OpenCore
Reference Manual (1.0.1)
[2024.09.11]
Copyright ©2018-2024 vit9696
This document provides information on the format of the OpenCore user configuration file used to set up the correct functioning of the macOS operating system. It is to be read as the official clarification of expected OpenCore behaviour. All deviations, if found in published OpenCore releases, shall be considered to be documentation or implementation issues which should be reported via the Acidanthera Bugtracker. An errata sheet is available in OpenCorePkg repository.
This document is structured as a specification and is not meant to provide a step-by-step guide to configuring an end-user Board Support Package (BSP). The intended audience of the document is anticipated to be programmers and engineers with a basic understanding of macOS internals and UEFI functionality. For these reasons, this document is available exclusively in English, and all other sources or translations of this document are unofficial and may contain errors.
Third-party articles, utilities, books, and similar, may be more useful for a wider audience as they could provide guide-like material. However, they are subject to their authors’ preferences, misinterpretations of this document, and unavoidable obsolescence. In cases of using such sources, such as Dortania’s OpenCore Install Guide and related material, please refer back to this document on every decision made and re-evaluate potential implications.
Please note that regardless of the sources used, users are required to fully understand every OpenCore configuration option, and the principles behind them, before posting issues to the Acidanthera Bugtracker.
Note: Creating this document would not have been possible without the invaluable contributions from other people: Andrey1970, Goldfish64, dakanji, PMheart, and several others, with the full list available in OpenCorePkg history.
The OC config file is guaranteed to be processed at least once if found. Subject to the OpenCore bootstrapping mechanism, the presence of multiple OC config files may lead to the reading of any of them. It is permissible for no OC Config file to be present on disk. In such cases, if the implementation does not abort the boot process, all values shall follow the rules of invalid values and optional values.
The OC config file has restrictions on size, nesting levels, and number of keys:
The OC config file may have up to 32,768 XML nodes within each plist object.
Reading malformed OC config files results in undefined behaviour. Examples of malformed OC config files include the following:
It is recommended, but not required, to abort loading malformed OC config files and to continue as if an OC config file is not present. For forward compatibility, it is recommended, but not required, for the implementation to warn about the use of invalid values.
The recommended approach to interpreting invalid values is to conform to the following convention where applicable:
Type | Value |
plist string | Empty string (<string></string>) |
plist data | Empty data (<data></data>) |
plist integer | 0 (<integer>0</integer>) |
plist boolean | False (<false/>) |
plist tristate | False (<false/>) |
The OC config file is separated into subsections, as described in separate sections of this document, and is designed so as to attempt not to enable anything by default as well as to provide kill switches via an Enable property for plist dict entries that represent optional plugins and similar.
The file is structured to group related elements in subsections as follows:
Root configuration entries consist of the following:
Basic validation of an OC config file is possible using the ocvalidate utility. Please note that the version of ocvalidate used must match the OpenCore release and that notwithstanding this, it may not detect all configuration issues present in an OC config file.
Note: To maintain system integrity, properties typically have predefined values even when such predefined values are not specified in the OC config file. However, all properties must be explicitly specified in the OC config file and this behaviour should not be relied on.
Figure 1. Directory Structure
When directory boot is used, the directory structure used should follow the descriptions in the Directory Structure figure. Available entries include:
Note: It is not guaranteed that paths longer than OC_STORAGE_SAFE_PATH_MAX (128 characters including the
0-terminator) will be accessible within OpenCore.
To install OpenCore, replicate the Configuration Structure described in the previous section in the EFI volume of a GPT partition. While corresponding sections of this document provide some information regarding external resources such as ACPI tables, UEFI drivers, or kernel extensions (kexts), completeness of the matter is out of the scope of this document. Information about kernel extensions may be found in a separate Kext List document available in the OpenCore repository. Vaulting information is provided in the Security Properties section of this document.
The OC config file, as with any property list file, can be edited with any text editor, such as nano or vim. However, specialised software may provide a better experience. On macOS, the preferred GUI application is Xcode. The ProperTree editor is a lightweight, cross-platform and open-source alternative.
It is strongly recommended to avoid configuration creation tools that are aware of the internal configuration structure as this may result in invalid configurations (since the structure gets constantly updated). If such tools are to be used despite this warning, ensure that only stable versions of OpenCore explicitly supported by such tools are used. In such cases, the use of open-source implementations with transparent binary generation (such as OCAT) is encouraged, given that other tools may contain malware. In addition, configurations created for a specific hardware setup should never be used on different hardware setups.
For BIOS booting, a third-party UEFI environment provider is required and OpenDuetPkg is one such UEFI environment provider for legacy systems. To run OpenCore on such a legacy system, OpenDuetPkg can be installed with a dedicated tool — BootInstall (bundled with OpenCore). Third-party utilities can be used to perform this on systems other than macOS.
For upgrade purposes, refer to the Differences.pdf document which provides information about changes to the configuration (as compared to the previous release) as well as to the Changelog.md document (which contains a list of modifications across all published updates).
OpenCore can be compiled as a standard EDK II package and requires the EDK II Stable package. The currently supported EDK II release is hosted in acidanthera/audk. Required patches for this package can be found in the Patches directory.
When updating the LaTeX documentation (e.g. Configuration.tex) please do not rebuild the PDF files till merging to master happens. This avoids unnecessary merge conflicts:
The only officially supported toolchain is XCODE5. Other toolchains might work but are neither supported nor recommended. Contributions of clean patches are welcome. Please do follow EDK II C Codestyle.
To compile with XCODE5, besides Xcode, users should also install NASM and MTOC. The latest Xcode version is recommended for use despite the toolchain name. An example command sequence is as follows:
git clone --depth=1 https://github.com/acidanthera/audk UDK cd UDK git submodule update --init --recommend-shallow rm -rf OpenCorePkg git clone --depth=1 https://github.com/acidanthera/OpenCorePkg . ./edksetup.sh make -C BaseTools build -a X64 -b RELEASE -t XCODE5 -p OpenCorePkg/OpenCorePkg.dsc
For IDE usage Xcode projects are available in the root of the repositories. Another approach could be using Language Server Protocols. For example, Sublime Text with LSP for Sublime Text plugin. Add compile_flags.txt file with similar content to the UDK root:
-I/UefiPackages/MdePkg -I/UefiPackages/MdePkg/Include -I/UefiPackages/MdePkg/Include/X64 -I/UefiPackages/MdeModulePkg -I/UefiPackages/MdeModulePkg/Include -I/UefiPackages/MdeModulePkg/Include/X64 -I/UefiPackages/OpenCorePkg/Include/AMI -I/UefiPackages/OpenCorePkg/Include/Acidanthera -I/UefiPackages/OpenCorePkg/Include/Apple -I/UefiPackages/OpenCorePkg/Include/Apple/X64 -I/UefiPackages/OpenCorePkg/Include/Duet -I/UefiPackages/OpenCorePkg/Include/Generic -I/UefiPackages/OpenCorePkg/Include/Intel -I/UefiPackages/OpenCorePkg/Include/Microsoft -I/UefiPackages/OpenCorePkg/Include/Nvidia -I/UefiPackages/OpenCorePkg/Include/VMware -I/UefiPackages/OvmfPkg/Include -I/UefiPackages/ShellPkg/Include -I/UefiPackages/UefiCpuPkg/Include -IInclude -include /UefiPackages/MdePkg/Include/Uefi.h -fshort-wchar -Wall -Wextra -Wno-unused-parameter -Wno-missing-braces -Wno-missing-field-initializers -Wno-tautological-compare -Wno-sign-compare -Wno-varargs -Wno-unused-const-variable -DOC_TARGET_NOOPT=1 -DNO_MSABI_VA_FUNCS=1
Note: /UefiPackages in the sample file denotes an absolute path.
Warning: Tool developers modifying config.plist or any other OpenCore files must ensure that their tools check the opencore-version NVRAM variable (see the Debug Properties section below) and warn users if the version listed is unsupported or prerelease. The OpenCore configuration may change across releases and such tools shall ensure that they carefully follow this document. Failure to do so may result in such tools being considered to be malware and blocked by any means.
As with any other project, we have conventions that we follow during development. All third-party contributors are advised to adhere to the conventions listed below before submitting patches. To minimise abortive work and the potential rejection of submissions, third-party contributors should initially raise issues to the Acidanthera Bugtracker for feedback before submitting patches.
Organisation. The codebase is contained in the OpenCorePkg repository, which is the primary EDK II package.
Design. The codebase is written in a subset of freestanding C11 (C17) supported by most modern toolchains used by EDK II. Applying common software development practices or requesting clarification is recommended if any particular case is not discussed below.
Codestyle. The codebase follows the EDK II codestyle with a few changes and clarifications.
The codebase incorporates EDK II debugging and few custom features to improve the experience.
The git-bisect functionality may be useful when trying to find problematic changes. Unofficial sources of per-commit OpenCore binary builds, such as Dortania, may also be useful.
ACPI (Advanced Configuration and Power Interface) is an open standard to discover and configure computer hardware. The ACPI specification defines standard tables (e.g. DSDT, SSDT, FACS, DMAR) and various methods (e.g. _DSM, _PRW) for implementation. Modern hardware needs few changes to maintain ACPI compatibility and some options for such changes are provided as part of OpenCore.
To compile and disassemble ACPI tables, the iASL compiler developed by ACPICA can be used. A GUI front-end to iASL compiler can be downloaded from Acidanthera/MaciASL.
ACPI changes apply globally (to every operating system) with the following effective order:
Note: RebaseRegions and SyncTableIds quirks are special and are processed after all other ACPI changes since they can only be applied on the final ACPI configuration including all the patches and added tables.
Applying the changes globally resolves the problems of incorrect operating system detection (consistent with the ACPI specification, not possible before the operating system boots), operating system chainloading, and difficult ACPI debugging. Hence, more attention may be required when writing changes to _OSI.
Applying the patches early makes it possible to write so called “proxy” patches, where the original method is patched in the original table and is implemented in the patched table.
There are several sources of ACPI tables and workarounds. Commonly used ACPI tables are provided with OpenCore, VirtualSMC, VoodooPS2, and WhateverGreen releases. Besides those, several third-party instructions may be found on the AppleLife Laboratory and DSDT subforums (e.g. Battery register splitting guide). A slightly more user-friendly explanation of some tables included with OpenCore can also be found in Dortania’s Getting started with ACPI guide. For more exotic cases, there are several alternatives such as daliansky’s ACPI sample collection ( English Translation by 5T33Z0 et al). Please note however, that suggested solutions from third parties may be outdated or may contain errors.
Add
Type: plist array
Failsafe: Empty
Description: Load selected tables from the OC/ACPI directory.
To be filled with plist dict values, describing each add entry. Refer to the Add Properties section below for details.
Delete
Type: plist array
Failsafe: Empty
Description: Remove selected tables from the ACPI stack.
To be filled with plist dict values, describing each delete entry. Refer to the Delete Properties section below for details.
Patch
Type: plist array
Failsafe: Empty
Description: Perform binary patches in ACPI tables before table addition or removal.
To be filled with plist dictionary values describing each patch entry. Refer to the Patch Properties section below for details.
Path
Type: plist string
Failsafe: Empty
Description: File paths meant to be loaded as ACPI tables. Example values include DSDT.aml,
SubDir/SSDT-8.aml, SSDT-USBX.aml, etc.
The ACPI table load order follows the item order in the array. ACPI tables are loaded from the OC/ACPI directory.
Note: All tables apart from tables with a DSDT table identifier (determined by parsing data, not by filename) insert new tables into the ACPI stack. DSDT tables perform a replacement of DSDT tables instead.
TableSignature
Type: plist data, 4 bytes
Failsafe: All zero (Match any table signature)
Description: Match table signature equal to this value.
Note: Do not use table signatures when the sequence must be replaced in multiple places. This is particularly relevant when performing different types of renames.
Base
Type: plist string
Failsafe: Empty (Ignored)
Description: Selects ACPI path base for patch lookup (or immediate replacement) by obtaining the offset to
the provided path.
Only fully-qualified absolute paths are supported (e.g. \_SB.PCI0.LPCB.HPET). Currently supported object types are: Device, Field, Method.
Note: Use with care, not all OEM tables can be parsed. Use ACPIe utility to debug. ACPIe compiled with DEBUG=1 make command produces helpful ACPI lookup tracing.
Find
Type: plist data
Failsafe: Empty
Description: Data to find. Must be equal to Replace in size if set.
Note: Can be empty, when Base is specified, immediate replacement after Base lookup happens in this case.
In most cases, ACPI patches are not useful and are harmful:
Some cases where patching is actually useful include:
The Tianocore AcpiAml.h source file may help with better understanding ACPI opcodes.
Note: Patches of different Find and Replace lengths are unsupported as they may corrupt ACPI tables and make the system unstable due to area relocation. If such changes are needed, the utilisation of “proxy” patching or the padding of NOP to the remaining area could be considered.
FadtEnableReset
Type: plist boolean
Failsafe: false
Description: Provide reset register and flag in FADT table to enable reboot and shutdown.
Mainly required on legacy hardware and a few newer laptops. Can also fix power-button shortcuts. Not recommended unless required.
RebaseRegions
Type: plist boolean
Failsafe: false
Description: Attempt to heuristically relocate ACPI memory regions. Not recommended.
ACPI tables are often generated dynamically by the underlying firmware implementation. Among the position-independent code, ACPI tables may contain the physical addresses of MMIO areas used for device configuration, typically grouped by region (e.g. OperationRegion). Changing firmware settings or hardware configuration, upgrading or patching the firmware inevitably leads to changes in dynamically generated ACPI code, which sometimes results in the shift of the addresses in the aforementioned OperationRegion constructions.
For this reason, the application of modifications to ACPI tables is extremely risky. The best approach is to make as few changes as possible to ACPI tables and to avoid replacing any tables, particularly DSDT tables. When this cannot be avoided, ensure that any custom DSDT tables are based on the most recent DSDT tables or attempt to remove reads and writes for the affected areas.
When nothing else helps, this option could be tried to avoid stalls at PCI Configuration Begin phase of macOS booting by attempting to fix the ACPI addresses. It is not a magic bullet however, and only works with the most typical cases. Do not use unless absolutely required as it can have the opposite effect on certain platforms and result in boot failures.
ResetHwSig
Type: plist boolean
Failsafe: false
Description: Reset FACS table HardwareSignature value to 0.
This works around firmware that fail to maintain hardware signature across the reboots and cause issues with waking from hibernation.
ResetLogoStatus
Type: plist boolean
Failsafe: false
Description: Reset BGRT table Displayed status field to false.
This works around firmware that provide a BGRT table but fail to handle screen updates afterwards.
SyncTableIds
Type: plist boolean
Failsafe: false
Description: Sync table identifiers with the SLIC table.
This works around patched tables becoming incompatible with the SLIC table causing licensing issues in older Windows operating systems.
This section allows the application of different types of UEFI modifications to operating system bootloaders, primarily the Apple bootloader (boot.efi). The modifications currently provide various patches and environment alterations for different firmware types. Some of these features were originally implemented as part of AptioMemoryFix.efi, which is no longer maintained. Refer to the Tips and Tricks section for instructions on migration.
Booter changes apply with the following effective order:
If this is used for the first time on customised firmware, the following requirements should be met before starting:
When debugging sleep issues, Power Nap and automatic power off (which appear to sometimes cause wake to black screen or boot loop issues on older platforms) may be temporarily disabled. The specific issues may vary, but ACPI tables should typically be looked at first.
Here is an example of a defect found on some Z68 motherboards. To turn Power Nap and the others off, run the following commands in Terminal:
sudo pmset autopoweroff 0 sudo pmset powernap 0 sudo pmset standby 0
Note: These settings may be reset by hardware changes and in certain other circumstances. To view their current state, use the pmset -g command in Terminal.
Patch
Type: plist array
Failsafe: Empty
Description: Perform binary patches in booter.
To be filled with plist dictionary values, describing each patch. Refer to the Patch Properties section below for details.
Address
Type: plist integer
Failsafe: 0
Description: Exceptional MMIO address, which memory descriptor should be left virtualised (unchanged) by
DevirtualiseMmio. This means that the firmware will be able to directly communicate with this memory region
during operating system functioning, because the region this value is in will be assigned a virtual address.
The addresses written here must be part of the memory map, have EfiMemoryMappedIO type and EFI_MEMORY_RUNTIME attribute (highest bit) set. The debug log can be used to find the list of the candidates.
AllowRelocationBlock
Type: plist boolean
Failsafe: false
Description: Allows booting macOS through a relocation block.
The relocation block is a scratch buffer allocated in the lower 4 GB used for loading the kernel and related structures by EfiBoot on firmware where the lower memory region is otherwise occupied by (assumed) non-runtime data. Right before kernel startup, the relocation block is copied back to lower addresses. Similarly, all the other addresses pointing to the relocation block are also carefully adjusted. The relocation block can be used when:
This quirk typically requires ProvideCustomSlide and AvoidRuntimeDefrag to be enabled to function correctly. Hibernation is not supported when booting with a relocation block, which will only be used if required when the quirk is enabled.
Note: While this quirk is required to run older macOS versions on platforms with used lower memory, it is not compatible with some hardware and macOS 11. In such cases, consider using EnableSafeModeSlide instead.
AvoidRuntimeDefrag
Type: plist boolean
Failsafe: false
Description: Protect from boot.efi runtime memory defragmentation.
This option fixes UEFI runtime services (date, time, NVRAM, power control, etc.) support on firmware that uses SMM backing for certain services such as variable storage. SMM may try to access memory by physical addresses in non-SMM areas but this may sometimes have been moved by boot.efi. This option prevents boot.efi from moving such data.
Note: Most types of firmware, apart from Apple and VMware, need this quirk.
DevirtualiseMmio
Type: plist boolean
Failsafe: false
Description: Remove runtime attribute from certain MMIO regions.
This quirk reduces the stolen memory footprint in the memory map by removing the runtime bit for known memory regions. This quirk may result in an increase of KASLR slides available but without additional measures, it is not necessarily compatible with the target board. This quirk typically frees between 64 and 256 megabytes of memory, present in the debug log, and on some platforms, is the only way to boot macOS, which otherwise fails with allocation errors at the bootloader stage.
This option is useful on all types of firmware, except for some very old ones such as Sandy Bridge. On certain firmware, a list of addresses that need virtual addresses for proper NVRAM and hibernation functionality may be required. Use the MmioWhitelist section for this.
DisableSingleUser
Type: plist boolean
Failsafe: false
Description: Disable single user mode.
This is a security option that restricts the activation of single user mode by ignoring the CMD+S hotkey and the -s boot argument. The behaviour with this quirk enabled is supposed to match T2-based model behaviour. Refer to this archived article to understand how to use single user mode with this quirk enabled.
Note: When Apple Secure Boot is enabled single user mode is always disabled.
DisableVariableWrite
Type: plist boolean
Failsafe: false
Description: Protect from macOS NVRAM write access.
This is a security option that restricts NVRAM access in macOS. This quirk requires OC_FIRMWARE_RUNTIME protocol implemented in OpenRuntime.efi.
Note: This quirk can also be used as an ad hoc workaround for defective UEFI runtime services implementations that are unable to write variables to NVRAM and results in operating system failures.
DiscardHibernateMap
Type: plist boolean
Failsafe: false
Description: Reuse original hibernate memory map.
This option forces the XNU kernel to ignore a newly supplied memory map and assume that it did not change after waking from hibernation. This behaviour is required by Windows to work. Windows mandates preserving runtime memory size and location after S4 wake.
Note: This may be used to workaround defective memory map implementations on older, rare legacy hardware. Examples of such hardware are Ivy Bridge laptops with Insyde firmware such as the Acer V3-571G. Do not use this option without a full understanding of the implications.
EnableSafeModeSlide
Type: plist boolean
Failsafe: false
Description: Patch bootloader to have KASLR enabled in safe mode.
This option is relevant to users with issues booting to safe mode (e.g. by holding shift or with using the -x boot argument). By default, safe mode forces 0 slide as if the system was launched with the slide=0 boot argument.
Note: The need for this option is dependent on the availability of safe mode. It can be enabled when booting to safe mode fails.
EnableWriteUnprotector
Type: plist boolean
Failsafe: false
Description: Permit write access to UEFI runtime services code.
This option bypasses W^X permissions in code pages of UEFI runtime services by removing write protection (WP) bit from CR0 register during their execution. This quirk requires OC_FIRMWARE_RUNTIME protocol implemented in OpenRuntime.efi.
Note: This quirk may potentially weaken firmware security. Please use RebuildAppleMemoryMap if the firmware supports memory attributes table (MAT). Refer to the OCABC: MAT support is 1/0 log entry to determine whether MAT is supported.
FixupAppleEfiImages
Type: plist boolean
Failsafe: false
Description: Fix errors in early Mac OS X boot.efi images.
Modern secure PE loaders will refuse to load boot.efi images from Mac OS X 10.4 to macOS 10.12 due to these files containing W^X errors (in all versions) and illegal overlapping sections (in 10.4 and 10.5 32-bit versions only).
This quirk detects these issues and pre-processes such images in memory, so that a modern loader will accept them.
Pre-processing in memory is incompatible with secure boot, as the image loaded is not the image on disk, so you cannot sign files which are loaded in this way based on their original disk image contents. Certain firmware will offer to register the hash of new, unknown images - this would still work. On the other hand, it is not particularly realistic to want to start these early, insecure images with secure boot anyway.
Note 1: The quirk is never applied during the Apple secure boot path for newer macOS. The Apple secure boot path includes its own separate mitigations for boot.efi W^X issues.
Note 2: When enabled, and when not processing for Apple secure boot, this quirk is applied to:
Note 3: This quirk is needed for Mac OS X 10.4 to macOS 10.12 (and higher, if Apple secure boot is not enabled), but only when the firmware itself includes a modern, more secure PE COFF image loader. This applies to current builds of OpenDuet, and to OVMF if built from audk source code.
ForceBooterSignature
Type: plist boolean
Failsafe: false
Description: Set macOS boot-signature to OpenCore launcher.
Booter signature, essentially a SHA-1 hash of the loaded image, is used by Mac EFI to verify the authenticity of the bootloader when waking from hibernation. This option forces macOS to use OpenCore launcher SHA-1 hash as a booter signature to let OpenCore shim hibernation wake on Mac EFI firmware.
Note: OpenCore launcher path is determined from LauncherPath property.
ForceExitBootServices
Type: plist boolean
Failsafe: false
Description: Retry ExitBootServices with new memory map on failure.
Try to ensure that the ExitBootServices call succeeds. If required, an outdated MemoryMap key argument can be used by obtaining the current memory map and retrying the ExitBootServices call.
Note: The need for this quirk is determined by early boot crashes of the firmware. Do not use this option without a full understanding of the implications.
ProtectMemoryRegions
Type: plist boolean
Failsafe: false
Description: Protect memory regions from incorrect access.
Some types of firmware incorrectly map certain memory regions:
This quirk attempts to fix the types of these regions, e.g. ACPI NVS for CSM or MMIO for MMIO.
Note: The need for this quirk is determined by artifacts, sleep wake issues, and boot failures. This quirk is typically only required by very old firmware.
ProtectSecureBoot
Type: plist boolean
Failsafe: false
Description: Protect UEFI Secure Boot variables from being written.
Reports security violation during attempts to write to db, dbx, PK, and KEK variables from the operating system.
Note: This quirk attempts to avoid issues with NVRAM implementations with fragmentation issues, such as on the MacPro5,1 as well as on certain Insyde firmware without garbage collection or with defective garbage collection.
ProtectUefiServices
Type: plist boolean
Failsafe: false
Description: Protect UEFI services from being overridden by the firmware.
Some modern firmware, including on virtual machines such as VMware, may update pointers to UEFI services during driver loading and related actions. Consequently, this directly obstructs other quirks that affect memory management, such as DevirtualiseMmio, ProtectMemoryRegions, or RebuildAppleMemoryMap, and may also obstruct other quirks depending on the scope of such.
GRUB Shim makes similar on-the-fly changes to various UEFI image services, which are also protected against by this quirk.
Note 1: On VMware, the need for this quirk may be determined by the appearance of the “Your Mac OS guest might run unreliably with more than one virtual core.” message.
Note 2: This quirk is needed for correct operation if OpenCore is chainloaded from GRUB with BIOS Secure Boot enabled.
ProvideCustomSlide
Type: plist boolean
Failsafe: false
Description: Provide custom KASLR slide on low memory.
