Difference between revisions of "Boot from MMC"

Revision as of 00:12, 12 February 2009

This section describes how to boot off an MMC memory card

Partition the card

Place the card into your reader, and unmount it if it is mounted.

Assuming it is the only mmc card, run fdisk:

sudo fdisk /dev/mmcblk0

Delete any partitions on the disk, in this case there were two:

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

Command (m for help): d
Selected partition 2

Create the kernel partition:

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

Command (m for help): d
Selected partition 2

Set it to FAT16 file system:

<code>
Command (m for help): t
Selected partition 1
Hex code (type L to list codes): 6
Changed system type of partition 1 to 6 (FAT16)

Create the root fs partition:

<code>
Command (m for help): n
Command action
   e   extended
   p   primary partition (1-4)
p
Partition number (1-4): 2
First cylinder (22-984, default 22): 22
Last cylinder, +cylinders or +size{K,M,G} (22-984, default 984): 984

Save the partition table:

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

Calling ioctl() to re-read partition table.

WARNING: Re-reading the partition table failed with error 13: Permission denied.
The kernel still uses the old table.
The new table will be used at the next reboot.

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

Format the card

Format the kernel partition

mkfs.vfat -F 16 /dev/mmcblk0p1 -n gum-uimage

Format the rootfs partition

mkfs.ext2 /dev/mmcblk0p2 -L gum-rootfs

Remove and reinsert the card, you should have two mmc drives, one called gum-uimage and one called gum-rootfs

Enable booting from MMC in kernel

If you don't have the user.collection directory setup to change the appropriate conf file, do so like:

mkdir -p $USERBRANCH
cp -r $GUMSTIXBRANCH/conf $USERBRANCH

Edit the conf file for your gumstix, eg for the verdex the file is:

$GUMSTIXTOP/user.collection/conf/machine/gumstix-custom-verdex.conf

Uncomment the line:

MACHINE_FEATURES  += "mmcroot"

The kernel will now build with the necessary drivers

Save the file and rebuild the image:

bitbake -c rebuild task-base-gumstix
bitbake -c rebuild gumstix-kernel
bitbake -c rebuild gumstix-basic-image

Put the images on the card

Copy the uimage file from the working directory to the uimage partition on the card, eg:

cp $GUMSTIXTOP/tmp/deploy/glibc/images/gumstix-custom-verdex/uImage-2.6.21-r1-gumstix-custom-verdex.bin /media/gum-uimage/uimage

Make sure the file on the card is named uimage

Copy the gumstix-factory.script to the uimage partition as well:

cp $GUMSTIXTOP/extras/mmc-root/gumstix-factory.script /media/gum-uimage

Unpack the root file system to the rootfs partition on the card, eg:

sudo tar -xvpzf $GUMSTIXTOP/tmp/deploy/glibc/images/gumstix-custom-verdex/Angstrom-gumstix-basic-image-glibc-ipk-2007.9-test-20090212-gumstix-custom-verdex.rootfs.tar.gz -C /media/gum-rootfs/ 

Unmount BOTH partitions.

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