---
title: Kernel Constants
framework: Kernel
role: collectionGroup
role_heading: API Collection
path: kernel/kernel_constants
---

# Kernel Constants

## Topics

### Constants

- [CONSISTENT_DEBUG_MAGIC_VAL](kernel/consistent_debug_magic_val.md)
- [CONSISTENT_DEBUG_PANIC_LEN](kernel/consistent_debug_panic_len.md)
- [CONSISTENT_DEBUG_PANIC_SOURCE_SK](kernel/consistent_debug_panic_source_sk.md)
- [CONSISTENT_DEBUG_PANIC_SOURCE_SPTM](kernel/consistent_debug_panic_source_sptm.md)
- [CONSISTENT_DEBUG_PANIC_SOURCE_TXM](kernel/consistent_debug_panic_source_txm.md)
- [CONSISTENT_DEBUG_VERSION_VAL](kernel/consistent_debug_version_val.md)
- [DEBUG_HEADER_CURRENT_VERSION](kernel/debug_header_current_version.md)
- [DEBUG_HEADER_ENTRY_SPTM](kernel/debug_header_entry_sptm.md)
- [DEBUG_HEADER_ENTRY_TXM](kernel/debug_header_entry_txm.md)
- [DEBUG_HEADER_ENTRY_XNU](kernel/debug_header_entry_xnu.md)
- [DEBUG_HEADER_MAGIC_VAL](kernel/debug_header_magic_val.md)
- [IOLockGroup](kernel/iolockgroup.md)
- [KERNEL_AUDIT_TOKEN](kernel/kernel_audit_token.md)
- [KERNEL_SECURITY_TOKEN](kernel/kernel_security_token.md)
- [NDR_record](kernel/ndr_record.md)
- [OSAdoptMemory](kernel/osadoptmemory.md)
- [OSAllocateMemory](kernel/osallocatememory.md)
- [OSAllocateMemoryZero](kernel/osallocatememoryzero.md)
- [PAGE_SHIFT_CONST](kernel/page_shift_const.md)
- [PE_arm_debug_panic_hook](kernel/pe_arm_debug_panic_hook.md)
- [PE_halt_restart](kernel/pe_halt_restart.md)
- [PE_kputc](kernel/pe_kputc.md)
- [PE_putc](kernel/pe_putc.md)
- [PE_state](kernel/pe_state.md)
- [UUID_NULL](kernel/uuid_null.md)
- [apfs_smr](kernel/apfs_smr.md)
- [arcade_upcall_subsystem](kernel/arcade_upcall_subsystem.md)
- [assert_boot_args_size_is_4096](kernel/assert_boot_args_size_is_4096.md)
- [audit_triggers_subsystem](kernel/audit_triggers_subsystem.md)
- [bcd2bin_data](kernel/bcd2bin_data.md)
- [bin2bcd_data](kernel/bin2bcd_data.md)
- [catch_exc_subsystem](kernel/catch_exc_subsystem.md)
- [catch_mach_exc_subsystem](kernel/catch_mach_exc_subsystem.md)
- [clock_reply_subsystem](kernel/clock_reply_subsystem-eav.md)
- [coalition_notification_subsystem](kernel/coalition_notification_subsystem.md)
- [cons_ops_index](kernel/cons_ops_index.md)
- [debug_container_malloc_size](kernel/debug_container_malloc_size.md)
- [debug_cpu_performance_degradation_factor](kernel/debug_cpu_performance_degradation_factor.md)
- [debug_iomalloc_size](kernel/debug_iomalloc_size.md)
- [debug_ivars_size](kernel/debug_ivars_size.md)
- [debug_malloc_size](kernel/debug_malloc_size.md)
- [desiredvnodes](kernel/desiredvnodes.md)
- [disable_iolog_serial_output](kernel/disable_iolog_serial_output.md)
- [disable_kprintf_output](kernel/disable_kprintf_output.md)
- [disable_serial_output](kernel/disable_serial_output.md)
- [do_notify_subsystem](kernel/do_notify_subsystem.md)
- [doubleagent_subsystem](kernel/doubleagent_subsystem.md)
- [ecc_panic_physical_address](kernel/ecc_panic_physical_address.md)
- [enable_dklog_serial_output](kernel/enable_dklog_serial_output.md)
- [fairplay_subsystem](kernel/fairplay_subsystem.md)
- [gGetDefaultBusSpeedsKey](kernel/ggetdefaultbusspeedskey.md)
- [gIOAVCUnitType](kernel/gioavcunittype.md)
- [gIOAllCPUInitializedKey](kernel/gioallcpuinitializedkey.md)
- [gIOAppPowerStateInterest](kernel/gioapppowerstateinterest.md)
- [gIOAssociatedServicesKey](kernel/gioassociatedserviceskey.md)
- [gIOBusyInterest](kernel/giobusyinterest.md)
- [gIOCatalogue](kernel/giocatalogue.md)
- [gIOClassKey](kernel/gioclasskey.md)