This option performs memory map analysis of the firmware and checks whether all slides (from 1 to 255) can be used. As boot.efi generates this value randomly with rdrand or pseudo randomly rdtsc, there is a chance of boot failure when it chooses a conflicting slide. In cases where potential conflicts exist, this option forces macOS to select a pseudo random value from the available values. This also ensures that the slide= argument is never passed to the operating system (for security reasons).
Note: The need for this quirk is determined by the OCABC: Only N/256 slide values are usable! message in the debug log.
ProvideMaxSlide
Type: plist integer
Failsafe: 0
Description: Provide maximum KASLR slide when higher ones are unavailable.
This option overrides the maximum slide of 255 by a user specified value between 1 and 254 (inclusive) when ProvideCustomSlide is enabled. It is assumed that modern firmware allocates pool memory from top to bottom, effectively resulting in free memory when slide scanning is used later as temporary memory during kernel loading. When such memory is not available, this option stops the evaluation of higher slides.
Note: The need for this quirk is determined by random boot failures when ProvideCustomSlide is enabled and the randomized slide falls into the unavailable range. When AppleDebug is enabled, the debug log typically contains messages such as AAPL: [EB|‘LD:LKC] } Err(0x9). To find the optimal value, append slide=X, where X is the slide value, to the boot-args and select the largest one that does not result in boot failures.
RebuildAppleMemoryMap
Type: plist boolean
Failsafe: false
Description: Generate macOS compatible Memory Map.
The Apple kernel has several limitations on parsing the UEFI memory map:
To workaround these limitations, this quirk applies memory attribute table permissions to the memory map passed to the Apple kernel and optionally attempts to unify contiguous slots of similar types if the resulting memory map exceeds 4 KB.
Note 1: Since several types of firmware come with incorrect memory protection tables, this quirk often comes paired with SyncRuntimePermissions.
Note 2: The need for this quirk is determined by early boot failures. This quirk replaces EnableWriteUnprotector on firmware supporting Memory Attribute Tables (MAT). This quirk is typically unnecessary when using OpenDuetPkg but may be required to boot Mac OS X 10.6, and earlier, for reasons that are as yet unclear.
ResizeAppleGpuBars
Type: plist integer
Failsafe: -1
Description: Reduce GPU PCI BAR sizes for compatibility with macOS.
This quirk reduces GPU PCI BAR sizes for Apple macOS up to the specified value or lower if it is unsupported. The specified value follows PCI Resizable BAR spec. While Apple macOS supports a theoretical 1 GB maximum, in practice all non-default values may not work correctly. For this reason the only supported value for this quirk is the minimal supported BAR size, i.e. 0. Use -1 to disable this quirk.
For development purposes one may take risks and try other values. Consider a GPU with 2 BARs:
Example 1: Setting ResizeAppleGpuBars to 1 GB will change BAR0 to 1 GB and leave BAR1 unchanged.
Example 2: Setting ResizeAppleGpuBars to 1 MB will change BAR0 to 256 MB and BAR0 to 2 MB.
Example 3: Setting ResizeAppleGpuBars to 16 GB will make no changes.
Note: See ResizeGpuBars quirk for general GPU PCI BAR size configuration and more details about the technology.
SetupVirtualMap
Type: plist boolean
Failsafe: false
Description: Setup virtual memory at SetVirtualAddresses.
Some types of firmware access memory by virtual addresses after a SetVirtualAddresses call, resulting in early boot crashes. This quirk workarounds the problem by performing early boot identity mapping of assigned virtual addresses to physical memory.
Note: The need for this quirk is determined by early boot failures.
SignalAppleOS
Type: plist boolean
Failsafe: false
Description: Report macOS being loaded through OS Info for any OS.
This quirk is useful on Mac firmware, which loads different operating systems with different hardware configurations. For example, it is supposed to enable Intel GPU in Windows and Linux in some dual-GPU MacBook models.
SyncRuntimePermissions
Type: plist boolean
Failsafe: false
Description: Update memory permissions for the runtime environment.
Some types of firmware fail to properly handle runtime permissions:
This quirk attempts to update the memory map and memory attributes table to correct this.
Note: The need for this quirk is indicated by early boot failures (note: includes halt at black screen as well as more obvious crash). Particularly likely to affect early boot of Windows or Linux (but not always both) on affected systems. Only firmware released after 2017 is typically affected.
Device configuration is provided to macOS with a dedicated buffer, called EfiDevicePathPropertyDatabase. This buffer is a serialised map of DevicePaths to a map of property names and their values.
Property data can be debugged with gfxutil. To obtain current property data, use the following command in macOS:
ioreg -lw0 -p IODeviceTree -n efi -r -x | grep device-properties | sed 's/.*<//;s/>.*//' > /tmp/device-properties.hex && gfxutil /tmp/device-properties.hex /tmp/device-properties.plist && cat /tmp/device-properties.plist
Device properties are part of the IODeviceTree (gIODT) plane of the macOS I/O Registry. This plane has several construction stages relevant for the platform initialisation. While the early construction stage is performed by the XNU kernel in the IODeviceTreeAlloc method, the majority of the construction is performed by the platform expert, implemented in AppleACPIPlatformExpert.kext.
AppleACPIPlatformExpert incorporates two stages of IODeviceTree construction implemented by calling
AppleACPIPlatformExpert::mergeDeviceProperties:
The application of the stages depends on the device presence in ACPI tables. The first stage applies very early but exclusively to the devices present in ACPI tables. The second stage applies to all devices much later after the PCI configuration and may repeat the first stage if the device was not present in ACPI.
For all kernel extensions that may inspect the IODeviceTree plane without probing, such as Lilu and its plugins (e.g. WhateverGreen), it is especially important to ensure device presence in the ACPI tables. A failure to do so may result in erratic behaviour caused by ignoring the injected device properties as they were not constructed at the first stage. See SSDT-IMEI.dsl and SSDT-BRG0.dsl for an example.
Add
Type: plist dict
Description: Sets device properties from a map (plist dict) of device paths to a map (plist dict) of variable
names and their values in plist multidata format.
Note 1: Device paths must be provided in canonic string format (e.g. PciRoot(0x0)/Pci(0x1,0x0)/Pci(0x0,0x0)).
Note 2: Existing properties will not be changed unless deleted in the DeviceProperties Delete section.
Delete
Type: plist dict
Description: Removes device properties from a map (plist dict) of device paths to an array (plist array)
of variable names in plist string format.
Note: Currently, existing properties may only exist on firmware with DeviceProperties drivers (e.g. Apple). Hence, there is typically no reason to delete variables unless a new driver has been installed.
Some known properties include:
This section allows the application of different kinds of kernelspace modifications on Apple Kernel ( XNU). The modifications currently provide driver (kext) injection, kernel and driver patching, and driver blocking.
Kernel and kext changes apply with the following effective order:
Add
Type: plist array
Failsafe: Empty
Description: Load selected kernel extensions (kexts) from the OC/Kexts directory.
To be filled with plist dict values, describing each kext. Refer to the Add Properties section below for details.
Note 1: The load order is based on the order in which the kexts appear in the array. Hence, dependencies must appear before kexts that depend on them.
Note 2: To track the dependency order, inspect the OSBundleLibraries key in the Info.plist file of the kext being added. Any kext included under the key is a dependency that must appear before the kext being added.
Note 3: Kexts may have inner kexts (Plugins) included in the bundle. Such Plugins must be added separately and follow the same global ordering rules as other kexts.
Block
Type: plist array
Failsafe: Empty
Description: Remove selected kernel extensions (kexts) from the prelinked kernel.
To be filled with plist dictionary values, describing each blocked kext. Refer to the Block Properties section below for details.
Force
Type: plist array
Failsafe: Empty
Description: Load kernel extensions (kexts) from the system volume if they are not cached.
To be filled with plist dict values, describing each kext. Refer to the Force Properties section below for details. This section resolves the problem of injecting kexts that depend on other kexts, which are not otherwise cached. The issue typically affects older operating systems, where various dependency kexts, such as IOAudioFamily or IONetworkingFamily may not be present in the kernel cache by default.
Note 1: The load order is based on the order in which the kexts appear in the array. Hence, dependencies must appear before kexts that depend on them.
Note 2: Force happens before Add.
Note 3: The signature of the “forced” kext is not checked in any way. This makes using this feature extremely dangerous and undesirable for secure boot.
Note 4: This feature may not work on encrypted partitions in newer operating systems.
Patch
Type: plist array
Failsafe: Empty
Description: Perform binary patches in kernel and drivers prior to driver addition and removal.
To be filled with plist dictionary values, describing each patch. Refer to the Patch Properties section below for details.
MaxKernel
Type: plist string
Failsafe: Empty
Description: Adds kernel extension on specified macOS version or older.
Kernel version can be obtained with uname -r command, and should look like 3 numbers separated by dots, for example 18.7.0 is the kernel version for 10.14.6. Kernel version interpretation is implemented as follows:
ParseDarwinV ersion(κ,λ,μ) = κ ⋅ 10000Where κ ∈ (0,99) is kernel version major + λ ⋅ 100 Where λ ∈ (0,99) is kernel version minor + μ Where μ ∈ (0,99) is kernel version patch |
Kernel version comparison is implemented as follows:
α | = | ||
β | = | ||
γ | = | ||
f(α,β,γ) = α ≤ γ ≤ β |
Here ParseDarwinV ersion argument is assumed to be 3 integers obtained by splitting Darwin kernel version string from left to right by the . symbol. FindDarwinV ersion function looks up Darwin kernel version by locating "Darwin Kernel Version κ.λ.μ" string in the kernel image.
MinKernel
Type: plist string
Failsafe: Empty
Description: Adds kernel extension on specified macOS version or newer.
Note: Refer to the Add MaxKernel description for matching logic.
MaxKernel
Type: plist string
Failsafe: Empty
Description: Blocks kernel extension on specified macOS version or older.
Note: Refer to the Add MaxKernel description for matching logic.
MinKernel
Type: plist string
Failsafe: Empty
Description: Blocks kernel extension on specified macOS version or newer.
Note: Refer to the Add MaxKernel description for matching logic.
Strategy
Type: plist string
Failsafe: Disable (Forcibly make the kernel driver kmod startup code return failure)
Description: Determines the behaviour of kernel driver blocking.
Valid values:
Note: It is risky to Exclude a kext that is a dependency of others.
Note 2: At this moment Exclude is only applied to prelinkedkernel and newer mechanisms.
Note 3: In most cases strategy Exclude requires the new kext to be injected as a replacement.
Cpuid1Data
Type: plist data, 16 bytes
Failsafe: All zero
Description: Sequence of EAX, EBX, ECX, EDX values to replace CPUID (1) call in XNU kernel.
This property primarily meets three requirements:
Note 1: It may also be the case that the CPU model is supported but there is no power management supported (e.g. virtual machines). In this case, MinKernel and MaxKernel can be set to restrict CPU virtualisation and dummy power management patches to the particular macOS kernel version.
Note 2: Only the value of EAX, which represents the full CPUID, typically needs to be accounted for and remaining bytes should be left as zeroes. The byte order is Little Endian. For example, C3 06 03 00 stands for CPUID 0x0306C3 (Haswell).
Note 3: For XCPM support it is recommended to use the following combinations. Be warned that one is required to set the correct frequency vectors matching the installed CPU.
Note 4: Be aware that the following configurations are unsupported by XCPM (at least out of the box):
Cpuid1Mask
Type: plist data, 16 bytes
Failsafe: All zero
Description: Bit mask of active bits in Cpuid1Data.
When each Cpuid1Mask bit is set to 0, the original CPU bit is used, otherwise set bits take the value of Cpuid1Data.
DummyPowerManagement
Type: plist boolean
Failsafe: false
Requirement: 10.4-12
Description: Disables AppleIntelCpuPowerManagement.
Note 1: This option is a preferred alternative to NullCpuPowerManagement.kext for CPUs without native power management driver in macOS.
Note 2: While this option is typically needed to disable AppleIntelCpuPowerManagement on unsupported platforms, it can also be used to disable this kext in other situations (e.g. with Cpuid1Data left blank).
MaxKernel
Type: plist string
Failsafe: Empty
Description: Emulates CPUID and applies DummyPowerManagement on specified macOS version or older.
Note: Refer to the Add MaxKernel description for matching logic.
MinKernel
Type: plist string
Failsafe: Empty
Description: Emulates CPUID and applies DummyPowerManagement on specified macOS version or newer.
Note: Refer to the Add MaxKernel description for matching logic.
MaxKernel
Type: plist string
Failsafe: Empty
Description: Adds kernel extension on specified macOS version or older.
Note: Refer to the Add MaxKernel description for matching logic.
MinKernel
Type: plist string
Failsafe: Empty
Description: Adds kernel extension on specified macOS version or newer.
Note: Refer to the Add MaxKernel description for matching logic.
MaxKernel
Type: plist string
Failsafe: Empty
Description: Patches data on specified macOS version or older.
Note: Refer to the Add MaxKernel description for matching logic.
MinKernel
Type: plist string
Failsafe: Empty
Description: Patches data on specified macOS version or newer.
Note: Refer to the Add MaxKernel description for matching logic.
AppleCpuPmCfgLock
Type: plist boolean
Failsafe: false
Requirement: 10.4
Description: Disables PKG_CST_CONFIG_CONTROL (0xE2) MSR
modification in AppleIntelCPUPowerManagement.kext, commonly causing early kernel panic, when it is locked
from writing.
Note: AppleIntelCPUPowerManagement.kext is removed as of macOS 13. However, a legacy version can be injected and thus get patched using this quirk.
Some types of firmware lock the PKG_CST_CONFIG_CONTROL MSR register and the bundled ControlMsrE2 tool can be used to check its state. Note that some types of firmware only have this register locked on some cores. As modern firmware provide a CFG Lock setting that allows configuring the PKG_CST_CONFIG_CONTROL MSR register lock, this option should be avoided whenever possible.
On APTIO firmware that do not provide a CFG Lock setting in the GUI, it is possible to access the option directly:
Warning: Variable offsets are unique not only to each motherboard but even to its firmware version. Never ever try to use an offset without checking.
On selected platforms, the ControlMsrE2 tool can also change such hidden options. Pass desired argument: lock, unlock for CFG Lock. Or pass interactive to find and modify other hidden options.
As a last resort, consider patching the BIOS (for advanced users only).
AppleXcpmCfgLock
Type: plist boolean
Failsafe: false
Requirement: 10.8 (not required for older)
Description: Disables PKG_CST_CONFIG_CONTROL (0xE2) MSR modification in XNU kernel, commonly causing early
kernel panic, when it is locked from writing (XCPM power management).
Note: This option should be avoided whenever possible. Refer to the AppleCpuPmCfgLock description for details.
AppleXcpmExtraMsrs
Type: plist boolean
Failsafe: false
Requirement: 10.8 (not required for older)
Description: Disables multiple MSR access critical for certain CPUs, which have no native XCPM support.
This is typically used in conjunction with the Emulate section on Haswell-E, Broadwell-E, Skylake-SP, and similar CPUs. More details on the XCPM patches are outlined in acidanthera/bugtracker#365.
Note: Additional not provided patches will be required for Ivy Bridge or Pentium CPUs. It is recommended to use AppleIntelCpuPowerManagement.kext for the former.
AppleXcpmForceBoost
Type: plist boolean
Failsafe: false
Requirement: 10.8 (not required for older)
Description: Forces maximum performance in XCPM mode.
This patch writes 0xFF00 to MSR_IA32_PERF_CONTROL (0x199), effectively setting maximum multiplier for all the time.
Note: While this may increase the performance, this patch is strongly discouraged on all systems but those explicitly dedicated to scientific or media calculations. Only certain Xeon models typically benefit from the patch.
CustomPciSerialDevice
Type: plist boolean
Failsafe: false
Requirement: 10.7
Description: Performs change of PMIO register base address on a customised PCI serial device.
The patch changes the PMIO register base address that the XNU kernel uses for serial input and output, from that of the default built-in COM1 serial port 0x3F8, to the base address stored in the first IO BAR of a specified PCI device or to a specific base address (e.g. 0x2F8 for COM2).
Note: By default, serial logging is disabled. serial=3 boot argument, which enables serial input and output, should be used for XNU to print logs to the serial port.
Note 2: In addition to this patch, kext Apple16X50PCI0 should be prevented from attaching to have kprintf method working properly. This can be achieved by using PCIeSerialDisable. In addition, for certain Thunderbolt cards the IOKit personality IOPCITunnelCompatible also needs to be set to true, which can be done by the PCIeSerialThunderboltEnable.kext attached at acidanthera/bugtracker#2003.
Note 3: For this patch to be correctly applied, Override must be enabled with all keys properly set in Custom, under section Misc->Serial.
Note 4: This patch is for PMIO support and is therefore not applied if UseMmio under section Misc->Serial->Custom is false. For MMIO, there are boot arguments pcie_mmio_uart=ADDRESS and mmio_uart=ADDRESS that allow the kernel to use MMIO for serial port access.
Note 5: The serial baud rate must be correctly set in both BaudRate under section Misc->Serial->Custom and via serialbaud=VALUE boot argument, both of which should match against each other. The default baud rate is 115200.
DisableIoMapper
Type: plist boolean
Failsafe: false
Requirement: 10.8 (not required for older)
Description: Disables IOMapper support in XNU (VT-d), which may conflict with the firmware implementation.
Note 1: This option is a preferred alternative to deleting DMAR ACPI table and disabling VT-d in firmware preferences, which does not obstruct VT-d support in other systems in case they need this.
Note 2: Misconfigured IOMMU in the firmware may result in broken devices such as ethernet or Wi-Fi adapters. For instance, an ethernet adapter may cycle in link-up link-down state infinitely and a Wi-Fi adapter may fail to discover networks. Gigabyte is one of the most common OEMs with these issues.
DisableIoMapperMapping
Type: plist boolean
Failsafe: false
Requirement: 13.3 (not required for older)
Description: Disables mapping PCI bridge device memory in IOMMU (VT-d).
This option resolves compatibility issues with Wi-Fi, Ethernet and Thunderbolt devices when AppleVTD is enabled on systems where the native DMAR table contains one or more Reserved Memory Regions and more than 16 GB memory is installed. On some systems, this quirk is only needed when iGPU is enabled.
Note 1: This quirk requires a native DMAR table that does not contain Reserved Memory Regions or a substitute SSDT-DMAR.aml in which Reserved Memory Regions have been removed.
Note 2: This option is not needed on AMD systems.
DisableLinkeditJettison
Type: plist boolean
Failsafe: false
Requirement: 11
Description: Disables __LINKEDIT jettison code.
This option lets Lilu.kext, and possibly other kexts, function in macOS Big Sur at their best performance levels without requiring the keepsyms=1 boot argument.
DisableRtcChecksum
Type: plist boolean
Failsafe: false
Requirement: 10.4
Description: Disables primary checksum (0x58-0x59) writing in AppleRTC.
Note 1: This option will not protect other areas from being overwritten, see RTCMemoryFixup kernel extension if this is desired.
Note 2: This option will not protect areas from being overwritten at firmware stage (e.g. macOS bootloader), see AppleRtcRam protocol description if this is desired.
ExtendBTFeatureFlags
Type: plist boolean
Failsafe: false
Requirement: 10.8-11
Description: Set FeatureFlags to 0x0F for full functionality of Bluetooth, including Continuity.
Note: This option is a substitution for BT4LEContinuityFixup.kext, which does not function properly due to late patching progress.
ExternalDiskIcons
Type: plist boolean
Failsafe: false
Requirement: 10.4
Description: Apply icon type patches to AppleAHCIPort.kext to force internal disk icons for all AHCI
disks.
Note: This option should be avoided whenever possible. Modern firmware typically have compatible AHCI controllers.
ForceAquantiaEthernet
Type: plist boolean
Failsafe: false
Requirement: 10.15.4
Description: Enable Aquantia AQtion based 10GbE network cards support.
This option enables Aquantia AQtion based 10GbE network cards support, which used to work natively before macOS 10.15.4.
Note: In order for Aquantia cards to properly function, DisableIoMapper must be disabled, DMAR ACPI table must not be dropped, and VT-d must be enabled in BIOS.
Note 2: While this patch should enable ethernet support for all Aquantia AQtion series, it has only been tested on AQC-107s based 10GbE network cards.
Note 3: To address AppleVTD incompatibilities after applying this quirk, the Reserved Memory Region section of the corresponding device in the DMAR ACPI table might be removed. This table should be disassembled and edited, then recompiled to AML with tool iASL. For the patched DMAR table to be added, the original one should be deleted. More details can be found at comment on commit 2441455.
ForceSecureBootScheme
Type: plist boolean
Failsafe: false
Requirement: 11
Description: Force x86 scheme for IMG4 verification.
Note: This option is required on virtual machines when using SecureBootModel different from x86legacy.
IncreasePciBarSize
Type: plist boolean
Failsafe: false
Requirement: 10.10
Description: Allows IOPCIFamily to boot with 2 GB PCI BARs.
Normally macOS restricts PCI BARs to 1 GB. Enabling this option (still) does not let macOS actually use PCI devices with larger BARs.
Note: This option should be avoided whenever possible. A need for this option indicates misconfigured or defective firmware.
PowerTimeoutKernelPanic
Type: plist boolean
Failsafe: false
Requirement: 10.15 (not required for older)
Description: Disables kernel panic on setPowerState timeout.
An additional security measure was added to macOS Catalina (10.15) causing kernel panic on power change timeout for Apple drivers. Sometimes it may cause issues on misconfigured hardware, notably digital audio, which sometimes fails to wake up. For debug kernels setpowerstate_panic=0 boot argument should be used, which is otherwise equivalent to this quirk.
ProvideCurrentCpuInfo
Type: plist boolean
Failsafe: false
Requirement: 10.4 (10.14)
Description: Provides current CPU info to the kernel.
This quirk works differently depending on the CPU:
SetApfsTrimTimeout
Type: plist integer
Failsafe: -1
Requirement: 10.14 (not required for older)
Description: Set trim timeout in microseconds for APFS filesystems on SSDs.
The APFS filesystem is designed in a way that the space controlled via the spaceman structure is either used or free. This may be different in other filesystems where the areas can be marked as used, free, and unmapped. All free space is trimmed (unmapped/deallocated) at macOS startup. The trimming procedure for NVMe drives happens in LBA ranges due to the nature of the DSM command with up to 256 ranges per command. The more fragmented the memory on the drive is, the more commands are necessary to trim all the free space.
Depending on the SSD controller and the level of drive fragmenation, the trim procedure may take a considerable amount of time, causing noticeable boot slowdown. The APFS driver explicitly ignores previously unmapped areas and repeatedly trims them on boot. To mitigate against such boot slowdowns, the macOS driver introduced a timeout (9.999999 seconds) that stops the trim operation when not finished in time.
On several controllers, such as Samsung, where the deallocation process is relatively slow, this timeout can be reached very quickly. Essentially, it means that the level of fragmentation is high, thus macOS will attempt to trim the same lower blocks that have previously been deallocated, but never have enough time to deallocate higher blocks. The outcome is that trimming on such SSDs will be non-functional soon after installation, resulting in additional wear on the flash.
One way to workaround the problem is to increase the timeout to an extremely high value, which at the cost of slow boot times (extra minutes) will ensure that all the blocks are trimmed. Setting this option to a high value, such as 4294967295 ensures that all blocks are trimmed. Alternatively, use over-provisioning, if supported, or create a dedicated unmapped partition where the reserve blocks can be found by the controller. Conversely, the trim operation can be mostly disabled by setting a very low timeout value, while 0 entirely disables it. Refer to this article for details.
Note: The failsafe value -1 indicates that this patch will not be applied, such that apfs.kext will remain untouched.
Note 2: On macOS 12.0 and above, it is no longer possible to specify trim timeout. However, trim can be disabled by setting 0.
Note 3: Trim operations are only affected at booting phase when the startup volume is mounted. Either specifying timeout, or completely disabling trim with 0, will not affect normal macOS running.
ThirdPartyDrives
Type: plist boolean
Failsafe: false
Requirement: 10.6 (not required for older)
Description: Apply vendor patches to IOAHCIBlockStorage.kext to enable native features for third-party drives, such
as TRIM on SSDs or hibernation support on 10.15 and newer.
Note: This option may be avoided on user preference. NVMe SSDs are compatible without the change. For AHCI SSDs on modern macOS version there is a dedicated built-in utility called trimforce. Starting from 10.15 this utility creates EnableTRIM variable in APPLE_BOOT_VARIABLE_GUID namespace with 01 00 00 00 value.
XhciPortLimit
Type: plist boolean
Failsafe: false
Requirement: 10.11+ (not required for older)
Description: Patch various kexts (AppleUSBXHCI.kext, AppleUSBXHCIPCI.kext, IOUSBHostFamily.kext) to remove
USB port count limit of 15 ports.
