PIC

OpenCore

Reference Manual (0.7.1)

[2021.06.17]

Copyright ©2018-2021 vit9696

Contents

 1 Introduction
  1.1 Generic Terms
 2 Configuration
  2.1 Configuration Terms
  2.2 Configuration Processing
  2.3 Configuration Structure
 3 Setup
  3.1 Directory Structure
  3.2 Installation and Upgrade
  3.3 Contribution
  3.4 Coding conventions
  3.5 Debugging
 4 ACPI
  4.1 Introduction
  4.2 Properties
  4.3 Add Properties
  4.4 Delete Properties
  4.5 Patch Properties
  4.6 Quirks Properties
 5 Booter
  5.1 Introduction
  5.2 Properties
  5.3 MmioWhitelist Properties
  5.4 Patch Properties
  5.5 Quirks Properties
 6 DeviceProperties
  6.1 Introduction
  6.2 Properties
  6.3 Common Properties
 7 Kernel
  7.1 Introduction
  7.2 Properties
  7.3 Add Properties
  7.4 Block Properties
  7.5 Emulate Properties
  7.6 Force Properties
  7.7 Patch Properties
  7.8 Quirks Properties
  7.9 Scheme Properties
 8 Misc
  8.1 Introduction
  8.2 Properties
  8.3 Boot Properties
  8.4 Debug Properties
  8.5 Security Properties
  8.6 Entry Properties
 9 NVRAM
  9.1 Introduction
  9.2 Properties
  9.3 Mandatory Variables
  9.4 Recommended Variables
  9.5 Other Variables
 10 PlatformInfo
  10.1 Properties
  10.2 Generic Properties
  10.3 DataHub Properties
  10.4 Memory Properties
  10.5 PlatformNVRAM Properties
  10.6 SMBIOS Properties
 11 UEFI
  11.1 Introduction
  11.2 Drivers
  11.3 Tools and Applications
  11.4 OpenCanopy
  11.5 OpenRuntime
  11.6 Properties
  11.7 APFS Properties
  11.8 AppleInput Properties
  11.9 Audio Properties
  11.10 Input Properties
  11.11 Output Properties
  11.12 ProtocolOverrides Properties
  11.13 Quirks Properties
  11.14 ReservedMemory Properties
 12 Troubleshooting
  12.1 Legacy Apple OS
  12.2 UEFI Secure Boot
  12.3 Windows support
  12.4 Debugging
  12.5 Tips and Tricks

1 Introduction

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.

1.1 Generic Terms

2 Configuration

2.1 Configuration Terms

2.2 Configuration Processing

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:

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 tristateFalse (<false/>)


2.3 Configuration Structure

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 nothwithstanding 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.

3 Setup

3.1 Directory Structure

The directory structure was unable to be rendered and was therefore removed.

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.

3.2 Installation and Upgrade

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. For a lightweight cross-platform and open-source alternative, the ProperTree editor can be utilised.

It is strongly advised not to use any software that is aware of the internal configration structure as it constantly gets out of date and will cause incorrect configuration to be generated. If it is a must desprite the warning one should make sure to only use stable versions of OpenCore with explicit support for the particular version in the app. The choice of open-source implementations with transparent binary generation is encouraged (e.g. OCAT), since other tools may contain malware. Remember that a configuration made for a different hardware setup shall never be used on another hardware setup.

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).

3.3 Contribution

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.

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 
git clone --depth=1 https://github.com/acidanthera/OpenCorePkg 
source edksetup.sh 
make -C BaseTools 
build -a X64 -b RELEASE -t XCODE5 -p OpenCorePkg/OpenCorePkg.dsc
Listing 1:Compilation Commands

For IDE usage Xcode projects are available in the root of the repositories. Another approach could be Sublime Text with EasyClangComplete plugin. Add .clang_complete 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
Listing 2:ECC Configuration

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.

3.4 Coding conventions

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.

3.5 Debugging

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.

4 ACPI

4.1 Introduction

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:

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.

4.2 Properties

  1. 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.

  2. 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.

  3. 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.

  4. Quirks
    Type: plist dict
    Description: Apply individual ACPI quirks described in the Quirks Properties section below.

4.3 Add Properties

  1. Comment
    Type: plist string
    Failsafe: Empty
    Description: Arbitrary ASCII string used to provide human readable reference for the entry. Whether this value is used is implementation defined.
  2. Enabled
    Type: plist boolean
    Failsafe: false
    Description: Set to true to add this ACPI table.
  3. 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.

4.4 Delete Properties

  1. All
    Type: plist boolean
    Failsafe: false (Only delete the first matched table)
    Description: Set to true to delete all ACPI tables matching the condition.
  2. Comment
    Type: plist string
    Failsafe: Empty
    Description: Arbitrary ASCII string used to provide human readable reference for the entry. Whether this value is used is implementation defined.
  3. Enabled
    Type: plist boolean
    Failsafe: false
    Description: Set to true to remove this ACPI table.
  4. OemTableId
    Type: plist data, 8 bytes
    Failsafe: All zero (Match any table OEM ID)
    Description: Match table OEM ID equal to this value.
  5. TableLength
    Type: plist integer
    Failsafe: 0 (Match any table size)
    Description: Match table size equal to this value.
  6. 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.

4.5 Patch Properties

  1. 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.

  2. BaseSkip
    Type: plist integer
    Failsafe: 0 (Do not skip any occurrences)
    Description: Number of found Base occurrences to skip before finds and replacements are applied.
  3. Comment
    Type: plist string
    Failsafe: Empty
    Description: Arbitrary ASCII string used to provide human readable reference for the entry. Whether this value is used is implementation defined.
  4. Count
    Type: plist integer
    Failsafe: 0 (Apply patch to all occurrences found)
    Description: Number of occurrences to patch.
  5. Enabled
    Type: plist boolean
    Failsafe: false
    Description: Set to true to apply this ACPI patch.
  6. 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.

  7. Limit
    Type: plist integer
    Failsafe: 0 (Search entire ACPI table)
    Description: Maximum number of bytes to search for.
  8. Mask
    Type: plist data
    Failsafe: Empty (Ignored)
    Description: Data bitwise mask used during find comparison. Allows fuzzy search by ignoring not masked (set to zero) bits. Must be equal to Replace in size if set.
  9. OemTableId
    Type: plist data, 8 bytes
    Failsafe: All zero (Match any table OEM ID)
    Description: Match table OEM ID equal to this value.
  10. Replace
    Type: plist data
    Failsafe: Empty
    Description: Replacement data of one or more bytes.
  11. ReplaceMask
    Type: plist data
    Failsafe: Empty (Ignored)
    Description: Data bitwise mask used during replacement. Allows fuzzy replacement by updating masked (set to non-zero) bits. Must be equal to Replace in size if set.
  12. Skip
    Type: plist integer
    Failsafe: 0 (Do not skip any occurrences)
    Description: Number of found occurrences to skip before replacements are applied.
  13. TableLength
    Type: plist integer
    Failsafe: 0 (Match any table size)
    Description: Match table size equal to this value.
  14. TableSignature
    Type: plist data, 4 bytes
    Failsafe: All zero (Match any table signature)
    Description: Match table signature equal to this value.

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.

4.6 Quirks Properties

  1. 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.

  2. NormalizeHeaders
    Type: plist boolean
    Failsafe: false
    Description: Cleanup ACPI header fields to workaround macOS ACPI implementation flaws that result in boot crashes. Reference: Debugging AppleACPIPlatform on 10.13 by Alex James (also known as theracermaster). The issue was fixed in macOS Mojave (10.14).
  3. 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.

