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These instructions assume you are using a Linux development machine.

The example below will show the steps for setting up a brand new card.  We will be creating 2 partitions on the card: a FAT partition that will contain the bootloaders and Linux kernel, and an ext3 partition that will contain the root file system.

Getting started

On my Ubuntu machine, the newly inserted card shows up as /dev/sde and that is the device name that will be used through this example. You should substitute the proper device name for your machine. You can use 'mount' or 'df' to see where the card mounts on your machine.

Let's unmount the device's existing file system before we get started with the process:

$ sudo umount /dev/sde1

If you are the type who likes to understand exactly what is going on, you can follow the manual process below.  If you just want to get the job done, you can use a script that automates this process.  See the article entitled  A script for partitioning/formatting a bootable SD/miroSD card, and then return to the INSTALLING THE BOOT FILES section below.

Partitioning the card

Now launch fdisk and create an empty partition table. Note that the argument for fdisk is the entire device (/dev/sde) not just a single partition (i.e. /dev/sde1):

# sudo fdisk /dev/sde

Command (m for help): o
Building a new DOS disklabel. Changes will remain in memory only,
until you decide to write them. After that, of course, the previous
content won't be recoverable.

Warning: invalid flag 0x0000 of partition table 4 will be corrected by w(rite)

Let's first look at the current card information:

Command (m for help): p

Disk /dev/sde: 2032 MB, 2032664576 bytes
64 heads, 63 sectors/track, 984 cylinders
Units = cylinders of 4032 * 512 = 2064384 bytes
Disk identifier: 0x00aa8e5c

   Device Boot      Start         End      Blocks   Id  System

Note the card size in bytes. We will needed it later in the process.

In order to create a bootable SD/microSD compatible with the OMAP3 boot ROM you must set a special geometry using the fdisk "Expert mode".

To go into "Expert" mode use the "x" command:

Command (m for help): x

Next we will set the geometry to 255 heads, 63 sectors and a calculated value for the number of cylinders required for the particular microSD card.

To calculate the number of cylinders, we take the 2032664576 bytes reported above by fdisk divided by 255 heads, 63 sectors and 512 bytes per sector:

2032664576 / 255 / 63 / 512 = 247.12 which we round down to 247 cylinders.

Expert command (m for help): h
Number of heads (1-256, default 4): 255

Expert command (m for help): s
Number of sectors (1-63, default 62): 63
Warning: setting sector offset for DOS compatiblity

Expert command (m for help): c
Number of cylinders (1-1048576, default 984): 247

Return to fdisk's main mode and create a new partition 32 MB FAT partition:

Expert command (m for help): r

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 1
First cylinder (1-247, default 1): 1
Last cylinder or +size or +sizeM or +sizeK (1-247, default 15): +32M

Change the partition type to FAT32:

Command (m for help): t
Selected partition 1
Hex code (type L to list codes): c
Changed system type of partition 1 to c (W95 FAT32 (LBA))

And mark it bootable:

Command (m for help): a
Partition number (1-4): 1

Next we create an ext3 partition for the rootfs:

Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (6-247, default 6): 6
Last cylinder or +size or +sizeM or +sizeK (6-247, default 247): 247

To verify our work, lets print the partition info:

Command (m for help): p

Disk /dev/sde: 2032 MB, 2032664576 bytes
255 heads, 63 sectors/track, 247 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x00aa8e5c

   Device Boot      Start         End      Blocks   Id  System
/dev/sde1   *           1           5       40131    c  W95 FAT32 (LBA)
/dev/sde2               6         247     1943865   83  Linux

Up to this point no changes have been made to the card itself, so our final step is to write the new partition table to the card and then exit:

Command (m for help): w
The partition table has been altered!

Calling ioctl() to re-read partition table.

WARNING: If you have created or modified any DOS 6.x
partitions, please see the fdisk manual page for additional
information.
Syncing disks.

