apfelkern

C API documentation extracted from the local macOS SDK headers (arm64, userspace and kernel configurations).

Why make this? Well, have you tried reading the official Apple documentation? To give you an example, try to figure out what mach_vm_map does.

If we look at the header files (no it's not in /usr/include) it turns out that they contain a lot of useful information that their documentation generation system ignores.

If you want me to add more components (Frameworks, XNU kernel parts), feel free to message me.

Recently added & changed (2)

Pages new or changed since the last production publish.

new	Objective-C runtime	9 pages
changed	Task restartable ranges	Task & thread coordination

Guides

Kernel Programming Guide MIG routines BSD man pages Kernel C++ classes Implementation sources

Frameworks

Private frameworksSkyLight (2305 symbols)

Mach

BSD / POSIX

Types & conventions

_types.h errno.h inttypes.h limits.h stdint.h sys/__endian.h sys/_endian.h sys/_select.h sys/_types.h sys/_types/_blkcnt_t.h sys/_types/_blksize_t.h sys/_types/_caddr_t.h sys/_types/_clock_t.h sys/_types/_ct_rune_t.h sys/_types/_dev_t.h sys/_types/_errno_t.h sys/_types/_fd_clr.h sys/_types/_fd_copy.h sys/_types/_fd_def.h sys/_types/_fd_isset.h sys/_types/_fd_set.h sys/_types/_fd_setsize.h sys/_types/_fd_zero.h sys/_types/_filesec_t.h sys/_types/_fsblkcnt_t.h sys/_types/_fsfilcnt_t.h sys/_types/_fsid_t.h sys/_types/_fsobj_id_t.h sys/_types/_gid_t.h sys/_types/_graftdmg_un.h sys/_types/_guid_t.h sys/_types/_id_t.h sys/_types/_in_addr_t.h sys/_types/_in_port_t.h sys/_types/_ino64_t.h sys/_types/_ino_t.h sys/_types/_int16_t.h sys/_types/_int32_t.h sys/_types/_int64_t.h sys/_types/_int8_t.h sys/_types/_intptr_t.h sys/_types/_iovec_t.h sys/_types/_key_t.h sys/_types/_mach_port_t.h sys/_types/_mbstate_t.h sys/_types/_mode_t.h sys/_types/_mount_t.h sys/_types/_nlink_t.h sys/_types/_null.h sys/_types/_o_dsync.h sys/_types/_o_sync.h sys/_types/_off_t.h sys/_types/_offsetof.h sys/_types/_os_inline.h sys/_types/_pid_t.h sys/_types/_posix_vdisable.h sys/_types/_ptrdiff_t.h sys/_types/_rsize_t.h sys/_types/_rune_t.h sys/_types/_s_ifmt.h sys/_types/_sa_family_t.h sys/_types/_seek_set.h sys/_types/_sigaltstack.h sys/_types/_sigset_t.h sys/_types/_size_t.h sys/_types/_socklen_t.h sys/_types/_ssize_t.h sys/_types/_suseconds_t.h sys/_types/_time_t.h sys/_types/_timespec.h sys/_types/_timeval.h sys/_types/_timeval32.h sys/_types/_timeval64.h sys/_types/_u_char.h sys/_types/_u_int.h sys/_types/_u_int16_t.h sys/_types/_u_int32_t.h sys/_types/_u_int64_t.h sys/_types/_u_int8_t.h sys/_types/_u_short.h sys/_types/_ucontext.h sys/_types/_ucontext64.h sys/_types/_uid_t.h sys/_types/_uintptr_t.h sys/_types/_useconds_t.h sys/_types/_uuid_t.h sys/_types/_va_list.h sys/_types/_vnode_t.h sys/_types/_wchar_t.h sys/_types/_wint_t.h sys/cdefs.h sys/endian.h sys/errno.h sys/param.h sys/syslimits.h sys/types.h sysexits.h

Threads & scheduling

pthread.h pthread/qos.h pthread/sched.h sched.h semaphore.h sys/posix_sem.h sys/qos.h sys/semaphore.h

Memory & IPC

mach_debug/hash_info.h mach_debug/ipc_info.h mach_debug/lockgroup_info.h mach_debug/mach_debug.h mach_debug/mach_debug_types.h mach_debug/page_info.h mach_debug/vm_info.h mach_debug/zone_info.h sys/buf.h sys/ipc.h sys/mbuf.h sys/mman.h sys/msg.h sys/posix_shm.h sys/sem.h sys/shm.h sys/vadvise.h sys/vm.h sys/vmmeter.h

Atomics, byte order & libkern

libkern/OSAtomic.h libkern/OSAtomicDeprecated.h libkern/OSAtomicQueue.h libkern/OSByteOrder.h libkern/OSCacheControl.h libkern/OSDebug.h libkern/OSKextLib.h libkern/OSReturn.h libkern/OSSpinLockDeprecated.h libkern/OSThermalNotification.h libkern/OSTypes.h

