The Morty, Pyro, Rocko, Sumo, Thud, Warrior, Zeus, Dunfell, Gatesgarth, Hardknott, Honister and Kirkstone branches are community supported. There is no warranty of any kind. At the time of creation they built, install and boot. However, only Kirkstone is a current Yocto LTS version. For Morty the separate parts (u-boot, kernel and rootfs) must be installed manually. After Pyro this is optional, you can use flashall or Flash Tool Lite and overwrite your factory image.
In the following we assume you want to use the latest (Kirkstone) and will only mention deviations for the older versions when absolutely needed.
When you install everything manually, the only permanent change is the u-boot update (but you might need to update IFWI as well), and that should not affect your ability to run your factory Edison Image. The kernel will be installed in a partition that is currently unused (the oversized OTA partition) and the rootfs on an external sd card or USB stick.
With the manual installation and the rootfs on external card or disk you must press ESC during boot and type a command to boot the external Sumo image. If you don’t the factory image will boot automatically.
If you use flashall or Flash Tool Lite the factory image is gone, but your new Hardknott will boot automatically.
We recommend trying the manual installation first and after you have established that you like it better then factory, then make the changes permanent.
Your home partition is left untouched and shared by the image on EMMC and the SD Card (if you have that). However, when you install the btrfs image everything is erased, see the btrfs section in this documentation.
Consider that the Edison allows you only to log in as root, and no root password is set. You know what can come of that. To secure the device, as a starting point you probably would like to create a user account, assign that sudo privileges, and configure sshd so that root logins are forbidden. This will still allow you to login via the console (the terminal connected via USB).
In case things go wrong, you can take the SD card, plug it in your computer (it is formatted as ext4, so under Windows that might not be so easy) and fix things from there.
If you really mess up the device, for instance by installing a broken u-boot (I did this), or break the u-boot environment variables in such a way that nothing boots, I provide the recovery tools and an image (or you can recover your own if you like). Note that recovery here means recover the Edison so that it will boot again. All the partitions (except the factory partition) will be wiped, so if you have anything important on the device, you might want to back that up in advance. In particular, the factory partition contains the address for the Bluetooth device, and if you manage to loose that there is now way to get it back. Make a copy of the files in /factory and save them in a safe place, whatever you do next.
Nevertheless, you might find ways to break the Edison that nobody thought off. In that case, I told you so, and you get to keep the pieces.
With that out the way: the original Edison kernel has the same potential to break things, is badly secured and the image software is based on sources that are many years old (i.e. has many known security issues). At least Yocto Dunfell and later are being actively maintained. And the kernel applied here is for now not more than 10 weeks behind the latest official Vanilla release.
© 2018 Ferry Toth