Note: This option should be avoided whenever possible. USB port limit is imposed by the amount of used bits in locationID format and there is no possible way to workaround this without heavy OS modification. The only valid solution is to limit the amount of used ports to 15 (discarding some). More details can be found on AppleLife.ru.
These properties are particularly relevant for older macOS operating systems. Refer to the Legacy Apple OS section for details on how to install and troubleshoot such macOS installations.
CustomKernel
Type: plist boolean
Failsafe: false
Description: Use customised kernel cache from the Kernels directory located at the root of the ESP partition.
Unsupported platforms including Atom and AMD require modified versions of XNU kernel in order to boot. This option provides the possibility to using a customised kernel cache which contains such modifications from ESP partition.
FuzzyMatch
Type: plist boolean
Failsafe: false
Description: Use kernelcache with different checksums when available.
On Mac OS X 10.6 and earlier, kernelcache filename has a checksum, which essentially is adler32 from SMBIOS product name and EfiBoot device path. On certain firmware, the EfiBoot device path differs between UEFI and macOS due to ACPI or hardware specifics, rendering kernelcache checksum as always different.
This setting allows matching the latest kernelcache with a suitable architecture when the kernelcache without suffix is unavailable, improving Mac OS X 10.6 boot performance on several platforms.
KernelArch
Type: plist string
Failsafe: Auto (Choose the preferred architecture automatically)
Description: Prefer specified kernel architecture (i386, i386-user32, x86_64) when available.
On Mac OS X 10.7 and earlier, the XNU kernel can boot with architectures different from the usual x86_64. This setting will use the specified architecture to boot macOS when it is supported by the macOS and the configuration:
i386-user32 — Use i386 (32-bit) kernel when available and force the use of 32-bit userspace on 64-bit capable processors if supported by the operating system.
The algorithm used to determine the preferred kernel architecture is set out below.
Determined EfiBoot version restricts architecture choice:
Unlike Mac OS X 10.7 (where certain board identifiers are treated as i386 only machines), and Mac OS X 10.5 or earlier (where x86_64 is not supported by the macOS kernel), Mac OS X 10.6 is very special. The architecture choice on Mac OS X 10.6 depends on many factors including not only the board identifier, but also the macOS product type (client vs server), macOS point release, and amount of RAM. The detection of all these is complicated and impractical, as several point releases had implementation flaws resulting in a failure to properly execute the server detection in the first place. For this reason when Auto is set, OpenCore on Mac OS X 10.6 falls back to the x86_64 architecture when it is supported by the board, as on Mac OS X 10.7. The 32-bit KernelArch options can still be configured explicitly however.
A 64-bit Mac model compatibility matrix corresponding to actual EfiBoot behaviour on Mac OS X 10.6.8 and 10.7.5 is outlined below.
Model | 10.6 (minimal) | 10.6 (client) | 10.6 (server) | 10.7 (any) |
Macmini | 4,x (Mid 2010) | 5,x (Mid 2011) | 4,x (Mid 2010) | 3,x (Early 2009) |
MacBook | Unsupported | Unsupported | Unsupported | 5,x (2009/09) |
MacBookAir | Unsupported | Unsupported | Unsupported | 2,x (Late 2008) |
MacBookPro | 4,x (Early 2008) | 8,x (Early 2011) | 8,x (Early 2011) | 3,x (Mid 2007) |
iMac | 8,x (Early 2008) | 12,x (Mid 2011) | 12,x (Mid 2011) | 7,x (Mid 2007) |
MacPro | 3,x (Early 2008) | 5,x (Mid 2010) | 3,x (Early 2008) | 3,x (Early 2008) |
Xserve | 2,x (Early 2008) | 2,x (Early 2008) | 2,x (Early 2008) | 2,x (Early 2008) |
Note: 3+2 and 6+4 hotkeys to choose the preferred architecture are unsupported as they are handled by EfiBoot and hence, difficult to detect.
KernelCache
Type: plist string
Failsafe: Auto
Description: Prefer specified kernel cache type (Auto, Cacheless, Mkext, Prelinked) when available.
Different variants of macOS support different kernel caching variants designed to improve boot performance. This setting prevents the use of faster kernel caching variants if slower variants are available for debugging and stability reasons. That is, by specifying Mkext, Prelinked will be disabled for e.g. 10.6 but not for 10.7.
The list of available kernel caching types and its current support in OpenCore is listed below.
macOS | i386 NC | i386 MK | i386 PK | x86_64 NC | x86_64 MK | x86_64 PK | x86_64 KC |
10.4 | YES | YES (V1) | NO (V1) | — | — | — | — |
10.5 | YES | YES (V1) | NO (V1) | — | — | — | — |
10.6 | YES | YES (V2) | YES (V2) | YES | YES (V2) | YES (V2) | — |
10.7 | YES | — | YES (V3) | YES | — | YES (V3) | — |
10.8-10.9 | — | — | — | YES | — | YES (V3) | — |
10.10-10.15 | — | — | — | — | — | YES (V3) | — |
11+ | — | — | — | — | — | YES (V3) | YES |
Note: The first version (V1) of the 32-bit prelinkedkernel is unsupported due to the corruption of kext symbol tables by the tools. On this version, the Auto setting will block prelinkedkernel booting. This also results in the keepsyms=1 boot argument being non-functional for kext frames on these systems.
This section contains miscellaneous configuration options affecting OpenCore operating system loading behaviour in addition to other options that do not readily fit into other sections.
OpenCore broadly follows the “bless” model, also known as the “Apple Boot Policy”. The primary purpose of the “bless” model is to allow embedding boot options within the file system (and be accessible through a specialised driver) as well as supporting a broader range of predefined boot paths as compared to the removable media list set out in the UEFI specification.
Partitions can only booted by OpenCore when they meet the requirements of a predefined Scan policy. This policy sets out which specific file systems a partition must have, and which specific device types a partition must be located on, to be made available by OpenCore as a boot option. Refer to the ScanPolicy property for details.
The scan process starts with enumerating all available partitions, filtered based on the Scan policy. Each partition may generate multiple primary and alternate options. Primary options represent operating systems installed on the media, while alternate options represent recovery options for the operating systems on the media.
Each primary and alternate option can be an auxiliary option or not.
The algorithm to determine boot options behaves as follows:
For each boot option found:
For each partition handle:
A .contentVisibility file may be placed next to the bootloader (such as boot.efi), or in the boot folder (for DMG folder based boot items). Example locations, as seen from within macOS, are:
In addition a .contentVisibility file may be placed in the instance-specific (for macOS) or absolute root folders related to a boot entry, for example:
These root folder locations are supported specifically for macOS, because non-Apple files next to the Apple bootloader are removed by macOS updates. It is supported but not recommended to place a .contentVisibility file in a non-macOS root location (such as the last location shown above), because it will hide all entries on the drive.
The .contentVisibility file, when present, may optionally target only specific instances of OpenCore. Its contents are [{Instance-List}:](Disabled|Auxiliary). If a colon (:) is present, the preceding Instance-List it is a comma separated list of InstanceIdentifier values (example: OCA,OCB:Disabled). When this list is present, the specified visibility is only applied if the InstanceIdentifier of the current instance of OpenCore is present in the list. When the list is not present, the specified visibility is applied for all instances of OpenCore.
Note 1: For any instance of OpenCore with no InstanceIdentifier value, the specified visibility from a .contentVisibility file with an Instance-List will never be applied.
Note 2: Visibilities with a visibility list will be treated as invalid, and so ignored, in earlier versions of OpenCore - which may be useful when comparing behaviour of older and newer versions.
Note 3: Avoid extraneous spaces in the .contentVisibility file: these will not be treated as whitespace, but as part of the adjacent token.
The display order of the boot options in the OpenCore picker and the boot process are determined separately from the scanning algorithm.
The display order is as follows:
The boot process is as follows:
Note 1: This process will only work reliably when the RequestBootVarRouting option is enabled or the firmware does not control UEFI boot options (OpenDuetPkg or custom BDS). When LauncherOption is not enabled, other operating systems may overwrite OpenCore settings and this property should therefore be enabled when planning to use other operating systems.
Note 2: UEFI variable boot options boot arguments will be removed, if present, as they may contain arguments that can compromise the operating system, which is undesirable when secure boot is enabled.
Note 3: Some operating systems, such as Windows, may create a boot option and mark it as the topmost option upon first boot or after NVRAM resets from within OpenCore. When this happens, the default boot entry choice will remain changed until the next manual reconfiguration.
BlessOverride
Type: plist array
Failsafe: Empty
Description: Add custom scanning paths through the bless model.
To be filled with plist string entries containing absolute UEFI paths to customised bootloaders such as \EFI\debian\grubx64.efi for the Debian bootloader. This allows non-standard boot paths to be automatically discovered by the OpenCore picker. Designwise, they are equivalent to predefined blessed paths, such as \System\Library\CoreServices\boot.efi or \EFI\Microsoft\Boot\bootmgfw.efi, but unlike predefined bless paths, they have the highest priority.
Entries
Type: plist array
Failsafe: Empty
Description: Add boot entries to OpenCore picker.
To be filled with plist dict values, describing each load entry. Refer to the Entry Properties section below for details.
Serial
Type: plist dict
Description: Perform serial port initialisation and configure PCD values required by BaseSerialPortLib16550
for serial ports to properly function. Values are listed and described in the Serial Properties and Serial Custom
Properties section below.
By enabling Init, this section ensures that the serial port is initialised when it is not done by firmware. In order for OpenCore to print logs to the serial port, bit 3 (i.e. serial logging) for Target under section Misc->Debug must be set.
When debugging with serial ports, BaseSerialPortLib16550 only recognises internal ones provided by the motherboard by default. If the option Override is enabled, this section will override the PCD values listed in BaseSerialPortLib16550.inf such that external serial ports (e.g. from a PCI card) will also function properly. Specifically, when troubleshooting macOS, in addition to overriding these PCD values, it is also necessary to turn the CustomPciSerialDevice kernel quirk on in order for the XNU to use such exterior serial ports.
Refer to MdeModulePkg.dec for the explanations of each key.
Tools
Type: plist array
Failsafe: Empty
Description: Add tool entries to the OpenCore picker.
To be filled with plist dict values, describing each load entry. Refer to the Entry Properties section below for details.
Note: Certain UEFI tools, such as UEFI Shell, can be very dangerous and MUST NOT appear in production configurations, paticularly in vaulted configurations as well as those protected by secure boot, as such tools can be used to bypass the secure boot chain. Refer to the UEFI section for examples of UEFI tools.
ConsoleAttributes
Type: plist integer
Failsafe: 0
Description: Sets specific attributes for the console.
The text renderer supports colour arguments as a sum of foreground and background colours based on the UEFI specification. The value for black background and for black foreground, 0, is reserved.
List of colour values and names:
Note: This option may not work well with the System text renderer. Setting a background different from black could help with testing GOP functionality.
HibernateMode
Type: plist string
Failsafe: None
Description: Hibernation detection mode. The following modes are supported:
Note: If the firmware can handle hibernation itself (valid for Mac EFI firmware), then None should be specified to hand-off hibernation state as is to OpenCore.
HibernateSkipsPicker
Type: plist boolean
Failsafe: false
Description: Do not show picker if waking from macOS hibernation.
Limitations:
HideAuxiliary
Type: plist boolean
Failsafe: false
Description: Set to true to hide auxiliary entries from the picker menu.
An entry is considered auxiliary when at least one of the following applies:
To display all entries, the picker menu can be reloaded into “Extended Mode” by pressing the Spacebar key. Hiding auxiliary entries may increase boot performance on multi-disk systems.
InstanceIdentifier
Type: plist string
Failsafe: Empty
Description: An optional identifier for the current instance of OpenCore.
This should typically be a short alphanumeric string. The current use of this value is to optionally target .contentVisibility files to specific instances of OpenCore, as explained in the Boot Algorithm section.
LauncherOption
Type: plist string
Failsafe: Disabled
Description: Register the launcher option in the firmware preferences for persistence.
Valid values:
Full — create or update the top priority boot option in UEFI variable storage at bootloader startup.
Short — create a short boot option instead of a complete one.
System — create no boot option but assume specified custom option is blessed.
This option allows integration with third-party operating system installation and upgrades (which may overwrite the \EFI\BOOT\BOOTx64.efi file). The BOOTx64.efi file is no longer used for bootstrapping OpenCore if a custom option is created. The custom path used for bootstrapping can be specified by using the LauncherPath option.
Note 1: Some types of firmware may have NVRAM implementation flaws, no boot option support, or other incompatibilities. While unlikely, the use of this option may result in boot failures and should only be used exclusively on boards known to be compatible. Refer to acidanthera/bugtracker#1222 for some known issues affecting Haswell and other boards.
Note 2: While NVRAM resets executed from OpenCore would not typically erase the boot option created in Bootstrap, executing NVRAM resets prior to loading OpenCore will erase the boot option. Therefore, for significant implementation updates, such as was the case with OpenCore 0.6.4, an NVRAM reset should be executed with Bootstrap disabled, after which it can be re-enabled.
Note 3: Some versions of Intel Visual BIOS (e.g. on Intel NUC) have an unfortunate bug whereby if any boot option is added referring to a path on a USB drive, from then on that is the only boot option which will be shown when any USB drive is inserted. If OpenCore is started from a USB drive on this firmware with LauncherOption set to Full or Short, this applies and only the OpenCore boot entry will be seen afterwards, when any other USB is inserted (this highly non-standard BIOS behaviour affects other software as well). The best way to avoid this is to leave LauncherOption set to Disabled or System on any version of OpenCore which will be started from a USB drive on this firmware. If the problem has already occurred the quickest reliable fix is:
It is alternatively possible to start OpenShell directly from the OpenCore boot menu, if you have a working configured OpenCore for the system. In that case, and if OpenCore has RequestBootVarRouting enabled, it will be necessary to run the command \EFI\OC\Tools\OpenControl.efi disable before using bcfg. (After OpenControl disable, it is necessary to either reboot or run OpenControl restore, before booting an operating system.) It is also possible to use efibootmgr within Linux to remove the offending entry, if you have a working version of Linux on the machine. Linux must be started either not via OpenCore, or via OpenCore with RequestBootVarRouting disabled for this to work.
LauncherPath
Type: plist string
Failsafe: Default
Description: Launch path for the LauncherOption property.
Default points to OpenCore.efi. User specified paths, e.g. \EFI\SomeLauncher.efi, can be used to provide custom loaders, which are supposed to load OpenCore.efi themselves.
PickerAttributes
Type: plist integer
Failsafe: 0
Description: Sets specific attributes for the OpenCore picker.
Different OpenCore pickers may be configured through the attribute mask containing OpenCore-reserved (BIT0~BIT15) and OEM-specific (BIT16~BIT31) values.
Current OpenCore values include:
0x0001 — OC_ATTR_USE_VOLUME_ICON, provides custom icons for boot entries:
OpenCore will attempt loading a volume icon by searching as follows, and will fallback to the default icon on failure:
Note 1: The Apple picker partially supports placing a volume icon file at the operating system’s Data volume root, /System/Volumes/Data/, when mounted at the default location within macOS. This approach is flawed: the file is neither accessible to OpenCanopy nor to the Apple picker when FileVault 2, which is meant to be the default choice, is enabled. Therefore, OpenCanopy does not attempt supporting Apple’s approach. A volume icon file may be placed at the root of the Preboot volume for compatibility with both OpenCanopy and the Apple picker, or use the Preboot per-volume location as above with OpenCanopy as a preferred alternative to Apple’s approach.
Note 2: Be aware that using a volume icon on any drive overrides the normal OpenCore picker behaviour for that drive of selecting the appropriate icon depending on whether the drive is internal or external.
0x0080 — OC_ATTR_USE_FLAVOUR_ICON, provides flexible boot entry content description, suitable for picking the best media across different content sets:
When enabled, the entry icon in OpenCanopy and the audio assist entry sound in OpenCanopy and builtin boot picker are chosen by something called content flavour. To determine content flavour the following algorithm is used:
The Flavour value is a sequence of : separated names limited to 64 characters of printable 7-bit ASCII. This is designed to support up to approximately five names. Each name refers to a flavour, with the first name having the highest priority and the last name having the lowest priority. Such a structure allows describing an entry in a more specific way, with icons selected flexibly depending on support by the audio-visual pack. A missing audio or icon file means the next flavour should be tried, and if all are missing the choice happens based on the type of the entry. Example flavour values: BigSur:Apple, Windows10:Windows. OpenShell:UEFIShell:Shell.
Using flavours means that you can switch between icon sets easily, with the flavour selecting the best available icons from each set. E.g. specifying icon flavour Debian:Linux will use the icon Debian.icns if provided, then will try Linux.icns, then will fall back to the default for an OS, which is HardDrive.icns.
Things to keep in mind:
0x0200 — OC_ATTR_REDUCE_MOTION, reduce password and menu animation in OpenCanopy, leaving only animations which communicate information not otherwise provided.
Note: These same animations, plus additional animations whose information is provided by voice-over, are automatically disabled when PickerAudioAssist is enabled.
PickerAudioAssist
Type: plist boolean
Failsafe: false
Description: Enable screen reader by default in the OpenCore picker.
For the macOS bootloader, screen reader preference is set in the preferences.efires archive in the isVOEnabled.int32 file and is controlled by the operating system. For OpenCore screen reader support, this option is an independent equivalent. Toggling screen reader support in both the OpenCore picker and the macOS bootloader FileVault 2 login window can also be done by using the Command + F5 key combination.
Note: The screen reader requires working audio support. Refer to the UEFI Audio Properties section for details.
PickerMode
Type: plist string
Failsafe: Builtin
Description: Choose picker used for boot management.
PickerMode describes the underlying boot management with an optional user interface responsible for handling boot options.
The following values are supported:
Upon success, the External mode may entirely disable all boot management in OpenCore except for policy enforcement. In the Apple mode, it may additionally bypass policy enforcement. Refer to the OpenCanopy plugin for an example of a custom user interface.
The OpenCore built-in picker contains a set of actions chosen during the boot process. The list of supported actions is similar to Apple BDS and typically can be accessed by holding action hotkeys during the boot process.
The following actions are currently considered:
Note 1: On non-Apple firmware KeySupport, OpenUsbKbDxe, or similar drivers are required for key handling. However, not all of the key handling functions can be implemented on several types of firmware.
Note 2: In addition to OPT, OpenCore supports using both the Escape and Zero keys to enter the OpenCore picker when ShowPicker is disabled. Escape exists to support co-existence with the Apple picker (including OpenCore Apple picker mode) and to support firmware that fails to report held OPT key, as on some PS/2 keyboards. In addition, Zero is provided to support systems on which Escape is already assigned to some other pre-boot firmware feature. In systems which do not require KeySupport, pressing and holding one of these keys from after power on until the picker appears should always be successful. The same should apply when using KeySupport mode if it is correctly configured for the system, i.e. with a long enough KeyForgetThreshold. If pressing and holding the key is not successful to reliably enter the picker, multiple repeated keypresses may be tried instead.
Note 3: On Macs with problematic GOP, it may be difficult to re-bless OpenCore if its bless status is lost. The BootKicker utility can be used to work around this problem, if set up as a Tool in OpenCore with FullNvramAccess enabled. It will launch the Apple picker, which allows selection of an item to boot next (with Enter), or next and from then on until the next change (with CTRL+Enter). Note that after the selection is made, the system will reboot before the chosen entry is booted. While this behaviour might seem surprising, it can be used both to switch which OpenCore installation is blessed, with CTRL+Enter, e.g. from a recovery OpenCore installation on CD (selected with the C key on boot) back to the main installion of OpenCore on the hard drive, if this is lost after an NVRAM reset. It can also be used, even when the native picker cannot be shown normally (unsupported GPU), to do a one-shot boot without OpenCore, e.g. to another OS or tool, or to an earlier version of macOS.
PickerVariant
Type: plist string
Failsafe: Auto
Description: Choose specific icon set to be used for boot management.
An icon set is a directory path relative to Resources\Image, where the icons and an optional manifest are located. It is recommended for the artists to use provide their sets in the Vendor\Set format, e.g. Acidanthera\GoldenGate.
Sample resources provided as a part of OcBinaryData repository provide the following icon set:
For convenience purposes there also are predefined aliases:
PollAppleHotKeys
Type: plist boolean
Failsafe: false
Description: Enable modifier hotkey handling in the OpenCore picker.
In addition to action hotkeys, which are partially described in the PickerMode section and are typically handled by Apple BDS, modifier keys handled by the operating system bootloader (boot.efi) also exist. These keys allow changing the behaviour of the operating system by providing different boot modes.
On certain firmware, using modifier keys may be problematic due to driver incompatibilities. To workaround this problem, this option allows registering certain hotkeys in a more permissive manner from within the OpenCore picker. Such extensions include support for tapping on key combinations before selecting the boot item, and for reliable detection of the Shift key when selecting the boot item, in order to work around the fact that hotkeys which are continuously held during boot cannot be reliably detected on many PS/2 keyboards.
This list of known modifier hotkeys includes:
TakeoffDelay
Type: plist integer, 32 bit
Failsafe: 0
Description: Delay in microseconds executed before handling the OpenCore picker startup and action
hotkeys.
Introducing a delay may give extra time to hold the right action hotkey sequence to, for instance, boot into recovery mode. On most systems, the appearance of the initial boot logo is a good indication of the time from which hotkeys can be held down. Earlier than this, the key press may not be registered. On some platforms, setting this option to a minimum of 5000-10000 microseconds is also required to access action hotkeys due to the nature of the keyboard driver.
If the boot chime is configured (see audio configuration options) then at the expense of slower startup, an even longer delay of half to one second (500000-1000000) may be used to create behaviour similar to a real Mac, where the chime itself can be used as a signal for when hotkeys can be pressed. The boot chime is inevitably later in the boot sequence in OpenCore than on Apple hardware, due to the fact that non-native drivers have to be loaded and connected first. Configuring the boot chime and adding this longer additional delay can also be useful in systems where fast boot time and/or slow monitor signal synchronisation may cause the boot logo not to be shown at all on some boots or reboots.
AppleDebug
Type: plist boolean
Failsafe: false
Description: Enable writing the boot.efi debug log to the OpenCore log.
Note: This option only applies to 10.15.4 and newer.
ApplePanic
Type: plist boolean
Failsafe: false
Description: Save macOS kernel panic output to the OpenCore root partition.
The file is saved as panic-YYYY-MM-DD-HHMMSS.txt. It is strongly recommended to set the keepsyms=1 boot argument to see debug symbols in the panic log. In cases where it is not present, the kpdescribe.sh utility (bundled with OpenCore) may be used to partially recover the stacktrace.
Development and debug kernels produce more useful kernel panic logs. Consider downloading and installing the KernelDebugKit from developer.apple.com when debugging a problem. To activate a development kernel, the boot argument kcsuffix=development should be added. Use the uname -a command to ensure that the current loaded kernel is a development (or a debug) kernel.
In cases where the OpenCore kernel panic saving mechanism is not used, kernel panic logs may still be found in the /Library/Logs/DiagnosticReports directory.
Starting with macOS Catalina, kernel panics are stored in JSON format and thus need to be preprocessed before passing to kpdescribe.sh:
cat Kernel.panic | grep macOSProcessedStackshotData | python3 -c 'import json,sys;print(json.load(sys.stdin)["macOSPanicString"])'
DisplayLevel
Type: plist integer, 64 bit
Failsafe: 0
Description: EDK II debug level bitmask (sum) showed onscreen. Unless Target enables console (onscreen) printing,
onscreen debug output will not be visible.
The following levels are supported (discover more in DebugLib.h):
LogModules
Type: plist string
Failsafe: *
Description: Filter log entries by module.
This option filters logging generated by specific modules, both in the log and onscreen. Two modes are supported:
When multiple log line identifiers are selected, comma (,) should be used as the splitter. For instance, +OCCPU,OCA,OCB means only OCCPU, OCA, OCB should be logged, while -OCCPU,OCA,OCB indicates these modules should be filtered out (i.e. not logged). Since there may be lines in the log with no valid prefix (i.e. log lines which are not generated by parts of OpenCore, but by other loaded drivers) then the special module name question mark (?) can be included in the list to include (with positive filtering) or exclude (with negative filtering) these non-standard lines. When no + or - symbol is specified, positive filtering (+) will be used. * alone as the option value indicates all modules being logged.
Note 1: Acronyms of libraries can be found in the Libraries section below.
