An immutable OS is fixed and mounted non-writable. Every update you get, every program you install is handled on top of it via containers or filesystem overlays so the underlying OS is untouched. Basically the same concept you know from smartphones or other devices with a “reset to factory settings” function. No matter how hard you screw up your system, you can always reset to the base OS, either by granulary deactivating things installed on top, or by a reset to the working base OS.
That’s interesting. Thanks.
So how are OS updates handled, they are not written into the main OS?
They are written but don’t replace something in the read-only OS. They are just overlayed, so once removed the original is still there. How they do it differs. There are actual overlay filesystems for the job, or some use btrfs where all subvolumes behave mostly like virtual partitions (and copies of a subvolume only take space for changes of the original).
Immutable in this context refers to an OS that can’t be changed while running. Steam deck does something like that. Basically the all of the OS system files are read only, so that the user or some malware can’t Bork the system. The only parts that are writable are the users profile directory and the logs.
You can still receive updates and install apps. It’s just that that’s handled a bit differently than with a standard OS.
E.g. it could be that the OS provider only issues complete updates, and then you either have to reboot. This is the case with steam os on the steam deck. The System portion of the OS is mounted read only during use.
Sounds pretty secure except for at the update stage, but you said that’s handled differently so maybe that’s more secure too.
Depending on the use case there’s usually a temporary system that’s there only to take the update from the user partition and apply it to the system partition. So even if you bork the update it’ll still boot into that environment and install the system again. Valve does provide bootable images to put on a USB stick if you do break it pretty bad. It’s just a PC, it doesn’t do much to stop you from wiping the disk. The route Android took is A/B devices, when you’re using A you update B and then reboot into B, then the next update you’ll be updating the A partition and reboot into it. Plus if the next one fails to boot for some reason you can revert to the old version as if nothing happened, and retry the update from scratch. Except Samsung, because I don’t know I guess they want to turn the updating into a whole experience of anticipation or whatever crap reason they have for it.
You see, some operating systems are mostly operated by sound. If you mute them, they stop working. So it makes sense that you can’t mute them.
What happens when an immutable OS meets an unstoppable OS?
Can god make an OS so immutable, even he can’t update it?
It’s complicated. Technically no, but God can roll out a new image with the updates, so in practice, yes?
Why is religion never simple…
