Setting up multi-boot on Pinephone (Pro or non-Pro)

Normal Linux installation process conceptually involves just a few steps:

• set up storage from which the system will run on the target device
• copy distributi­on's files from installation media to the storage media
• install and set up a bootloader
• reboot

If you're an Arch Linux user, this is nothing new to you, because you're doing this manually whenever you install Arch Linux. The process is documented on Arch Linux Wiki and you either follow the steps in the wiki, or you already know the 4 step process by heart, and just tell the system to perform the individual steps by typing a bunch of commands to console. You have some end result in mind, and you tell the system what it should do to achieve your desired result.

If you use Debian (or similar OS), things are different. Instead of you just telling the system what to do, the installation program asks you in a step by step manner what the result of the installation process should look like. You don't need to know how to achieve the result. Installation program will take what you dreamed up, and tranforms it into series of steps needed to achieve the result, and performs the steps for you in the background.

Typical Pinephone Linux distributi­on's insta­llation process takes this progression into an extreme, will not bother you with any questions and options, and simply offers pre-made disk images for cloning onto some storage in your phone (eMMC or SD card). You have no way to alter anything. There's no installation process. The installation happened on someone else's com­puter, and you just get a disk image of the result. This image contains ready-made parititon scheme, filesystems, bootloader, bootloader setup, etc. It's simple, but not flexible at all.

Why multi-boot on Pinephone

Multi-boot simply means that you want to have multiple options of what OS to boot or how to boot it on a single phone. For example you may want a regular keyboard/mouse driven laptop/desktop OS setup on one hand (either for convergence, or for use with the physical keyboard) and mobile optimized phone OS on the other.

Or maybe you want to have a stable installation of your favorite mobile OS combined with installation of the same OS from testing branch on the fast internal storage, so that you can get a sneak peak of what the next major upgrade will bring you, to see if there are any show stopper changes or bugs, before upgrading your daily driver installation.

Or maybe you're just tired of having to remove back cover and pop in SD card with Jumpdrive, each time you want to perform a backup of your OS by the way of disk imaging, before trying risky things, and you want to have Jumpdrive be part of a normal boot menu, to be able to just boot it anytime you want, to do backups, or manual recovery, or debug logs from a chrashing OS.

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