The core of OSes need to be treated more like read-only firmware that only gets updated as-needed and is unable to be over-written by itself, e.g., send a reque

The core of OSes need to be treated more like read-only firmware that only gets updated as-needed and is unable to be over-written by itself, e.g., send a request to the BIOS to look for a valid public-key signed image file to be applied on reboot. Flash is so cheap, 64 GiB mirrored SSD devices should be available for operating system images on system boards. Leave OS images as signed squashfs files on a dumb flash FS like exFAT. Delta updates can be applied by stripping-out entropic-metadata, patching and recompressing a previous release to arrive at the valid signature of a complete latest release. Mixing operating systems, configuration, programs and user data in together is a recipe for fail.