- [gIOCompatibilityMatchKey](kernel/giocompatibilitymatchkey.md)
- [gIOCompatibilityPropertiesKey](kernel/giocompatibilitypropertieskey.md)
- [gIOConsoleSecurityInterest](kernel/gioconsolesecurityinterest.md)
- [gIODKDebug](kernel/giodkdebug.md)
- [gIODTAssociatedServiceKey](kernel/giodtassociatedservicekey.md)
- [gIODTBridgeModelKey](kernel/giodtbridgemodelkey.md)
- [gIODTDefaultInterruptController](kernel/giodtdefaultinterruptcontroller.md)
- [gIODTPlane](kernel/giodtplane.md)
- [gIODriverKitRequiredEntitlementsKey](kernel/giodriverkitrequiredentitlementskey.md)
- [gIODriverKitTestDriverEntitlementKey](kernel/giodriverkittestdriverentitlementkey.md)
- [gIODriverKitUserClientEntitlementAllowAnyKey](kernel/giodriverkitusercliententitlementallowanykey.md)
- [gIODriverKitUserClientEntitlementAllowThirdPartyUserClientsKey](kernel/giodriverkitusercliententitlementallowthirdpartyuserclientskey.md)
- [gIODriverKitUserClientEntitlementCommunicatesWithDriversKey](kernel/giodriverkitusercliententitlementcommunicateswithdriverskey.md)
- [gIOEthernetDisabledWakeOnLANFilterGroup](kernel/gioethernetdisabledwakeonlanfiltergroup.md)
- [gIOEthernetWakeOnLANFilterGroup](kernel/gioethernetwakeonlanfiltergroup.md)
- [gIOExclaveAssignedKey](kernel/gioexclaveassignedkey.md)
- [gIOFirstMatchNotification](kernel/giofirstmatchnotification.md)
- [gIOFirstPublishNotification](kernel/giofirstpublishnotification.md)
- [gIOGeneralInterest](kernel/giogeneralinterest.md)
- [gIOKitDebug](kernel/giokitdebug.md)
- [gIOKitTrace](kernel/giokittrace.md)
- [gIOModuleIdentifierKernelKey](kernel/giomoduleidentifierkernelkey.md)
- [gIOModuleIdentifierKey](kernel/giomoduleidentifierkey.md)
- [gIONetworkFilterGroup](kernel/gionetworkfiltergroup.md)
- [gIOOpenInterest](kernel/gioopeninterest.md)
- [gIOPathKey](kernel/giopathkey.md)
- [gIOPowerPlane](kernel/giopowerplane.md)
- [gIOPriorityPowerStateInterest](kernel/gioprioritypowerstateinterest.md)
- [gIOProbeScoreKey](kernel/gioprobescorekey.md)
- [gIOPublishNotification](kernel/giopublishnotification.md)
- [gIORegistryEntryAllowableSetPropertiesKey](kernel/gioregistryentryallowablesetpropertieskey.md)
- [gIORegistryEntryDefaultLockingSetPropertiesKey](kernel/gioregistryentrydefaultlockingsetpropertieskey.md)
- [gIOTerminatedNotification](kernel/gioterminatednotification.md)
- [gIOTrackingLeakScanCallback](kernel/giotrackingleakscancallback.md)
- [gIOUserClassesKey](kernel/giouserclasseskey.md)
- [gIOUserClientEntitlementsKey](kernel/giousercliententitlementskey.md)
- [gIOUserServerPreserveUserspaceRebootKey](kernel/giouserserverpreserveuserspacerebootkey.md)
- [gIOWillTerminateNotification](kernel/giowillterminatenotification.md)
- [gOSKextUnresolved](kernel/goskextunresolved.md)
- [gPEClockFrequencyInfo](kernel/gpeclockfrequencyinfo.md)
- [gPESerialBaud](kernel/gpeserialbaud.md)
- [gPlatformECID](kernel/gplatformecid.md)
- [gPlatformInterruptControllerName](kernel/gplatforminterruptcontrollername.md)
- [gPlatformMemoryID](kernel/gplatformmemoryid.md)
- [hex2ascii_data](kernel/hex2ascii_data.md)
- [hv_callbacks](kernel/hv_callbacks.md)
- [hv_disable](kernel/hv_disable.md)
- [hv_support_available](kernel/hv_support_available.md)
- [iftovt_tab](kernel/iftovt_tab.md)
- [in6addr_any](kernel/in6addr_any.md)
- [in6addr_linklocal_allnodes](kernel/in6addr_linklocal_allnodes.md)
- [in6addr_linklocal_allrouters](kernel/in6addr_linklocal_allrouters.md)
- [in6addr_linklocal_allv2routers](kernel/in6addr_linklocal_allv2routers.md)
- [in6addr_loopback](kernel/in6addr_loopback.md)
