Big Sur and Monterey allow kernel extensions with limitations, particularly on M1 models. Full details, including how to control them.
kernel extension
How the kernel relies on its extensions to make your Mac work, and has highest privilege for stability and security. How this must change for Apple Silicon.
For the great majority of Mac users, M1 series Macs are a big step forward. But some users want the impossible. What can’t M1 Macs do?
According to macOS Help, safe mode stops some software from loading, and performs a check of the startup disk. Here’s a more detailed and accurate account of what it does.
Once the kernel takes over from iBoot, there’s a lot of hardware to get running before the SSV can be properly validation, and kernel extensions loaded.
Sometimes known as iBoot1 and iBoot2, they start work with the LocalPolicy for the intended boot volume, validating its vital components.
Understanding each of the four stages in the Secure Booting of an M1 Mac. These are summarised in diagram available here.
This article has now been extensively corrected and modified.
What’s the difference between an app and kernel memory leak? How would you notice one, and how to investigate it, and (sometimes) work around the problem.
Management of kernel extensions has changed significantly in Big Sur and later. This overview for users contrasts kexts with user-level extensions which are replacing them.
The Eclectic Light Company 