Note 2: Messages printed before the configuration of the log protocol cannot be filtered from the early on screen log, but on being de-buffered from the early log buffer, will be filtered as requested for other log targets.
Note 3: To avoid missing key issues, warning and error log messages are not filtered.
SysReport
Type: plist boolean
Failsafe: false
Description: Produce system report on ESP folder.
This option will create a SysReport directory in the ESP partition unless already present. The directory will contain ACPI, SMBIOS, and audio codec dumps. Audio codec dumps require an audio backend driver to be loaded.
Note: To maintain system integrity, the SysReport option is not available in RELEASE builds. Use a DEBUG build if this option is required.
Target
Type: plist integer
Failsafe: 0
Description: A bitmask (sum) of enabled logging targets. Logging output is hidden by default and this option must be
set when such output is required, such as when debugging.
The following logging targets are supported:
Console logging prints less than the other variants. Depending on the build type (RELEASE, DEBUG, or NOOPT) different amount of logging may be read (from least to most).
To obtain Data Hub logs, use the following command in macOS (Note that Data Hub logs do not log kernel and kext patches):
ioreg -lw0 -p IODeviceTree | grep boot-log | sort | sed 's/.*<\(.*\)>.*/\1/' | xxd -r -p
UEFI variable log does not include some messages and has no performance data. To maintain system integrity, the log size is limited to 32 kilobytes. Some types of firmware may truncate it much earlier or drop completely if they have no memory. Using the non-volatile flag will cause the log to be written to NVRAM flash after every printed line.
To obtain UEFI variable logs, use the following command in macOS:
nvram 4D1FDA02-38C7-4A6A-9CC6-4BCCA8B30102:boot-log | awk '{gsub(/%0d%0a%00/,"");gsub(/%0d%0a/,"\n")}1'
Warning 1: Certain firmware appear to have defective NVRAM garbage collection. As a result, they may not be able to always free space after variable deletion. Do not enable non-volatile NVRAM logging on such devices unless specifically required.
While the OpenCore boot log already contains basic version information including build type and date, this information may also be found in the opencore-version NVRAM variable even when boot logging is disabled.
File logging will create a file named opencore-YYYY-MM-DD-HHMMSS.txt (in UTC) under the EFI volume root with log contents (the upper case letter sequence is replaced with date and time from the firmware). Please be warned that some file system drivers present in firmware are not reliable and may corrupt data when writing files through UEFI. Log writing is attempted in the safest manner and thus, is very slow. Ensure that DisableWatchDog is set to true when a slow drive is used. Try to avoid frequent use of this option when dealing with flash drives as large I/O amounts may speed up memory wear and render the flash drive unusable quicker.
Warning 2: It is possible to enable fast file logging, which requires a fully compliant firmware FAT32 driver. On drivers with incorrect FAT32 write support (e.g. APTIO IV, but maybe others) this setting can result in corruption up to and including an unusable ESP filesystem, therefore be prepared to recreate the ESP partition and all of its contents if testing this option. This option can increase logging speed significantly on some suitable firmware, but may make little speed difference on some others.
When interpreting the log, note that the lines are prefixed with a tag describing the relevant location (module) of the log line allowing better attribution of the line to the functionality.
The list of currently used tags is as follows.
Drivers and tools:
Libraries:
FullNvramAccess
Type: plist boolean
Failsafe: false
Description: Disable OpenRuntime NVRAM protection during usage of a tool.
This disables all of the NVRAM protections provided by OpenRuntime.efi, during the time a tool is in use. It should normally be avoided, but may be required for instance if a tool needs to access NVRAM directly without the redirections put in place by RequestBootVarRouting.
Note: This option is only valid for Tools and cannot be specified for Entries (is always false).
Path
Type: plist string
Failsafe: Empty
Description: Entry location depending on entry type.
RealPath
Type: plist boolean
Failsafe: false
Description: Pass full path to the tool when launching.
This should typically be disabled as passing the tool directory may be unsafe with tools that accidentally attempt to access files without checking their integrity. Reasons to enable this property may include cases where tools cannot work without external files or may need them for enhanced functionality such as memtest86 (for logging and configuration), or Shell (for automatic script execution).
Note: This option is only valid for Tools and cannot be specified for Entries (is always true).
TextMode
Type: plist boolean
Failsafe: false
Description: Run the entry in text mode instead of graphics mode.
This setting may be beneficial for some older tools that require text output as all the tools are launched in graphics mode by default. Refer to the Output Properties section below for information on text modes.
AllowSetDefault
Type: plist boolean
Failsafe: false
Description: Allow CTRL+Enter and CTRL+Index handling to set the default boot option in the OpenCore
picker.
Note 1: May be used in combination with Shift+Enter or Shift+Index when PollAppleHotKeys is enabled.
Note 2: In order to support systems with unresponsive modifiers during preboot (which includes V1 and V2 KeySupport mode on some firmware) OpenCore also allows holding the =/+ key in order to trigger ‘set default’ mode.
ApECID
Type: plist integer, 64 bit
Failsafe: 0
Description: Apple Enclave Identifier.
Setting this value to any non-zero 64-bit integer will allow using personalised Apple Secure Boot identifiers. To use this setting, generate a random 64-bit number with a cryptographically secure random number generator. As an alternative, the first 8 bytes of SystemUUID can be used for ApECID, this is found in macOS 11 for Macs without the T2 chip.
With this value set and SecureBootModel valid (and not Disabled), it is possible to achieve Full Security of Apple Secure Boot.
To start using personalised Apple Secure Boot, the operating system must be reinstalled or personalised. Until the operating system is personalised, only macOS DMG recovery can be loaded. In cases where DMG recovery is missing, it can be downloaded by using the macrecovery utility and saved in com.apple.recovery.boot as explained in the Tips and Tricks section. Note that DMG loading needs to be set to Signed to use any DMG with Apple Secure Boot.
To personalise an existing operating system, use the bless command after loading to macOS DMG recovery. Mount the system volume partition, unless it has already been mounted, and execute the following command:
bless --folder "/Volumes/Macintosh HD/System/Library/CoreServices" \ --bootefi --personalize
On macOS 11 and newer the dedicated x86legacy model always uses ApECID. When this configuration setting is left as 0 first 8 bytes of system-id variable are used instead.
On macOS versions before macOS 11, which introduced a dedicated x86legacy model for models without the T2 chip, personalised Apple Secure Boot may not work as expected. When reinstalling the operating system, the macOS Installer from macOS 10.15 and older will often run out of free memory on the /var/tmp partition when trying to install macOS with the personalised Apple Secure Boot. Soon after downloading the macOS installer image, an Unable to verify macOS error message will appear.
To workaround this issue, allocate a dedicated RAM disk of 2 MBs for macOS personalisation by entering the following commands in the macOS recovery terminal before starting the installation:
disk=$(hdiutil attach -nomount ram://4096) diskutil erasevolume HFS+ SecureBoot $disk diskutil unmount $disk mkdir /var/tmp/OSPersonalizationTemp diskutil mount -mountpoint /var/tmp/OSPersonalizationTemp $disk
AuthRestart
Type: plist boolean
Failsafe: false
Description: Enable VirtualSMC-compatible authenticated restart.
Authenticated restart is a way to reboot FileVault 2 enabled macOS without entering the password. A dedicated terminal command can be used to perform authenticated restarts: sudo fdesetup authrestart. It is also used when installing operating system updates.
VirtualSMC performs authenticated restarts by splitting and saving disk encryption keys between NVRAM and RTC, which despite being removed as soon as OpenCore starts, may be considered a security risk and thus is optional.
BlacklistAppleUpdate
Type: plist boolean
Failsafe: false
Description: Ignore boot options trying to update Apple peripheral firmware (e.g. MultiUpdater.efi).
Note: Certain operating systems, such as macOS Big Sur, are incapable of disabling firmware updates by using the run-efi-updater NVRAM variable.
DmgLoading
Type: plist string
Failsafe: Signed
Description: Define Disk Image (DMG) loading policy used for macOS Recovery.
Valid values:
EnablePassword
Type: plist boolean
Failsafe: false
Description: Enable password protection to facilitate sensitive operations.
Password protection ensures that sensitive operations such as booting a non-default operating system (e.g. macOS recovery or a tool), resetting NVRAM storage, trying to boot into a non-default mode (e.g. verbose mode or safe mode) are not allowed without explicit user authentication by a custom password. Currently, password and salt are hashed with 5000000 iterations of SHA-512.
Note: This functionality is still under development and is not ready for production environments.
ExposeSensitiveData
Type: plist integer
Failsafe: 0x6
Description: Sensitive data exposure bitmask (sum) to operating system.
The exposed booter path points to OpenCore.efi or its booter depending on the load order. To obtain the booter path, use the following command in macOS:
nvram 4D1FDA02-38C7-4A6A-9CC6-4BCCA8B30102:boot-path
To use a booter path to mount a booter volume, use the following command in macOS:
u=$(nvram 4D1FDA02-38C7-4A6A-9CC6-4BCCA8B30102:boot-path | sed 's/.*GPT,\([^,]*\),.*/\1/'); \ if [ "$u" != "" ]; then sudo diskutil mount $u ; fi
To obtain the current OpenCore version, use the following command in macOS:
nvram 4D1FDA02-38C7-4A6A-9CC6-4BCCA8B30102:opencore-version
If the OpenCore version is not exposed the variable will contain UNK-000-0000-00-00 sequence.
To obtain OEM information, use the following commands in macOS:
nvram 4D1FDA02-38C7-4A6A-9CC6-4BCCA8B30102:oem-product # SMBIOS Type1 ProductName nvram 4D1FDA02-38C7-4A6A-9CC6-4BCCA8B30102:oem-vendor # SMBIOS Type2 Manufacturer nvram 4D1FDA02-38C7-4A6A-9CC6-4BCCA8B30102:oem-board # SMBIOS Type2 ProductName
HaltLevel
Type: plist integer, 64 bit
Failsafe: 0x80000000 (DEBUG_ERROR)
Description: EDK II debug level bitmask (sum) causing CPU to halt (stop execution) after obtaining a message of
HaltLevel. Possible values match DisplayLevel values.
Note 1: A halt will only occur if bit 0 (i.e. enable logging) for Target under section Misc->Debug is set.
Note 2: A halt will only occur after the configuration is loaded and logging is configured. If any log messages occur at the specified halt level in early log (i.e. before this), they will cause a halt when they are flushed to the log once it has been configured.
ScanPolicy
Type: plist integer, 32 bit
Failsafe: 0x10F0103
Description: Define operating system detection policy.
This value allows preventing scanning (and booting) untrusted sources based on a bitmask (sum) of a set of flags. As it is not possible to reliably detect every file system or device type, this feature cannot be fully relied upon in open environments, and additional measures are to be applied.
Third party drivers may introduce additional security (and performance) consideratons following the provided scan policy. The active Scan policy is exposed in the scan-policy variable of 4D1FDA02-38C7-4A6A-9CC6-4BCCA8B30102 GUID for UEFI Boot Services only.
Note: Given the above description, a value of 0xF0103 is expected to do the following:
The combination reads as:
SecureBootModel
Type: plist string
Failsafe: Default
Description: Apple Secure Boot hardware model.
Sets Apple Secure Boot hardware model and policy. Specifying this value defines which operating systems will be bootable. Operating systems shipped before the specified model was released will not boot.
Valid values:
Warning: Not all Apple Secure Boot models are supported on all hardware configurations.
Apple Secure Boot appeared in macOS 10.13 on models with T2 chips. Prior to macOS 12 PlatformInfo and SecureBootModel were independent, allowing Apple Secure Boot can be used with any SMBIOS with and without T2. Starting with macOS 12 SecureBootModel must match the SMBIOS Mac model. Default model derives the model based on SMBIOS board identifier, either set automatically via the Generic section or set manually via the SMBIOS section. If there is no board identifier override the model will be derived heuristically from OEM SMBIOS.
Setting SecureBootModel to any valid value but Disabled is equivalent to Medium Security of Apple Secure Boot. The ApECID value must also be specified to achieve Full Security. Check ForceSecureBootScheme when using Apple Secure Boot on a virtual machine.
Note that enabling Apple Secure Boot is demanding on invalid configurations, faulty macOS installations, and on unsupported setups.
Things to consider:
The installed operating system may have sometimes outdated Apple Secure Boot manifests on the Preboot partition, resulting in boot failures. This is likely to be the case when an “OCB: Apple Secure Boot prohibits this boot entry, enforcing!” message is logged.
When this happens, either reinstall the operating system or copy the manifests (files with .im4m extension, such as boot.efi.j137.im4m) from /usr/standalone/i386 to /Volumes/Preboot/<UUID>/System/Library/CoreServices. Here, <UUID> is the system volume identifier. On HFS+ installations, the manifests should be copied to /System/Library/CoreServices on the system volume.
For more details on how to configure Apple Secure Boot with UEFI Secure Boot, refer to the UEFI Secure Boot section.
Vault
Type: plist string
Failsafe: Secure
Description: Enables the OpenCore vaulting mechanism.
Valid values:
The vault.plist file should contain SHA-256 hashes for all files used by OpenCore. The presence of this file is highly recommended to ensure that unintentional file modifications (including filesystem corruption) do not go unnoticed. To create this file automatically, use the create_vault.sh script. Notwithstanding the underlying file system, the path names and cases between config.plist and vault.plist must match.
The vault.sig file should contain a raw 256 byte RSA-2048 signature from a SHA-256 hash of vault.plist. The signature is verified against the public key embedded into OpenCore.efi.
To embed the public key, either one of the following should be performed:
The RSA public key 520 byte format description can be found in Chromium OS documentation. To convert the public key from X.509 certificate or from PEM file use RsaTool.
The complete set of commands to:
Can look as follows:
cd /Volumes/EFI/EFI/OC /path/to/create_vault.sh . /path/to/RsaTool -sign vault.plist vault.sig vault.pub off=$(($(strings -a -t d OpenCore.efi | grep "=BEGIN OC VAULT=" | cut -f1 -d' ')+16)) dd of=OpenCore.efi if=vault.pub bs=1 seek=$off count=528 conv=notrunc rm vault.pub
Note 1: While it may appear obvious, an external method is required to verify OpenCore.efi and BOOTx64.efi for secure boot path. For this, it is recommended to enable UEFI SecureBoot using a custom certificate and to sign OpenCore.efi and BOOTx64.efi with a custom key. More details on customising secure boot on modern firmware can be found in the Taming UEFI SecureBoot paper (in Russian).
Note 2: Regardless of this option, vault.plist is always used when present, and both vault.plist and vault.sig are used and required when a public key is embedded into OpenCore.efi, and errors will abort the boot process in either case. Setting this option allows OpenCore to warn the user if the configuration is not as required to achieve an expected higher security level.
Custom
Type: plist dict
Description: Update serial port properties in BaseSerialPortLib16550.
This section lists the PCD values that are used by the BaseSerialPortLib16550. When option Override is set to false, this dictionary is optional.
Init
Type: plist boolean
Failsafe: false
Description: Perform serial port initialisation.
This option will perform serial port initialisation within OpenCore prior to enabling (any) debug logging.
Refer to the Debugging section for details.
Override
Type: plist boolean
Failsafe: false
Description: Override serial port properties. When this option is set to false, no keys from Custom will be
overridden.
This option will override serial port properties listed in the Serial Custom Properties section below.
BaudRate
Type: plist integer
Failsafe: 115200
Description: Set the baud rate for serial port.
This option will override the value of gEfiMdeModulePkgTokenSpaceGuid.PcdSerialBaudRate defined in MdeModulePkg.dec.
ClockRate
Type: plist integer
Failsafe: 1843200
Description: Set the clock rate for serial port.
This option will override the value of gEfiMdeModulePkgTokenSpaceGuid.PcdSerialClockRate defined in MdeModulePkg.dec.
DetectCable
Type: plist boolean
Failsafe: false
Description: Enable serial port cable detection.
This option will override the value of gEfiMdeModulePkgTokenSpaceGuid.PcdSerialDetectCable defined in MdeModulePkg.dec.
ExtendedTxFifoSize
Type: plist integer
Failsafe: 64
Description: Set the extended transmit FIFO size for serial port.
This option will override the value of gEfiMdeModulePkgTokenSpaceGuid.PcdSerialExtendedTxFifoSize defined in MdeModulePkg.dec.
FifoControl
Type: plist integer
Failsafe: 0x07
Description: Configure serial port FIFO Control settings.
This option will override the value of gEfiMdeModulePkgTokenSpaceGuid.PcdSerialFifoControl defined in MdeModulePkg.dec.
LineControl
Type: plist integer
Failsafe: 0x07
Description: Configure serial port Line Control settings.
This option will override the value of gEfiMdeModulePkgTokenSpaceGuid.PcdSerialLineControl defined in MdeModulePkg.dec.
PciDeviceInfo
Type: plist data
Failsafe: 0xFF
Description: Set PCI serial device information.
This option will override the value of gEfiMdeModulePkgTokenSpaceGuid.PcdSerialPciDeviceInfo defined in MdeModulePkg.dec.
Note: The maximum allowed size of this option is 41 bytes. Refer to acidanthera/bugtracker#1954 for more details.
Note 2: This option can be set by running the FindSerialPort tool.
RegisterAccessWidth
Type: plist integer
Failsafe: 8
Description: Set serial port register access width.
This option will override the value of gEfiMdeModulePkgTokenSpaceGuid.PcdSerialRegisterAccessWidth defined in MdeModulePkg.dec.
RegisterBase
Type: plist integer
Failsafe: 0x03F8
Description: Set the base address of serial port registers.
This option will override the value of gEfiMdeModulePkgTokenSpaceGuid.PcdSerialRegisterBase defined in MdeModulePkg.dec.
RegisterStride
Type: plist integer
Failsafe: 1
Description: Set the serial port register stride in bytes.
This option will override the value of gEfiMdeModulePkgTokenSpaceGuid.PcdSerialRegisterStride defined in MdeModulePkg.dec.
UseHardwareFlowControl
Type: plist boolean
Failsafe: false
Description: Enable serial port hardware flow control.
This option will override the value of gEfiMdeModulePkgTokenSpaceGuid.PcdSerialUseHardwareFlowControl defined in MdeModulePkg.dec.
UseMmio
Type: plist boolean
Failsafe: false
Description: Indicate whether the serial port registers are in MMIO space.
This option will override the value of gEfiMdeModulePkgTokenSpaceGuid.PcdSerialUseMmio defined in MdeModulePkg.dec.
This section allows setting non-volatile UEFI variables commonly described as NVRAM variables. Refer to man nvram for details. The macOS operating system extensively uses NVRAM variables for OS — Bootloader — Firmware intercommunication. Hence, the supply of several NVRAM variables is required for the proper functioning of macOS.
Each NVRAM variable consists of its name, value, attributes (refer to UEFI specification), and its GUID, representing which ‘section’ the NVRAM variable belongs to. The macOS operating system makes use of several GUIDs, including but not limited to:
Note: Some of the variables may be added by the PlatformNVRAM or Generic subsections of the PlatformInfo section. Please ensure that variables set in this section do not conflict with items in those subsections as the implementation behaviour is undefined otherwise.
The OC_FIRMWARE_RUNTIME protocol implementation, currently offered as a part of the OpenRuntime driver, is often required for macOS to function properly. While this brings many benefits, there are some limitations that should be considered for certain use cases.
Add
Type: plist dict
Description: Sets NVRAM variables from a map (plist dict) of GUIDs to a map (plist dict) of variable
names and their values in plist multidata format. GUIDs must be provided in canonic string format in upper
or lower case (e.g. 8BE4DF61-93CA-11D2-AA0D-00E098032B8C).
The EFI_VARIABLE_BOOTSERVICE_ACCESS and EFI_VARIABLE_RUNTIME_ACCESS attributes of created variables are set. Variables will only be set if not present or deleted. That is, to overwrite an existing variable value, add the variable name to the Delete section. This approach enables the provision of default values until the operating system takes the lead.
Note: The implementation behaviour is undefined when the plist key does not conform to the GUID format.
LegacyOverwrite
Type: plist boolean
Failsafe: false
Description: Permits overwriting firmware variables from nvram.plist.
Note: Only variables accessible from the operating system will be overwritten.
LegacySchema
Type: plist dict
Description: Allows setting certain NVRAM variables from a map (plist dict) of GUIDs to an array
(plist array) of variable names in plist string format.
* value can be used to accept all variables for certain GUID.
WARNING: Choose variables carefully, as the nvram.plist file is not vaulted. For instance, do not include boot-args or csr-active-config, as these can be used to bypass SIP.
WriteFlash
Type: plist boolean
Failsafe: false
Description: Enables writing to flash memory for all added variables.
Note: This value should be enabled on most types of firmware but is left configurable to account for firmware that may have issues with NVRAM variable storage garbage collection or similar.
The nvram command can be used to read NVRAM variable values from macOS by concatenating the GUID and name variables separated by a : symbol. For example, nvram 7C436110-AB2A-4BBB-A880-FE41995C9F82:boot-args.
A continuously updated variable list can be found in a corresponding document: NVRAM Variables.
Warning: These variables may be added by the PlatformNVRAM or Generic subsections of the PlatformInfo section. Using PlatformInfo is the recommended way of setting these variables.
The following variables are mandatory for macOS functioning:
The following variables are recommended for faster startup or other improvements:
The following variables may be useful for certain configurations or troubleshooting:
7C436110-AB2A-4BBB-A880-FE41995C9F82:boot-args Kernel arguments, used to pass configuration to Apple kernel and drivers. There are many arguments, which may be found by looking for the use of PE_parse_boot_argn function in the kernel or driver code. Some of the known boot arguments include:
serial=VALUE (configure serial logging mode) — The following bits are used by XNU:
There are multiple external places summarising macOS argument lists: example 1, example 2.
7C436110-AB2A-4BBB-A880-FE41995C9F82:bootercfg Booter arguments, similar to boot-args but for boot.efi. Accepts a set of arguments, which are hexadecimal 64-bit values with or without 0x. At different stages boot.efi will request different debugging (logging) modes (e.g. after ExitBootServices it will only print to serial). Several booter arguments control whether these requests will succeed. The list of known requests is covered below:
In 10.15, debugging support was defective up to the 10.15.4 release due to refactoring issues as well as the introduction of a new debug protocol. Some of the arguments and their values below may not be valid for versions prior to 10.15.4. The list of known arguments is covered below:
boot-save-log=VALUE — debug log save mode for normal boot.
wake-save-log=VALUE — debug log save mode for hibernation wake.
breakpoint=VALUE — enables debug breaks (missing in production boot.efi).
console=VALUE — enables console logging.
embed-log-dt=VALUE — enables DeviceTree logging.
log-level=VALUE — log level bitmask.
serial=VALUE — enables serial logging.
timestamps=VALUE — enables timestamp logging.
log=VALUE — deprecated starting from 10.15.
debug=VALUE — deprecated starting from 10.15.
Note: Enable the AppleDebug option to display verbose output from boot.efi on modern macOS versions. This will save the log to the general OpenCore log file. For versions before 10.15.4, set bootercfg to log=1. This will print verbose output onscreen.
7C436110-AB2A-4BBB-A880-FE41995C9F82:SystemAudioVolumeDB Current system audio volume level in decibels (dB). 8-bit signed integer. The value represents the audio offset (gain if positive, attenuation if negative) in dB relative to the amplifier reference value of 0 dB. Exactly which volume level is represented by 0 dB depends on the codec (and potentially on the specific amplifier within the codec) but it is normally at or near the maximum available amplifier volume. Typical values of this variable range from approximately -60 (the exact value depends on the audio hardware) up to exactly 0. On non-typical audio hardware, the value may go above zero.
Note: Unlike SystemAudioVolume, this value is not capped.
5EDDA193-A070-416A-85EB-2A1181F45B18:PEXConf PCI expansion slot configuration for MacPro7,1. 8-byte sequence describing default PCI slot configuration. Each byte refers to a configuration for a dedicated PCI slot.
Refer to the support page for more details on how MacPro7,1 slots are configured.
Platform information consists of several identification fields generated or filled manually to be compatible with macOS services. The base part of the configuration may be obtained from AppleModels, which itself generates a set of interfaces based on a database in YAML format. These fields are written to three destinations:
Most of the fields specify the overrides in SMBIOS, and their field names conform to EDK2 SmBios.h header file. However, several important fields reside in Data Hub and NVRAM. Some of the values can be found in more than one field and/or destination, so there are two ways to control their update process: manual, where all the values are specified (the default), and semi-automatic, where (Automatic) only certain values are specified, and later used for system configuration.
The dmidecode utility can be used to inspect SMBIOS contents and a version with macOS specific enhancements can be downloaded from Acidanthera/dmidecode.