- [in6addr_nodelocal_allnodes](kernel/in6addr_nodelocal_allnodes.md)
- [iocompressionstats_notification_subsystem](kernel/iocompressionstats_notification_subsystem.md)
- [iokit_iomd_setownership_enabled](kernel/iokit_iomd_setownership_enabled.md)
- [kIOFWAVCAsyncCmdFreed](kernel/kiofwavcasynccmdfreed.md)
- [kMaxWaitForValidSelfID](kernel/kmaxwaitforvalidselfid.md)
- [kOSBooleanFalse](kernel/kosbooleanfalse.md)
- [kOSBooleanTrue](kernel/kosbooleantrue.md)
- [kauth_null_guid](kernel/kauth_null_guid.md)
- [kcdata_invalid_iter](kernel/kcdata_invalid_iter.md)
- [kdebug_enable](kernel/kdebug_enable.md)
- [kernel_task](kernel/kernel_task.md)
- [kernproc](kernel/kernproc.md)
- [kext_assertions_enable](kernel/kext_assertions_enable.md)
- [kpc_actionid](kernel/kpc_actionid.md)
- [kpc_supported](kernel/kpc_supported.md)
- [kpc_threads_counting](kernel/kpc_threads_counting.md)
- [libkern::adopt_memory](kernel/libkern_adopt_memory.md)
- [libkern::allocate_memory](kernel/libkern_allocate_memory.md)
- [libkern::allocate_memory_zero](kernel/libkern_allocate_memory_zero.md)
- [lz4_decode_scratch_size](kernel/lz4_decode_scratch_size.md)
- [lz4_encode_scratch_size](kernel/lz4_encode_scratch_size.md)
- [lz4_hash_table_size](kernel/lz4_hash_table_size.md)
- [mach_absolutetime_asleep](kernel/mach_absolutetime_asleep.md)
- [mach_absolutetime_last_sleep](kernel/mach_absolutetime_last_sleep.md)
- [main_device_port](kernel/main_device_port.md)
- [masterAudioFunctions](kernel/masteraudiofunctions-umg.md)
- [max_mem](kernel/max_mem.md)
- [mem_size](kernel/mem_size.md)
- [memory_error_notification_subsystem](kernel/memory_error_notification_subsystem.md)
- [msghdrs](kernel/msghdrs.md)
- [msginfo](kernel/msginfo.md)
- [msgmaps](kernel/msgmaps.md)
- [msgpool](kernel/msgpool.md)
- [msqids](kernel/msqids.md)
- [mt_core_supported](kernel/mt_core_supported.md)
- [nconsops](kernel/nconsops.md)
- [nfs_ticks](kernel/nfs_ticks.md)
- [oop_jit_conversion](kernel/oop_jit_conversion.md)
- [osbuild_config](kernel/osbuild_config.md)
- [osbuilder](kernel/osbuilder.md)
- [osrelease](kernel/osrelease.md)
- [ostype](kernel/ostype-hrt.md)
- [osversion](kernel/osversion.md)
- [page_mask](kernel/page_mask.md)
- [page_shift](kernel/page_shift.md)
- [page_size](kernel/page_size.md)
- [phy_read_panic](kernel/phy_read_panic.md)
- [phy_write_panic](kernel/phy_write_panic.md)
- [receive_sysdiagnose_notification_subsystem](kernel/receive_sysdiagnose_notification_subsystem-382.md)
- [receive_vfs_nspace_subsystem](kernel/receive_vfs_nspace_subsystem.md)
- [selwait](kernel/selwait.md)
- [serialmode](kernel/serialmode.md)
- [signgam](kernel/signgam.md)
- [spec_vnodeop_p](kernel/spec_vnodeop_p.md)
- [speclisth](kernel/speclisth.md)
- [task_access_subsystem](kernel/task_access_subsystem-661.md)
- [telemetry_notification_subsystem](kernel/telemetry_notification_subsystem-3gl.md)
- [version](kernel/version.md)
- [version_major](kernel/version_major.md)
- [version_minor](kernel/version_minor.md)
- [version_prerelease_level](kernel/version_prerelease_level.md)
- [version_revision](kernel/version_revision.md)
- [version_stage](kernel/version_stage.md)
- [version_variant](kernel/version_variant.md)
- [vnop_monitor_desc](kernel/vnop_monitor_desc.md)
- [vttoif_tab](kernel/vttoif_tab.md)

## See Also

### Additional Reference

- [Kernel Functions](kernel/kernel_functions.md)
- [Kernel Structures](kernel/kernel_structures.md)
- [Kernel Data Types](kernel/kernel_data_types.md)
- [Kernel Enumerations](kernel/kernel_enumerations.md)