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macOS Big Sur 11.0.1 Universal Apps Release Notes

Update your apps to support Macs with Apple silicon.

Overview

The macOS 11 Universal Apps beta SDK aids in the creation of Universal Mac apps that run on both Apple silicon and Intel-based Mac computers running macOS Big Sur 11. The SDK comes bundled with Xcode 12.2, available from the Mac App Store. For information on the compatibility requirements for Xcode 12.2, see Xcode 12.2 Release Notes.

This page is specific to the Developer Transition Kit. For additional macOS 11 changes, see macOS Big Sur 11.0.1 Release Notes.

General

Known Issues

Auto Unlock

Known Issues

  • Auto Unlock is unsupported. (63733266)

Code Signing

New Features

  • New in macOS 11 on Macs with Apple silicon, and starting in macOS Big Sur 11 beta 6, the operating system enforces that any executable must be signed before it’s allowed to run. There isn’t a specific identity requirement for this signature: a simple ad-hoc signature is sufficient. This new behavior doesn’t change the long-established policy that our users and developers can run arbitrary code on their Macs, and is designed to simplify the execution policies on Macs with Apple silicon and enable the system to better detect code modifications. This new policy doesn’t apply to translated x86 binaries running under Rosetta 2, nor does it apply to macOS 11 running on Intel-based platforms.

    To reduce the impact on existing development workflows, starting with Xcode 12 beta 4, the toolchain will now automatically sign your executables whenever you build from Xcode, or use command-line utilities such as clang(1) or ld(1). Since this signing mechanism generates signatures directly at link time, and doesn’t cover any resource other than the executable, it is expected to be faster than a traditional codesign(1) invocation. If you use a custom workflow involving tools that modify a binary after linking (e.g. strip or install_name_tool) you might need to manually call codesign(1) as an additional build phase to properly ad-hoc sign your binary. These new signatures are not bound to the specific machine that was used to build the executable, they can be verified on any other system and will be sufficient to comply with the new default code signing requirement on Macs with Apple silicon. However, given that these signatures do not bear any valid identity, binaries signed this way cannot pass through Gatekeeper.

    Xcode toolchains have been updated in the latest Xcode beta to automatically apply ad-hoc signatures at link time to support projects that might not already be configured for signing. Install the most current Xcode beta to ensure you have up-to-date tooling support.

    Software previously built on your Developer Transition Kit might need to be either re-built with new tools, or re-signed with codesign -s - —preserve-metadata=identifier,entitlements,flags,runtime -f <path to mach-O>, to resolve issues from using earlier releases of the toolchain, or correct executables that have incorrect or missing code signatures. To check the validity of a signature, run codesign -v -vvvv —ignore-resources <path to mach-O>. If the command indicates “valid on disk (not all contents verified)” and “satisfies its Designated Requirement”, the code is valid under this policy. (51911409)

Device Management

Known Issues

Disk Utility

Known Issues

  • Formatting an external disk as APFS (encrypted) isn’t currently supported. (63209956)

  • You might encounter a kernel panic when attempting to create a new APFS container. (67701824)

Displays

Known Issues

  • HDR displays might show unexpected graphical artifacts. (64372135)

FairPlay

Known Issues

  • FairPlay and FairPlay Streaming support is unavailable, including playback in both native apps and via Rosetta 2. (51825430, 57564513, 63559609, 64439476)

Kernel

Known Issues

Printing

Known Issues

  • You might experience difficulty adding a printer. (64512490)

    Workaround: Open /System/Library/CoreServices/ in Finder and select the AddPrinter app. Choose Get Info from the File menu, then enable the “Open using Rosetta” option. Restart your Mac and try adding the printer again.

Pro Display XDR

Known Issues

  • The Developer Transition Kit is intended for use primarily with the Apple Display (P3-500 nits) preset on Pro Display XDR, as it doesn’t support any Pro Display XDR reference presets. Select the Apple Display (P3-500 nits) preset using a supported Mac before connecting the Pro Display XDR to the Developer Transition Kit, otherwise you might encounter the following:

    If the Pro Display XDR is configured to use a HDR preset, a “High Dynamic Range” checkbox appears in Displays Preferences even though the checkbox has no effect.

    If the Pro Display XDR is configured to use one of the Reference Modes, the brightness control and the “Automatically adjust brightness” checkbox might appear enabled in Displays Preferences, even though they have no effect while in a Reference Mode. (63837010, 63837824)

Software Update

Known Issues

  • You might receive a Download failed error when attempting to use Software Update. (65198213)

    Workaround: Download the full installer or the restore image instead of using Software Update.

  • A full installer update is required to update from macOS 11 Big Sur beta 5 to beta 7. Installing via Software Update is supported if your Developer Transition Kit is running beta 3, 4, or 6. (67997566)

New Features

  • In addition to the existing Apple Configurator 2 “restore” (erase) mode, “revive” (update) mode is now supported for Developer Transition Kit restore images. (63168698)

Virtualization

Known Issues

  • Virtualization isn’t supported on the Developer Transition Kit. Support can be tested using the kern.hv_support sysctl.

New Features

  • New Hypervisor APIs supporting arm64 virtualization on Macs with Apple silicon are available.

See Also

macOS 11