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macOS can be booted from a .dmg for decades already, why make a "sealed" "read-only" volume if the updater then unseals it, basically copies all files from the
by WesolyKubeczek 6y ago
macOS can be booted from a .dmg for decades already, why make a "sealed" "read-only" volume if the updater then unseals it, basically copies all files from the update package into it, those files including generated stuff like the shared dyld cache, and then re-seals the volume again, recalculating all the checksums?
All that work the updater does seems really superfluous, since the System volume is declared "immutable". Why replace files on it? Just drop a .dmg, boot from it.
- kitsunesoba 6y agoI don't know enough about macOS system internals to confidently speak about them, but my guess is that there's some kind of legacy cruft/holdover that's preventing a direct disk image replacement for updates. Wouldn't be surprised if this were fixed in the next major release or two, likely paired with dropping support for something.