Automatic
Type: plist boolean
Failsafe: false
Description: Generate PlatformInfo based on the Generic section instead of using values from the DataHub,
NVRAM, and SMBIOS sections.
Enabling this option is useful when Generic section is flexible enough:
Warning: Setting this option to false is strongly discouraged when intending to update platform information. A false setting is typically only valid for minor corrections to SMBIOS values on legacy Apple hardware. In all other cases, setting Automatic to false may lead to hard-to-debug errors resulting from inconsistent or invalid settings.
DataHub
Type: plist dictionary
Description: Update Data Hub fields in non-Automatic mode.
Note: This section is ignored and may be removed when Automatic is true.
Generic
Type: plist dictionary
Description: Update all fields in Automatic mode.
Note: This section is ignored but may not be removed when Automatic is false.
Memory
Type: plist dictionary
Description: Define custom memory configuration.
Note: This section is ignored and may be removed when CustomMemory is false.
PlatformNVRAM
Type: plist dictionary
Description: Update platform NVRAM fields in non-Automatic mode.
Note: This section is ignored and may be removed when Automatic is true.
SMBIOS
Type: plist dictionary
Description: Update SMBIOS fields in non-Automatic mode.
Note: This section is ignored and may be removed when Automatic is true.
UpdateDataHub
Type: plist boolean
Failsafe: false
Description: Update Data Hub fields. These fields are read from the Generic or DataHub sections depending on the
setting of the Automatic property.
Note: The implementation of the Data Hub protocol in EFI firmware on virtually all systems, including Apple hardware, means that existing Data Hub entries cannot be overridden. New entries are added to the end of the Data Hub instead, with macOS ignoring old entries. This can be worked around by replacing the Data Hub protocol using the ProtocolOverrides section. Refer to the DataHub protocol override description for details.
UpdateNVRAM
Type: plist boolean
Failsafe: false
Description: Update NVRAM fields related to platform information.
These fields are read from the Generic or PlatformNVRAM sections depending on the setting of the Automatic property. All the other fields are to be specified with the NVRAM section.
If UpdateNVRAM is set to false, the aforementioned variables can be updated with the NVRAM section. If UpdateNVRAM is set to true, the behaviour is undefined when any of the fields are present in the NVRAM section.
UpdateSMBIOSMode
Type: plist string
Failsafe: Create
Description: Update SMBIOS fields approach:
Note: A side effect of using the Custom approach that it makes SMBIOS updates exclusive to macOS, avoiding a collision with existing Windows activation and custom OEM software but potentially obstructing the operation of Apple-specific tools.
UseRawUuidEncoding
Type: plist boolean
Failsafe: false
Description: Use raw encoding for SMBIOS UUIDs.
Each UUID AABBCCDD-EEFF-GGHH-IIJJ-KKLLMMNNOOPP is essentially a hexadecimal 16-byte number. It can be encoded in two ways:
The SMBIOS specification did not explicitly specify the encoding format for the UUID up to SMBIOS 2.6, where it stated that Little Endian encoding shall be used. This led to the confusion in both firmware implementations and system software as different vendors used different encodings prior to that.
OpenCore always sets a recent SMBIOS version (currently 3.2) when generating the modified DMI tables. If UseRawUuidEncoding is enabled, the Big Endian format is used to store the SystemUUID data. Otherwise, the Little Endian format is used.
Note: This preference does not affect UUIDs used in DataHub and NVRAM as they are not standardised and are added by Apple. Unlike SMBIOS, they are always stored in the Big Endian format.
ARTFrequency
Type: plist integer, 64-bit
Failsafe: 0 (Automatic)
Description: Sets ARTFrequency in gEfiProcessorSubClassGuid.
This value contains CPU ART frequency, also known as crystal clock frequency. Its existence is exclusive to the Skylake generation and newer. The value is specified in Hz, and is normally 24 MHz for the client Intel segment, 25 MHz for the server Intel segment, and 19.2 MHz for Intel Atom CPUs. macOS till 10.15 inclusive assumes 24 MHz by default.
Note: On Intel Skylake X ART frequency may be a little less (approx. 0.25%) than 24 or 25 MHz due to special EMI-reduction circuit as described in Acidanthera Bugtracker.
FSBFrequency
Type: plist integer, 64-bit
Failsafe: 0 (Automatic)
Description: Sets FSBFrequency in gEfiProcessorSubClassGuid.
Sets CPU FSB frequency. This value equals to CPU nominal frequency divided by CPU maximum bus ratio and is specified in Hz. Refer to MSR_NEHALEM_PLATFORM_INFO (CEh) MSR value to determine maximum bus ratio on modern Intel CPUs.
Note: This value is not used on Skylake and newer but is still provided to follow suit.
StartupPowerEvents
Type: plist integer, 64-bit
Failsafe: 0
Description: Sets StartupPowerEvents in gEfiMiscSubClassGuid. The value found on Macs is power
management state bitmask, normally 0. Known bits read by X86PlatformPlugin.kext:
AdviseFeatures
Type: plist boolean
Failsafe: false
Description: Updates FirmwareFeatures with supported bits.
Added bits to FirmwareFeatures:
Note: On most newer firmwares these bits are already set, the option may be necessary when "upgrading" the firmware with new features.
MLB
Type: plist string
Failsafe: Empty (OEM specified or not installed)
Description: Refer to SMBIOS BoardSerialNumber.
Specify special string value OEM to extract current value from NVRAM (MLB variable) or SMBIOS and use it throughout the sections. This feature can only be used on Mac-compatible firmware.
ROM
Type: plist multidata, 6 bytes
Failsafe: Empty (OEM specified or not installed)
Description: Refer to 4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14:ROM.
Specify special string value OEM to extract current value from NVRAM (ROM variable) and use it throughout the sections. This feature can only be used on Mac-compatible firmware.
SpoofVendor
Type: plist boolean
Failsafe: false
Description: Sets SMBIOS vendor fields to Acidanthera.
It can be dangerous to use “Apple” in SMBIOS vendor fields for reasons outlined in the SystemManufacturer description. However, certain firmware may not provide valid values otherwise, which could obstruct the operation of some software.
SystemMemoryStatus
Type: plist string
Failsafe: Auto
Description: Indicates whether system memory is upgradable in PlatformFeature. This controls the visibility of the
Memory tab in “About This Mac”.
Valid values:
Note: On certain Mac models, such as the MacBookPro10,x and any MacBookAir, SPMemoryReporter.spreporter will ignore PT_FEATURE_HAS_SOLDERED_SYSTEM_MEMORY and assume that system memory is non-upgradable.
SystemSerialNumber
Type: plist string
Failsafe: Empty (OEM specified or not installed)
Description: Refer to SMBIOS SystemSerialNumber.
Specify special string value OEM to extract current value from NVRAM (SSN variable) or SMBIOS and use it throughout the sections. This feature can only be used on Mac-compatible firmware.
SystemUUID
Type: plist string, GUID
Failsafe: Empty (OEM specified or not installed)
Description: Refer to SMBIOS SystemUUID.
Specify special string value OEM to extract current value from NVRAM (system-id variable) or SMBIOS and use it throughout the sections. Since not every firmware implementation has valid (and unique) values, this feature is not applicable to some setups, and may provide unexpected results. It is highly recommended to specify the UUID explicitly. Refer to UseRawUuidEncoding to determine how SMBIOS value is parsed.
Devices
Type: plist array
Failsafe: Empty
Description: Specifies the custom memory devices to be added.
To be filled with plist dictionary values, describing each memory device. Refer to the Memory Devices Properties section below. This should include all memory slots, even if unpopulated.
ErrorCorrection
Type: plist integer, 8-bit
Failsafe: 0x03
SMBIOS: Physical Memory Array (Type 16) — Memory Error Correction
Description: Specifies the primary hardware error correction or detection method supported by the memory.
FormFactor
Type: plist integer, 8-bit
Failsafe: 0x02
SMBIOS: Memory Device (Type 17) — Form Factor
Description: Specifies the form factor of the memory. On Macs, this should typically be DIMM or SODIMM.
Commonly used form factors are listed below.
When CustomMemory is false, this value is automatically set based on Mac product name.
When Automatic is true, the original value from the the corresponding Mac model will be set if available. Otherwise, the value from OcMacInfoLib will be set. When Automatic is false, a user-specified value will be set if available. Otherwise, the original value from the firmware will be set. If no value is provided, the failsafe value will be set.
Type
Type: plist integer, 8-bit
Failsafe: 0x02
SMBIOS: Memory Device (Type 17) — Memory Type
Description: Specifies the memory type. Commonly used types are listed below.
TypeDetail
Type: plist integer, 16-bit
Failsafe: 0x4
SMBIOS: Memory Device (Type 17) — Type Detail
Description: Specifies additional memory type information.
Manufacturer
Type: plist string
Failsafe: Unknown
SMBIOS: Memory Device (Type 17) — Manufacturer
Description: Specifies the manufacturer of this memory device.
For empty slot this must be set to NO DIMM for macOS System Profiler to correctly display memory slots on certain Mac models, e.g. MacPro7,1. MacPro7,1 imposes additional requirements on the memory layout:
FirmwareFeatures
Type: plist data, 8 bytes
Failsafe: Empty (Not installed)
Description: This variable comes in pair with FirmwareFeaturesMask. Specifies the values of NVRAM variables:
FirmwareFeaturesMask
Type: plist data, 8 bytes
Failsafe: Empty (Not installed)
Description: This variable comes in pair with FirmwareFeatures. Specifies the values of NVRAM variables:
BIOSVersion
Type: plist string
Failsafe: Empty (OEM specified)
SMBIOS: BIOS Information (Type 0) — BIOS Version
Description: Firmware version. This value gets updated and takes part in update delivery configuration
and macOS version compatibility. This value could look like MM71.88Z.0234.B00.1809171422 in older
firmware and is described in BiosId.h. In newer firmware, it should look like 236.0.0.0.0 or
220.230.16.0.0 (iBridge: 16.16.2542.0.0,0). iBridge version is read from BridgeOSVersion variable, and
is only present on macs with T2.
Apple ROM Version BIOS ID: MBP151.88Z.F000.B00.1811142212 Model: MBP151 EFI Version: 220.230.16.0.0 Built by: root@quinoa Date: Wed Nov 14 22:12:53 2018 Revision: 220.230.16 (B&I) ROM Version: F000_B00 Build Type: Official Build, RELEASE Compiler: Apple LLVM version 10.0.0 (clang-1000.2.42) UUID: E5D1475B-29FF-32BA-8552-682622BA42E1 UUID: 151B0907-10F9-3271-87CD-4BF5DBECACF5
ProcessorType
Type: plist integer, 16-bit
Failsafe: 0 (Automatic)
SMBIOS: APPLE_SMBIOS_TABLE_TYPE131 - ProcessorType
Description: Combined of Processor Major and Minor types.
Automatic value generation attempts to provide the most accurate value for the currently installed CPU. When this fails, please raise an issue and provide sysctl machdep.cpu and dmidecode output. For a full list of available values and their limitations (the value will only apply if the CPU core count matches), refer to the Apple SMBIOS definitions header here.
SystemProductName
Type: plist string
Failsafe: Empty (OEM specified)
SMBIOS: System Information (Type 1), Product Name
Description: Preferred Mac model used to mark the device as supported by the operating system. This value must be
specified by any configuration for later automatic generation of the related values in this and other SMBIOS tables and
related configuration parameters. If SystemProductName is not compatible with the target operating system,
-no_compat_check boot argument may be used as an override.
Note: If SystemProductName is unknown, and related fields are unspecified, default values should be assumed as being set to MacPro6,1 data. The list of known products can be found in AppleModels.
UEFI (Unified Extensible Firmware Interface) is a specification that defines a software interface between an operating system and platform firmware. This section allows loading additional UEFI modules as well as applying tweaks to the onboard firmware. To inspect firmware contents, apply modifications and perform upgrades UEFITool and supplementary utilities can be used.
Depending on the firmware, a different set of drivers may be required. Loading an incompatible driver may lead the system to unbootable state or even cause permanent firmware damage. Some of the known drivers are listed below:
HDA audio support driver in UEFI firmware for most Intel and some other analog audio controllers. Staging driver, refer to acidanthera/bugtracker#740 for known issues in AudioDxe. |
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Open source BTRFS file system driver, required for booting with OpenLinuxBoot from a file system which is now quite commonly used with Linux. |
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CSM video driver implementing graphics output protocol based on VESA and legacy BIOS interfaces. Used for UEFI firmware with fragile GOP support (e.g. low resolution). Requires ReconnectGraphicsOnConnect. Included in OpenDuet out of the box. |
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Screenshot making driver saving images to the root of OpenCore partition (ESP) or any available writeable filesystem upon pressing F10. Accepts optional driver argument --enable-mouse-click to additionally take screenshot on mouse click. (It is recommended to enable this option only if a keypress would prevent a specific screenshot, and disable it again after use.) This is a modified version of CrScreenshotDxe driver by Nikolaj Schlej. |
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Early beta release firmware-embeddable driver providing pre-OpenCore non-native GPU support on MacPro5,1. Installation instructions can be found in the Utilities/EnableGop directory of the OpenCore release zip file - proceed with caution. |
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Proprietary ExFAT file system driver for Bootcamp support commonly found in Apple firmware. For Sandy Bridge and earlier CPUs, the ExFatDxeLegacy driver should be used due to the lack of RDRAND instruction support. |
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Open source EXT4 file system driver, required for booting with OpenLinuxBoot from the file system most commonly used with Linux. |
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OpenCore plugin implementing OC_BOOT_ENTRY_PROTOCOL to add an entry to the boot picker menu which reboots into UEFI firmware settings, when this is supported by the firmware. |
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Recommended. Proprietary HFS file system driver with bless support commonly found in Apple firmware. For Sandy Bridge and earlier CPUs, the HfsPlusLegacy driver should be used due to the lack of RDRAND instruction support. |
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HII services support driver from MdeModulePkg. This driver is included in most types of firmware starting with the Ivy Bridge generation. Some applications with GUI, such as UEFI Shell, may need this driver to work properly. |
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FAT filesystem driver from FatPkg. This driver is embedded in all UEFI firmware and cannot be used from OpenCore. Several types of firmware have defective FAT support implementation that may lead to corrupted filesystems on write attempts. Embedding this driver within the firmware may be required in case writing to the EFI partition is needed during the boot process. |
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NVMe support driver from MdeModulePkg. This driver is included in most firmware starting with the Broadwell generation. For Haswell and earlier, embedding it within the firmware may be more favourable in case a NVMe SSD drive is installed. |
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OpenCore plugin implementing graphical interface. |
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OpenCore plugin implementing OC_FIRMWARE_RUNTIME protocol. |
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OpenCore plugin implementing OC_BOOT_ENTRY_PROTOCOL to allow detection and booting of legacy operating systems from OpenCore on Macs, OpenDuet and systems with a CSM. |
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OpenCore plugin implementing OC_BOOT_ENTRY_PROTOCOL to allow direct detection and booting of Linux distributions from OpenCore, without chainloading via GRUB. |
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New Technologies File System (NTFS) read-only driver. NTFS is the primary file system for Microsoft Windows versions that are based on Windows NT. |
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USB keyboard driver adding support for AppleKeyMapAggregator protocols on top of a custom USB keyboard driver implementation. This is an alternative to builtin KeySupport, which may work better or worse depending on the firmware. |
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Partition management driver with Apple Partitioning Scheme support. This driver can be used to support loading older DMG recoveries such as OS X 10.9 using Apple Partitioning Scheme, or for loading other macOS Installers where these were created using the Apple Partitioning Scheme (creating macOS Installers using GPT avoids the need for this). OpenDuet already includes this driver. |
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OpenCore plugin offering emulated NVRAM support. OpenDuet already includes this driver. |
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PS/2 keyboard driver from MdeModulePkg. OpenDuetPkg and some types of firmware may not include this driver, but it is necessary for PS/2 keyboard to work. Note, unlike OpenUsbKbDxe this driver has no AppleKeyMapAggregator support and thus requires KeySupport to be enabled. |
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PS/2 mouse driver from MdeModulePkg. Some very old laptop firmware may not include this driver but it is necessary for the touchpad to work in UEFI graphical interfaces such as OpenCanopy. |
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HFS file system driver with bless support. This driver is an alternative to a closed source HfsPlus driver commonly found in Apple firmware. While it is feature complete, it is approximately 3 times slower and is yet to undergo a security audit. |
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OpenCore plugin implementing OC_BOOT_ENTRY_PROTOCOL to add a configurable Reset NVRAM entry to the boot picker menu. |
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OpenCore plugin implementing OC_BOOT_ENTRY_PROTOCOL to add a configurable Toggle SIP entry to the boot picker menu. |
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USB mouse driver from MdeModulePkg. Some virtual machine firmware such as OVMF may not include this driver but it is necessary for the mouse to work in UEFI graphical interfaces such as OpenCanopy. |
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XHCI USB controller support driver from MdeModulePkg. This driver is included in most types of firmware starting with the Sandy Bridge generation. For earlier firmware or legacy systems, it may be used to support external USB 3.0 PCI cards. |
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Driver marked with * are bundled with OpenCore. To compile the drivers from UDK (EDK II) the same command used for OpenCore compilation can be taken, but choose a corresponding package:
git clone https://github.com/acidanthera/audk UDK cd UDK source edksetup.sh make -C BaseTools build -a X64 -b RELEASE -t XCODE5 -p FatPkg/FatPkg.dsc build -a X64 -b RELEASE -t XCODE5 -p MdeModulePkg/MdeModulePkg.dsc
Standalone tools may help to debug firmware and hardware. Some of the known tools are listed below. While some tools can be launched from within OpenCore (Refer to the Tools subsection for more details), most should be run separately either directly or from Shell.
To boot into OpenShell or any other tool directly save OpenShell.efi under the name of EFI\BOOT\BOOTX64.EFI on a FAT32 partition. It is typically unimportant whether the partition scheme is GPT or MBR.
While the previous approach works both on Macs and other computers, an alternative Mac-only approach to bless the tool on an HFS+ or APFS volume:
sudo bless --verbose --file /Volumes/VOLNAME/DIR/OpenShell.efi \ --folder /Volumes/VOLNAME/DIR/ --setBoot
Note 1: /System/Library/CoreServices/BridgeVersion.bin should be copied to /Volumes/VOLNAME/DIR.
Note 2: To be able to use the bless command, disabling System Integrity Protection is necessary.
Note 3: To be able to boot Secure Boot might be disabled if present.
Some of the known tools are listed below (builtin tools are marked with *):
Display Apple BootPicker menu (for Macs with compatible firmware). |
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Test BeepGen protocol and generate audio signals of different style and length. |
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Reset NVRAM alternative bundled as a standalone tool. |
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Simple implementation of SIP-related features of Apple csrutil. |
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Render the console font pages which the Builtin renderer provides. |
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Test GraphicsOutput protocol with a simple scenario. |
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Test keyboard input in SimpleText mode. |
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Memory testing utility. |
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Unlock and lock back NVRAM protection for other tools to be able to get full NVRAM access when launching from OpenCore. |
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OpenCore-configured UEFI Shell for compatibility with a broad range of firmware. |
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Perform EPID provisioning (requires certificate data configuration). |
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Utility to perform system reset. Takes reset type as an argument: coldreset, firmware, shutdown, warmreset. Defaults to coldreset. |
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Utility to read and write RTC (CMOS) memory. |
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Check CFG Lock (MSR 0xE2 write protection) consistency across all cores and change such hidden options on selected platforms. |
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Check Intel PTT (Platform Trust Technology) capability on the platform, which allows using fTPM 2.0 if enabled. The tool does not check whether fTPM 2.0 is actually enabled. |
OpenCanopy is a graphical OpenCore user interface that runs in External PickerMode and relies on OpenCorePkg OcBootManagementLib similar to the builtin text interface.
OpenCanopy requires graphical resources located in Resources directory to run. Sample resources (fonts and images) can be found in OcBinaryData repository. Customised icons can be found over the internet (e.g. here or there).
OpenCanopy provides full support for PickerAttributes and offers a configurable builtin icon set. The chosen icon set may depend on the DefaultBackgroundColor variable value. Refer to PickerVariant for more details.
Predefined icons are saved in the PickerVariant-derived subdirectory of the \EFI\OC\Resources\Image directory. A full list of supported icons (in .icns format) is provided below. When optional icons are missing, the closest available icon will be used. External entries will use Ext-prefixed icon if available (e.g. OldExtHardDrive.icns).
Note: In the following all dimensions are normative for the 1x scaling level and shall be scaled accordingly for other levels.
Predefined labels are saved in the \EFI\OC\Resources\Label directory. Each label has .lbl or .l2x suffix to represent the scaling level. Full list of labels is provided below. All labels are mandatory.
Note: All labels must have a height of exactly 12 px. There is no limit for their width.
Label and icon generation can be performed with bundled utilities: disklabel and icnspack. Font is Helvetica 12 pt times scale factor.
Font format corresponds to AngelCode binary BMF. While there are many utilities to generate font files, currently it is recommended to use dpFontBaker to generate bitmap font ( using CoreText produces best results) and fonverter to export it to binary format.
OpenRuntime is an OpenCore plugin implementing OC_FIRMWARE_RUNTIME protocol. This protocol implements multiple features required for OpenCore that are otherwise not possible to implement in OpenCore itself as they are needed to work in runtime, i.e. during operating system functioning. Feature highlights:
OpenLegacyBoot is an OpenCore plugin implementing OC_BOOT_ENTRY_PROTOCOL. It aims to detect and boot legacy installed operating systems on supported systems, such as OpenDuet and Mac models capable of legacy booting.
Usage:
OpenLegacyBoot does not require any additional filesystem drivers such as OpenNtfsDxe.efi to be loaded for base functionality, but loading them will enable the use of .contentDetails and .VolumeIcon.icns files for boot entry customisation.
No additional configuration should work well in most circumstances, but if required the following options for the driver may be specified in UEFI/Drivers/Arguments:
--hide-devices - String value, no default.
When this option is present and has one or more values separated by semicolons
(e.g. --hide-devices=PciRoot(0x0)/Pci(0x1F,0x2)/Sata(0x0,0xFFFF,0x0)/HD(2,GPT,...)), it disables scanning
the specified disks for legacy operating system boot sectors.
OpenLinuxBoot is an OpenCore plugin implementing OC_BOOT_ENTRY_PROTOCOL. It aims to automatically detect and boot most Linux distros without additional configuration.
Usage is as follows:
If OpenCore has already been manually set up to boot Linux, e.g. via BlessOverride or via Entries then then these settings may be removed so that the Linux distribution is not displayed twice in the boot menu.
It is recommended to install Linux with its default bootloader, even though this will not be actively used when booting via OpenLinuxBoot. This is because OpenLinuxBoot has to detect the correct kernel options to use, and does so by looking in files left by the default bootloader. If no bootloader was installed (or these options cannot be found) booting is still possible, but the correct boot options must be manually specified before OpenLinuxBoot will attempt to start the distro.
OpenLinuxBoot typically requires filesystem drivers that are not available in firmware, such as EXT4 and BTRFS drivers. These drivers can be obtained from external sources. Drivers tested in basic scenarios can be downloaded from OcBinaryData. Be aware that these drivers are not tested for reliability in all scenarious, nor did they undergo tamper-resistance testing, therefore they may carry potential security or data-loss risks.
Most Linux distros require the ext4_x64 driver, a few may require the btrfs_x64 driver, and a few may require no additional file system driver: it depends on the filesystem of the boot partition of the installed distro, and on what filesystems are already supported by the system’s firmware. LVM is not currently supported - this is because it is not believed that there is currently a stand-alone UEFI LVM filesystem driver.
Be aware of the SyncRuntimePermissions quirk, which may need to be set to avoid early boot failure (typically halting with a black screen) of the Linux kernel, due to a firmware bug of some firmware released after 2017. When present and not mitigated by this quirk, this affects booting via OpenCore with or without OpenLinuxBoot.
After installing OpenLinuxBoot, it is recommended to compare the options shown in the OpenCore debug log when booting (or attempting to boot) a given distro against the options seen using the shell command cat /proc/cmdline when the same distro has been booted via its native bootloader. In general (for safety and security of the running distro) these options should match, and if they do not it is recommended to use the driver arguments below (in particular LINUX_BOOT_ADD_RO, LINUX_BOOT_ADD_RW, autoopts:{PARTUUID} and autoopts) to modify the options as required. Note however that the following differences are normal and do not need to be fixed:
If using OpenLinuxBoot with Secure Boot, users may wish to install a user built, user signed Shim bootloader giving SBAT and MOK integration, as explained in OpenCore ShimUtils.
