System partition mode documentation

[hacker1024]

There's no documentation about the "System partition mode" checkbox, on the custom ROM adding screen.

All I know from a few guides is that it's needed for Magisk, but there's no information anywhere about what it actually does.

[cosmicdan]

Just in case anybody comes here via Google (like I did), the technical explanation from the original commit covers it: https://github.com/AdrianDC/multirom_bootable_recovery/commit/7e42fad68f7c421ba1e4a859c22fa815f9781f93

[cosmicdan]

My own possibly-wrong but easy-to-understand explanation: it sets the ROM/slot up to use a new mount method that is compatible with Magisk (and possibly other ZIPs).