  4. 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.

  5. 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.

  6. 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.

5 Booter

5.1 Introduction

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.

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.

5.2 Properties

  1. MmioWhitelist
    Type: plist array
    Description: To be filled with plist dict values, describing addresses critical for particular firmware functioning when DevirtualiseMmio quirk is in use. Refer to the MmioWhitelist Properties section below for details.
  2. 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.

  3. Quirks
    Type: plist dict
    Description: Apply individual booter quirks described in the Quirks Properties section below.

5.3 MmioWhitelist Properties

  1. 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.

  2. Comment
    Type: plist string
    Failsafe: Empty
    Description: Arbitrary ASCII string used to provide human readable reference for the entry. Whether this value is used is implementation defined.
  3. Enabled
    Type: plist boolean
    Failsafe: false
    Description: Exclude MMIO address from the devirtualisation procedure.

5.4 Patch Properties

  1. Arch
    Type: plist string
    Failsafe: Any (Apply to any supported architecture)
    Description: Booter patch architecture (i386, x86_64).
  2. Comment
    Type: plist string
    Failsafe: Empty
    Description: Arbitrary ASCII string used to provide human readable reference for the entry. Whether this value is used is implementation defined.
  3. Count
    Type: plist integer
    Failsafe: 0 (Apply to all occurrences found)
    Description: Number of patch occurrences to apply.
  4. Enabled
    Type: plist boolean
    Failsafe: false
    Description: Set to true to activate this booter patch.
  5. Find
    Type: plist data
    Failsafe: Empty
    Description: Data to find. Must be equal to Replace in size if set.
  6. Identifier
    Type: plist string
    Failsafe: Any (Match any booter)
    Description: Apple for macOS booter (typically boot.efi); or a name with a suffix, such as bootmgfw.efi, for a specific booter.
  7. Limit
    Type: plist integer
    Failsafe: 0 (Search the entire booter)
    Description: Maximum number of bytes to search for.
  8. Mask
    Type: plist data
    Failsafe: Empty (Ignored)
    Description: Data bitwise mask used during find comparison. Allows fuzzy search by ignoring not masked (set to zero) bits. Must be equal to Find in size if set.
  9. Replace
    Type: plist data
    Failsafe: Empty
    Description: Replacement data of one or more bytes.
  10. ReplaceMask
    Type: plist data
    Failsafe: Empty (Ignored)
    Description: Data bitwise mask used during replacement. Allows fuzzy replacement by updating masked (set to non-zero) bits. Must be equal to Replace in size if set.
  11. Skip
    Type: plist integer
    Failsafe: 0 (Do not skip any occurrences)
    Description: Number of found occurrences to skip before replacements are applied.

5.5 Quirks Properties

  1. 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 requires ProvideCustomSlide to be enabled and typically also requires enabling AvoidRuntimeDefrag 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. EnableWriteUnprotector
    Type: plist boolean
    Failsafe: false
    Description: Permit write access to UEFI runtime services code.

    This option bypasses RX 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.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

    Note: 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.

  14. 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.

  15. 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.

  16. 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 macOS 10.6, and earlier, for reasons that are as yet unclear.

  17. 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.

  18. 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.

  19. 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. Only firmware released after 2017 is typically affected.

6 DeviceProperties

6.1 Introduction

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:

  1. During ACPI table initialisation through the recursive ACPI namespace scanning by the calls to
    AppleACPIPlatformExpert::createDTNubs.
  2. During IOService registration (IOServices::registerService) callbacks implemented as a part of
    AppleACPIPlatformExpert::platformAdjustService function and its private worker method
    AppleACPIPlatformExpert::platformAdjustPCIDevice specific to the PCI devices.

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.

6.2 Properties

  1. 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.

  2. 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.

6.3 Common Properties

Some known properties include:

7 Kernel

7.1 Introduction

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.

7.2 Properties

  1. 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.

  2. 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.

  3. Emulate
    Type: plist dict
    Description: Emulate certain hardware in kernelspace via parameters described in the Emulate Properties section below.
  4. 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.

  5. 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.

  6. Quirks
    Type: plist dict
    Description: Apply individual kernel and driver quirks described in the Quirks Properties section below.
  7. Scheme
    Type: plist dict
    Description: Define kernelspace operation mode via parameters described in the Scheme Properties section below.

7.3 Add Properties

  1. Arch
    Type: plist string
    Failsafe: Any (Apply to any supported architecture)
    Description: Kext architecture (i386, x86_64).
  2. BundlePath
    Type: plist string
    Failsafe: Empty
    Description: Kext bundle path (e.g. Lilu.kext or MyKext.kext/Contents/PlugIns/MySubKext.kext).
  3. Comment
    Type: plist string
    Failsafe: Empty
    Description: Arbitrary ASCII string used to provide human readable reference for the entry. Whether this value is used is implementation defined.
  4. Enabled
    Type: plist boolean
    Failsafe: false
    Description: Set to true to add this kernel extension.
  5. ExecutablePath
    Type: plist string
    Failsafe: Empty
    Description: Kext executable path relative to bundle (e.g. Contents/MacOS/Lilu).
  6. 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 = {
 P arseDarwinV  ersion(MinKernel),               If MinKernel is valid
 0                                            Otherwise
    β = {
 P arseDarwinV  ersion(MaxKernel),               If MaxKernel is valid

 ∞                                            Otherwise
    γ = {
 P arseDarwinV  ersion(FindDarwinV ersion()),    If valid "Darwin Kernel Version" is found
 ∞                                            Otherwise
          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.

  7. 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.

  8. PlistPath
    Type: plist string
    Failsafe: Empty
    Description: Kext Info.plist path relative to bundle (e.g. Contents/Info.plist).

7.4 Block Properties

  1. Arch
    Type: plist string
    Failsafe: Any (Apply to any supported architecture)
    Description: Kext block architecture (i386, x86_64).
  2. Comment
    Type: plist string
    Failsafe: Empty
    Description: Arbitrary ASCII string used to provide human readable reference for the entry. Whether this value is used is implementation defined.
  3. Enabled
    Type: plist boolean
    Failsafe: false
    Description: Set to true to block this kernel extension.
  4. Identifier
    Type: plist string
    Failsafe: Empty
    Description: Kext bundle identifier (e.g. com.apple.driver.AppleTyMCEDriver).
  5. 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.

  6. 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.

7.5 Emulate Properties

  1. 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.

    Note 4: Be aware that the following configurations are unsupported by XCPM (at least out of the box):

  2. 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.

  3. DummyPowerManagement
    Type: plist boolean
    Failsafe: false
    Requirement: 10.4
    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).

  4. 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.

  5. 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.

7.6 Force Properties

  1. Arch
    Type: plist string
    Failsafe: Any (Apply to any supported architecture)
    Description: Kext architecture (i386, x86_64).
  2. BundlePath
    Type: plist string
    Failsafe: Empty
    Description: Kext bundle path (e.g. System\Library \Extensions \IONetworkingFamily.kext).
  3. Comment
    Type: plist string
    Failsafe: Empty
    Description: Arbitrary ASCII string used to provide human readable reference for the entry. Whether this value is used is implementation defined.
  4. Enabled
    Type: plist boolean
    Failsafe: false
    Description: Set to true to load this kernel extension from the system volume when not present in the kernel cache.
  5. ExecutablePath
    Type: plist string
    Failsafe: Empty
    Description: Kext executable path relative to bundle (e.g. Contents/MacOS/IONetworkingFamily).
  6. Identifier
    Type: plist string
    Failsafe: Empty
    Description: Kext identifier to perform presence checking before adding (e.g. com.apple.iokit.IONetworkingFamily). Only drivers which identifiers are not be found in the cache will be added.
  7. 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.