The default parameter values should work well with no changes under most circumstances, but if required the following options for the driver may be specified in UEFI/Drivers/Arguments:
flags - Default: all flags are set except the following:
Available flags are:
0x00000080 (bit 7) — LINUX_BOOT_SCAN_OTHER, Allows scanning for entries on file systems not matched by any of the above.
The following notes apply to all of the above options:
Note 1: Apple filesystems APFS and HFS are never scanned.
Note 2: Regardless of the above flags, a file system must first be allowed by Misc/Security/ScanPolicy before it can be seen by OpenLinuxBoot or any other OC_BOOT_ENTRY_PROTOCOL driver.
Note 3: It is recommended to enable scanning LINUX_ROOT and LINUX_DATA in both OpenLinuxBoot flags and Misc/Security/ScanPolicy in order to be sure to detect all valid Linux installs, since Linux boot filesystems are very often marked as LINUX_DATA.
0x00000200 (bit 9) — LINUX_BOOT_USE_LATEST, When a Linux entry generated by OpenLinuxBoot is selected as the default boot entry in OpenCore, automatically switch to the latest kernel when a new version is installed.
When this option is set, an internal menu entry id is shared between kernel versions from the same install of Linux. Linux boot options are always sorted highest kernel version first, so this means that the latest kernel version of the same install always shows as the default, with this option set.
Note: This option is recommended on all systems.
Flag values can be specified in hexadecimal beginning with 0x or in decimal, e.g. flags=0x80 or flags=128. It is also possible to specify flags to add or remove, using syntax such as flags+=0xC000 to add all debugging options or flags-=0x400 to remove the LINUX_BOOT_ADD_RO option.
autoopts:{PARTUUID}[+]="{options}" - Default: not set.
Allows manually specifying kernel options to use in autodetect mode for a given partition only. Replace the text {PARTUUID} with the specific partition UUID on which the kernels are stored (in normal layout, the partition which contains /boot), e.g. autoopts:11223344-5566-7788-99aa-bbccddeeff00+="vt.handoff=7". If specified with += then these options are used in addition to any autodetected options, if specified with = they are used instead. Used for autodetected Linux only – values specified here are never used for entries created from /loader/entries/*.conf files.
Note: The PARTUUID value to be specified here is typically the same as the PARTUUID seen in root=PARTUUID=... in the Linux kernel boot options (view using cat /proc/cmdline). Alternatively, and for more advanced scenarios, it is possible to examine how the distro’s partitions are mounted using the Linux mount command, and then find out the partuuid of relevant mounted partitions by examining the output of ls -l /dev/disk/by-partuuid.
autoopts[+]="{options}" - Default: None specified.
Allows manually specifying kernel options to use in autodetect mode. The alternative format autoopts:{PARTUUID} is more suitable where there are multiple distros, but autoopts with no PARTUUID required may be more convenient for just one distro. If specified with += then these are used in addition to autodetected options, if specified with = they are used instead. Used for autodetected Linux only – values specified here are never used for entries created from /loader/entries/*.conf files.
As example usage, it is possible to use += format to add a vt.handoff options, such as autoopts+="vt.handoff=7" or autoopts+="vt.handoff=3" (check cat /proc/cmdline when booted via the distro’s default bootloader) on Ubuntu and related distros, in order to add the vt.handoff option to the auto-detected GRUB defaults, and avoid a flash of text showing before the distro splash screen.
OpenLinuxBoot can detect the loader/entries/*.conf files created according to the Boot Loader Specification or the closely related systemd BootLoaderSpecByDefault. The former is specific to systemd-boot and is used by Arch Linux, the latter applies to most Fedora-related distros including Fedora itself, RHEL and variants.
Where the above files are not present, OpenLinuxBoot can autodetect and boot {boot}/vmlinuz* kernel files directly. It links these automatically – based on the kernel version in the filename – to their associated {boot}/init* ramdisk files. This applies to most Debian-related distros, including Debian itself, Ubuntu and variants.
When autodetecting in /boot as part of the root filesystem, OpenLinuxBoot looks in /etc/default/grub for kernel boot options and /etc/os-release for the distro name. When autodetecting in a standalone boot partition (i.e. when /boot has its own mount point), OpenLinuxBoot cannot autodetect kernel arguments and all kernel arguments except initrd=... must be fully specified by hand using autoopts=... or autoopts:{partuuid}=... (+= variants of these options will not work, as these only add additional arguments).
BootLoaderSpecByDefault (but not pure Boot Loader Specification) can expand GRUB variables in the *.conf files – and this is used in practice in certain distros such as CentOS. In order to handle this correctly, when this situation is detected OpenLinuxBoot extracts all variables from {boot}/grub2/grubenv and also any unconditionally set variables from {boot}/grub2/grub.cfg, and then expands these where required in *.conf file entries.
The only currently supported method of starting Linux kernels relies on their being compiled with EFISTUB. This applies to almost all modern distros, particularly those which use systemd. Note that most modern distros use systemd as their system manager, even though most do not use systemd-boot as their bootloader.
systemd-boot users (probably almost exclusively Arch Linux users) should be aware that OpenLinuxBoot does not support the systemd-boot–specific Boot Loader Interface; therefore efibootmgr rather than bootctl must be used for any low-level Linux command line interaction with the boot menu.
In addition to the OpenLinuxBoot plugin, the following OC_BOOT_ENTRY_PROTOCOL plugins are made available to add optional, configurable boot entries to the OpenCore boot picker.
Adds a menu entry which resets NVRAM and immediately restarts. Additionally adds support for hotkey CMD+OPT+P+R to perform the same action. Note that on some combinations of firmware and drivers, the TakeoffDelay option must be configured in order for this and other builtin hotkeys to be reliably detected.
Note 1: It is known that some Lenovo laptops have a firmware bug, which makes them unbootable after performing NVRAM reset. Refer to acidanthera/bugtracker#995 for details.
Note 2: If LauncherOption is set to Full or Short then the OpenCore boot entry is protected. Resetting NVRAM will normally erase any other boot options not specified via BlessOverride, for example Linux installations to custom locations and not using the OpenLinuxBoot driver, or user-specified UEFI boot menu entries. To obtain reset NVRAM functionality which does not remove other boot options, it is possible to use the --preserve-boot option (though see the warning specified).
The following configuration options may be specified in the Arguments section for this driver:
--preserve-boot - Boolean flag, enabled if present.
If enabled, BIOS boot entries are not cleared during NVRAM reset. This option should be used with caution, as some boot problems can be fixed by clearing these entries.
--apple - Boolean flag, enabled if present.
On Apple firmware only, this performs a system NVRAM reset. This can result in additional, desirable operations such as NVRAM garbage collection. This is achieved by setting the ResetNVRam NVRAM variable. Where available, this has the same effect as pressing CMD+OPT+P+R during native boot, although note that if accessed from the menu entry only one boot chime will be heard.
Note 1: Due to using system NVRAM reset, this option is not compatible with the --preserve-boot option and will override it, therefore all BIOS boot entries will be removed.
Note 2: Due to using system NVRAM reset, the OpenCore boot option cannot be preserved and OpenCore will have to either be reselected in the native boot picker or re-blessed.
Note 3: On non-Apple hardware, this option will still set this variable but the variable will not be recognised by the firmware and no NVRAM reset will happen.
Provides a boot entry for enabling and disabling System Integrity Protection (SIP) in OpenCore picker.
While macOS is running, SIP involves multiple configured software protection systems, however all the information about which of these protections to enable is stored in the single Apple NVRAM variable csr-active-config. As long as this variable is set before macOS startup, SIP will be fully configured, so setting the variable using this boot option (or in any other way, before macOS starts) has exactly the same end result as configuring SIP using the csrutil command in macOS Recovery.
csr-active-config will be toggled between 0 for enabled, and a user-specified or default value for disabled.
Options for the driver should be specified as plain text values separated by whitespace in the Arguments section of Driver entry. Available options are:
--show-csr - Boolean flag, enabled if present.
If enabled, show the current hexadecimal value of csr-active-config in the boot entry name. This option will not work in OpenCanopy when used in combination with OC_ATTR_USE_GENERIC_LABEL_IMAGE in PickerAttributes.
Numerical value - Default value 0x27F.
Specify the csr-active-config value to use to disabled SIP. This can be specified as hexadecimal, beginning with 0x, or as decimal. For more info see Note 2 below.
Note 1: It is recommended not to run macOS with SIP disabled. Use of this boot option may make it easier to quickly disable SIP protection when genuinely needed - it should be re-enabled again afterwards.
Note 2: The default value for disabling SIP with this boot entry is 0x27F. For comparison, csrutil disable with no other arguments on macOS Big Sur and Monterey sets 0x7F, and on Catalina it sets 0x77. The OpenCore default value of 0x27F is a variant of the Big Sur and Monterey value, chosen as follows:
Adds a menu entry which will reboot into UEFI firmware settings, when supported. No menu entry added and logs a warning when not supported.
High Definition Audio (HDA) support driver in UEFI firmware for most Intel and some other analog audio controllers.
Note: AudioDxe is a staging driver, refer to acidanthera/bugtracker#740 for known issues.
Most UEFI audio configuration is handled via the UEFI Audio Properties section, but in addition some of the following configuration options may be required in order to allow AudioDxe to correctly drive certain devices. All options are specified as text strings, separated by space if more than one option is required, in the Arguments property for the driver within the UEFI/Drivers section:
--codec-setup-delay - Integer value, default 0.
Amount of time in milliseconds to wait for all widgets to come fully on, applied per codec during driver connection phase. In most systems this should not be needed and a faster boot will be achieved by using Audio section SetupDelay if any audio setup delay is required. Where required, values of up to one second may be needed.
--force-codec - Integer value, no default.
Force use of an audio codec, this value should be equal to Audio section AudioCodec. Can result in faster boot especially when used in conjuction with --force-device.
--force-device - String value, no default.
When this option is present and has a value (e.g. --force-device=PciRoot(0x0)/Pci(0x1f,0x3)), it forces AudioDxe to connect to the specified PCI device, even if the device does not report itself as an HDA audio controller.
During driver connection, AudioDxe automatically provides audio services on all supported codecs of all available HDA controllers. However, if the relevant controller is misreporting its identity (typically, it will be reporting itself as a legacy audio device instead of an HDA controller) then this argument may be required.
Applies if the audio device can be made to work in macOS, but shows no sign of being detected by AudioDxe (e.g. when including DEBUG_INFO in DisplayLevel and using a DEBUG build of AudioDxe, no controller and codec layout information is displayed during the Connecting drivers... phase of OpenCore log).
--gpio-setup - Default value is 0 (GPIO setup disabled) if argument is not provided, or 7 (all GPIO setup stages stages enabled) if the argument is provided with no value.
Available values, which may be combined by adding, are:
If audio appears to be ‘playing’ on the correct codec, e.g. based on the debug log, but no sound is heard on any channel, it is suggested to use --gpio-setup (with no value) in the AudioDxe driver arguments. If specified with no value, all stages will be enabled (equivalent of specifying 7). If this produces sound, it is then possible to try fewer bits, e.g. --gpio-setup=1, --gpio-setup=3, to find out which stages are actually required.
Note: Value 7 (all flags enabled) of this option – as required for the MacPro5,1 – is compatible with most systems, but is known to cause problems with sound (previous sounds are not allowed to finish before new sounds start) on a small number of other systems, hence this option is not enabled by default.
--gpio-pins - Default: 0, auto-detect.
Specifies which GPIO pins should be operated on by --gpio-setup. This is a bit mask, with possible values from 0x0 to 0xFF. The usable maximum depends on the number if available pins on the audio out function group of the codec in use, e.g. it is 0x3 (lowest two bits) if two GPIO pins are present, 0x7 if three pins are present, etc.
When --gpio-setup is enabled (i.e. non-zero), then 0 is a special value for --gpio-pins, meaning that the pin mask will be auto-generated based on the reported number of GPIO pins on the specified codec (see AudioCodec), e.g. if the codec’s audio out function group reports 4 GPIO pins, a mask of 0xF will be used. The value in use can be seen in the debug log in a line such as:
HDA: GPIO setup on pins 0x0F - Success
Values for driver parameters can be specified in hexadecimal beginning with 0x or in decimal, e.g. --gpio-pins=0x12 or --gpio-pins=18.
--restore-nosnoop - Boolean flag, enabled if present.
AudioDxe clears the Intel HDA No Snoop Enable (NSNPEN) bit. On some systems, this change must be reversed on exit in order to avoid breaking sound in Windows or Linux. If so, this flag should be added to AudioDxe driver arguments. Not enabled by default, since restoring the flag can prevent sound from working in macOS on some other systems.
--use-conn-none - Boolean flag, enabled if present.
On some sound cards enabling this option will enable additional usable audio channels (e.g. the bass or treble speaker of a pair, where only one is found without it).
Note: Enabling this option may increase the available channels, in which case any custom setting of AudioOutMask may need to be changed to match the new channel list.
Provides in-memory emulated NVRAM implementation. This can be useful on systems with fragile (e.g. MacPro5,1, see discussion linked from this forum post) or incompatible NVRAM implementations. This driver is included by default in OpenDuet.
In addition to installing emulated NVRAM, this driver additionally installs an OpenCore compatible protocol enabling the following:
Recommended configuration settings for this driver:
OpenRuntime.efi specified after OpenVariableRuntimeDxe.efi (when applicable), also loaded using LoadEarly=true for correct operation of RequestBootVarRouting.
LegacySchema populated.
Variable loading happens prior to the NVRAM Delete (and Add) phases. Unless LegacyOverwrite is enabled, it will not overwrite any existing variable. Variables allowed for loading and for saving with CTRL+Enter must be specified in LegacySchema.
In order to allow changes to NVRAM within macOS to be captured and saved, an additional script must be installed. An example of such script can be found in Utilities/LogoutHook/Launchd.command.
Note 1: This driver requires working FAT write support in firmware, and sufficient free space on the OpenCore EFI partition for up to three saved NVRAM files.
Note 2: The nvram.plist (and nvram.fallback if present) files must have a root plist dictionary type and contain two fields:
Note 3: When setting up legacy NVRAM, it can be convenient to set <string>*</string> as the value for the following three GUID keys in LegacySchema:
This enables all variables saved by Launchd.command to be saved to nvram.plist, therefore it allows all arbitrary user test variables (e.g. as set by sudo nvram foo=bar) to be saved. Using this permissive policy is also future-proof against any changes in the variables which need to be passed from macOS update setup to the macOS Installer stage, in order for it to succeed. Nevertheless, once emulated NVRAM is set up, only allowing known strictly required variables (as shown in OpenCore’s sample .plist files) is considerably more secure. See also the following warning about the overall security of loading NVRAM variables from a non-vaulted file.
Warning: The ability to load NVRAM from a file on disk can be dangerous, as it passes unprotected data to firmware variable services. Only use when no hardware NVRAM implementation is provided by the firmware or when the NVRAM implementation available in firmware is incompatible or dangerously fragile (e.g. in a state where excessive use may cause bricked hardware).
OpenCore combined with OpenVariableRuntimeDxe will only use a given saved nvram.plist file once, if it is used to launch a macOS Installer boot entry. After that the used settings are moved to nvram.used and fallback settings, if any, from nvram.fallback are used instead. Launchd.command itself always copies the previous NVRAM settings to fallback, each time it saves new settings.
This strategy is used to work round the limitation that the Launchd.command script is not running, and therefore cannot save NVRAM changes (particularly default boot entry changes), during the second and subsequent restarts of the macOS installer.
In brief, this fallback strategy allows full or incremental OTA updates of recent macOS, which are started from within an existing macOS (with the Launchd.command script installed), to proceed without manual intervention.
However, for full installs, there can be more than one full restart back to the macOS Installer entry. In this case the fallback strategy will lose track of the correct startup item (i.e. macOS Installer) from the second reboot onwards. Equally, if installing to a drive other than the current default boot partition, this will not be automatically selected after the installer completes, as it would be when using non-emulated NVRAM. (This behaviour remains preferable to not having the fallback strategy, in which case a macOS Installer entry would be continually recreated in the picker menu, even once it no longer exists).
In both the above two cases it is recommended to use the following settings, to make it easy to manually control which boot entry is selected during the installer process:
The first reboot should correctly select macOS Installer. For second and subsequent reboots, if a macOS Installer entry is still present it should be manually selected (using just Enter, not CTRL+Enter). Once a macOS Installer entry is no longer present, the entry for the new OS will still be automatically selected if it was the previous boot default. If not, it should be manually selected (at this point, CTRL+Enter is a good idea as any final remaining installation restarts will be to this entry).
Note 1: When using emulated NVRAM but not installing from within an existing installed macOS (i.e. when installing from within macOS Recovery, or from an installation USB), please refer to this forum post (in Russian) for additional options.
Note 2: After upgrading from an earlier macOS version to macOS Sonoma, the Launchd.command script should be reinstalled, as a different strategy is required in order for NVRAM to be saved successfully.
Note 3: In macOS Sonoma the following additional constraints apply to the ESP partition on which OpenCore is installed, in order for the Launchd.command script to work successfully:
Audio
Type: plist dict
Description: Configure audio backend support described in the Audio Properties section below.
Unless documented otherwise (e.g. ResetTrafficClass) settings in this section are for UEFI audio support only (e.g. OpenCore generated boot chime and audio assist) and are unrelated to any configuration needed for OS audio support (e.g. AppleALC).
UEFI audio support provides a way for upstream protocols to interact with the selected audio hardware and resources. All audio resources should reside in \EFI\OC\Resources\Audio directory. Currently the supported audio file formats are MP3 and WAVE PCM. While it is driver-dependent which audio stream format is supported, most common audio cards support 16-bit signed stereo audio at 44100 or 48000 Hz.
Audio file path is determined by audio type, audio localisation, and audio path. Each filename looks as follows: [audio type]_[audio localisation]_[audio path].[audio ext]. For unlocalised files filename does not include the language code and looks as follows: [audio type]_[audio path].[audio ext]. Audio extension can either be mp3 or wav.
Audio localisation is determined separately for macOS bootloader and OpenCore. For macOS bootloader it is set in preferences.efires archive in systemLanguage.utf8 file and is controlled by the operating system. For OpenCore the value of prev-lang:kbd variable is used. When native audio localisation of a particular file is missing, English language (en) localisation is used. Sample audio files can be found in OcBinaryData repository.
ConnectDrivers
Type: plist boolean
Failsafe: false
Description: Perform UEFI controller connection after driver loading.
This option is useful for loading drivers following UEFI driver model as they may not start by themselves. Examples of such drivers are filesystem or audio drivers. While effective, this option may not be necessary for drivers performing automatic connection, and may slightly slowdown the boot.
Note: Some types of firmware, particularly those made by Apple, only connect the boot drive to speed up the boot process. Enable this option to be able to see all the boot options when running multiple drives.
Drivers
Type: plist array
Failsafe: Empty
Description: Load selected drivers from OC/Drivers directory.
To be filled with plist dict values, describing each driver. Refer to the Drivers Properties section below.
ProtocolOverrides
Type: plist dict
Description: Force builtin versions of certain protocols described in the ProtocolOverrides Properties section
below.
Note: all protocol instances are installed prior to driver loading.
EnableJumpstart
Type: plist boolean
Failsafe: false
Description: Load embedded APFS drivers from APFS containers.
An APFS EFI driver is bundled in all bootable APFS containers. This option performs the loading of signed APFS drivers (consistent with the ScanPolicy). Refer to the “EFI Jumpstart” section of the Apple File System Reference for details.
GlobalConnect
Type: plist boolean
Failsafe: false
Description: Perform full device connection during APFS loading.
Every handle is connected recursively instead of the partition handle connection typically used for APFS driver loading. This may result in additional time being taken but can sometimes be the only way to access APFS partitions on certain firmware, such as those on older HP laptops.
HideVerbose
Type: plist boolean
Failsafe: false
Description: Hide verbose output from APFS driver.
APFS verbose output can be useful for debugging.
JumpstartHotPlug
Type: plist boolean
Failsafe: false
Description: Load APFS drivers for newly connected devices.
Permits APFS USB hot plug which enables loading APFS drivers, both at OpenCore startup and during OpenCore picker display. Disable if not required.
MinDate
Type: plist integer
Failsafe: 0
Description: Minimal allowed APFS driver date.
The APFS driver date connects the APFS driver with the calendar release date. Apple ultimately drops support for older macOS releases and APFS drivers from such releases may contain vulnerabilities that can be used to compromise a computer if such drivers are used after support ends. This option permits restricting APFS drivers to current macOS versions.
MinVersion
Type: plist integer
Failsafe: 0
Description: Minimal allowed APFS driver version.
The APFS driver version connects the APFS driver with the macOS release. Apple ultimately drops support for older macOS releases and APFS drivers from such releases may contain vulnerabilities that can be used to compromise a computer if such drivers are used after support ends. This option permits restricting APFS drivers to current macOS versions.
AppleEvent
Type: plist string
Failsafe: Auto
Description: Determine whether the OpenCore builtin or the OEM Apple Event protocol is used.
This option determines whether the OEM Apple Event protocol is used (where available), or whether OpenCore’s reversed engineered and updated re-implementation is used. In general OpenCore’s re-implementation should be preferred, since it contains updates such as noticeably improved fine mouse cursor movement and configurable key repeat delays.
CustomDelays
Type: plist boolean
Failsafe: false
Description: Enable custom key repeat delays when using the OpenCore re-implementation of the Apple Event
protocol. Has no effect when using the OEM Apple implementation (see AppleEvent setting).
GraphicsInputMirroring
Type: plist boolean
Failsafe: false
Description: Apple’s own implementation of AppleEvent prevents keyboard input during graphics applications from
appearing on the basic console input stream.
With the default setting of false, OpenCore’s builtin implementation of AppleEvent replicates this behaviour.
On non-Apple hardware this can stop keyboard input working in graphics-based applications such as Windows BitLocker which use non-Apple key input methods.
The recommended setting on all hardware is true.
Note: AppleEvent’s default behaviour is intended to prevent unwanted queued keystrokes from appearing after exiting graphics-based UEFI applications; this issue is already handled separately within OpenCore.
KeyInitialDelay
Type: plist integer
Failsafe: 50 (500ms before first key repeat)
Description: Configures the initial delay before keyboard key repeats in the OpenCore re-implementation of the Apple
Event protocol, in units of 10ms.
The Apple OEM default value is 50 (500ms).
Note 1: On systems not using KeySupport, this setting may be freely used to configure key repeat behaviour.
Note 2: On systems using KeySupport, but which do not show the ‘two long delays’ behavior (see Note 3) and/or which always show a solid ‘set default’ indicator (see KeyForgetThreshold) then this setting may also be freely used to configure key repeat initial delay behaviour, except that it should never be set to less than KeyForgetThreshold to avoid uncontrolled key repeats.
Note 3: On some systems using KeySupport, you may find that you see one additional slow key repeat before normal speed key repeat starts, when holding a key down. If so, you may wish to configure KeyInitialDelay and KeySubsequentDelay according to the instructions at Note 3 of KeySubsequentDelay.
KeySubsequentDelay
Type: plist integer
Failsafe: 5 (50ms between subsequent key repeats)
Description: Configures the gap between keyboard key repeats in the OpenCore re-implementation of the Apple Event
protocol, in units of 10ms.
The Apple OEM default value is 5 (50ms). 0 is an invalid value for this option (will issue a debug log warning and use 1 instead).
Note 1: On systems not using KeySupport, this setting may be freely used to configure key repeat behaviour.
Note 2: On systems using KeySupport, but which do not show the ‘two long delays’ behaviour (see Note 3) and/or which always show a solid ‘set default’ indicator (see KeyForgetThreshold) (which should apply to many/most systems using AMI KeySupport mode) then this setting may be freely used to configure key repeat subsequent delay behaviour, except that it should never be set to less than KeyForgetThreshold to avoid uncontrolled key repeats.
Note 3: On some systems using KeySupport, particularly KeySupport in non-AMI mode, you may find that after configuring KeyForgetThreshold you get one additional slow key repeat before normal speed key repeat starts, when holding a key down. On systems where this is the case, it is an unavoidable artefect of using KeySupport to emulate raw keyboard data, which is not made available by UEFI. While this ‘two long delays’ issue has minimal effect on overall usability, nevertheless you may wish to resolve it, and it is possible to do so as follows:
The above procedure works as follows:
PointerDwellClickTimeout
Type: plist integer
Failsafe: 0
Description: Configure pointer dwell-clicking single left click timeout in milliseconds in the OpenCore
re-implementation of the Apple Event protocol. Has no effect when using the OEM Apple implementation (see
AppleEvent setting).
