11/12/2022 0 Comments Mac os x utilities version 1.0 33![]() ![]() First, LLB doesn’t lock the flag in the Boot Progress Register, so that when Fallback Recovery (frOS) has loaded, any attempt to use Startup Security Utility or bputil will fail. When the double-press and hold action with the Power button has been used instead, a similar boot process ensues, with two important differences. Finally, recoveryOS is loaded and run, with one key setting: because of the flag set in the Boot Progress Register, both Startup Security Utility and bputil are enabled, and shouldn’t return errors. ![]() #Mac os x utilities version 1.0 33 fullThere’s no scope for recoveryOS to load third-party kernel extensions, of course, as it’s running in Full Security mode. LLB then hands over to a custom iBoot (stage 2) which performs validations and loads a fixed set of firmware, kernel extensions, and the device tree. It also locks a flag in the Boot Progress Register to indicate that this is a user-initiated launch of recoveryOS. As that can’t be downgraded below Full Security, that should be straightforward. To achieve that, LLB validates LocalPolicy for recoveryOS. In all normal circumstances, the Power button will simply have been pressed and held, which calls for 1 True Recovery (1TR). At some early stage, though, the LLB has to determine which of the two recovery modes has been called, according to the pattern of presses on the Power button. Pressing the Power button starts what appears to be a normal boot process, with the Boot ROM handing over to the first stage LLB to start firmware signature validation. #Mac os x utilities version 1.0 33 macThe end result is far more consistent, coherent and capable.Īs I explained a couple of days ago, there are only two ways for a user to boot an M1 Mac into a Recovery mode: press and hold the Power button for the normal mode, or press twice and hold the Power button for fallback recovery mode instead, when it’s available. Unlike Recovery and its related modes on Intel Macs, which include some UEFI apps, Apple has completely redesigned the recovery environment, which is kept in its own container (partition) on the internal SSD. Having looked at how an M1 Mac boots into macOS yesterday, today it’s the turn of its unique Recovery system. ![]()
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