  8. 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.

  9. PlistPath
    Type: plist string
    Failsafe: Empty
    Description: Kext Info.plist path relative to bundle (e.g. Contents/Info.plist).

7.7 Patch Properties

  1. Arch
    Type: plist string
    Failsafe: Any (Apply to any supported architecture)
    Description: Kext patch architecture (i386, x86_64).
  2. Base
    Type: plist string
    Failsafe: Empty (Ignored)
    Description: Selects symbol-matched base for patch lookup (or immediate replacement) by obtaining the address of the provided symbol name.
  3. Comment
    Type: plist string
    Failsafe: Empty
    Description: Arbitrary ASCII string used to provide human readable reference for the entry. Whether this value is used is implementation defined.
  4. Count
    Type: plist integer
    Failsafe: 0
    Description: Number of patch occurrences to apply. 0 applies the patch to all occurrences found.
  5. Enabled
    Type: plist boolean
    Failsafe: false
    Description: This kernel patch will not be used unless set to true.
  6. Find
    Type: plist data
    Failsafe: Empty (Immediate replacement at Base)
    Description: Data to find. Must be equal to Replace in size if set.
  7. Identifier
    Type: plist string
    Failsafe: Empty
    Description: Kext bundle identifier (e.g. com.apple.driver.AppleHDA) or kernel for kernel patch.
  8. Limit
    Type: plist integer
    Failsafe: 0 (Search entire kext or kernel)
    Description: Maximum number of bytes to search for.
  9. Mask
    Type: plist data
    Failsafe: Empty (Ignored)
    Description: Data bitwise mask used during find comparison. Allows fuzzy search by ignoring not masked (set to zero) bits. Must be equal to Replace in size if set.
  10. 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.

  11. 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.

  12. Replace
    Type: plist data
    Failsafe: Empty
    Description: Replacement data of one or more bytes.
  13. ReplaceMask
    Type: plist data
    Failsafe: Empty (Ignored)
    Description: Data bitwise mask used during replacement. Allows fuzzy replacement by updating masked (set to non-zero) bits. Must be equal to Replace in size if set.
  14. Skip
    Type: plist integer
    Failsafe: 0 (Do not skip any occurrences)
    Description: Number of found occurrences to skip before replacements are applied.

7.8 Quirks Properties

  1. 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.

    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:

    1. Download UEFITool and IFR-Extractor.
    2. Open the firmware image in UEFITool and find CFG Lock unicode string. If it is not present, the firmware may not have this option and the process should therefore be discontinued.
    3. Extract the Setup.bin PE32 Image Section (the UEFITool found) through the Extract Body menu option.
    4. Run IFR-Extractor on the extracted file (e.g. ./ifrextract Setup.bin Setup.txt).
    5. Find CFG Lock, VarStoreInfo (VarOffset/VarName): in Setup.txt and remember the offset right after it (e.g. 0x123).
    6. Download and run Modified GRUB Shell compiled by brainsucker or use a newer version by datasone.
    7. Enter setup_var 0x123 0x00 command, where 0x123 should be replaced by the actual offset, and reboot.

    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).

  2. 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.

  3. 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.

  4. 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.

  5. CustomSMBIOSGuid
    Type: plist boolean
    Failsafe: false
    Requirement: 10.4
    Description: Performs GUID patching for UpdateSMBIOSMode Custom mode. Usually relevant for Dell laptops.
  6. 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.

  7. 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.

  8. 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.

  9. ExtendBTFeatureFlags
    Type: plist boolean
    Failsafe: false
    Requirement: 10.8
    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.

  10. 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.

  11. 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.

  12. IncreasePciBarSize
    Type: plist boolean
    Failsafe: false
    Requirement: 10.10
    Description: Increases 32-bit PCI bar size in IOPCIFamily from 1 to 4 GBs.

    Note: This option should be avoided whenever possible. A need for this option indicates misconfigured or defective firmware.

  13. LapicKernelPanic
    Type: plist boolean
    Failsafe: false
    Requirement: 10.6 (64-bit)
    Description: Disables kernel panic on LAPIC interrupts.
  14. LegacyCommpage
    Type: plist boolean
    Failsafe: false
    Requirement: 10.4 - 10.6
    Description: Replaces the default 64-bit commpage bcopy implementation with one that does not require SSSE3, useful for legacy platforms. This prevents a commpage no match for last panic due to no available 64-bit bcopy functions that do not require SSSE3.
  15. PanicNoKextDump
    Type: plist boolean
    Failsafe: false
    Requirement: 10.13 (not required for older)
    Description: Prevent kernel from printing kext dump in the panic log preventing from observing panic details. Affects 10.13 and above.
  16. 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.

  17. ProvideCurrentCpuInfo
    Type: plist boolean
    Failsafe: false
    Requirement: 10.8
    Description: Provides current CPU info to the kernel.

    This quirk currently provides the correct TSC and FSB values to the kernel, as well as disables CPU topology validation.

    Note: These patches currently target Microsoft Hyper-V and may need to be extended for other purposes.

  18. 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. Set this option to a high value, such as 4294967295, to ensure 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 disabled by setting a very low timeout value. e.g. 999. Refer to this article for details.

  19. 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.

  20. 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.

7.9 Scheme Properties

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.

  1. FuzzyMatch
    Type: plist boolean
    Failsafe: false
    Description: Use kernelcache with different checksums when available.

    On macOS 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 macOS 10.6 boot performance on several platforms.

  2. KernelArch
    Type: plist string
    Failsafe: Auto (Choose the preferred architecture automatically)
    Description: Prefer specified kernel architecture (i386, i386-user32, x86_64) when available.

    On macOS 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:

    The algorithm used to determine the preferred kernel architecture is set out below.

    1. arch argument in image arguments (e.g. when launched via UEFI Shell) or in boot-args variable overrides any compatibility checks and forces the specified architecture, completing this algorithm.
    2. OpenCore build architecture restricts capabilities to i386 and i386-user32 mode for the 32-bit firmware variant.
    3. Determined EfiBoot version restricts architecture choice:
      • 10.4-10.5 — i386 or i386-user32 (only on 32-bit firmware)
      • 10.6 — i386, i386-user32, or x86_64
      • 10.7 — i386 or x86_64
      • 10.8 or newer — x86_64
    4. If KernelArch is set to Auto and SSSE3 is not supported by the CPU, capabilities are restricted to i386-user32 if supported by EfiBoot.
    5. Board identifier (from SMBIOS) based on EfiBoot version disables x86_64 support on an unsupported model if any i386 variant is supported. Auto is not consulted here as the list is not overridable in EfiBoot.
    6. KernelArch restricts the support to the explicitly specified architecture (when not set to Auto) if the architecture remains present in the capabilities.
    7. The best supported architecture is chosen in this order: x86_64, i386, i386-user32.

    Unlike macOS 10.7 (where certain board identifiers are treated as the i386 only machines), and macOS 10.5 or earlier (where x86_64 is not supported by the macOS kernel), macOS 10.6 is very special. The architecture choice on macOS 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, OpenCore on macOS 10.6 falls back on the x86_64 architecture whenever it is supported by the board, as it is on macOS 10.7.

    A 64-bit Mac model compatibility matrix corresponding to actual EfiBoot behaviour on macOS 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.

  3. 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 NCi386 MKi386 PKx86_64 NCx86_64 MKx86_64 PKx86_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.

8 Misc

8.1 Introduction

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.

