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 ...

Preparing the microSD card

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

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