MDS, Big Sur, and Apple Silicon Challenges

Apple simultaneously released new Mac hardware, a new OS (Big Sur), and transitioned to a new processor (Apple Silicon) on a single day. We have been tracking the changes with Big Sur builds and the Developer Transition Kit (DTK), but with the release of Big Sur and the new Macs, we are able to test on shipping hardware with a shipping OS. This applies to both Intel Macs and the new Silicon Macs. We tested with a 2020 MacBook Air (Intel) and the new 2020 MacBook Air (M1). Our focus was deploying Macs using MDS for this hardware and Big Sur. This article outlines the issues discovered, feedback filed, and some recommendations for mitigating these issues.

Intel Mac Big Sur Issues

Issue : Intel Macs upgrading to Big Sur from Catalina Recovery

MDS deploys Macs by running workflows from macOS recovery to wipe, install macOS, and install packages (either when the workflow is running, after the OS is installed, or at first boot). Every recent macOS installer has a command line tool called “startosinstall” that provides a command line way to install macOS on a target volume and specify packages to install after the OS is installed. In prior versions of macOS, booting to a recovery that is newer than the OS that is being installed has been problematic (e.g., booting to a Catalina recovery and installing Mojave). However, installing a newer OS (like Catalina) when booted from a older recovery (like Mojave) has worked fine. With Big Sur, it was discovered that running startosinstall from a Big Sur installer on a Catalina recovery partition cause the installer to crash.

This issue was filed Aug 18, 2020 as FB#8454260 and has not been responded to by Apple.

The same issue applies to a Catalina external drive trying to upgrade to Big Sur using a Big Sur installer. Both environments are the same.

Workaround: Boot from a Big Sur internet recovery before running an MDS workflow.

Update: Apple is aware of the issue and a fix is in the works.

Issue #2: Big Sur Internet Recovery not always available

In order to workaround the issue of upgrading to Big Sur in a Catalina recovery, it is recommended to boot to Big Sur internet recovery by holding Command-Option-R (⌘-⌥-R) on a Mac that supports Big Sur. However, some Macs will not boot to Big Sur even if the Mac is compatible. It has been suggested that a firmware/bridgeOS is required in Catalina, but we have seen a Mac that has Big Sur installed on it with the most recent version of bridgeOS not able to boot to Big Sur recovery. It is unknown why Big Sur was not available in Internet Recovery; however, manually reinstalling Catalina, then upgrading to Big Sur from Catalina in the booted OS, allowed the Mac to successfully boot to Big Sur Internet Recovery.

Issue not filed with Apple since it can no longer be replicated with test hardware. If this issue affects you, please file a feedback issue and let me know the FB#.

Workaround: Install Catalina, then Big Sur from Catalina. Once Big Sur is installed, boot to Big Sur recovery and run MDS workflow to install Big Sur and packages.

Issue #3: Missing WiFi in Big Sur Recovery

On the 2020 MacBook Air and MacBook Pro, it has been reported that when booting to Big Sur recovery, Wi-Fi is not available. It does not show up in recovery, Internet Recovery, or when booting externally; the Wi-Fi menu does not appear, and using networksetup to join by SSID is unsuccessful, returning a hardware not available message. Wi-Fi works fine if booted to Catalina. Attempts to re-install Big Sur fail due to lack of network since a network connection is required.

Issue filed by Joseph Chicote FB#8901618

Workaround: use a USB ethernet dongle to provide network.

Update: Apple is aware of the issue and a fix is in the works.

Apple Silicon Mac Big Sur Issues

Issue : Cannot run startosinstall

In Apple Silicon Macs, the recovery environment requires the user to press and hold the power button to enter in recovery. Once booted to recovery, the Terminal is available. However, as of macOS 11.1 beta, when startosinstall is run from a valid Big Sur installer, a message is printed that this tool is not supported in Apple Silicon recovery. Without this tool, it is not possible to automate the re-install of macOS from recovery. Apple provides other methods (such as Apple Configurator 2 or MDM/DEP workflows), but those methods do not allow a Mac in an unknown state to be wiped and macOS reinstalled in a timely, efficient manner. It is common for people upgrading from one Mac to another to “turn in” the old Mac when receiving the new Mac. It is critical for large organizations to be able to wipe and reinstall macOS on a large number of Macs.

Filed as Issue FB#8923918

Workaround: Use Apple configurator or MDM to wipe Macs, then run an MDS workflow to install non-OS install packages.

Issue #2: Selecting recovery remotely

In CI/CD environments, it is common to boot to recovery, wipe and reinstall macOS, and provision software automatically. With Intel Macs, it was possible use a keyboard combination remotely (⌘-R) to boot to recovery and automate the process of deploying the Mac. With Apple Silicon Macs, the power button is not able to be sent as a remote keyboard command and physical access it required to boot to recovery. This makes deploying Macs as CI/CD Macs difficult to deploy.

Submitted Feedback: FB#8923930

Issue is in the process of being written up. This article will update once it has been filed.

What can you do to help?

If any of these issues affect you or your organization, here is what you can do to help get this resolved:

  1. If you have an AppleCare support contract, escalate the issue with your AppleCare contact. Be sure to let them know the number of Macs affected.
  2. If you see any of these issues affecting your ability to buy or deploy new Macs, contact your Account Executive, Apple SE, or Reseller. Point them to this article and/or the feedback numbers. Apple tracks customer feedback in a system called “Voice of the Customer”. Make sure to let them know how many potential future Mac purchases this may affect.
  3. File a feedback. Go to https://feedbackassistant.apple.com and write up the issue and reference the FB number above. This helps Apple see the number of “dups” an issue has and hopefully raises the priority.