macOS has changed fundamentally. So has troubleshooting it. Secure Boot, the SSV, and Gatekeeper checks bring changes in strategy.
Secure Boot
Apple silicon Macs are better-equipped to prevent and deal with disaster. Restoring in DFU mode is extremely unusual, and more powerful than anything you can do with an Intel Mac.
Why can some with Apple silicon Macs create and boot from external disks, while others seem doomed to failure?
Maybe you’ve just forgotten the password, or perhaps the owner/user of the Mac is no longer able to enter it. How to restore access to different models.
in Mac OS 8 and 9, you could patch the system direct. OS X was harder, and became sprawling and interdependent, encouraging users to reinstall macOS. That has now ended with the introduction of the SSV.
Assigning ownership to an external bootable disk doesn’t always work in Recovery mode on an M1 Mac. But there’s an easy workaround.
M1 Macs are different, as they always start booting from their internal SSD. Basic configurations are simple, reliable with well-established disaster recovery methods.
A strange volume named xART or xarts, secure memory management, and long random numbers: how they fit together to protect against replay attacks.
One command, bless, used to do it all, copying boot.efi to the right place and declaring the volume bootable in its header. Where are we with Big Sur and M1 Macs?
Soon after Apple started delivering M1 Macs, users found that they couldn’t boot them from external disks. Six months later, this has largely been fixed. What went wrong?
The Eclectic Light Company 