Apple Silicon Macs to Feature New Boot and Recovery Interface, New Mac Sharing Mode Replacing Target Disk Mode
Existing Macs include a number of macOS Recovery options at boot-up that are accessed using key combinations. For example, Command-R boots Macs in Recovery mode, and Command-Option-P-R resets the NVRAM. On Apple Silicon Macs, these key combinations are being replaced by an on-screen Startup Manager interface.
In the new system architecture, users can hold down the power button on their Mac to access the new startup screen, which features recovery options for reinstalling macOS, as well as options to boot as normal, shut down, and restart.
Apple is also replacing Target Disk Mode, which is used to transfer data between two Macs, with what's called Mac Sharing Mode. Mac Sharing Mode turns the system into an SMB file sharing server, providing another Mac with file-level access to user data. User authentication is required to access the service.
In addition, Startup Disk is a new feature that enables user to select different security modes for startup volumes. Full security, enabled by default, provides the same best-in-class security as enjoyed by Apple's iOS devices and let users boot from an external disk without reducing the security of the system.
Meanwhile, Reduced security mode provides more flexibility by allowing users to disable System Integrity Protection and run any version of macOS, including those that are no longer signed by Apple.
Lastly, Apple Silicon Macs run separate security policies for each OS installation, whereas Intel-based Macs operate on a less flexible system-wide security policy. For more details on this and the other new startup features, check out the full WWDC session on the Apple developer website.