Events & kqueue

poll.h sys/ev.h sys/event.h sys/poll.h sys/select.h

Time

sys/time.h sys/timeb.h sys/times.h sys/timex.h time.h

Terminals

sys/ioctl_compat.h sys/termios.h sys/tty.h sys/ttychars.h sys/ttycom.h sys/ttydefaults.h termios.h util.h

Audit (BSM)

bsm/audit.h bsm/audit_domain.h bsm/audit_errno.h bsm/audit_fcntl.h bsm/audit_filter.h bsm/audit_internal.h bsm/audit_kevents.h bsm/audit_record.h bsm/audit_session.h bsm/audit_socket_type.h bsm/audit_uevents.h bsm/libbsm.h

Tracing & debugging

asl.h sys/conf.h sys/dtrace.h sys/fasttrap.h sys/gmon.h sys/kdebug.h sys/kdebug_signpost.h sys/kernel_types.h sys/lockstat.h sys/log_data.h sys/msgbuf.h sys/random.h sys/snapshot.h sys/sys_domain.h sys/syslog.h sys/trace.h syslog.h

Kernel (KEXT)

TODO: extract C++ classes

kern/ primitives

kern/arithmetic_128.h kern/assert.h kern/backtrace.h kern/block_hint.h kern/cambria_layout.h kern/circle_queue.h kern/clock.h kern/coalition.h kern/cs_blobs.h kern/debug.h kern/ecc.h kern/energy_perf.h kern/exc_guard.h kern/exc_resource.h kern/ext_paniclog.h kern/extmod_statistics.h kern/host.h kern/hv_io_notifier.h kern/hv_support.h kern/hv_support_kern.h kern/hv_support_kext.h kern/hvg_hypercall.h kern/ipc_mig.h kern/kcdata.h kern/kcdata_private.h kern/kern_cdata.h kern/kern_types.h kern/kext_alloc.h kern/ledger.h kern/llc_error.h kern/lock_attr.h kern/lock_group.h kern/lock_mtx.h kern/lock_rw.h kern/lock_sleep.h kern/lock_types.h kern/locks.h kern/macro_help.h kern/monotonic.h kern/mpqueue.h kern/mpsc_queue.h kern/panic_call.h kern/percpu.h kern/policy_internal.h kern/priority_queue.h kern/processor.h kern/queue.h kern/remote_time.h kern/restartable.h kern/sched_prim.h kern/smr_types.h kern/stackshot_kpi.h kern/task.h kern/task_ref.h kern/telemetry.h kern/thread.h kern/thread_call.h kern/thread_group.h kern/timer_call.h kern/trap_telemetry.h kern/trustcache.h kern/turnstile.h kern/waitq.h kern/work_interval.h

Mach (kernel)

mach/arcade_upcall_server.h mach/arm64/asm.h mach/arm/_structs.h mach/arm/sdt_isa.h mach/arm/syscall_sw.h mach/arm/thread_status.h mach/arm/vm_param.h mach/audit_triggers_server.h mach/clock_reply_server.h mach/coalition_notification_server.h mach/doubleagent_mig_server.h mach/exc_server.h mach/fairplayd_notification_server.h mach/iocompressionstats_notification_server.h mach/ktrace_background.h mach/mach_exc_server.h mach/mach_host.h mach/mach_interface.h mach/mach_port.h mach/mach_time.h mach/mach_types.h mach/mach_vm.h mach/mach_voucher_attr_control.h mach/mach_voucher_types.h mach/machine/asm.h mach/machine/sdt.h mach/memory_error_notification_server.h mach/memory_object_types.h mach/message.h mach/notify_server.h mach/port.h mach/semaphore.h mach/shared_memory_server.h mach/shared_region.h mach/sysdiagnose_notification_server.h mach/task.h mach/task_access.h mach/task_access_server.h mach/task_info.h mach/telemetry_notification_server.h mach/thread_act.h mach/upl.h mach/vfs_nspace.h mach/vfs_nspace_server.h mach/vm_map.h mach/vm_param.h mach/vm_statistics.h mach/vm_types.h mach/vm_types_unsafe.h

