Project Mu Basecore Repository

Host Type & Toolchain	Build Status	Test Status	Code Coverage
Windows_VS2022
Ubuntu_GCC5

This repository is part of Project Mu. Please see Project Mu for details https://microsoft.github.io/mu.

For more details about the repository, refer to RepoDetails.md.

Branch Status - release/202608

Status:	In Development
Entered Development:	2026/08/21 (Date EDK2 started accepting changes which were not in a previous release)
Anticipated Stabilization:	Feb 2027

Branch Changes - release/202608

Breaking Changes-dev

• Header include guards
  • Many headers replaced named #ifndef/#define include guards with #pragma once. Normal inclusion is unchanged, but consumers must not test or define another header's former guard macro to detect or suppress it.
• ArmPkg
  • ArmExceptionLib and DefaultExceptionHandlerLib were moved from ArmPkg and merged into UefiCpuPkg/CpuExceptionHandlerLib. Replace calls to DefaultExceptionHandler() with DumpCpuContext(), add UefiCpuPkg.dec as a package dependency, and update platform DSC library mappings.
  • Library/MmuLib/BaseMmuLib.inf was removed. Standalone MM consumers should migrate to Library/StandaloneMmMmuLib/ArmMmuStandaloneMmLib.inf and update their library class usage as needed.
• BaseTools
  • GenFv supports selective rebasing through the new Xip=TRUE/FALSE FDF rule keyword. When FvForceRebase=TRUE and any file in an FV uses Xip=TRUE, only files marked Xip=TRUE are rebased; platforms adopting selective rebasing must update the relevant FDF rules.
  • Visual Studio 2015 and 2017 toolchain support was removed. Windows builds and CI must use VS2019, VS2022, or VS2026.
  • The deprecated GCC48, GCC49, and GCC5 toolchain definitions were removed. Platforms using these toolchain tags must migrate to GCC.
  • X64 images built with GCC, CLANGDWARF, CLANGPDB, VS2022, or VS2026 now use 4 KiB section alignment by default. SEC, PEI_CORE, and PEIM XIP images retain their previous alignment through module-specific linker flags. Platforms with firmware-size constraints or loaders that assume smaller alignment must review their generated images.
• CryptoPkg
  • Library/BaseCryptLibOnProtocolPpi/DxeCryptLib.inf, SmmCryptLib.inf, and StandaloneMmCryptLib.inf were removed as part of the OneCrypto transition. Replace them with the corresponding instances under Library/BaseCryptLibOnOneCrypto and add the required OneCrypto binary drivers and loaders to the platform DSC.
  • Library/BaseCryptLibOnProtocolPpi/RuntimeDxeCryptLib.inf and Library/BaseCryptLibMbedTls/UnitTestHostBaseCryptLib.inf were removed with no direct OneCrypto replacement. Runtime and host-test consumers must remove these mappings and select a crypto instance supported by their execution environment.
  • Projects requiring PEI hashing support through the CryptoLib should use Library\BaseCryptLibOnProtocolPpi\PeiCryptLib.inf and include the
• EmbeddedPkg
  • The PrePiLib APIs changed: FfsFindSectionDataWithHook() now takes an AuthenticationStatus output parameter and FfsProcessFvFile() now takes a ParentVolumeHandle parameter.
• MdeModulePkg
  • PartitionDxe, DxeTpm2MeasureBootLib, and DxeTpmMeasureBootLib now depend on the new GptLib library class. Platforms that build these modules must map GptLib to MdeModulePkg/Library/GptLib/GptLib.inf in their DSC files.
  • Library/RealTimeClockLibNull/RealTimeClockLibNull.inf was removed with no direct replacement. Platforms that mapped RealTimeClockLib to this null instance must use a platform RTC implementation or provide their own null implementation if unsupported RTC behavior is still required.