The algorithm to determine boot options behaves as follows:

  1. Obtain all available partition handles filtered based on the Scan policy (and driver availability).
  2. Obtain all available boot options from the BootOrder UEFI variable.
  3. For each boot option found:
  4. For each partition handle:
  5. Custom entries and tools, except such pre-constructed previously, are added as primary options without any checks with respect to Auxiliary.
  6. System entries, such as Reset NVRAM, are added as primary auxiliary options.

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 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.

8.2 Properties

  1. Boot
    Type: plist dict
    Description: Apply the boot configuration described in the Boot Properties section below.
  2. BlessOverride
    Type: plist array
    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.

  3. Debug
    Type: plist dict
    Description: Apply debug configuration described in the Debug Properties section below.
  4. Entries
    Type: plist array
    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.

  5. Security
    Type: plist dict
    Description: Apply the security configuration described in the Security Properties section below.
  6. Tools
    Type: plist array
    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.

8.3 Boot Properties

  1. 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.

  2. 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.

  3. 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.

  4. LauncherOption
    Type: plist string
    Failsafe: Disabled
    Description: Register the launcher option in the firmware preferences for persistence.

    Valid values:

    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.

  5. 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.

  6. 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:

  7. 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.

  8. 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:

  9. ShowPicker
    Type: plist boolean
    Failsafe: false
    Description: Show a simple picker to allow boot entry selection.
  10. 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 some platforms, setting this option to a minimum of 5000-10000 microseconds may be required to access action hotkeys due to the nature of the keyboard driver.

  11. Timeout
    Type: plist integer, 32 bit
    Failsafe: 0
    Description: Timeout in seconds in the OpenCore picker before automatic booting of the default boot entry. Set to 0 to disable.
  12. 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 access the Apple picker. The BootKicker utility can be blessed to workaround this problem even without loading OpenCore. On some Macs however, the BootKicker utility cannot be run from OpenCore.

  13. 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:

8.4 Debug Properties

  1. 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.

  2. 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 | 
      python -c 'import json,sys;print(json.load(sys.stdin)["macOSPanicString"])'
  3. DisableWatchDog
    Type: plist boolean
    Failsafe: false
    Description: Some types of firmware may not succeed in booting the operating system quickly, especially in debug mode. This results in the watchdog timer aborting the process. This option turns off the watchdog timer.
  4. DisplayDelay
    Type: plist integer
    Failsafe: 0
    Description: Delay in microseconds executed after every printed line visible onscreen (i.e. console).
  5. 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):

  6. SerialInit
    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. Serial port configuration is defined via PCDs at compile time in gEfiMdeModulePkgTokenSpaceGuid GUID.

    Default values as found in MdeModulePkg.dec are as follows:

    Refer to the Debugging section for details.

  7. 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.

  8. 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: 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.

    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:

8.5 Security Properties

  1. AllowNvramReset
    Type: plist boolean
    Failsafe: false
    Description: Allow CMD+OPT+P+R handling and enable showing NVRAM Reset entry in OpenCore picker.

    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: Resetting NVRAM will also erase any boot options not backed up using the bless command. For example, Linux installations to custom locations not specified in BlessOverride

  2. 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.

  3. AllowToggleSip
    Type: plist boolean
    Failsafe: false
    Description: Enable entry for disabling and enabling System Integrity Protection in OpenCore picker.

    This will toggle Apple NVRAM variable csr-active-config between 0 for SIP Enabled and a practical default value for SIP Disabled (currently 0x26F).

    Note1: It is strongly recommended not to make a habit of running 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.

    Note2: OC uses 0x26F even though csrutil disable on Big Sur sets 0x7F. To explain the choice:

    Note3: For any other value which you may need to use, it is possible to configure CsrUtil.efi as a TextMode Tools entry to configure a different value, e.g. use toggle 0x6F in Arguments to toggle the SIP disabled value set by default by csrutil disable --no-internal in Big Sur.

  4. 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. Unless the operating system is personalised, macOS DMG recovery cannot 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 bless --folder "/Volumes/Macintosh HD/System/Library/CoreServices" \ 
      --bootefi --personalize

    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
  5. 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.

  6. 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.

  7. DmgLoading
    Type: plist string
    Failsafe: Signed
    Description: Define Disk Image (DMG) loading policy used for macOS Recovery.

    Valid values:

  8. 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.

  9. 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

    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
  10. 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.
  11. PasswordHash
    Type: plist data 64 bytes
    Failsafe: all zero
    Description: Password hash used when EnabledPassword is set.
  12. PasswordSalt
    Type: plist data
    Failsafe: empty
    Description: Password salt used when EnabledPassword is set.
  13. 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: vault.plist and vault.sig are used regardless of this option when vault.plist is present or a public key is embedded into OpenCore.efi. Setting this option will only ensure configuration sanity, and abort the boot process otherwise.

  14. 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:

  15. 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:

    Apple Secure Boot appeared in macOS 10.13 on models with T2 chips. Since PlatformInfo and SecureBootModel are independent, Apple Secure Boot can be used with any SMBIOS with and without T2. 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:

    1. As with T2 Macs, all unsigned kernel extensions as well as several signed kernel extensions, including NVIDIA Web Drivers, cannot be installed.
    2. The list of cached kernel extensions may be different, resulting in a need to change the list of Added or Forced kernel extensions. For example, IO80211Family cannot be injected in this case.
    3. System volume alterations on operating systems with sealing, such as macOS 11, may result in the operating system being unbootable. Do not try to disable system volume encryption unless Apple Secure Boot is disabled.
    4. Boot failures might occur when the platform requires certain settings, but they have not been enabled because the associated issues were not discovered earlier. Be extra careful with IgnoreInvalidFlexRatio or HashServices.
    5. Operating systems released before Apple Secure Boot was released (e.g. macOS 10.12 or earlier), will still boot until UEFI Secure Boot is enabled. This is so because Apple Secure Boot treats these as incompatible and they are then handled by the firmware (as Microsoft Windows is).
    6. On older CPUs (e.g. before Sandy Bridge), enabling Apple Secure Boot might cause slightly slower loading (by up to 1 second).
    7. As the Default value will increase with time to support the latest major released operating system, it is not recommended to use the ApECID and the Default settings together.
    8. Installing macOS with Apple Secure Boot enabled is not possible while using HFS+ target volumes. This may include HFS+ formatted drives when no spare APFS drive is available.

    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.

8.6 Entry Properties

  1. Arguments
    Type: plist string
    Failsafe: Empty
    Description: Arbitrary ASCII string used as boot arguments (load options) of the specified entry.
  2. Auxiliary
    Type: plist boolean
    Failsafe: false
    Description: Set to true to hide this entry when HideAuxiliary is also set to true. Press the Spacebar key to enter “Extended Mode” and display the entry when hidden.
  3. Comment
    Type: plist string
    Failsafe: Empty
    Description: Arbitrary ASCII string used to provide a human readable reference for the entry. Whether this value is used is implementation defined.
  4. Enabled
    Type: plist boolean
    Failsafe: false
    Description: Set to true activate this entry.
  5. Flavour
    Type: plist string
    Failsafe: Auto
    Description: Specify the content flavour for this entry. See OC_ATTR_USE_FLAVOUR_ICON flag for documentation.
  6. Name
    Type: plist string
    Failsafe: Empty
    Description: Human readable entry name displayed in the OpenCore picker.
  7. Path
    Type: plist string
    Failsafe: Empty
    Description: Entry location depending on entry type.
  8. 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 property is only valid for Tools and cannot be specified for Entries (is always true).

  9. 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.

9 NVRAM

9.1 Introduction

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.

