maemo.org - Talk - GUIDE: Maemo on SD card

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- Nokia N900 (https://talk.maemo.org/forumdisplay.php?f=44)

- - GUIDE: Maemo on SD card (https://talk.maemo.org/showthread.php?t=83719)

GUIDE: Maemo on SD card

Maemo on SD card

DISCLAIMER: THIS GUIDE CAN POTENTIALLY BRICK YOUR PHONE, THE AUTHOR IS NOT RESPONSIBLE FOR ANY DAMAGE TO YOUR PHONE

Introduction:
In this guide i will explain how to move Maemo from the internal flash to the SD card, this guide is based on what i did to unbrick my phone so it might not be 100% accurate as my success in it was mostly trial-on-error, however , the steps in this guide ARE correct, of that i am sure, it might just be that i forgot something,

Benefits:

More rootfs space
(If using U-Boot)No need for flasher anymore
Unbricking USB-less phones or preventing irreversable bricks on such devices
rootfs free for alternative OS/storage/whatever you might want to use it for

Requirements:

Ability to build your own (N900) kernel.
(Recommended) U-Boot
Linux PC with working UBI and nandsim (If you don't have this, the SDK VM will do fine.)
MicroSD card ( 1GB or larger )
U-Boot mkimage (uboot-mkimage package in SDK VM)

Steps:

Step 0 - Clean eMMC:
If the N900 /home partition contains optified apps/Maemo programs, you will need to format/reflash eMMC, this can be done through flashing a new eMMC image or through the devices x-terminal.
If you dont do this, the phone might get stuck at the bootscreen!

Step 1 - Partitioning SD card:
If using U-Boot, you need to create a small (a couple of MB's) FAT16 (msdos) partition before the main partition
Either way, you now need to format the main partition ext3 and mount it somewhere on your development machine

Step 2 - Mounting root filesystem:
Either enter these commands one by one or make it a script:

Code:

modprobe mtdblock

modprobe ubi

modprobe nandsim first_id_byte=0x20 second_id_byte=0xaa third_id_byte=0x00 fourth_id_byte=0x15

#I reccommend testing if nandsim works by catting /proc/mtd, that should yield:

#dev:    size   erasesize  name

#mtd0: 10000000 00020000 "NAND simulator partition 0"

#

#MAKE SURE THE NUMBER AFTER mtd MATCHES THE ONES IN

#THE NEXT COMMANDS OR YOU WILL NUKE A REAL FLASH

#CHIP IN YOUR DEVELOPMENT BOX

 

dd if=rootfs.jffs2 of=/dev/mtdblock0 bs=2048

ubiattach /dev/ubi_ctrl -m 0

mount -t ubifs ubi0_0 <PREFERRED MOUNT POINT>

Step 3 - Transferring rootfs:
Use the following command for this, -r will make cp recurse into directories, -p will make it preserve ownership and access masks.

Code:

cp -r -p <ROOTFS MOUNTPOINT>/* <SDCARD PART2 MOUNTPOINT>

Step 4 - Configuring your kernel:
Use your preferred ARM (GNU EABI) toolchain for this, or use scratchbox, you need to use the default config for the N900 (rx51_defconfig), and make the following changes:

Built in ext3 filesystem
Built in MMC subsystem
Built in OMAP MMC host driver (The one already set to module)
Command line: "/dev/mmcblk0p<PARTITION> rootwait rw init=/sbin/preinit" (Partition is 1 for flasher boot and 2 for U-Boot users)
Disable cpufreq or build as module. (WORKAROUND for kernel panic when combining mmc and cpufreq)
(Only for extra debugging) Framebuffer console built in

Now build the kernel and modules, install modules to the sdcard's /lib/modules/<KERNEL_NAME>'

Step 5 (U-Boot) - Configuring U-Boot
First you need to turn your kernel into an U-Boot kernel image:

Code:

mkimage  -A arm -O linux -T kernel -C none -a 80008000 -e 80008000 -n MaemoSD -d <PATH TO zImage> <SD BOOT PART MOUNTPT>/lmaemosd

Next you need to create a file containing the following code:

Code:

mmc init

echo "Booting Maemo from SD card"

fatload mmc 0:1 ${loadaddr} maemosd

setenv atags ${nolo_atagaddr}

bootm ${loadaddr}

which you need to turn into a U-Boot script with:

Code:

mkimage  -A arm -O linux -T script -C none -a 0 -e 0 -n MaemoLoader -d <PATH TO SCRIPT SOURCE> <SD BOOT PART MOUNTPT>/boot.scr

Step 5(Flasher) - Flashing your new kernel
Put your N900 into flashing mode and run:

Code:

flasher-3.5 -k <PATH TO zImage> -f -R

Step 6 - Testing
Unmount all SD card partitions and put it in your phone, it should boot into Maemo, to verify that it has worked, open xterm and enter df -h, it should show a significantly larger rootfs!

Credits:
x86 - rootfs mount guide
DocScrutinizer and other people from #maemo - Helping me fix some problems with this