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by cesarb
696 days ago
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> You would "just pick the previous kernel from the boot menu". That's funny, cause in this case you could "just delete the file causing the issue." Anything can sound easy and simple if you state it that way. One small difference, is that choosing the kernel from the boot menu is done before unlocking the encrypted drive, so no recovery keys would be necessary. And yes, choosing an entry from a menu (which automatically appears when the last boot has failed) is simpler than entering recovery mode and typing a command, even without disk encryption. A better analogue would be a bad update on a non-kernel package which is critical to the boot sequence, for instance systemd or glibc. Unless it's one of the distributions which snapshot the whole root filesystem before doing a package update. |
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It's not filesystem snapshots either. It keeps track of input parameters and then "rebuilds" the system to achieve the desired state. It sounds like it would be slow, but you've still got those build outputs cached from the first time, so it's quite snappy.
If you took a bad update, and then boot to a previous revision, the bad update is still in the cache, but it's not pointed to by anything. Admittedly it takes some discipline to maintain that determinism, but it's discipline that pays off.