Keyboard shortcuts

Press ← or → to navigate between chapters

Press S or / to search in the book

Press ? to show this help

Press Esc to hide this help

The Apple SDK requirement

Building PureDarwin currently requires MacOSX11.3.sdk.tar.xz, a copy of Apple’s macOS 11.3 SDK. It is proprietary, it cannot be fetched automatically, and it cannot be redistributed, so you have to supply it.

This is a known problem and removing it is on the roadmap. It is not a blocker for the 20.5.0 release, but it is the reason a build is not a single command on a clean machine.

Registering it

nix-store --add-fixed sha256 /path/to/MacOSX11.3.sdk.tar.xz

Expected sha256:

9adc1373d3879e1973d28ad9f17c9051b02931674a3ec2a2498128989ece2cb1

If it is missing, the build stops with:

MacOSX11.3.sdk.tar.xz (Apple SDK, proprietary - not fetchable/redistributable)
is not yet in your Nix store. Register your local copy with:
  nix-store --add-fixed sha256 /path/to/MacOSX11.3.sdk.tar.xz

How it is wired in

The mechanism is requireFile: Nix knows the hash and the message, but has no way to obtain the file. The flake also carries an allowUnfreePredicate narrowly scoped to this one name, so nothing else unfree slips in.

The canonical definition lives in nix/pkgs/toolchain/apple-sdk-pinned.nix, which unpacks it to:

$out/Platforms/MacOSX.platform/Developer/SDKs/MacOSX.sdk

with a MacOSX11.3.sdk symlink beside it. Every port that needs a sysroot repeats the same requireFile block; there is no shared helper for it yet.

Never hardcode a path to your own copy into a Nix file. The requireFile pattern is deliberate: it fails with instructions rather than with a path that only works on one machine.

Other licensing

The SDK is the one proprietary prerequisite, but it is not the only licensing question in the tree: corecrypto is GPL and in the default build, some of Apple’s published source carries no usable grant, and GPL-licensed extras like fbDOOM are deliberately kept outside the tree using the same requireFile-style opt-in as the SDK. See Licensing.

Why it is still needed

The SDK supplies headers and stub libraries that the project has not yet replaced with its own. Every component that stops needing it is one step closer to a fully open build; several already have their own headers, and the guest headers under pd-guest-headers/ exist precisely so in-guest compilers never see Apple’s.

The work to finish this is tracked on the Roadmap alongside the related item of completing the Nix-on-macOS host path.