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.
Secure Boot
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?
macOS 11.4 has finally fixed all the problems with installing current and older macOS on external disks, and booting an M1 Mac from them.
What are a new kernel extension and a private framework doing in macOS 11.4? Here are some details, and suggestions for further research.
One command in Terminal which instantly disables any support, and why you can’t (yet) boot your M1 Mac in Linux.
The Eclectic Light Company 