  1. Not all tools may be aware of protected namespaces.
    When RequestBootVarRouting is used, Boot-prefixed variable access is restricted and protected in a separate namespace. To access the original variables, tools must be aware of the OC_FIRMWARE_RUNTIME logic.

9.2 Properties

  1. 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.

  2. Delete
    Type: plist dict
    Description: Removes NVRAM variables from a map (plist dict) of GUIDs to an array (plist array) of variable names in plist string format.
  3. LegacyEnable
    Type: plist boolean
    Failsafe: false
    Description: Enables loading a NVRAM variable file named nvram.plist from EFI volume root.

    This file must have a root plist dictionary type and contain two fields:

    Variable loading happens prior to the Delete (and Add) phases. Unless LegacyOverwrite is enabled, it will not overwrite any existing variable. Variables allowed to be set must be specified in LegacySchema.

    Third-party scripts may be used to create nvram.plist file. An example of such script can be found in Utilities. The use of third-party scripts may require ExposeSensitiveData set to 0x3 to provide boot-path variable with the OpenCore EFI partition UUID.

    Warning: This feature 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 is incompatible.

  4. 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.

  5. 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.

  6. 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.

9.3 Mandatory 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:

9.4 Recommended Variables

The following variables are recommended for faster startup or other improvements:

9.5 Other Variables

The following variables may be useful for certain configurations or troubleshooting:

10 PlatformInfo

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.

10.1 Properties

  1. 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.

  2. CustomMemory
    Type: plist boolean
    Failsafe: false
    Description: Use custom memory configuration defined in the Memory section. This completely replaces any existing memory configuration in SMBIOS, and is only active when UpdateSMBIOS is set to true.
  3. 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.

  4. 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.

  5. UpdateSMBIOS
    Type: plist boolean
    Failsafe: false
    Description: Update SMBIOS fields. These fields are read from the Generic or SMBIOS sections depending on the setting of the Automatic property.
  6. 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.

  7. 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.

  8. 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.

  9. 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.

  10. Memory
    Type: plist dictionary
    Description: Define custom memory configuration.

    Note: This section is ignored and may be removed when CustomMemory is false.

  11. 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.

  12. 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.

10.2 Generic Properties

  1. 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.

  2. 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.

  3. MaxBIOSVersion
    Type: plist boolean
    Failsafe: false
    Description: Sets BIOSVersion to 9999.999.999.999.999, recommended for legacy Macs when using Automatic PlatformInfo, to avoid BIOS updates in unofficially supported macOS versions.
  4. 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.

  5. ProcessorType
    Type: plist integer
    Failsafe: 0 (Automatic)
    Description: Refer to SMBIOS ProcessorType.
  6. SystemProductName
    Type: plist string
    Failsafe: Empty (OEM specified or not installed)
    Description: Refer to SMBIOS SystemProductName.
  7. 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.

  8. 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.

  9. 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.

  10. 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.

10.3 DataHub Properties

  1. PlatformName
    Type: plist string
    Failsafe: Empty (Not installed)
    Description: Sets name in gEfiMiscSubClassGuid. The value found on Macs is platform in ASCII.
  2. SystemProductName
    Type: plist string
    Failsafe: Empty (Not installed)
    Description: Sets Model in gEfiMiscSubClassGuid. The value found on Macs is equal to SMBIOS SystemProductName in Unicode.
  3. SystemSerialNumber
    Type: plist string
    Failsafe: Empty (Not installed)
    Description: Sets SystemSerialNumber in gEfiMiscSubClassGuid. The value found on Macs is equal to SMBIOS SystemSerialNumber in Unicode.
  4. SystemUUID
    Type: plist string, GUID
    Failsafe: Empty (Not installed)
    Description: Sets system-id in gEfiMiscSubClassGuid. The value found on Macs is equal to SMBIOS SystemUUID (with swapped byte order).
  5. BoardProduct
    Type: plist string
    Failsafe: Empty (Not installed)
    Description: Sets board-id in gEfiMiscSubClassGuid. The value found on Macs is equal to SMBIOS BoardProduct in ASCII.
  6. BoardRevision
    Type: plist data, 1 byte
    Failsafe: 0
    Description: Sets board-rev in gEfiMiscSubClassGuid. The value found on Macs seems to correspond to internal board revision (e.g. 01).
  7. 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:
  8. InitialTSC
    Type: plist integer, 64-bit
    Failsafe: 0
    Description: Sets InitialTSC in gEfiProcessorSubClassGuid. Sets initial TSC value, normally 0.
  9. 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.

  10. 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.

  11. DevicePathsSupported
    Type: plist integer, 32-bit
    Failsafe: 0 (Not installed)
    Description: Sets DevicePathsSupported in gEfiMiscSubClassGuid. Must be set to 1 for AppleACPIPlatform.kext to append SATA device paths to Boot#### and efi-boot-device-data variables. Set to 1 on all modern Macs.
  12. SmcRevision
    Type: plist data, 6 bytes
    Failsafe: Empty (Not installed)
    Description: Sets REV in gEfiMiscSubClassGuid. Custom property read by VirtualSMC or FakeSMC to generate SMC REV key.
  13. SmcBranch
    Type: plist data, 8 bytes
    Failsafe: Empty (Not installed)
    Description: Sets RBr in gEfiMiscSubClassGuid. Custom property read by VirtualSMC or FakeSMC to generate SMC RBr key.
  14. SmcPlatform
    Type: plist data, 8 bytes
    Failsafe: Empty (Not installed)
    Description: Sets RPlt in gEfiMiscSubClassGuid. Custom property read by VirtualSMC or FakeSMC to generate SMC RPlt key.

10.4 Memory Properties

  1. DataWidth
    Type: plist integer, 16-bit
    Failsafe: 0xFFFF (unknown)
    SMBIOS: Memory Device (Type 17) — Data Width
    Description: Specifies the data width, in bits, of the memory. A DataWidth of 0 and a TotalWidth of 8 indicates that the device is being used solely to provide 8 error-correction bits.
  2. 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.

  3. 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.
  4. 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.

  5. MaxCapacity
    Type: plist integer, 64-bit
    Failsafe: 0
    SMBIOS: Physical Memory Array (Type 16) — Maximum Capacity
    Description: Specifies the maximum amount of memory, in bytes, supported by the system.
  6. TotalWidth
    Type: plist integer, 16-bit
    Failsafe: 0xFFFF (unknown)
    SMBIOS: Memory Device (Type 17) — Total Width
    Description: Specifies the total width, in bits, of the memory, including any check or error-correction bits. If there are no error-correction bits, this value should be equal to DataWidth.
  7. 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.
  8. TypeDetail
    Type: plist integer, 16-bit
    Failsafe: 0x4
    SMBIOS: Memory Device (Type 17) — Type Detail
    Description: Specifies additional memory type information.
10.4.1 Memory Device Properties
  1. AssetTag
    Type: plist string
    Failsafe: Unknown
    SMBIOS: Memory Device (Type 17) — Asset Tag
    Description: Specifies the asset tag of this memory device.
  2. BankLocator
    Type: plist string
    Failsafe: Unknown
    SMBIOS: Memory Device (Type 17) — Bank Locator
    Description: Specifies the physically labeled bank where the memory device is located.
  3. DeviceLocator
    Type: plist string
    Failsafe: Unknown
    SMBIOS: Memory Device (Type 17) — Device Locator
    Description: Specifies the physically-labeled socket or board position where the memory device is located.
  4. 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:

  5. PartNumber
    Type: plist string
    Failsafe: Unknown
    SMBIOS: Memory Device (Type 17) — Part Number
    Description: Specifies the part number of this memory device.
  6. SerialNumber
    Type: plist string
    Failsafe: Unknown
    SMBIOS: Memory Device (Type 17) — Serial Number
    Description: Specifies the serial number of this memory device.
  7. Size
    Type: plist integer, 32-bit
    Failsafe: 0
    SMBIOS: Memory Device (Type 17) — Size
    Description: Specifies the size of the memory device, in megabytes. 0 indicates this slot is not populated.
  8. Speed
    Type: plist integer, 16-bit
    Failsafe: 0
    SMBIOS: Memory Device (Type 17) — Speed
    Description: Specifies the maximum capable speed of the device, in megatransfers per second (MT/s). 0 indicates an unknown speed.

