How to boot from MicroSD Card

Introduction

This how to explains how to boot IGEPv2 or IGEP Module using a microSD card.

Theory

OMAP35xx or DM37xx processors can boot from a microSD. IGEPv2 or IGEP Module uses the microSD card as highest boot priority, it means that the processor try to boot from the microsd card before try to boot from other devices such the OneNand.

Exist some rules for boot from a microSD card.

• The microsd card must be content at latest 2 partitions.
• The first one must be primary partition with the boot flag mark and formated using FAT filesystem.
• All names used in this partition must be msdos names, it means you cannot use a extended names.
• The processor must load a first program called MLO, this program must reside in the first partition, this program it's also called x-loader.

The processor ONLY load and execute the MLO program and ignore all the rest. Prerequisites ==

• PC with Linux (We use for this how to Ubuntu 11.04
• MicroSD Card (4 Gbytes - class 4)
• Tools such, fdisk, mkfs.ext3, mkfs.vfat, gparted ...

Preparing the microSD card

Insert a new microsd card in your PC, you should see in your dmesg somthing like this after insert a new microsd card:

mmc0: new high speed SDHC card at address 0001
mmcblk0: mmc0:0001 00000 3.79 GiB
mmcblk0: unknown partition table

Ensure all in your microsd card it's erased:

$ sudo dd if=/dev/zero of=/dev/mmcblk0 bs=1024 count=1024
[sudo] password for jdoe:
1024+0 records in
1024+0 records out
1048576 bytes (1.0 MB) copied, 0.43556 s, 2.4 MB/s

We will use the gparted program for create the partitions, if you don't have this program installed then you must install it with this command:

sudo apt-get install gparted

When the install procedure ends you can call the program from your system tools menu or directly using a terminal console.