OMAP Wireless Connectivity AM37x Preparing SD Card

Preparing an SD Card

To prepare an SD card suitable to boot from, you need to have the following files:

• MLO - an add-on for u-boot to load from the SD card
• u-boot.bin - u-boot Linux loader binary file
• uImage - image of Linux kernel, to be loaded by u-boot
• root file system that will be mounted by the board

Steps to be followed to create a boot-able SD card:

1. Enter the SD card and find the name provided by the Linux system to the new device. For example, in Ubuntu distribution, the command 'sudo fdisk -l' will list under which device name each disk is known to the system. Assume that the inserted card got the name /dev/sdc.
2. Perform Partitioning

• Format the card: dd if=/dev/zero of=/dev/sdc bs=1024 count=1024
• Run sudo fdisk /dev/sdc

   add a new partion (option n)
   make a primary partition (option p)
   select the partition number as 1
   select the first cylinder as 1 (the default gets taken on pressing enter) and last cylinder as 100

   add a new partion (option n)
   make a primary partition (option p)
   select the partition number as 2
   select the first cylinder as 101 (the default gets taken on pressing enter) and select the last cylinder as default value by pressing enter.
   Start writing and exit (option w)

3. Generate the file systems

• Generate first partition as FAT with label 'boot': sudo mkfs.vfat -F 32 -n boot /dev/sdc1
• Generate second partition as ext3 with label 'rootfs': sudo mkfs.ext3 -L rootfs /dev/sdc2

4. Copy the files

• First partion will contain boot files: MLO, u-boot and uImage. The order in which the files are copied is significant:

mount /dev/sdc1 /mnt
cp MLO /mnt/MLO
cp u-boot.bin /mnt/u-boot.bin
cp uImage /mnt/uImage
umount /dev/sdc1

• Second partion will contain the root file system to be mounted by Linux on the board:

mount /dev/sdc2 /mnt
tar zxvf some-rootfs.tar.gz -C /mnt
chmod 755 /mnt
umount /dev/sdc2

The SD card is now ready.