10.5 PlatformNVRAM Properties

  1. BID
    Type: plist string
    Failsafe: Empty (Not installed)
    Description: Specifies the value of NVRAM variable 4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14:HW_BID.
  2. ROM
    Type: plist data, 6 bytes
    Failsafe: Empty (Not installed)
    Description: Specifies the values of NVRAM variables 4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14:HW_ROM and 4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14:ROM.
  3. MLB
    Type: plist string
    Failsafe: Empty (Not installed)
    Description: Specifies the values of NVRAM variables 4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14:HW_MLB and 4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14:MLB.
  4. FirmwareFeatures
    Type: plist data, 8 bytes
    Failsafe: Empty (Not installed)
    Description: This variable comes in pair with FirmwareFeaturesMask. Specifies the values of NVRAM variables:
  5. FirmwareFeaturesMask
    Type: plist data, 8 bytes
    Failsafe: Empty (Not installed)
    Description: This variable comes in pair with FirmwareFeatures. Specifies the values of NVRAM variables:
  6. SystemSerialNumber
    Type: plist string
    Failsafe: Empty (Not installed)
    Description: Specifies the values of NVRAM variables 4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14:HW_SSN and 4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14:SSN.
  7. SystemUUID
    Type: plist string
    Failsafe: Empty (Not installed)
    Description: Specifies the value of NVRAM variable 4D1EDE05-38C7-4A6A-9CC6-4BCCA8B38C14:system-id for boot services only. The value found on Macs is equal to SMBIOS SystemUUID.

10.6 SMBIOS Properties

  1. BIOSVendor
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: BIOS Information (Type 0) — Vendor
    Description: BIOS Vendor. All rules of SystemManufacturer do apply.
  2. 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

  3. BIOSReleaseDate
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: BIOS Information (Type 0) — BIOS Release Date
    Description: Firmware release date. Similar to BIOSVersion. May look like 12/08/2017.
  4. SystemManufacturer
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: System Information (Type 1) — Manufacturer
    Description: OEM manufacturer of the particular board. Use failsafe unless strictly required. Do not override to contain Apple Inc. on non-Apple hardware, as this confuses numerous services present in the operating system, such as firmware updates, eficheck, as well as kernel extensions developed in Acidanthera, such as Lilu and its plugins. In addition it will also make some operating systems such as Linux unbootable.
  5. 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.

  6. SystemVersion
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: System Information (Type 1) — Version
    Description: Product iteration version number. May look like 1.1.
  7. SystemSerialNumber
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: System Information (Type 1) — Serial Number
    Description: Product serial number in defined format. Known formats are described in macserial.
  8. SystemUUID
    Type: plist string, GUID
    Failsafe: Empty (OEM specified)
    SMBIOS: System Information (Type 1) — UUID
    Description: A UUID is an identifier that is designed to be unique across both time and space. It requires no central registration process.
  9. SystemSKUNumber
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: System Information (Type 1) — SKU Number
    Description: Mac Board ID (board-id). May look like Mac-7BA5B2D9E42DDD94 or Mac-F221BEC8 in older models. Sometimes it can be just empty.
  10. SystemFamily
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: System Information (Type 1) — Family
    Description: Family name. May look like iMac Pro.
  11. BoardManufacturer
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: Baseboard (or Module) Information (Type 2) - Manufacturer
    Description: Board manufacturer. All rules of SystemManufacturer do apply.
  12. BoardProduct
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: Baseboard (or Module) Information (Type 2) - Product
    Description: Mac Board ID (board-id). May look like Mac-7BA5B2D9E42DDD94 or Mac-F221BEC8 in older models.
  13. BoardVersion
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: Baseboard (or Module) Information (Type 2) - Version
    Description: Board version number. Varies, may match SystemProductName or SystemProductVersion.
  14. BoardSerialNumber
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: Baseboard (or Module) Information (Type 2) — Serial Number
    Description: Board serial number in defined format. Known formats are described in macserial.
  15. BoardAssetTag
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: Baseboard (or Module) Information (Type 2) — Asset Tag
    Description: Asset tag number. Varies, may be empty or Type2 - Board Asset Tag.
  16. BoardType
    Type: plist integer
    Failsafe: 0 (OEM specified)
    SMBIOS: Baseboard (or Module) Information (Type 2) — Board Type
    Description: Either 0xA (Motherboard (includes processor, memory, and I/O) or 0xB (Processor/Memory Module). Refer to Table 15 – Baseboard: Board Type for details.
  17. BoardLocationInChassis
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: Baseboard (or Module) Information (Type 2) — Location in Chassis
    Description: Varies, may be empty or Part Component.
  18. ChassisManufacturer
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: System Enclosure or Chassis (Type 3) — Manufacturer
    Description: Board manufacturer. All rules of SystemManufacturer do apply.
  19. ChassisType
    Type: plist integer
    Failsafe: 0 (OEM specified)
    SMBIOS: System Enclosure or Chassis (Type 3) — Type
    Description: Chassis type. Refer to Table 17 — System Enclosure or Chassis Types for details.
  20. ChassisVersion
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: System Enclosure or Chassis (Type 3) — Version
    Description: Should match BoardProduct.
  21. ChassisSerialNumber
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: System Enclosure or Chassis (Type 3) — Version
    Description: Should match SystemSerialNumber.
  22. ChassisAssetTag
    Type: plist string
    Failsafe: Empty (OEM specified)
    SMBIOS: System Enclosure or Chassis (Type 3) — Asset Tag Number
    Description: Chassis type name. Varies, could be empty or MacBook-Aluminum.
  23. PlatformFeature
    Type: plist integer, 32-bit
    Failsafe: 0xFFFFFFFF (OEM specified on Apple hardware, do not provide the table otherwise)
    SMBIOS: APPLE_SMBIOS_TABLE_TYPE133 - PlatformFeature
    Description: Platform features bitmask (Missing on older Macs). Refer to AppleFeatures.h for details.
  24. SmcVersion
    Type: plist data, 16 bytes
    Failsafe: All zero (OEM specified on Apple hardware, do not provide the table otherwise)
    SMBIOS: APPLE_SMBIOS_TABLE_TYPE134 - Version
    Description: ASCII string containing SMC version in upper case. Missing on T2 based Macs.
  25. FirmwareFeatures
    Type: plist data, 8 bytes
    Failsafe: 0 (OEM specified on Apple hardware, 0 otherwise)
    SMBIOS: APPLE_SMBIOS_TABLE_TYPE128 - FirmwareFeatures and ExtendedFirmwareFeatures
    Description: 64-bit firmware features bitmask. Refer to AppleFeatures.h for details. Lower 32 bits match FirmwareFeatures. Upper 64 bits match ExtendedFirmwareFeatures.
  26. FirmwareFeaturesMask
    Type: plist data, 8 bytes
    Failsafe: 0 (OEM specified on Apple hardware, 0 otherwise)
    SMBIOS: APPLE_SMBIOS_TABLE_TYPE128 - FirmwareFeaturesMask and ExtendedFirmwareFeaturesMask
    Description: Supported bits of extended firmware features bitmask. Refer to AppleFeatures.h for details. Lower 32 bits match FirmwareFeaturesMask. Upper 64 bits match ExtendedFirmwareFeaturesMask.
  27. 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.

