It is possible but not recommended.
okreader might be abandoned but what it does still stands. KOReader runs on top of the linux kernel and needs a couple of blobs to figure out it runs on kobos. okReader reimplements those blobs as free software.
Other than that, you'll only need to hook in the init scripts of the kobo system (or deploy your own init scripts in your rootfs)
If your kobo has an internal sdcard and you're not worried of open it, making a backup and solder into the serial header you're free to go. You can also try without a serial port if you forget about erasing rakuten kobo or tweak the rootfs in any way other than lauching KO after the dots animation.
You can expect no support during your endeavour, which is a big plus for me on the world of hacking for fun, but most people want to avoid that to squeeze 5 seconds each boot.
|