Thursday, December 16, 2021

How Recovery Works on M1 Series Macs

Howard Oakley:

These recent macOS updates break from two traditions: for M1 models, their ‘firmware’ update also brings a new Recovery system which is based on the latest macOS, in this case 12.0.1 even when the update is 11.6.1, and a single Recovery system is installed in each APFS container with one or more bootable systems.


1 True Recovery (1TR) is engaged as usual by pressing and holding the Power button until the display shows that Options are loading or have loaded. This can only be engaged by the user pressing the Power button, and only 1TR supports the full features, including Startup Security Utility, which you can use to change its Secure Boot settings.


Let’s say that you have an M1 Mac with two Monterey boot systems: one on the internal SSD, the other on an external SSD. To change the Secure Boot settings for the internal SSD, your Mac must boot into the Recovery system installed on the internal SSD, which is in the same container and paired with that macOS system. To change the Secure Boot settings for the external SSD, you must first boot from that external SSD, shut down, then start up in Recovery, which will be the Recovery volume on the external SSD.

Unlike in Big Sur, the Recovery system in the boot container on the internal SSD doesn’t have the ability to change Secure Boot settings for the bootable system on the external SSD.

I think this means that if you install a beta version of macOS, even on a different drive, your firmware 1TR gets replaced with a beta version.


Update (2021-12-17): Howard Oakley:

Yes, but:

  • the firmware rOS is a fallback now, not the primary rOS
  • the firmware itself gets upgraded anyway, which is usually more worrying
  • on an M1, you can always restore firmware and rOS in DFU mode.

So it’s not as bad as it might sound. I think.

Howard Oakley:

Unlike Intel Macs, M1 series Macs can’t enter Startup Manager, to pick a boot volume early in the boot process, using the Option key. There are two main methods available on M1 models: the Startup Disk pane in macOS, and entering Recovery, where a different Startup Manager can be accessed either from the opening screen or later in the Apple menu.

4 Comments RSS · Twitter

What a pain. Someone explain to me how this is better or preferable to what we had before.

The pain is in the technical detail, not Recovery mode itself.
M1 Recovery mode doesn't require you to memorise or look up any arcane startup key combinations. There's just the single action to engage it.
What's provided in Recovery is better laid-out and more navigable.
It's also more reliable - the fallback recovery system is a separate container/partition on the internal SSD, not just a volume within the bootable system.
Why don't you try it out?

Bri is right. Howard, this is just change for change's sake. If there is no tangible improvement to a system, then changing it is fashion rather than function. Bell bottoms this year, slim leg last year. Apple is wasting everyone's time. You're a very smart guy, and your SilentKnight is essential software, but far too keen to excuse and make excuses for Apple.

Kevin Schumacher

Being more reliable is not a tangible improvement? Being easier to use is not a tangible improvement?

What exactly do you deem a necessary change, then?

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