11 UEFI

11.1 Introduction

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.

11.2 Drivers

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:

AudioDxe*

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.

CrScreenshotDxe*

Screenshot making driver saving images to the root of OpenCore partition (ESP) or any available writeable filesystem upon pressing F10. This is a modified version of CrScreenshotDxe driver by Nikolaj Schlej.

ExFatDxe

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.

HfsPlus

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.

HiiDatabase*

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.

EnhancedFatDxe

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.

NvmExpressDxe*

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.

OpenCanopy*

OpenCore plugin implementing graphical interface.

OpenRuntime*

OpenCore plugin implementing OC_FIRMWARE_RUNTIME protocol.

OpenUsbKbDxe*

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.

OpenPartitionDxe*

Partition management driver with Apple Partitioning Scheme support. This driver can be used to support loading older DMG recoveries such as macOS 10.9 using Apple Partitioning Scheme. OpenDuet already includes this driver.

Ps2KeyboardDxe*

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.

Ps2MouseDxe*

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.

OpenHfsPlus*

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.

UsbMouseDxe*

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.

XhciDxe*

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.

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

11.3 Tools and Applications

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
Listing 3:Blessing tool

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 *):

BootKicker*

Enter Apple BootPicker menu (exclusive for Macs with compatible GPUs).

ChipTune*

Test BeepGen protocol and generate audio signals of different style and length.

CleanNvram*

Reset NVRAM alternative bundled as a standalone tool.

CsrUtil*

Simple implementation of SIP-related features of Apple csrutil.

GopStop*

Test GraphicsOutput protocol with a simple scenario.

KeyTester*

Test keyboard input in SimpleText mode.

MemTest86

Memory testing utility.

OpenControl*

Unlock and lock back NVRAM protection for other tools to be able to get full NVRAM access when launching from OpenCore.

OpenShell*

OpenCore-configured UEFI Shell for compatibility with a broad range of firmware.

PavpProvision

Perform EPID provisioning (requires certificate data configuration).

ResetSystem*

Utility to perform system reset. Takes reset type as an argument: coldreset, firmware, shutdown, warmreset. Defaults to coldreset.

RtcRw*

Utility to read and write RTC (CMOS) memory.

ControlMsrE2*

Check CFG Lock (MSR 0xE2 write protection) consistency across all cores and change such hidden options on selected platforms.

11.4 OpenCanopy

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.

11.5 OpenRuntime

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:

11.6 Properties

  1. APFS
    Type: plist dict
    Failsafe: None
    Description: Provide APFS support as configured in the APFS Properties section below.
  2. Audio
    Type: plist dict
    Failsafe: None
    Description: Configure audio backend support described in the Audio Properties section below.

    Audio support provides a way for upstream protocols to interact with the selected hardware and audio 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.

  3. 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.

  4. Drivers
    Type: plist array
    Failsafe: None
    Description: Load selected drivers from OC/Drivers directory.

    To be filled with string filenames meant to be loaded as UEFI drivers.

  5. Input
    Type: plist dict
    Failsafe: None
    Description: Apply individual settings designed for input (keyboard and mouse) in the Input Properties section below.
  6. Output
    Type: plist dict
    Failsafe: None
    Description: Apply individual settings designed for output (text and graphics) in the Output Properties section below.
  7. ProtocolOverrides
    Type: plist dict
    Failsafe: None
    Description: Force builtin versions of certain protocols described in the ProtocolOverrides Properties section below.

    Note: all protocol instances are installed prior to driver loading.

  8. Quirks
    Type: plist dict
    Failsafe: None
    Description: Apply individual firmware quirks described in the Quirks Properties section below.
  9. ReservedMemory
    Type: plist array
    Description: To be filled with plist dict values, describing memory areas exclusive to specific firmware and hardware functioning, which should not be used by the operating system. Examples of such memory regions could be the second 256 MB corrupted by the Intel HD 3000 or an area with faulty RAM. Refer to the ReservedMemory Properties section below for details.

11.7 APFS Properties

  1. 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.

  2. 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.

  3. HideVerbose
    Type: plist boolean
    Failsafe: false
    Description: Hide verbose output from APFS driver.

    APFS verbose output can be useful for debugging.

  4. 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.

  5. 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.

  6. 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.

11.8 AppleInput Properties

  1. AppleEvent
    Type: plist string
    Failsafe: Auto
    Description: Determine whether OC builtin or OEM Apple Event protocol is used.

    This option determines whether Apple’s 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.

  2. CustomDelays
    Type: plist boolean
    Failsafe: false
    Description: Enable custom key repeat delays when using the OpenCore implementation of the Apple Event protocol. Has no effect when using the OEM Apple implementation (see AppleEvent setting).
  3. KeyInitialDelay
    Type: plist integer
    Failsafe: 50 (500ms before first key repeat)
    Description: Configures the initial delay before keyboard key repeats in OpenCore implementation of 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.

  4. KeySubsequentDelay
    Type: plist integer
    Failsafe: 5 (50ms between subsequent key repeats)
    Description: Configures the gap between keyboard key repeats in OpenCore implementation of 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:

  5. PointerSpeedDiv
    Type: plist integer
    Failsafe: 1
    Description: Configure pointer speed divisor in OpenCore implementation of 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.

  6. PointerSpeedMul
    Type: plist integer
    Failsafe: 1
    Description: Configure pointer speed multiplier in OpenCore implementation of 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.

11.9 Audio Properties

  1. 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.

  2. 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)

    As an alternative, gfxutil -f HDEF command can be used in macOS. Specifying an empty device path will result in the first available audio controller being used.

  3. AudioOut
    Type: plist integer
    Failsafe: 0
    Description: Index of the output port of the specified codec starting from 0.

    This typically contains the index of the green out of the builtin analog audio controller (HDEF). The number of output nodes (N) 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)

    The quickest way to find the right port is to bruteforce the values from 0 to N - 1.

  4. 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 a dedicated audio port (AudioOut) of the specified codec (AudioCodec) located on the audio controller (AudioDevice).

  5. MinimumVolume
    Type: plist integer
    Failsafe: 0
    Description: Minimal heard volume level from 0 to 100.

    The screen reader will use this volume level when the calculated volume level is lower than MinimumVolume and the boot chime will not play if the calculated volume level is lower than MinimumVolume.

  6. 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 MinimumVolume and VolumeAmplifier settings as well as the SystemAudioVolume NVRAM variable. Possible values include:

    Note: Enabled can be used in separate from StartupMute NVRAM variable to avoid conflicts when the firmware is able to play the boot chime.

  7. 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 alctsel property instead.

  8. SetupDelay
    Type: plist integer
    Failsafe: 0
    Description: Audio codec reconfiguration delay in microseconds.

    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.

  9. VolumeAmplifier
    Type: plist integer
    Failsafe: 0
    Description: Multiplication coefficient for system volume to raw volume linear translation from 0 to 1000.

    Volume level range read from SystemAudioVolume varies depending on the codec. To transform read value in [0, 127] range into raw volume range [0, 100] the read value is scaled to VolumeAmplifier percents:

    RawV olume = MIN(SystemAudioV--olume-∗-VolumeAmplif-ier-
                100,100)

    Note: the transformation used in macOS is not linear, but it is very close and this nuance is thus ignored.