Formatting the new partitions

We format the first partition as a FAT file system (the -n parameter gives it a label of FAT, you can change or omit this if you like):

#  sudo mkfs.vfat -F 32 /dev/sde1 -n FAT
mkfs.vfat 2.11 (12 Mar 2005)

We format the second partition as an ext3 file system:

$ sudo mkfs.ext3 /dev/sde2
mke2fs 1.40.8 (13-Mar-2008)
Filesystem label=
OS type: Linux
Block size=4096 (log=2)
Fragment size=4096 (log=2)
121920 inodes, 485966 blocks
24298 blocks (5.00%) reserved for the super user
First data block=0
Maximum filesystem blocks=499122176
15 block groups
32768 blocks per group, 32768 fragments per group
8128 inodes per group
Superblock backups stored on blocks: 
	32768, 98304, 163840, 229376, 294912

Writing inode tables: done                            
Creating journal (8192 blocks): done
Writing superblocks and filesystem accounting information: ^[done

This filesystem will be automatically checked every 36 mounts or
180 days, whichever comes first.  Use tune2fs -c or -i to override.

Installing the boot files

This instructions below will assume that:

• your machine is an Overo
• you downloaded the Overo images and Gnome rootfs from the Downloads section of this site

There are three files required on the first (FAT) partition to boot your OMAP3 processor:

1. MLO: the boot-loader loader - this small program is loaded into the OMAP3 processor's static RAM. It does some minimal configuration of system memory and io pins and then loads the second file.
2. u-boot.bin: the boot loader
3. uImage: the linux kernel

It is important that these three files have precisely these names.

Mount the FAT partition of your microSD card. This example will assume that you have mounted it at /media/card:

sudo mount /dev/sde1 /media/card

Due to constraints of the mask boot ROM in the OMAP processor, MLO should be written first:

$ sudo cp ~/Desktop/MLO-overo /media/card/MLO

Then copy u-boot and the linux kernel to the card:

$ sudo cp ~/Desktop/u-boot-overo.bin /media/card/u-boot.bin
$ sudo cp ~/Desktop/uImage-overo-2.6.X-rX.bin /media/card/uImage

You can now unmount the FAT partition:

$ sudo umount /dev/sde1

At this point you have a bootable FAT partition.

Installing the Root file system

The final step is to untar your rootfs onto the ext3 partition that you created above.

Note that this step can be dangerous. You do not want to untar your OMAP3 rootfs onto the root of your development machine file system.  Be careful!

$ sudo mount /dev/sde2 /media/card

Now untar your rootfs:

$ cd /media/card
$ sudo tar xvjf ~/Desktop/gnome-rX.tar.bz2 

You can now unmount the ext3 partition:

$ sudo umount /dev/sde2

It is now safe to remove the SD/microSD card from your development machines card slot.

Insert the card in your OMAP3 machine and press the reset button (on Beagle be sure to hold down the User button when pressing and releasing the reset button in order to ensure that the Beagle boots from the SD card)

Have fun exploring!

To change your display resolution see the article Changing the display resolution.

But please read the section below first!

A few words about the U-boot environment partition

It is recommended that you erase the u-boot environment partition every time you install a new version of u-boot.  This will cause u-boot to use its default environment.

The images on this site are always matched sets - the u-boot default enviroment will be appropriate for the kernel and rootfs in the set.  You should only change the default u-boot environment if you know what you are doing.  You shouldn't normally need to change this default unless you want to use a different display resolution than the default 1024x768.

To erase the u-boot environment partition, press any key during the boot sequence when u-boot prints the following message:

Hit any key to stop autoboot:

Then, at the command prompt for Overo type:

Overo # nand erase 240000 20000

NAND erase: device 0 offset 0x240000, size 0x20000
Erasing at 0x240000 -- 100% complete.
OK
Overo # reset

For Beagle, type:

OMAP3 beagleboard.org # nand erase 260000 20000

NAND erase: device 0 offset 0x260000, size 0x20000
Erasing at 0x260000 -- 100% complete.
OK
OMAP3 beagleboard.org # reset

Your machine will now reboot and you will see confirmation thas you have successfully erased the environment partition whe u-boot prints the following message:

*** Warning - bad CRC or NAND, using default environment