BSD (kernel)

miscfs/devfs/devfs.h miscfs/fifofs/fifo.h miscfs/specfs/specdev.h miscfs/union/union.h sys/__endian.h sys/_endian.h sys/_structs.h sys/_types.h sys/_types/_caddr_t.h sys/_types/_fd_def.h sys/_types/_null.h sys/_types/_offsetof.h sys/_types/_ptrdiff_t.h sys/_types/_rsize_t.h sys/_types/_size_t.h sys/_types/_uintptr_t.h sys/_types/_user32_itimerval.h sys/_types/_user32_ntptimeval.h sys/_types/_user32_timespec.h sys/_types/_user32_timeval.h sys/_types/_user32_timex.h sys/_types/_user64_itimerval.h sys/_types/_user64_ntptimeval.h sys/_types/_user64_timespec.h sys/_types/_user64_timeval.h sys/_types/_user64_timex.h sys/_types/_user_timespec.h sys/_types/_user_timeval.h sys/_types/_va_list.h sys/_types/_wchar_t.h sys/appleapiopts.h sys/attr.h sys/cdefs.h sys/commpage.h sys/conf.h sys/constrained_ctypes.h sys/dir.h sys/dirent.h sys/disk.h sys/dkstat.h sys/domain.h sys/errno.h sys/ev.h sys/event.h sys/fcntl.h sys/file.h sys/imgact.h sys/ioctl.h sys/ipc.h sys/kauth.h sys/kdebug.h sys/kdebug_kernel.h sys/kdebug_private.h sys/kern_control.h sys/kern_event.h sys/kernel.h sys/kernel_types.h sys/kpi_mbuf.h sys/kpi_socket.h sys/kpi_socketfilter.h sys/lock.h sys/malloc.h sys/mbuf.h sys/md5.h sys/mman.h sys/mount.h sys/msg.h sys/namei.h sys/param.h sys/proc.h sys/random.h sys/resource.h sys/resource_private.h sys/select.h sys/sem.h sys/shm.h sys/signal.h sys/socket.h sys/socketvar.h sys/sockio.h sys/stat.h sys/stdio.h sys/sysctl.h sys/syslog.h sys/systm.h sys/time.h sys/timex.h sys/ttycom.h sys/types.h sys/ubc.h sys/ucontext.h sys/ucred.h sys/uio.h sys/un.h sys/unicode.h sys/unistd.h sys/utfconv.h sys/vm.h sys/vmparam.h sys/vnode.h sys/vnode_if.h sys/wait.h sys/xattr.h uuid/uuid.h vfs/vfs_support.h

libkern & os

libkern/Block.h libkern/OSAtomic.h libkern/OSBase.h libkern/OSKextLib.h libkern/OSMalloc.h libkern/OSTypes.h libkern/_OSByteOrder.h libkern/arm/OSByteOrder.h libkern/arm/_OSByteOrder.h libkern/c++/OSAllocation.h libkern/c++/OSArray.h libkern/c++/OSBoolean.h libkern/c++/OSBoundedArray.h libkern/c++/OSBoundedArrayRef.h libkern/c++/OSBoundedPtr.h libkern/c++/OSBoundedPtrFwd.h libkern/c++/OSCPPDebug.h libkern/c++/OSCollection.h libkern/c++/OSCollectionIterator.h libkern/c++/OSContainers.h libkern/c++/OSData.h libkern/c++/OSDictionary.h libkern/c++/OSEndianTypes.h libkern/c++/OSIterator.h libkern/c++/OSLib.h libkern/c++/OSMetaClass.h libkern/c++/OSNumber.h libkern/c++/OSObject.h libkern/c++/OSOrderedSet.h libkern/c++/OSPtr.h libkern/c++/OSSerialize.h libkern/c++/OSSet.h libkern/c++/OSSharedPtr.h libkern/c++/OSString.h libkern/c++/OSSymbol.h libkern/c++/OSUnserialize.h libkern/c++/bounded_array.h libkern/c++/bounded_array_ref.h libkern/c++/bounded_ptr.h libkern/c++/bounded_ptr_fwd.h libkern/c++/intrusive_shared_ptr.h libkern/c++/safe_allocation.h libkern/copyio.h libkern/crc.h libkern/crypto/crypto.h libkern/crypto/md5.h libkern/crypto/rand.h libkern/crypto/sha1.h libkern/libkern.h libkern/locks.h libkern/machine/OSByteOrder.h libkern/sysctl.h libkern/tree.h libkern/version.h libkern/zconf.h libkern/zlib.h mach-o/fat.h mach-o/fixup-chains.h mach-o/loader.h mach-o/nlist.h os/alloc_util.h os/atomic.h os/base.h os/cpp_util.h os/log.h os/object.h os/trace.h

IOKit

Mach-O

File format

mach-o/compact_unwind_encoding.h mach-o/fat.h mach-o/fixup-chains.h mach-o/loader.h mach-o/nlist.h mach-o/ranlib.h mach-o/reloc.h mach-o/stab.h

Runtime & dyld

mach-o/arch.h mach-o/dyld.h mach-o/dyld_images.h mach-o/getsect.h mach-o/ldsyms.h mach-o/swap.h mach-o/utils.h

