#
Metal kernels 🤘

Instructions on this page assume that you installed Nix with the Determinate Nix installer.

##
Targeted macOS versions

Since new macOS versions get adopted quickly, we only support the latest major macOS version except for the first weeks after a release, when we also support the previous major version.

We currently support macOS 26.0 and later on ARM64 (Apple silicon).

##
Requirements

To build a Metal kernel, the following requirements must be met:

- Xcode 26.x must be available on the build machine.

- `xcode-select -p` must point to the Xcode 26 installation, typically `/Applications/Xcode.app/Contents/Developer`. If this is not the case, you can set the path with: `sudo xcode-select -s /path/to/Xcode.app/Contents/Developer`

- The Metal Toolchain must be installed. Starting with macOS 26, this is a separate download from Xcode. You can install it with: `xcodebuild -downloadComponent MetalToolchain`

- The Nix sandbox should be set to `relaxed`, because the Nix derivation that builds the kernel must have access to Xcode and the Metal Toolchain. You can verify this by checking that `/etc/nix/nix.custom.conf` contains the line:

      sandbox = relaxed

  If you had to add the line, make sure to restart the Nix daemon:

      sudo launchctl kickstart -k system/systems.determinate.nix-daemon

You can check these requirements as follows. First, you can check the Xcode version as follows:

    $ xcodebuild -version
    Xcode 26.1
    Build version 17B55

The reported version must be 26.0 or newer. Then you can validate that the Metal Toolchain is installed with:

    $ xcodebuild -showComponent metalToolchain
    Asset Path: /System/Library/AssetsV2/com_apple_MobileAsset_MetalToolchain/68d8db6212b48d387d071ff7b905df796658e713.asset/AssetData
    Build Version: 17B54
    Status: installed
    Toolchain Identifier: com.apple.dt.toolchain.Metal.32023
    Toolchain Search Path: /private/var/run/com.apple.security.cryptexd/mnt/com.apple.MobileAsset.MetalToolchain-v17.2.54.0.mDxgz0

Update on GitHub