Source Tree

A map of the repository. The short version: src/ is Darwin, nix/ is everything around it, tools/ is what the host needs to build Darwin at all.

src/Kernel

src/Kernel/xnu is the kernel. Alongside it, libkmod and libfirehose_kernel, and src/Kernel/Extensions, which holds the kexts. They fall into groups:

• Platform: PDACPIPlatform (built on uACPI), AppleI386GenericPlatform, AppleAPIC, AppleI386PCI, IOACPIFamily, IOPCIFamily, and the ARM equivalents PDArmPlatformExpert, PDArmPCI.
• Storage: IOStorageFamily, IOATAFamily and IOATABlockStorage, IONVMEFamily, RavynAHCIPort, PDBcm2835SD, plus the optical families.
• Filesystems: ext4 and Ext4FileSystemDriver (the root filesystem on every target), hfs with HFSEncodings, msdosfs, apfs, AppleFileSystemDriver.
• Graphics: IOGraphicsFamily, IOGOPFramebuffer, IOIntelFramebuffer, IOVirtIOGPU, IONDRVSupport.
• Input, USB, network, audio: IOHIDFamily, ApplePS2Controller, IOUSBFamily with its EHCI/OHCI/UHCI plugins, RavynXHCIPort, IONetworkingFamily, PDE1000, PDRealtek8111, IOVirtIONet, RavynHDAudio.
• Support: corecrypto, pthread, GTrace, GMetric.

Note the licence on corecrypto: it and the CommonCrypto code above it are GPL, and unlike the other GPL software the project uses, they are part of the default build. It descends from rafirafi’s 2016 pdcrypto because no alternative existed. Replacing it is on the roadmap and matters if you are redistributing PureDarwin.

The ext4 driver is worth calling out. Darwin has no ext4, and PureDarwin uses it as the root filesystem, so it is entirely project code and has been the source of a long list of subtle bugs (see Debugging).

src/Libraries

The userland foundation. Apple publishes some of this; the rest is written here.

• The core: libSystem (and its many sub-libraries), dyld, libcxx, libcxxabi, libunwind, llvm-libc, libdarwin, architecture, AvailabilityVersions.
• Objective-C and frameworks: objc4, CoreFoundation, Foundation, CoreServices, IOKit, DiskArbitration, Security with libDER, SystemConfiguration and libSystemConfiguration, ProtocolBuffer, SymptomReporter, WirelessDiagnostics, CommonCrypto, CrashReporterClient.
• Services: XPC (which includes launchd, launchctl and notifyd), syslog, libsystem_trace, mDNSResponder, libresolv, bootp, eap8021x, ppp.
• Graphics support: OpenGL, libdrm, libgbm, and the project’s own PDGOP, PDSurface and PDVirglShim.

src/Frameworks

CoreGraphics and Onyx2D. Early, and on the roadmap for real work.

src/Userspace

The commands that make the system usable: shell_cmds, text_cmds, system_cmds, diskdev_cmds, ps, ping, ioreg, sw_vers, startx, netsetup, mdnsd, the ext4tool and ext4util maintenance utilities, iomediacheck, mousemon, pcmplay, tcc, fbdoom, and the two Xorg drivers xf86-video-puredarwingop and xf86-input-puredarwin.

src/ThirdParty

Upstream projects vendored because they needed real porting work: wayland, wayland-protocols, wlroots, sway.

projects/

libapfsrw. The README there also lists a planned libhfsrw that does not exist yet.

nix/

The ports under nix/pkgs/ are grouped by what they are:

ls nix/pkgs/<group> is the current answer for any of them.

tools/

Host-side build tools: cctools, mig, unifdef, dtrace_ctf, xar, iig-selfhost. See Host tools and toolchains.

cmake/

The CMake helper modules. See The CMake tree.