When the timeout expires, a single left click is issued at the current position. 0 indicates the timeout is disabled.
PointerDwellDoubleClickTimeout
Type: plist integer
Failsafe: 0
Description: Configure pointer dwell-clicking single left double click timeout in milliseconds in the OpenCore
re-implementation of the Apple Event protocol. Has no effect when using the OEM Apple implementation (see
AppleEvent setting).
When the timeout expires, a single left double click is issued at the current position. 0 indicates the timeout is disabled.
PointerDwellRadius
Type: plist integer
Failsafe: 0
Description: Configure pointer dwell-clicking tolerance radius in pixels in the OpenCore re-implementation of
the Apple Event protocol. Has no effect when using the OEM Apple implementation (see AppleEvent
setting).
The radius is scaled by UIScale. When the pointer leaves this radius, the timeouts for PointerDwellClickTimeout and PointerDwellDoubleClickTimeout are reset and the new position is the centre for the new dwell-clicking tolerance radius.
PointerPollMask
Type: plist integer, 32 bit
Failsafe: -1
Description: Configure indices of polled pointers.
Selects pointer devices to poll for AppleEvent motion events. -1 implies all devices. A bit sum is used to determine particular devices. E.g. to enable devices 0, 2, 3 the value will be 1+4+8 (corresponding powers of two). A total of 32 configurable devices is supported.
Certain pointer devices can be present in the firmware even when no corresponding physical devices are available. These devices usually are placeholders, aggregate devices, or proxies. Gathering information from these devices may result in inaccurate motion activity in the user interfaces and even cause performance issues. Disabling such pointer devices is recommended for laptop setups having issues of this kind.
The amount of pointer devices available in the system can be found in the log. Refer to Found N pointer devices message for more details.
Note: Has no effect when using the OEM Apple implementation (see AppleEvent setting).
PointerPollMax
Type: plist integer
Failsafe: 0
Description: Configure maximum pointer polling period in ms.
This is the maximum period the OpenCore builtin AppleEvent driver polls pointer devices (e.g. mice, trackpads) for motion events. The period is increased up to this value as long as the devices do not respond in time. The current implementation defaults to 80 ms. Setting 0 leaves this default unchanged.
Certain trackpad drivers often found in Dell laptops can be very slow to respond when no physical movement happens. This can affect OpenCanopy and FileVault 2 user interface responsiveness and loading times. Increasing the polling periods can reduce the impact.
Note: The OEM Apple implementation uses a polling rate of 2 ms.
PointerPollMin
Type: plist integer
Failsafe: 0
Description: Configure minimal pointer polling period in ms.
This is the minimal period the OpenCore builtin AppleEvent driver polls pointer devices (e.g. mice, trackpads) for motion events. The current implementation defaults to 10 ms. Setting 0 leaves this default unchanged.
Note: The OEM Apple implementation uses a polling rate of 2 ms.
PointerSpeedDiv
Type: plist integer
Failsafe: 1
Description: Configure pointer speed divisor in the OpenCore re-implementation of the Apple Event protocol. Has no
effect when using the OEM Apple implementation (see AppleEvent setting).
Configures the divisor for pointer movements. The Apple OEM default value is 1. 0 is an invalid value for this option.
Note: The recommended value for this option is 1. This value may optionally be modified in combination with PointerSpeedMul, according to user preference, to achieve customised mouse movement scaling.
PointerSpeedMul
Type: plist integer
Failsafe: 1
Description: Configure pointer speed multiplier in the OpenCore re-implementation of the Apple Event protocol. Has
no effect when using the OEM Apple implementation (see AppleEvent setting).
Configures the multiplier for pointer movements. The Apple OEM default value is 1.
Note: The recommended value for this option is 1. This value may optionally be modified in combination with PointerSpeedDiv, according to user preference, to achieve customised mouse movement scaling.
AudioCodec
Type: plist integer
Failsafe: 0
Description: Codec address on the specified audio controller for audio support.
This typically contains the first audio codec address on the builtin analog audio controller (HDEF). Audio codec addresses, e.g. 2, can be found in the debug log (marked in bold-italic):
OCAU: 1/3 PciRoot(0x0)/Pci(0x1,0x0)/Pci(0x0,0x1)/VenMsg(<redacted>,00000000) (4 outputs)
OCAU: 2/3 PciRoot(0x0)/Pci(0x3,0x0)/VenMsg(<redacted>,00000000) (1 outputs)
OCAU: 3/3 PciRoot(0x0)/Pci(0x1B,0x0)/VenMsg(<redacted>,02000000) (7 outputs)
As an alternative, this value can be obtained from IOHDACodecDevice class in I/O Registry containing it in IOHDACodecAddress field.
AudioDevice
Type: plist string
Failsafe: Empty
Description: Device path of the specified audio controller for audio support.
This typically contains builtin analog audio controller (HDEF) device path, e.g. PciRoot(0x0)/Pci(0x1b,0x0). The list of recognised audio controllers can be found in the debug log (marked in bold-italic):
OCAU: 1/3 PciRoot(0x0)/Pci(0x1,0x0)/Pci(0x0,0x1)/VenMsg(<redacted>,00000000) (4 outputs)
OCAU: 2/3 PciRoot(0x0)/Pci(0x3,0x0)/VenMsg(<redacted>,00000000) (1 outputs)
OCAU: 3/3 PciRoot(0x0)/Pci(0x1B,0x0)/VenMsg(<redacted>,02000000) (7 outputs)
If using AudioDxe, the available controller device paths are also output on lines formatted like this:
HDA: Connecting controller - PciRoot(0x0)/Pci(0x1B,0x0)
Finally, gfxutil -f HDEF command can be used in macOS to obtain the device path.
Specifying an empty device path results in the first available codec and audio controller being used. The value of AudioCodec is ignored in this case. This can be a convenient initial option to try to get UEFI audio working. Manual settings as above will be required when this default value does not work.
AudioOutMask
Type: plist integer
Failsafe: -1
Description: Bit field indicating which output channels to use for UEFI sound.
Audio mask is 1 « audio output (equivalently 2 ^ audio output). E.g. for audio output 0 the bitmask is 1, for output 3 it is 8, and for outputs 0 and 3 it is 9.
The number of available output nodes (N) for each HDA codec is shown in the debug log (marked in bold-italic), audio outputs 0 to N - 1 may be selected:
OCAU: 1/3 PciRoot(0x0)/Pci(0x1,0x0)/Pci(0x0,0x1)/VenMsg(<redacted>,00000000) (4 outputs)
OCAU: 2/3 PciRoot(0x0)/Pci(0x3,0x0)/VenMsg(<redacted>,00000000) (1 outputs)
OCAU: 3/3 PciRoot(0x0)/Pci(0x1B,0x0)/VenMsg(<redacted>,02000000) (7 outputs)
When AudioDxe is used then additional information about each output channel is logged during driver binding, including the bitmask for each output. The bitmask values for the desired outputs should be added together to obtain the AudioOutMask value:
HDA: | Port widget @ 0x9 is an output (pin defaults 0x2B4020) (bitmask 1)
HDA: | Port widget @ 0xA is an output (pin defaults 0x90100112) (bitmask 2)
HDA: | Port widget @ 0xB is an output (pin defaults 0x90100110) (bitmask 4)
HDA: | Port widget @ 0x10 is an output (pin defaults 0x4BE030) (bitmask 8)
Further information on the available output channels may be found from a Linux codec dump using the command:
cat /proc/asound/card{n}/codec#{m}
Using AudioOutMask, it is possible to play sound to more than one channel (e.g. main speaker plus bass speaker; headphones plus speakers) as long as all the chosen outputs support the sound file format in use; if any do not then no sound will play and a warning will be logged.
When all available output channels on the codec support the available sound file format then a value of -1 will play sound to all channels simultaneously. If this does not work it will usually be quickest to try each available output channel one by one, by setting AudioOutMask to 1, 2, 4, etc., up to 2 ^ N - 1, in order to work out which channel(s) produce sound.
AudioSupport
Type: plist boolean
Failsafe: false
Description: Activate audio support by connecting to a backend driver.
Enabling this setting routes audio playback from builtin protocols to specified (AudioOutMask) dedicated audio ports of the specified codec (AudioCodec), located on the specified audio controller (AudioDevice).
DisconnectHda
Type: plist boolean
Failsafe: false
Description: Disconnect HDA controller before loading drivers.
May be required on some systems (e.g. Apple hardware, VMware Fusion guest) to allow a UEFI sound driver (such as AudioDxe) to take control of the audio hardware.
Note: In addition to this option, most Apple hardware also requires the --gpio-setup driver argument which is dealt with in the AudioDxe section.
MaximumGain
Type: plist integer
Failsafe: -15
Description: Maximum gain to use for UEFI audio, specified in decibels (dB) with respect to amplifier reference
level of 0 dB (see note 1).
All UEFI audio will use this gain setting when the system amplifier gain read from the SystemAudioVolumeDB NVRAM variable is higher than this. This is to avoid over-loud UEFI audio when the system volume is set very high, or the SystemAudioVolumeDB NVRAM value has been misconfigured.
Note 1: Decibels (dB) specify gain (postive values; increase in volume) or attenuation (negative values; decrease in volume) compared to some reference level. When you hear the sound level of a jet plane expressed as 120 decibels, say, the reference level is the sound level just audible to an average human. However generally in acoustic science and computer audio any reference level can be specified. Intel HDA and macOS natively use decibels to specify volume level. On most Intel HDA hardware the reference level of 0 dB is the loudest volume of the hardware, and all lower volumes are therefore negative numbers. The quietest volume on typical sound hardware is around -55 dB to -60 dB.
Note 2: Matching how macOS handles decibel values, this value is converted to a signed byte; therefore values outside −128 dB to +127 dB (which are well beyond physically plausible volume levels) are not allowed.
Note 3: Digital audio output – which does not have a volume slider in-OS – ignores this and all other gain settings, only mute settings are relevant.
MinimumAssistGain
Type: plist integer
Failsafe: -30
Description: Minimum gain in decibels (dB) to use for picker audio assist.
The screen reader will use this amplifier gain if the system amplifier gain read from the SystemAudioVolumeDB NVRAM variable is lower than this.
Note 1: In addition to this setting, because audio assist must be audible to serve its function, audio assist is not muted even if the OS sound is muted or the StartupMute NVRAM variable is set.
Note 2: See MaximumGain for an explanation of decibel volume levels.
MinimumAudibleGain
Type: plist integer
Failsafe: -128
Description: Minimum gain in decibels (dB) at which to attempt to play any sound.
The boot chime will not play if the system amplifier gain level in the SystemAudioVolumeDB NVRAM variable is lower than this.
Note 1: This setting is designed to save unecessary pauses due to audio setup at inaudible volume levels, when no sound will be heard anyway. Whether there are inaudible volume levels depends on the hardware. On some hardware (including Apple) the audio values are well enough matched to the hardware that the lowest volume levels available are very quiet but audible, whereas on some other hardware combinations, the lowest part of the volume range may not be audible at all.
Note 2: See MaximumGain for an explanation of decibel volume levels.
PlayChime
Type: plist string
Failsafe: Auto
Description: Play chime sound at startup.
Enabling this setting plays the boot chime using the builtin audio support. The volume level is determined by the SystemAudioVolumeDB NVRAM variable. Supported values are:
Note 1: Enabled can be used separately from the StartupMute NVRAM variable to avoid conflicts when the firmware is able to play the boot chime.
Note 2: Regardless of this setting, the boot chime will not play if system audio is muted, i.e. if the SystemAudioVolume NVRAM variable has bit 0x80 set.
ResetTrafficClass
Type: plist boolean
Failsafe: false
Description: Set HDA Traffic Class Select Register to TC0.
AppleHDA kext will function correctly only if TCSEL register is configured to use TC0 traffic class. Refer to Intel I/O Controller Hub 9 (ICH9) Family Datasheet (or any other ICH datasheet) for more details about this register.
Note: This option is independent from AudioSupport. If AppleALC is used it is preferred to use AppleALC alctcsel property instead.
SetupDelay
Type: plist integer
Failsafe: 0
Description: Audio codec reconfiguration delay in milliseconds.
Some codecs require a vendor-specific delay after the reconfiguration (e.g. volume setting). This option makes it configurable. A typical delay can be up to 0.5 seconds.
LoadEarly
Type: plist boolean
Failsafe: false
Description: Load the driver early in the OpenCore boot process, before NVRAM setup.
Note: Do not enable this option unless specifically recommended to do so for a given driver and purpose.
KeyFiltering
Type: plist boolean
Failsafe: false
Description: Enable keyboard input sanity checking.
Apparently some boards such as the GA Z77P-D3 may return uninitialised data in EFI_INPUT_KEY with all input protocols. This option discards keys that are neither ASCII, nor are defined in the UEFI specification (see tables 107 and 108 in version 2.8).
KeyForgetThreshold
Type: plist integer
Failsafe: 0
Description: Treat duplicate key presses as held keys if they arrive during this timeout, in 10 ms units. Only
applies to systems using KeySupport.
AppleKeyMapAggregator protocol is supposed to contain a fixed length buffer of currently pressed keys. However, the majority of the drivers which require KeySupport report key presses as interrupts, with automatically generated key repeat behaviour with some defined initial and subsequent delay. As a result, to emulate the raw key behaviour required by several Apple boot systems, we use a timeout to merge multiple repeated keys which are submitted within a small timeout window.
This option allows setting this timeout based on the platform. The recommended value for the majority of platforms is from 5 (50 milliseconds) to 7 (70 milliseconds), although values up to 9 (90 milliseconds) have been observed to be required on some PS/2 systems. For reference, holding a key on VMware will repeat roughly every 20 milliseconds and the equivalent value for APTIO V is 30-40 milliseconds. KeyForgetThreshold should be configured to be longer than this. Thus, it is possible to configure a lower KeyForgetThreshold value on platforms with a faster native driver key repeat rate, for more responsive input, and it is required to set a higher value on slower platforms.
Pressing keys one after the other results in delays of at least 60 and 100 milliseconds for the same platforms. Ideally, KeyForgetThreshold should remain lower than this value, to avoid merging real key presses.
Tuning the value of KeyForgetThreshold is necessary for accurate and responsive keyboard input on systems on which KeySupport is enabled, and it is recommended to follow the instructions below to tune it correctly for your system.
Note 1: To tune KeyForgetThreshold, you may use the ‘set default’ indicator within either OpenCanopy or the builtin picker. If KeyForgetThreshold is too low then the ‘set default’ indicator will continue to flicker while CTRL or =/+ is held down. You should configure the lowest value which avoids this flicker. On some systems (e.g. Aptio IV and potentially other systems using AMI KeySupport mode) you will be able to find a minimum KeyForgetThreshold value at which the ‘set default’ indicator goes on and stays on with no flicker at all - if so, use this value. On most other systems using KeySupport, you will find that the ‘set default’ indicator will flicker once, when first pressing and holding the CTRL or =/+ key, and then after a further very brief interval will go on and stay on. On such systems, you should chose the lowest value of KeyForgetThreshold at which you see only one initial flicker and then no subsequent flickering. (Where this happens, it is an unavoidable artefect on those systems of using KeySupport to emulate raw keyboard data, which is not made available by UEFI.)
Note 2: KeyForgetThreshold should never need to be more than about 9 or 10 at most. If it is set to a value much higher than this, it will result in noticeably unresponsive keyboard input. Therefore, for overall key responsiveness, it is strongly recommended to configure a relatively lower value, at which the ‘set default’ indicator flickers once and then does not flicker, rather than using a much higher value (i.e. significantly greater than 10), which you may be able to find but should not use, where the ‘set default’ indicator does not flicker at all.
KeySupport
Type: plist boolean
Failsafe: false
Description: Enable internal keyboard input translation to AppleKeyMapAggregator protocol.
This option activates the internal keyboard interceptor driver, based on AppleGenericInput, also known as AptioInputFix, to fill the AppleKeyMapAggregator database for input functioning. In cases where a separate driver such as OpenUsbKbDxe is used, this option should never be enabled. Additionally, this option is not required and should not be enabled with Apple firmware.
KeySupportMode
Type: plist string
Failsafe: Auto
Description: Set internal keyboard input translation to AppleKeyMapAggregator protocol mode.
Note: Currently V1, V2, and AMI unlike Auto only do filtering of the particular specified protocol. This may change in the future versions.
KeySwap
Type: plist boolean
Failsafe: false
Description: Swap Command and Option keys during submission.
This option may be useful for keyboard layouts with Option key situated to the right of Command key.
PointerSupport
Type: plist boolean
Failsafe: false
Description: Enable internal pointer driver.
This option implements standard UEFI pointer protocol (EFI_SIMPLE_POINTER_PROTOCOL) through certain OEM protocols. The option may be useful on Z87 ASUS boards, where EFI_SIMPLE_POINTER_PROTOCOL is defective.
PointerSupportMode
Type: plist string
Failsafe: Empty
Description: Set OEM protocol used for internal pointer driver.
Currently the only supported variant is ASUS, using specialised protocol available on certain Z87 and Z97 ASUS boards. More details can be found in LongSoft/UefiTool#116. The value of this property cannot be empty if PointerSupport is enabled.
TimerResolution
Type: plist integer
Failsafe: 0
Description: Set architecture timer resolution.
This option allows updating the firmware architecture timer period with the specified value in 100 nanosecond units. Setting a lower value typically improves performance and responsiveness of the interface and input handling.
The recommended value is 50000 (5 milliseconds) or slightly higher. Select ASUS Z87 boards use 60000 for the interface. Apple boards use 100000. In case of issues, this option can be left as 0 to not change the timer resolution.
ClearScreenOnModeSwitch
Type: plist boolean
Failsafe: false
Description: Some types of firmware only clear part of the screen when switching from graphics to text mode,
leaving a fragment of previously drawn images visible. This option fills the entire graphics screen with black
colour before switching to text mode.
Note: This option only applies to System renderer.
ConsoleFont
Type: plist string
Failsafe: Empty (use OpenCore builtin console font)
Description: Specify the console font to use for OpenCore Builtin text renderer.
The font file must be located in EFI/OC/Resources/Font/{font-name}.hex and must be 8x16 resolution. Various console fonts can be found online in either .bdf or .hex format. .bdf can be converted to .hex format using gbdfed (available for Linux or macOS).
There is often no need to change console font, the main use-case being to provide an extended character set for those relatively rare EFI applications which have multi-lingual support (e.g. memtest86).
The OcBinaryData repository includes:
Terminus and TerminusCore are provided under the SIL Open Font License, Version 1.1. Some additional GPL licensed fonts from the EPTO Fonts library, converted to the required .hex format, can be found here.
Note 1: On many newer systems the System text renderer already provides a full set of international characters, in which case this can be used without requiring the Builtin renderer and a custom font.
Note 2: This option only affects the Builtin text renderer and only takes effect from the point at which the Builtin renderer is configured. When console output is visible before this point, it is using the system console font.
ConsoleMode
Type: plist string
Failsafe: Empty (Maintain current console mode)
Description: Sets console output mode as specified with the WxH (e.g. 80x24) formatted string.
Set to Max to attempt using the largest available console mode.
Note: This field is best left empty on most types of firmware.
DirectGopRendering
Type: plist boolean
Failsafe: false
Description: Use builtin graphics output protocol renderer for console.
On certain firmware, such as on the MacPro5,1, this may provide better performance or fix rendering issues. However, this option is not recommended unless there is an obvious benefit as it may result in issues such as slower scrolling.
This renderer fully supports AppleEg2Info protocol and will provide screen rotation for all EFI applications. In order to provide seamless rotation compatibility with EfiBoot, builtin AppleFramebufferInfo should also be used, i.e. it may need to be overridden on Mac EFI.
ForceResolution
Type: plist boolean
Failsafe: false
Description: Forces Resolution to be set in cases where the desired resolution is not available by default, such as on
legacy Intel GMA and first generation Intel HD Graphics (Ironlake/Arrandale). Setting Resolution to Max will try to
pull the largest available resolution from the connected display’s EDID.
Note: This option depends on the OC_FORCE_RESOLUTION_PROTOCOL protocol being present. This protocol is currently only supported by OpenDuetPkg. The OpenDuetPkg implementation currently only supports Intel iGPUs and certain ATI GPUs.
GopBurstMode
Type: plist boolean
Failsafe: false
Description: Enable write-combining (WC) caching for GOP memory, if system firmware has not already enabled
it.
Some older firmware (e.g. EFI-era Macs) fails to set write-combining caching (aka burst mode) for GOP memory, even though the CPU supports it. Setting this can give a considerable speed-up for GOP operations, especially on systems which require DirectGopRendering.
Note 1: This quirk takes effect whether or not DirectGopRendering is set, and in some cases may give a noticeable speed-up to GOP operations even when DirectGopRendering is false.
Note 2: On most systems from circa 2013 onwards, write-combining caching is already applied by the firmware to GOP memory, in which case GopBurstMode is unnecessary. On such systems enabling the quirk should normally be harmless, producing an OCC: debug log entry indicating that burst mode is already started.
Note 3: Some caution should be taken when enabling this quirk, as it has been observed to cause hangs on a few systems. Since additional guards have been added to try to prevent this, please log a bugtracker issue if such a system is found.
GopPassThrough
Type: plist string
Failsafe: Disabled
Description: Provide GOP protocol instances on top of UGA protocol instances.
This option provides the GOP protocol via a UGA-based proxy for firmware that do not implement the protocol. The supported values for the option are as follows:
Note: This option requires ProvideConsoleGop to be enabled.
IgnoreTextInGraphics
Type: plist boolean
Failsafe: false
Description: Some types of firmware output text onscreen in both graphics and text mode. This is typically unexpected
as random text may appear over graphical images and cause UI corruption. Setting this option to true will discard all
text output if console control is not in Text mode.
Note: This option only applies to the System renderer.
InitialMode
Type: plist string
Failsafe: Auto
Description: Selects the internal ConsoleControl mode in which TextRenderer will operate.
Available values are Auto, Text and Graphics. Text and Graphics specify the named mode. Auto uses the current mode of the system ConsoleControl protocol when one exists, defaulting to Text mode otherwise.
UEFI firmware typically supports ConsoleControl with two rendering modes: Graphics and Text. Some types of firmware do not provide a native ConsoleControl and rendering modes. OpenCore and macOS expect text to only be shown in Text mode but graphics to be drawn in any mode, and this is how the OpenCore Builtin renderer behaves. Since this is not required by the UEFI specification, behaviour of the system ConsoleControl protocol, when it exists, may vary.
ProvideConsoleGop
Type: plist boolean
Failsafe: false
Description: Ensure GOP (Graphics Output Protocol) on console handle.
macOS bootloader requires GOP or UGA (for 10.4 EfiBoot) to be present on console handle, yet the exact location of the graphics protocol is not covered by the UEFI specification. This option will ensure GOP and UGA, if present, are available on the console handle.
Note: This option will also replace incompatible implementations of GOP on the console handle, as may be the case on the MacPro5,1 when using modern GPUs.
ReconnectGraphicsOnConnect
Type: plist boolean
Failsafe: false
Description: Reconnect all graphics drivers during driver connection.
On certain firmware, it may be desireable to use an alternative graphics driver, for example BiosVideo.efi, providing better screen resolution options on legacy machines, or a driver supporting ForceResolution. This option attempts to disconnect all currently connected graphics drivers before connecting newly loaded drivers.
Note: This option requires ConnectDrivers to be enabled.
ReconnectOnResChange
Type: plist boolean
Failsafe: false
Description: Reconnect console controllers after changing screen resolution.
On certain firmware, the controllers that produce the console protocols (simple text out) must be reconnected when the screen resolution is changed via GOP. Otherwise, they will not produce text based on the new resolution.
Note: On several boards this logic may result in black screen when launching OpenCore from Shell and thus it is optional. In versions prior to 0.5.2 this option was mandatory and not configurable. Please do not use this unless required.
ReplaceTabWithSpace
Type: plist boolean
Failsafe: false
Description: Some types of firmware do not print tab characters or everything that follows them, causing difficulties in
using the UEFI Shell’s builtin text editor to edit property lists and other documents. This option makes the console
output spaces instead of tabs.
Note: This option only applies to System renderer.
Resolution
Type: plist string
Failsafe: Empty (Maintain current screen resolution)
Description: Sets console output screen resolution.
On HiDPI screens APPLE_VENDOR_VARIABLE_GUID UIScale NVRAM variable may need to be set to 02 to enable HiDPI scaling in Builtin text renderer, FileVault 2 UEFI password interface, and boot screen logo. Refer to the Recommended Variables section for details.
