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Getting started with Kobo reader hacking

Introduction

I have a Kobo ereader ( a first generation one, without wifi). It is a relatively open e-reader platform:

  1. Source code for the kernel (and some other things) was made available by Kobo developers at

    https://github.com/kobolabs/Kobo-Reader

  2. Kobo can boot of an external sd-card, in fact it is one of the methods for upgrading firmware

    http://bordersau.zendesk.com/entries/234241-how-do-i-update-my-kobo-firmware-if-i-am-using-linux

  3. While source code for the main reader application is not made public there is a public plug-in interface that allows for extension of the main reader application.

Running Your own

Booting sd-card

  1. Format sd-card as ext3
  2. Populate with your choice of root

    A good place to start is the firmware update sd-card linked earlier. Just edit etc/init.d/rcS to disable firmware update and add your code.

  3. Power off your reader and insert sd-card into it
  4. While holding down middle button on D-pad press power button
  5. Keep holding down middle button until squares start appearing on the screen

Use commands show_pic and led to see if it is running your code.

Patching Kobo startup script

Kobo startup is rather simple: it just runs /etc/init.d/rcS . This script does minimal set up (mounts mainly) then it launches main reader application: nickel. What we want to do is add the following lines to rcS file

if [ -f /mnt/onboard/runme.sh ] ; then sh /mnt/onboard/runme.sh >/mnt/onboard/out.txt 2>/mnt/onboard/err.txt & fi

This will run runme.sh script on startup if it is present on the internal flash drive of the Kobo reader. The outputs of that script will be redirected to files out.txt and err.txt for standard/error outputs.

You have two options to get that change into the firmware: 1. Modify firmware files on your PC and then re-flash modified firmware 1. Boot sd-card image with a script that modifies internal firmware.

Of the two options second one is probably the easiest. Here is a relevant part of the official sd_upgrade_fs.sh

```

upgrade_filesystem

mkdir -p /mnt/flash
echo "Upgrade filesystem"
mount /dev/mtdblock4 /mnt/flash -t yaffs2
cd /mnt/flash
/bin/show_pic /pic/02.jpg
tar zxvf /files/${dev_name}/fs.tgz
sync
sleep 1
sync
cd /
umount /mnt/flash

end upgrade_filesystem

```

see: http://bordersau.zendesk.com/entries/234241-how-do-i-update-my-kobo-firmware-if-i-am-using-linux

Once you have the patch in place you can experiment with your Kobo without booting sd-card.

References

While some of the above is a result of original investigations done by me, a lot of it is sourced from various other sources online.

Here is an incomplete list of sources