Advanced booting

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This article covers advanced booting procedures and configuration options. For the vast majority of people booting from a flash card will cover everything they need to know.


[edit] Multi-boot

The process for setting up a multi-boot is similar to Booting from a flash card. It's a good idea to ensure that the first partition is a FAT/data partition - this keeps things simple.

A sample partition layout on an 8Gb card might be:

  • 2GB primary vfat data
  • 2GB primary everyday
  • 2GB primary debian
  • 512MB logical test1 (diablo)
  • 512MB logical test2 (chinook)
  • 512MB logical test3 (diablo)

Be aware that the kernel initfs supports a limited number of partitions; this can be extended to 6 but no further. This requires editing /home/user/local/bin/initfs_flasher/initfs.bootmenu.jffs2 to add the dev nodes using mknod (eg: mknod -m600 initfs/dev/mmcblk0p5 b 254 5)

When cloning, you may edit to remove the TARGET= line and then run it as follows:

TARGET=/dev/mmcblk0p5 ./ 1

To create pristine images of Diablo/Chinook, follow the instructions for Modifying the root image, but once you have the rootfs.jffs2 image extracted, you can follow the mount instructions and rsync the rootfs to the tablet.

I used this script (which now works fine)

# This script connects to the tablet and sends the selected rootfs to the selected partition
mkdir -p $IMAGE_DIR
# unpack fiasco
mknod /tmp/mtdblock0 b 31 0
modprobe loop
losetup /dev/loop0 $IMAGE_DIR/rootfs.jffs2 
modprobe block2mtd
modprobe mtdblock
# Note that on a host running 2.6.27-rc2 (and probably *much* earlier), the ,128KiB sets the erase size.
echo "/dev/loop0,128KiB" > /sys/module/block2mtd/parameters/block2mtd
modprobe jffs2
mkdir /tmp/jffs2
# mount the rootfs ro
mount -t jffs2 -o ro /tmp/mtdblock0 /tmp/jffs2
# copy files
ssh root@nut insmod /mnt/initfs/lib/modules/2.6.21-omap1/ext2.ko \; mkdir /tst \; mount $PART -o noatime /tst
(cd /tmp/jffs2;tar cf - . | ssh root@nut cd /tst\;tar xf -)
# rsync may not work
# rsync -av /tmp/jffs2/ root@nut:/tst/
ssh root@nut umount /tst \; rmdir /tst
#clean up
umount /tmp/jffs2
rmmod jffs2
rmmod mtdblock
rmmod block2mtd
losetup -d /dev/loop0
rm -f /tmp/mtdblock0
rmdir /tmp/jffs2
rm -rf $IMAGE_DIR

[edit] Boot messages

So if you want to see the kernel boot log or dmesg type output when you boot here's how (thanks to qwerty12 for the pointers)

Check you have an up-to-date initfs - does this file exist:


If not then install fanoush's bootmenu/initfs.

Log into the tablet and remount initfs so you can edit it directly. (If this doesn't make you nervous then you should stop now!)

mount -o remount,rw /mnt/initfs

Now grab some kernel modules from here:

and copy the 4 modules you find in



/mnt/initfs/lib/modules/`uname -r`/

I extracted them on my host and did:

scp drivers/video/console/* root@nut:/mnt/initfs/lib/modules/2.6.21-omap1/

Now, for each bootmenu where you want a bootlog, edit /mnt/initfs/ and add

softcursor bitblit font fbcon

to any MENU_N_MODULES= lines Also add a line like this (where MENU_2 will differ for you):



MENU_4_NAME="Diablo Test"
MENU_4_MODULES="mbcache ext2 softcursor bitblit font fbcon"
[ -d "/sys/block/${INT_CARD}/${MENU_4_DEVICE}" ] || MENU_4_NAME="(${MENU_4_NAME}) N/A"

Finally, remount the initfs as ro and reboot.

mount -oremount,ro /mnt/initfs/

Once your system starts, don't forget to run

/mnt/initfs/usr/bin/fb_update_mode manual

or the display will run slowly.

[edit] Initfs hacking

Work in progress - move along

In case it isn't blindingly obvious - messing with the initfs and your tablet flash can burn you.

Note: The tools and data used whilst flashing must be stored on linux filesystems - not FAT/FAT32.

If you are brave you can edit your initfs directly if you mount initfs read-write:

mount -oremount,rw /mnt/initfs
vi $random_files

Don't forget to put it back:

mount -oremount,ro /mnt/initfs

This can be randomly dangerous if initfs partition is almost full (true for anything before Diablo) because your initfs can run out space whilst you are saving due to the way jffs2/flash systems work. Basically you may end in situation when even 'rm file' returns 'no space left on device'. Diablo update enlarged initfs partition from 2MB to 4MB so there is enough free space to make jffs2 garbage collector work properly (unless you fill it up again).

A safer approach (taken from fanoush's script) is:

cd somewhere_on_a_linux_fs
mkdir initfs.orig
mount -t jffs2 /dev/mtdblock3 initfs.orig
cp -a initfs.orig initfs
umount initfs.orig
# edit intifs/...

Then, once it's all edited and ready, you create a jffs2 and burn it.

mkfs.jffs2 -r initfs -o my_initfs.jffs2 -e 128 -l -n
chroot /mnt/initfs mount -t jffs2 -o remount,ro /dev/mtdblock3 /
echo " *** caching old initfs to memory (for crash prevention)"
# block level, probably useless
dd if=/dev/mtdblock3 of=/dev/null bs=65536 2>/dev/null
# file level, read all interesting stuff (should be enough to cache dsme and bme)
tar cf - /mnt/initfs/usr /mnt/initfs/lib /mnt/initfs/bin /mnt/initfs/sbin >/dev/null 2>/dev/null
flash_eraseall -j /dev/mtd3
echo " *** flashing $1 image ..."
nandwrite -a -p /dev/mtd3 $1

Then reboot (/sbin/reboot) as soon as possible. dsme and bme daemons are running from (old) initfs and by reflashing underlying filesystem you just cut the branch they are sitting on. Caching done before flashing does not solve it completely.

At this point you will probably realise that grabbing fanoush's script and inserting a few extra commands to drop you to a shell etc is a lot easier than doing it all by hand. Or you may start another shell while initfs_flash script is waiting for your answer (include telnet/dropbear/bootmenu.conf?) and modify stuff in initfs_flasher/initfs/.

[edit] Devices

The standard initfs is missing some devices that may be useful on sd cards with lots of partitions so:

mknod -m600 initfs/dev/mmcblk0p3 b 254 3 2>/dev/null
mknod -m600 initfs/dev/mmcblk0p4 b 254 4 2>/dev/null
mknod -m600 initfs/dev/mmcblk0p5 b 254 5 2>/dev/null
mknod -m600 initfs/dev/mmcblk0p6 b 254 6 2>/dev/null
mknod -m600 initfs/dev/mmcblk0p7 b 254 7 2>/dev/null

mknod -m600 initfs/dev/mmcblk1p3 b 254 11 2>/dev/null
mknod -m600 initfs/dev/mmcblk1p4 b 254 12 2>/dev/null
mknod -m600 initfs/dev/mmcblk1p5 b 254 13 2>/dev/null
mknod -m600 initfs/dev/mmcblk1p6 b 254 14 2>/dev/null
mknod -m600 initfs/dev/mmcblk1p7 b 254 15 2>/dev/null