Note: This will fail when console handle has no GOP protocol. When the firmware does not provide it, it can be added with ProvideConsoleGop set to true.
SanitiseClearScreen
Type: plist boolean
Failsafe: false
Description: Some types of firmware reset screen resolutions to a failsafe value (such as 1024x768) on the
attempts to clear screen contents when large display (e.g. 2K or 4K) is used. This option attempts to apply a
workaround.
Note: This option only applies to the System renderer. On all known affected systems, ConsoleMode must be set to an empty string for this option to work.
TextRenderer
Type: plist string
Failsafe: BuiltinGraphics
Description: Chooses renderer for text going through standard console output.
Currently two renderers are supported: Builtin and System. The System renderer uses firmware services for text rendering, however with additional options provided to sanitize the output. The Builtin renderer bypasses firmware services and performs text rendering on its own. Each renderer supports a different set of options. It is recommended to use the Builtin renderer, as it supports HiDPI mode and uses full screen resolution.
Each renderer provides its own ConsoleControl protocol (in the case of SystemGeneric only, this passes some operations through to the system ConsoleControl protocol, if one exists).
Valid values of this option are combinations of the renderer to use and the ConsoleControl mode to set on the underlying system ConsoleControl protocol before starting. To control the initial mode of the provided ConsoleControl protocol once started, use the InitialMode option.
The use of BuiltinGraphics is straightforward. For most platforms, it is necessary to enable ProvideConsoleGop and set Resolution to Max. The BuiltinText variant is an alternative to BuiltinGraphics for some very old and defective laptop firmware, which can only draw in Text mode.
The use of System protocols is more complicated. Typically, the preferred setting is SystemGraphics or SystemText. Enabling ProvideConsoleGop, setting Resolution to Max, enabling ReplaceTabWithSpace is useful on almost all platforms. SanitiseClearScreen, IgnoreTextInGraphics, and ClearScreenOnModeSwitch are more specific, and their use depends on the firmware.
Note: Some Macs, such as the MacPro5,1, may have incompatible console output when using modern GPUs, and thus only BuiltinGraphics may work for them in such cases. NVIDIA GPUs may require additional firmware upgrades.
UIScale
Type: plist integer, 8 bit
Failsafe: -1
Description: User interface scaling factor.
Corresponds to 4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14:UIScale variable.
Note 1: Automatic scale factor detection works on the basis of total pixel area and may fail on small HiDPI displays, in which case the value may be manually managed using the NVRAM section.
Note 2: When switching from manually specified NVRAM variable to this preference an NVRAM reset may be needed.
UgaPassThrough
Type: plist boolean
Failsafe: false
Description: Provide UGA protocol instances on top of GOP protocol instances.
Some types of firmware do not implement the legacy UGA protocol but this may be required for screen output by older EFI applications such as EfiBoot from 10.4.
AppleAudio
Type: plist boolean
Failsafe: false
Description: Replaces Apple audio protocols with builtin versions.
Apple audio protocols allow OpenCore and the macOS bootloader to play sounds and signals for screen reading or audible error reporting. Supported protocols are beep generation and VoiceOver. The VoiceOver protocol is only provided natively by Gibraltar machines (T2), however versions of macOS which support VoiceOver will see and use the implementation provided by OpenCore, on screens such as FileVault 2 unlock. VoiceOver is not supported before macOS High Sierra (10.13). Older macOS versions use the AppleHDA protocol (which is not currently implemented) instead.
Only one set of audio protocols can be available at a time, so this setting should be enabled in order to enable audio playback in the OpenCore user interface on Mac systems implementing some of these protocols.
Note: The backend audio driver needs to be configured in UEFI Audio section for these protocols to be able to stream audio.
AppleBootPolicy
Type: plist boolean
Failsafe: false
Description: Replaces the Apple Boot Policy protocol with a builtin version. This may be used to ensure APFS
compatibility on VMs and legacy Macs.
Note: This option is advisable on certain Macs, such as the MacPro5,1, that are APFS compatible but on which the Apple Boot Policy protocol has recovery detection issues.
AppleEg2Info
Type: plist boolean
Failsafe: false
Description: Replaces the Apple EFI Graphics 2 protocol with a builtin version.
Note 1: This protocol allows newer EfiBoot versions (at least 10.15) to expose screen rotation to macOS. Refer to ForceDisplayRotationInEFI variable description on how to set screen rotation angle.
Note 2: On systems without native support for ForceDisplayRotationInEFI, DirectGopRendering=true is also required for this setting to have an effect.
AppleFramebufferInfo
Type: plist boolean
Failsafe: false
Description: Replaces the Apple Framebuffer Info protocol with a builtin version. This may be used to override
framebuffer information on VMs and legacy Macs to improve compatibility with legacy EfiBoot such as the one
in Mac OS X 10.4.
Note: The current implementation of this property results in it only being active when GOP is available (it is always equivalent to false otherwise).
AppleRtcRam
Type: plist boolean
Failsafe: false
Description: Replaces the Apple RTC RAM protocol with a builtin version.
Note: Builtin version of Apple RTC RAM protocol may filter out I/O attempts to certain RTC memory addresses. The list of addresses can be specified in 4D1FDA02-38C7-4A6A-9CC6-4BCCA8B30102:rtc-blacklist variable as a data array.
AppleSmcIo
Type: plist boolean
Failsafe: false
Description: Replaces the Apple SMC I/O protocol with a builtin version.
This protocol replaces the legacy VirtualSmc UEFI driver, and is compatible with any SMC kernel extension. However, in case the FakeSMC kernel extension is used, manual NVRAM key variable addition may be needed.
DataHub
Type: plist boolean
Failsafe: false
Description: Replaces the Data Hub protocol with a builtin version.
Note: This will discard all previous entries if the protocol was already installed, so all properties required for the safe operation of the system must be specified in the configuration file.
DeviceProperties
Type: plist boolean
Failsafe: false
Description: Replaces the Device Property protocol with a builtin version. This may be used to ensure full
compatibility on VMs and legacy Macs.
Note: This will discard all previous entries if the protocol was already installed, so all properties required for safe operation of the system must be specified in the configuration file.
FirmwareVolume
Type: plist boolean
Failsafe: false
Description: Wraps Firmware Volume protocols, or installs a new version, to support custom cursor images for
FileVault 2. Set to true to ensure FileVault 2 compatibility on anything other than on VMs and legacy Macs.
Note: Several virtual machines, including VMware, may have corrupted cursor images in HiDPI mode and thus, may also require enabling this setting.
ActivateHpetSupport
Type: plist boolean
Failsafe: false
Description: Activates HPET support.
Older boards like ICH6 may not always have HPET setting in the firmware preferences, this option tries to force enable it.
DisableSecurityPolicy
Type: plist boolean
Failsafe: false
Description: Disable platform security policy.
Note: This setting disables various security features of the firmware, defeating the purpose of any kind of Secure Boot. Do NOT enable if using UEFI Secure Boot.
EnableVectorAcceleration
Type: plist boolean
Failsafe: false
Description: Enable AVX vector acceleration of SHA-512 and SHA-384 hashing algorithms.
Note: This option may cause issues on certain laptop firmwares, including Lenovo.
EnableVmx
Type: plist boolean
Failsafe: false
Description: Enable Intel virtual machine extensions.
Note: Required to allow virtualization in Windows on some Mac hardware. VMX is enabled or disabled and locked by BIOS before OpenCore starts on most firmware. Use BIOS to enable virtualization where possible.
ExitBootServicesDelay
Type: plist integer
Failsafe: 0
Description: Adds delay in microseconds after EXIT_BOOT_SERVICES event.
This is a very rough workaround to circumvent the Still waiting for root device message on some APTIO IV firmware (ASUS Z87-Pro) particularly when using FileVault 2. It appears that for some reason, they execute code in parallel to EXIT_BOOT_SERVICES, which results in the SATA controller being inaccessible from macOS. A better approach is required and Acidanthera is open to suggestions. Expect 3 to 5 seconds to be adequate when this quirk is needed.
ForceOcWriteFlash
Type: plist boolean
Failsafe: false
Description: Enables writing to flash memory for all OpenCore-managed NVRAM system variables.
Note: This value should be disabled on most types of firmware but is left configurable to account for firmware that may have issues with volatile variable storage overflows or similar. Boot issues across multiple OSes can be observed on e.g. Lenovo Thinkpad T430 and T530 without this quirk. Apple variables related to Secure Boot and hibernation are exempt from this for security reasons. Furthermore, some OpenCore variables are exempt for different reasons, such as the boot log due to an available user option, and the TSC frequency due to timing issues. When toggling this option, a NVRAM reset may be required to ensure full functionality.
ForgeUefiSupport
Type: plist boolean
Failsafe: false
Description: Implement partial UEFI 2.x support on EFI 1.x firmware.
This setting allows running some software written for UEFI 2.x firmware, such as NVIDIA GOP Option ROMs, on hardware with older EFI 1.x firmware (e.g. MacPro5,1).
IgnoreInvalidFlexRatio
Type: plist boolean
Failsafe: false
Description: Some types of firmware (such as APTIO IV) may contain invalid values in the MSR_FLEX_RATIO
(0x194) MSR register. These values may cause macOS boot failures on Intel platforms.
Note: While the option is not expected to harm unaffected firmware, its use is recommended only when specifically required.
ReloadOptionRoms
Type: plist boolean
Failsafe: false
Description: Query PCI devices and reload their Option ROMs if available.
For example, this option allows reloading NVIDIA GOP Option ROM on older Macs after the firmware version is upgraded via ForgeUefiSupport.
RequestBootVarRouting
Type: plist boolean
Failsafe: false
Description: Request redirect of all Boot prefixed variables from EFI_GLOBAL_VARIABLE_GUID to
OC_VENDOR_VARIABLE_GUID.
This quirk requires OC_FIRMWARE_RUNTIME protocol implemented in OpenRuntime.efi. The quirk lets default boot entry preservation at times when the firmware deletes incompatible boot entries. In summary, this quirk is required to reliably use the Startup Disk preference pane in firmware that is not compatible with macOS boot entries by design.
By redirecting Boot prefixed variables to a separate GUID namespace with the help of RequestBootVarRouting quirk we achieve multiple goals:
ResizeGpuBars
Type: plist integer
Failsafe: -1
Description: Configure GPU PCI BAR sizes.
This quirk sets GPU PCI BAR sizes as specified or chooses the largest available below the ResizeGpuBars value. The specified value follows PCI Resizable BAR spec. Use 0 for 1 MB, 1 for 2 MB, 2 for 4 MB, and so on up to 19 for 512 GB.
Resizable BAR technology allows to ease PCI device programming by mapping a configurable memory region, BAR, into CPU address space (e.g. VRAM to RAM) as opposed to a fixed memory region. This technology is necessary, because one cannot map the largest memory region by default, for the reasons of backwards compatibility with older hardware not supporting 64-bit BARs. Consequentially devices of the last decade use BARs up to 256 MB by default (4 remaining bits are used by other data) but generally allow resizing them to both smaller and larger powers of two (e.g. from 1 MB up to VRAM size).
Operating systems targeting x86 platforms generally do not control PCI address space, letting UEFI firmware decide on the BAR addresses and sizes. This illicit practice resulted in Resizable BAR technology being unused up until 2020 despite being standardised in 2008 and becoming widely available in the hardware soon after.
Modern UEFI firmware allow the use of Resizable BAR technology but generally restrict the configurable options to failsafe default (OFF) and maximum available (ON). This quirk allows to fine-tune this value for testing and development purposes.
Consider a GPU with 2 BARs:
Example 1: Setting ResizeGpuBars to 1 GB will change BAR0 to 1 GB and leave BAR1 unchanged.
Example 2: Setting ResizeGpuBars to 1 MB will change BAR0 to 256 MB and BAR0 to 2 MB.
Example 3: Setting ResizeGpuBars to 16 GB will change BAR0 to 8 GB and leave BAR1 unchanged.
Note 1: This quirk shall not be used to workaround macOS limitation to address BARs over 1 GB. ResizeAppleGpuBars should be used instead.
Note 2: While this quirk can increase GPU PCI BAR sizes, this will not work on most firmware as is, because the quirk does not relocate BARs in memory, and they will likely overlap. In most cases it is best to either update the firmware to the latest version or customise it with a specialised driver like ReBarUEFI.
ResizeUsePciRbIo
Type: plist boolean
Failsafe: false
Description: Use PciRootBridgeIo for ResizeGpuBars and ResizeAppleGpuBars
The quirk makes ResizeGpuBars and ResizeAppleGpuBars use PciRootBridgeIo instead of PciIo. This is needed on systems with a buggy PciIo implementation where trying to configure Resizable BAR results in Capability I/O Error. Typically this is required on older systems which have been modified with ReBarUEFI.
ShimRetainProtocol
Type: plist boolean
Failsafe: false
Description: Request Linux Shim to keep protocol installed for subsequent image loads.
This option is only required if chaining OpenCore from Shim. It must be set in order to allow OpenCore to launch items which are verified by certificates present in Shim, but not in the system Secure Boot database.
TscSyncTimeout
Type: plist integer
Failsafe: 0
Description: Attempts to perform TSC synchronisation with a specified timeout.
The primary purpose of this quirk is to enable early bootstrap TSC synchronisation on some server and laptop models when running a debug XNU kernel. For the debug kernel the TSC needs to be kept in sync across the cores before any kext could kick in rendering all other solutions problematic. The timeout is specified in microseconds and depends on the amount of cores present on the platform, the recommended starting value is 500000.
This is an experimental quirk, which should only be used for the aforementioned problem. In all other cases, the quirk may render the operating system unstable and is not recommended. The recommended solution in the other cases is to install a kernel extension such as VoodooTSCSync, TSCAdjustReset, or CpuTscSync (a more specialised variant of VoodooTSCSync for newer laptops).
Note: This quirk cannot replace the kernel extension because it cannot operate in ACPI S3 (sleep wake) mode and because the UEFI firmware only provides very limited multicore support which prevents precise updates of the MSR registers.
UnblockFsConnect
Type: plist boolean
Failsafe: false
Description: Some types of firmware block partition handles by opening them in By Driver mode, resulting in an
inability to install File System protocols.
Note: This quirk is useful in cases where unsuccessful drive detection results in an absence of boot entries.
Address
Type: plist integer
Failsafe: 0
Description: Start address of the reserved memory region, which should be allocated as reserved effectively
marking the memory of this type inaccessible to the operating system.
The addresses written here must be part of the memory map, have a EfiConventionalMemory type, and be page-aligned (4 KBs).
Note: Some types of firmware may not allocate memory areas used by S3 (sleep) and S4 (hibernation) code unless CSM is enabled causing wake failures. After comparing the memory maps with CSM disabled and enabled, these areas can be found in the lower memory and can be fixed up by doing the reservation. Refer to the Sample.plist file for details.
Type
Type: plist string
Failsafe: Reserved
Description: Memory region type matching the UEFI specification memory descriptor types. Mapping:
Older operating systems may be more complicated to install, but are sometimes necessary for various reasons. While a compatible board identifier and CPUID are the obvious requirements for proper functioning of an older operating system, there are many other less obvious things to consider. This section covers a common set of issues relevant to installing older macOS operating systems.
While newer operating systems can be downloaded over the internet, older operating systems did not have installation media for every minor release. For compatible distributions of such, download a device-specific image and modify it if necessary. Visit this archived Apple Support article for a list of the bundled device-specific builds for legacy operating systems. However, as this may not always be accurate, the latest versions are listed below.
Model checking may also be erased by editing OSInstall.mpkg with e.g. Flat Package Editor by making Distribution script to always return true in hwbeModelCheck function. Since updating the only file in the image and not corrupting other files can be difficult and may cause slow booting due to kernel cache date changes, it is recommended to script image rebuilding as shown below:
#!/bin/bash # Original.dmg is original image, OSInstall.mpkg is patched package mkdir RO hdiutil mount Original.dmg -noverify -noautoopen -noautoopenrw -noautofsck -mountpoint RO cp RO/.DS_Store DS_STORE hdiutil detach RO -force rm -rf RO hdiutil convert Original.dmg -format UDRW -o ReadWrite.dmg mkdir RW xattr -c OSInstall.mpkg hdiutil mount ReadWrite.dmg -noverify -noautoopen -noautoopenrw -noautofsck -mountpoint RW cp OSInstall.mpkg RW/System/Installation/Packages/OSInstall.mpkg killall Finder fseventsd rm -rf RW/.fseventsd cp DS_STORE RW/.DS_Store hdiutil detach RW -force rm -rf DS_STORE RW hdiutil convert ReadWrite.dmg -format UDZO -o ReadOnly.dmg
OpenCore is designed to provide a secure boot chain between firmware and operating system. On most x86 platforms trusted loading is implemented via UEFI Secure Boot model. Not only OpenCore fully supports this model, but it also extends its capabilities to ensure sealed configuration via vaulting and provide trusted loading to the operating systems using custom verification, such as Apple Secure Boot. Proper secure boot chain requires several steps and careful configuration of certain settings as explained below:
Can I install Windows?
While no official Windows support is provided, 64-bit UEFI Windows installations (Windows 8 and above) prepared with Boot Camp are supposed to work. Third-party UEFI installations as well as systems partially supporting UEFI boot, such as Windows 7, might work with some extra precautions. Things to consider:
What additional software do I need?
To enable operating system switching and install relevant drivers in the majority of cases Windows support software from Boot Camp is required. For simplicity of the download process or when configuring an already installed Windows version a third-party utility, Brigadier, can be used successfully. Note, that 7-Zip may be downloaded and installed prior to using Brigadier.
Remember to always use the latest version of Windows support software from Boot Camp, as versions prior to 6.1 do not support APFS, and thus will not function correctly. To download newest software pass most recent Mac model to Brigadier, for example ./brigadier.exe -m iMac19,1. To install Boot Camp on an unsupported Mac model afterwards run PowerShell as Administrator and enter msiexec /i BootCamp.msi. If there is a previous version of Boot Camp installed it should be removed first by running msiexec /x BootCamp.msi command. BootCamp.msi file is located in BootCamp/Drivers/Apple directory and can be reached through Windows Explorer.
While Windows support software from Boot Camp solves most of compatibility problems, the rest may still have to be addressed manually:
Why do I see Basic data partition in the Boot Camp Startup Disk control panel?
The Boot Camp control panel uses the GPT partition table to obtain each boot option name. After installing Windows separately, the partition has to be relabelled manually. This can be done with many utilities including the open-source gdisk utility. Reference example:
PS C:\gdisk> .\gdisk64.exe \\.\physicaldrive0 GPT fdisk (gdisk) version 1.0.4 Command (? for help): p Disk \\.\physicaldrive0: 419430400 sectors, 200.0 GiB Sector size (logical): 512 bytes Disk identifier (GUID): DEC57EB1-B3B5-49B2-95F5-3B8C4D3E4E12 Partition table holds up to 128 entries Main partition table begins at sector 2 and ends at sector 33 First usable sector is 34, last usable sector is 419430366 Partitions will be aligned on 2048-sector boundaries Total free space is 4029 sectors (2.0 MiB) Number Start (sector) End (sector) Size Code Name 1 2048 1023999 499.0 MiB 2700 Basic data partition 2 1024000 1226751 99.0 MiB EF00 EFI system partition 3 1226752 1259519 16.0 MiB 0C01 Microsoft reserved ... 4 1259520 419428351 199.4 GiB 0700 Basic data partition Command (? for help): c Partition number (1-4): 4 Enter name: BOOTCAMP Command (? for help): w Final checks complete. About to write GPT data. THIS WILL OVERWRITE EXISTING PARTITIONS!! Do you want to proceed? (Y/N): Y OK; writing new GUID partition table (GPT) to \\.\physicaldrive0. Disk synchronization succeeded! The computer should now use the new partition table. The operation has completed successfully.
How do I choose Windows BOOTCAMP with custom NTFS drivers?
Third-party drivers providing NTFS support, such as NTFS-3G, Paragon NTFS, Tuxera NTFS or Seagate Paragon Driver disrupt certain macOS functionality, including the Startup Disk preference pane normally used for operating system selection. While the recommended option remains not to use such drivers as they commonly corrupt the filesystem, and prefer the driver bundled with macOS with optional write support ( command or GUI), there still exist vendor-specific workarounds for their products: Tuxera, Paragon, etc.
Similar to other projects working with hardware OpenCore supports auditing and debugging. The use of NOOPT or DEBUG build modes instead of RELEASE can produce a lot more debug output. With NOOPT source level debugging with GDB or IDA Pro is also available. For GDB check OpenCore Debug page. For IDA Pro, version 7.3 or newer is needed, and Debugging the XNU Kernel with IDA Pro may also help.
To obtain the log during boot serial port debugging can be used. Serial port debugging is enabled in Target, e.g. 0xB for onscreen with serial. To initialise serial within OpenCore use Init configuration option under Misc->Serial with other values properly set. For macOS the best choice is CP2102-based UART devices. Connect motherboard TX to USB UART RX, and motherboard GND to USB UART GND. Use screen utility to get the output, or download GUI software, such as CoolTerm.
Note: On several motherboards (and possibly USB UART dongles) PIN naming may be incorrect. It is very common to have GND swapped with RX, thus, motherboard “TX” must be connected to USB UART GND, and motherboard “GND” to USB UART RX.
Remember to enable COM port in firmware settings, and never use USB cables longer than 1 meter to avoid output corruption. To additionally enable XNU kernel serial output debug=0x8 boot argument is needed.
How do I debug boot failures?
Obtaining the actual error message is usually adequate. For this, ensure that:
If there is no obvious error, check the available workarounds in the Quirks sections one by one. For early boot troubleshooting, for instance, when OpenCore menu does not appear, using UEFI Shell (bundled with OpenCore) may help to see early debug messages.
How do I debug macOS boot failures?
How do I customise boot entries?
OpenCore follows standard Apple Bless model and extracts the entry name from .contentDetails and .disk_label.contentDetails files in the booter directory if present. These files contain an ASCII string with an entry title, which may then be customised by the user.
How do I choose the default boot entry?
OpenCore uses the primary UEFI boot option to select the default entry. This choice can be altered from UEFI Setup, with the macOS Startup Disk preference, or the Windows Boot Camp Control Panel. Since choosing OpenCore’s BOOTx64.EFI as a primary boot option limits this functionality in addition to several types of firmware deleting incompatible boot options, potentially including those created by macOS, users are strongly encouraged to use the RequestBootVarRouting quirk, which will preserve the selection made in the operating system within the OpenCore variable space. Note, that RequestBootVarRouting requires a separate driver for functioning.
What is the simplest way to install macOS?
Copy online recovery image (*.dmg and *.chunklist files) to com.apple.recovery.boot directory on a FAT32 partition with OpenCore. Load the OpenCore picker and choose the entry, it will have a (dmg) suffix. Custom name may be created by providing .contentDetails file.
To download recovery online macrecovery.py can be used.
For offline installation refer to How to create a bootable installer for macOS article. Apart from App Store and softwareupdate utility there also are third-party utilities to download an offline image.
Why do online recovery images (*.dmg) fail to load?
This may be caused by missing HFS+ driver, as all presently known recovery volumes have HFS+ filesystem.
Can I use this on Apple hardware or virtual machines?
Yes. Virtual machines and most relatively modern Mac models, as far back as the MacPro3,1, are fully supported. While specific detail relevant to Mac hardware is often limited, some ongoing instructions can be found on MacRumors.com.
Why must Find&Replace patches be equal in size?
For machine code (x86 code) it is not possible to do differently sized replacements due to relative addressing. For ACPI code this is risky, and is technically equivalent to ACPI table replacement, thus not implemented. More detailed explanation can be found on AppleLife.ru or in the ACPI section of this document.
How can I decide which Booter quirks to use?
These quirks originate from AptioMemoryFix driver but provide a wider set of changes specific to modern systems. Note, that OpenRuntime driver is required for most configurations. To get a configuration similar to AptioMemoryFix the following set of quirks should be enabled:
However, as of today, such set is strongly discouraged as some of these quirks are not necessary to be enabled or need additional quirks. For example, DevirtualiseMmio and ProtectUefiServices are often required, while DiscardHibernateMap and ForceExitBootServices are rarely necessary.
Unfortunately for some quirks such as RebuildAppleMemoryMap, EnableWriteUnprotector, ProtectMemoryRegions, SetupVirtualMap, and SyncRuntimePermissions there is no definite approach even on similar systems, so trying all their combinations may be required for optimal setup. Refer to individual quirk descriptions in this document for details.