New Macs with Apple Silicon will feature revamped macOS boot and recovery features, based on iPhone and iPad Secure Boot. Although it uses the same boot process, it has been enhanced for Mac and will support multiple macOS installs, multiple versions of macOS, and recovery flows.
Advanced boot options such as holding down shortcut keys to boot into recovery mode, target disk mode, or single-user mode, will work without remembering any shortcut keys. All these start-ups keys will be replaced with user interface interactions. Users will simply need to press and hold the power button, or Touch ID button, on their Mac to bring up the new Startup options. Users will still be able to use shortcut keys when the new Startup options load, but they will not need to press and hold any combination of keys to boot into a particular mode.
macOS Recovery on Apple Silicon Macs will also feature two new features called Mac Sharing Mode and Startup Disk. Mac Sharing Mode will replace Target Disk Mode and utilize SMB file sharing to allow access to user data. Startup Disk will allow selecting full or reduced security modes for the various disks in a Mac. Full security mode will provide the same security features that you get on an iPhone, while supporting booting from external disk. This will be the default mode in Apple Silicon Macs. Meanwhile, reduced security mode will allow users to install any compatible version of macOS, and notarized 3rd-party kernel extensions.
Contrary to speculations that Apple will be locking down the Mac through the introduction of Apple Silicon, the company shared that it will allow users to disable Secure Boot, Root Volume Authentication, and System Integrity Protection.
Apple shared these details, and more, in a session during WWDC 2020 called 'Explore the new system architecture of Apple Silicon Macs'. The session went into details of how Apple Silicon differs from Intel processors on an architecture level and the modern features and advantages it will bring to the Mac. Apple Silicon will utilize a unified memory architecture for CPU and GPU, allowing apps to gain performance and security benefits as long as they utilize Metal and other Apple frameworks.
