Revision as of 14:38, 31 August 2010

Installing MeeGo to N900 on external MMC card

NOTE: Read the whole guide before doing any steps from this guide to make sure you understand everything.

If you do not want to erase the NAND partition or the internal 32G eMMC from the N900 device, this installation is for you. What you need for this installation is a raw image that can be put to the MMC card and kernel (same kernel that is installed to the MMC).

You may want to check for the most recent N900 sanity tests on the Quality/HandsetTestReport to see how much functionality is known to work on the N900.

Installing Rootfs on external MMC card

First what you need, is a microSD memory card which does not contain any information that you need, as it will be erased during this operation.

The steps in this guide require an MMC card of at least 2gb, however some cards offer slight variations in capacity, so better to take a 4gb card to be on the safe side :)

Linux

When inserting the microSD memory card in the card reader, you need to find out what the proper device for the card is. This can be done with for example fdisk:

sudo fdisk -l

An example output (NOTE: The /dev/sdX is used as an example on your PC this might be also called /dev/mmcblk0, /dev/sdd or something else)

$ sudo fdisk -l
...
Disk /dev/sdX: 3965 MB, 3965714432 bytes
194 heads, 30 sectors/track, 1330 cylinders
Units = cylinders of 5820 * 512 = 2979840 bytes
Disk identifier: 0x0001ab40

   Device Boot      Start         End      Blocks   Id  System
/dev/sdX1               1         588     1708984   83  Linux

NOTE: The .raw image contains the partition table as well. So the image needs to be written to /dev/sdX not /dev/sdX1.

After you are 100% sure that the /dev/sdX is the microSD memory card you just inserted in the card reader, you can use for example dd to put the image to the card:

$ sudo dd bs=4096 if=<raw_image> of=/dev/sdX

The dd does not show any progress until the file is written to the device, so be patient.

Although sending a USR1 signal to a running dd process makes it print I/O statistics to standard error and then resume copying:

$ dd if=/dev/zero of=/dev/null& pid=$!

from another term:

$ kill -USR1 $pid 

dd will output:

328356+0 records in 328356+0 records out 1344946176 bytes (1.3 GB) copied, 105.625 s, 12.7 MB/s

After this, you can insert the card in the N900.

Windows

1. Download and install bzip2 to Windows http://gnuwin32.sourceforge.net/packages/bzip2.htm
2. Uncompress raw image in command prompt "bunzip2.exe <compressed raw image>"
3. Download the Win32DiskImager.exe program: https://launchpad.net/win32-image-writer/+download (zip file)
4. Unzip the file and extract the contents to a known directory
5. Run W32DiskImager.exe
6. Select the MeeGo image file (note you must write *.* file name to see all files)
7. Select the drive letter which corresponds to the microSD memory card.
8. Click the "Write" button to byte-copy the image to the microSD memory card.

On the N900 itself

This should be a last resort solution.

1. Download and unpack the raw image to a desktop computer (see above).
2. un-mount the microSD memory card

sudo gainroot
umount /dev/mmcblkXpY
dd if=/home/user/MyDocs/meego-image.raw of=/dev/mmcblk1

Notes

• X, Y in umount command should be the device number and partition number, usually 1, 1, but maybe 0, 1 or something else, use:

cat /proc/partitions

for detailed information.

• There might be more than one partition on the microSD memory card, though it is unlikely.
• It is possible to download the compressed image to your N900 but it is not recommended as it takes very long to unpack.
• `dd` does not give any output while it is copying, so be patient.

Load or flash kernel on N900

NOTE: Back cover must be closed to boot from MMC.

NOTE: If you have a flashing jig, you will need to put a magnet at the red location marked here

Before the MeeGo is able to boot you need also load the kernel (vmlinuz) provided with the raw image to the device. This can be done with the flasher

$ sudo flasher-3.5 -l -b -k <kernel>

NOTE: The command above will only load the kernel to the device, so next time you boot the device the original kernel should be used and your Maemo 5 OS should boot normally.

If you want to flash the kernel to your device so that it is not forgotten when it is powered off use option -f instead of option -l on command above.