XPC

xpc/activity.h xpc/availability.h xpc/base.h xpc/connection.h xpc/debug.h xpc/endpoint.h xpc/listener.h xpc/peer_requirement.h xpc/rich_error.h xpc/session.h xpc/xpc.h

Objective-C runtime

Types & selectors

objc/NSObjCRuntime.h new objc/objc-api.h new objc/objc.h new

Synchronization & exceptions

objc/objc-exception.h new objc/objc-sync.h new

Legacy utilities

objc/hashtable2.h new objc/objc-auto.h new

Dispatch

dispatch/base.h dispatch/block.h dispatch/data.h dispatch/dispatch.h dispatch/group.h dispatch/introspection.h dispatch/io.h dispatch/object.h dispatch/once.h dispatch/queue.h dispatch/semaphore.h dispatch/source.h dispatch/time.h dispatch/workloop.h

os/

os/activity.h os/atomic.h os/availability.h os/base.h os/clock.h os/lock.h os/log.h os/object.h os/os_sync_wait_on_address.h os/overflow.h os/proc.h os/signpost.h os/trace.h os/trace_base.h os/workgroup.h os/workgroup_base.h os/workgroup_interval.h os/workgroup_object.h os/workgroup_parallel.h

EndpointSecurity

EndpointSecurity/ESClient.h EndpointSecurity/ESMessage.h EndpointSecurity/ESMessageCore.h EndpointSecurity/ESTypes.h EndpointSecurity/EndpointSecurity.h

CommonCrypto

CommonCrypto/CommonCrypto.h CommonCrypto/CommonCryptoError.h CommonCrypto/CommonCryptor.h CommonCrypto/CommonDigest.h CommonCrypto/CommonHMAC.h CommonCrypto/CommonKeyDerivation.h CommonCrypto/CommonRandom.h CommonCrypto/CommonSymmetricKeywrap.h

Neon (Arm SIMD)

Headers

arm_bf16.h arm_neon.h arm_vector_types.h

Intrinsics

Arithmetic Multiply & multiply-accumulate Comparison Shifts & inserts Logical & bit manipulation Reduction & pairwise Rounding, square root & estimates Conversion, narrowing & widening Reinterpret casts Move, duplicate & lanes Permute & table lookup Load & store Dot product & matrix multiply Complex arithmetic Cryptography FP8

About & caveats

apfelkern hosts C API documentation generated from the macOS SDK headers installed on my own machine. It is not affiliated with, endorsed by, or reviewed by Apple.

Build environment:

macOS	26.4.1
SDK	26.4 (MacOSX.sdk, Command Line Tools)
architecture	arm64; Intel-only headers and preprocessor branches are excluded
configuration	userspace corpora: default userspace preprocessor context; Kernel (KEXT) corpus: `-DKERNEL`
compiler	Apple clang version 21.0.0 (clang-2100.0.123.102)
Neon headers	the compiler’s own `arm_neon.h` and the headers it includes (/Library/Developer/CommandLineTools/usr/lib/clang/21/include), parsed with the toolchain’s libclang
xnu source used for verification	apple-oss-distributions/xnu @ f6217f8 (2025-10-16)
generated	2026-09-25

Unless specified otherwise, descriptions are extracted from macOS header comments, MIG .defs files and SDK man pages.

CMU/MIT Mach reference: Where applicable, description and notes from the Carnegie Mellon Mach kernel (CMU Mach) interface manual pages (fetched from <web.mit.edu/darwin/src/modules>) are supplied. This data is licensed under the free-use license (© Carnegie Mellon University) and may not apply to XNU.

GNU Mach reference: Where applicable, description and notes from the GNU Mach Reference Manual (fetched from http://gnu.org/software/hurd/gnumach-doc/) are supplied. This data is licensed under the GNU Free Documentation License 1.2+ (© Free Software Foundation) and may not apply to XNU.

LLVM project source: Selected LLDB debugserver source files (https://github.com/llvm/llvm-project), and the Neon declarations, which come from the compiler's own arm_neon.h (Apple clang's copy of the LLVM header, not part of the macOS SDK). Licensed under the Apache License v2.0 with LLVM Exceptions.

Apple open-source implementation sources: Selected XNU, Mach Interface Generator, and libpthread files from Apple OSS Distributions are hosted as implementation references. A pinned objc4 revision from the same source is cited for the Objective-C runtime example; the Objective-C corpus itself uses installed SDK headers. The Apple portions carry Apple Public Source License 2.0 notices. Individual files may carry additional copyright, license, and permission notices; consult the notices retained in each hosted source file or linked source repository. These source revisions may differ from the installed macOS components.

Generated descriptions: Functions with no documentation in any of these sources have an LLM-generated description shown below them showing the XNU source files consulted. These descriptions are unreviewed and may contain errors.

Build diagnostics — 33 error / 3 warning lines from the last build (mostly SDK headers that don't compile standalone; skipped).