11.10 Input Properties

  1. 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).

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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.

11.11 Output Properties

  1. TextRenderer
    Type: plist string
    Failsafe: BuiltinGraphics
    Description: Chooses renderer for text going through standard console output.

    Currently two renderers are supported: Builtin and System. System renderer uses firmware services for text rendering. Builtin bypassing firmware services and performs text rendering on its own. Different renderers support a different set of options. It is recommended to use Builtin renderer, as it supports HiDPI mode and uses full screen resolution.

    UEFI firmware typically supports ConsoleControl with two rendering modes: Graphics and Text. Some types of firmware do not support ConsoleControl and rendering modes. OpenCore and macOS expect text to only be shown in Graphics mode and graphics to be drawn in any mode. Since this is not required by UEFI specification, exact behaviour varies.

    Valid values are combinations of text renderer and rendering mode:

    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 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.

  2. 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. This option is currently ignored as the Builtin text renderer only supports one console mode.

    Note: This field is best left empty on most types of firmware.

  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. 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.

  8. 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 when console control is in a different mode from Text.

    Note: This option only applies to the System renderer.

  9. 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.

  10. 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.

  11. 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.

  12. 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.

  13. 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.

11.12 ProtocolOverrides Properties

  1. 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 specific to Gibraltar machines (T2) and 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.

  2. 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.

  3. AppleDebugLog
    Type: plist boolean
    Failsafe: false
    Description: Replaces the Apple Debug Log protocol with a builtin version.
  4. AppleEg2Info
    Type: plist boolean
    Failsafe: false
    Description: Replaces the Apple EFI Graphics 2 protocol with a builtin version.

    Note: 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.

  5. 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 macOS 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).

  6. AppleImageConversion
    Type: plist boolean
    Failsafe: false
    Description: Replaces the Apple Image Conversion protocol with a builtin version.
  7. AppleImg4Verification
    Type: plist boolean
    Failsafe: false
    Description: Replaces the Apple IMG4 Verification protocol with a builtin version. This protocol is used to verify im4m manifest files used by Apple Secure Boot.
  8. AppleKeyMap
    Type: plist boolean
    Failsafe: false
    Description: Replaces Apple Key Map protocols with builtin versions.
  9. 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.

  10. AppleSecureBoot
    Type: plist boolean
    Failsafe: false
    Description: Replaces the Apple Secure Boot protocol with a builtin version.
  11. 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.

  12. AppleUserInterfaceTheme
    Type: plist boolean
    Failsafe: false
    Description: Replaces the Apple User Interface Theme protocol with a builtin version.
  13. 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.

  14. 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.

  15. 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.

  16. HashServices
    Type: plist boolean
    Failsafe: false
    Description: Replaces Hash Services protocols with builtin versions. Set to true to ensure FileVault 2 compatibility on platforms with defective SHA-1 hash implementations. This can be determined by an invalid cursor size when UIScale is set to 02. Platforms earlier than APTIO V (Haswell and older) are typically affected.
  17. OSInfo
    Type: plist boolean
    Failsafe: false
    Description: Replaces the OS Info protocol with a builtin version. This protocol is typically used by the firmware and other applications to receive notifications from the macOS bootloader.
  18. UnicodeCollation
    Type: plist boolean
    Failsafe: false
    Description: Replaces unicode collation services with builtin versions. Set to true to ensure UEFI Shell compatibility on platforms with defective unicode collation implementations. Legacy Insyde and APTIO platforms on Ivy Bridge, and earlier, are typically affected.

11.13 Quirks Properties

  1. 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.

  2. EnableVectorAcceleration
    Type: plist boolean
    Failsafe: false
    Description: Enable AVX vector acceleration of SHA-512 and SHA-384 hashing algorithms.
  3. 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.

  4. 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.

  5. 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 like NVIDIA GOP Option ROMs on hardware with older EFI 1.x firmware like MacPro5,1.

  6. 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.

  7. ReleaseUsbOwnership
    Type: plist boolean
    Failsafe: false
    Description: Attempt to detach USB controller ownership from the firmware driver. While most types of firmware manage to do this properly, or at least have an option for this, some do not. As a result, the operating system may freeze upon boot. Not recommended unless specifically required.
  8. 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.

  9. 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:

  10. 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.

  11. 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.

11.14 ReservedMemory Properties

  1. 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.

  2. Comment
    Type: plist string
    Failsafe: Empty
    Description: Arbitrary ASCII string used to provide human readable reference for the entry. Whether this value is used is implementation defined.
  3. Size
    Type: plist integer
    Failsafe: 0
    Description: Size of the reserved memory region, must be page-aligned (4 KBs).
  4. Type
    Type: plist string
    Failsafe: Reserved
    Description: Memory region type matching the UEFI specification memory descriptor types. Mapping:
  5. Enabled
    Type: plist boolean
    Failsafe: false
    Description: This region will not be reserved unless set to true.

12 Troubleshooting

12.1 Legacy Apple OS

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.

12.1.1 macOS 10.8 and 10.9
12.1.2 macOS 10.7
12.1.3 macOS 10.6

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
12.1.4 macOS 10.5
12.1.5 macOS 10.4

12.2 UEFI Secure Boot

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:

  1. Enable Apple Secure Boot by setting SecureBootModel to run macOS. Note, that not every macOS is compatible with Apple Secure Boot and there are several other restrictions as explained in Apple Secure Boot section.
  2. Disable DMG loading by setting DmgLoading to Disabled if users have concerns of loading old vulnerable DMG recoveries. This is not required, but recommended. For the actual tradeoffs see the details in DMG loading section.
  3. Make sure that APFS JumpStart functionality restricts the loading of old vulnerable drivers by setting MinDate and MinVersion to 0. More details are provided in APFS JumpStart section. An alternative is to install apfs.efi driver manually.
  4. Make sure that Force driver loading is not needed and all the operating systems are still bootable.
  5. Make sure that ScanPolicy restricts loading from undesired devices. It is a good idea to prohibit all removable drivers or unknown filesystems.
  6. Sign all the installed drivers and tools with the private key. Do not sign tools that provide administrative access to the computer, such as UEFI Shell.
  7. Vault the configuration as explained Vaulting section.
  8. Sign all OpenCore binaries (BOOTX64.efi, BOOTIa32.efi, OpenCore.efi, custom launchers) used on this system with the same private key.
  9. Sign all third-party operating system (not made by Microsoft or Apple) bootloaders if needed. For Linux there is an option to install Microsoft-signed Shim bootloader as explained on e.g. Debian Wiki.
  10. Enable UEFI Secure Boot in firmware preferences and install the certificate with a private key. Details on how to generate a certificate can be found in various articles, such as this one, and are out of the scope of this document. If Windows is needed one will also need to add the Microsoft Windows Production CA 2011. To launch option ROMs or to use signed Linux drivers, Microsoft UEFI Driver Signing CA will also be needed.
  11. Password-protect changing firmware settings to ensure that UEFI Secure Boot cannot be disabled without the user’s knowledge.

12.3 Windows support

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.
Listing 4:Relabeling Windows volume

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.

12.4 Debugging

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 SerialInit configuration option. 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.

12.5 Tips and Tricks

  1. 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.

  2. How do I debug macOS boot failures?
  3. 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.

  4. 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.

  5. 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.

  6. 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.

  7. Can I use this on Apple hardware or virtual machines?

    Sure, most relatively modern Mac models including MacPro5,1 and virtual machines are fully supported. Even though there are little to none specific details relevant to Mac hardware, some ongoing instructions can be found on MacRumors.com.

  8. 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.

  9. 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.