FAT32 filesystem)
      t, b (change 1G partition to be W95 FAT32)
      a, 1 (make the FAT partition bootable)
      n, p, 2, <use default>, <use default, rest of disk>
      p (verify it is linux)
      w (write out the updates)

4) Format the partitions
   mkfs.vfat -F 32 -n boot /dev/sdc1
   mkfs.ext4 -L root /dev/sdc2

5) Mount the boot partition
   mount /dev/sdc1 /mnt

6) Copy the boot images from my download directory to the FAT32 boot partition. Substitute <path to> with the directory where you downloaded these images
   cd /mnt
   cp <path to>/BOOT.BIN .
   cp <path to>/image.ub .

7) Unmount the boot partition
   umount /mnt

8) Create the root filesystem on the root partition Substitute <path to> with the directory where you downloaded the rootfs.ext4 file.
   WARNING: BE VERY CAREFUL WITH THIS COMMAND. BE SURE YOU CHOOSE THE SD CARD device in /dev, e.g., /dev/sdc2
   dd if=<path to>/rootfs.ext4 of=/dev/sdc2


9) Check that there are no errors once this command finishes. Double check it succeeded by mounting the root partition
   mount /dev/sdc2 /mnt

10) Check that the root filesystem exists
   cd /mnt
   ls
   (You should see a list of directories, such as root, etc)

11) Unmount the root partition
   umount /mnt

12) Plug the SD card into you ZYBO board and power on. Use minicom -s and /dev/ttyUSB1 to logon