  • The InternalEventServices protocol and PcdInternalEventServicesEnabled were removed, including INTERNAL_EVENT_SERVICES_PROTOCOL_GUID, WAIT_FOR_EVENT_INTERNAL, WaitForEventInternal, and gInternalEventServicesProtocolGuid. The related private DXE Core interfaces CoreWaitForEventInternal() and InternalEventServicesInit() were also removed. Consumers must use the standard boot-services WaitForEvent() interface at TPL_APPLICATION and refactor waits at higher TPLs into event-driven callbacks.
  • The NonDiscoverableDeviceUniqueId protocol was removed, including EDKII_NON_DISCOVERABLE_DEVICE_UNIQUE_ID_PROTOCOL_GUID, NON_DISCOVERABLE_DEVICE_UNIQUE_ID_PROTOCOL_REVISION, MAX_NON_DISCOVERABLE_PCI_DEVICE_ID, NON_DISCOVERABLE_DEVICE_UNIQUE_ID_PROTOCOL, and gEdkiiNonDiscoverableDeviceUniqueIdProtocolGuid. Stop installing the protocol; non-discoverable PCI devices now receive IDs from discovery order. Consumers that require stable device identity must use a platform-owned identification mechanism instead of the ID returned by EFI_PCI_IO_PROTOCOL.GetLocation().
  • The private DXE Core GetBucketMemoryType() interface was removed from Core/Dxe/Mem/Imem.h. Out-of-tree DXE Core changes must use the current memory-map and memory-protection infrastructure instead of calling this removed helper.
  • Universal/Variable/RuntimeDxe/RuntimeDxeUnitTest/VariableRuntimeDxeUnitTest.inf was removed. Test DSC files must remove this module. Its private test headers, assertion GUID #define values, SCT shim macros, and test function declarations were also removed; use the remaining focused variable unit tests or platform-owned conformance tests for equivalent coverage.
• MdePkg
  • Library/BaseMmuLibNull/BaseMmuLibNull.inf and the MmuLib library class were removed. Platforms must remove null MmuLib mappings. The header and its MmuSetAttributes(), MmuClearAttributes(), and MmuGetAttributes() interfaces were also removed; consumers must migrate to the architecture-specific MMU library or the CPU, memory-attribute, or MM memory-attribute protocol appropriate to their execution environment.
  • The Cpu2 protocol and the BaseLib EnableInterruptsAndSleep() API were removed, including EFI_CPU2_PROTOCOL_GUID, EFI_CPU2_PROTOCOL, EFI_CPU_ENABLE_AND_WAIT_FOR_INTERRUPT, EnableAndForWaitInterrupt, and gEfiCpu2ProtocolGuid. CPU drivers must stop producing this protocol. For normal DXE idle handling, use gIdleLoopEventGuid and perform the architecture-specific sleep operation from the CPU driver's idle-loop callback, as in UefiCpuPkg/CpuDxe.
  • EFI_SW_DXE_CORE_EC_IMAGE_LOAD_FAILURE was removed from Pi/PiStatusCode.h. Code emitting this MU-specific status code must remove the report or define and use a platform-owned status-code value; there is no direct replacement in PiStatusCode.h.
• SecurityPkg
  • TPM2 helper functions were moved from Tpm2CommandLib to the new Tpm2HelpLib library class. Platforms that build affected modules must map Tpm2HelpLib to SecurityPkg/Library/Tpm2HelpLib/Tpm2HelpLib.inf in their DSC files.
• StandaloneMmPkg
  • Library/FvLib/FvLib.inf was removed. Consumers should map the FvLib library class to MdePkg/Library/FvLib/FvLib.inf and add MdePkg/MdePkg.dec as a package dependency if needed.
  • Library/StandaloneMmCoreEntryPointNull/StandaloneMmCoreEntryPointNull.inf was removed. Map StandaloneMmCoreEntryPoint to MdePkg/Library/StandaloneMmCoreEntryPoint/StandaloneMmCoreEntryPoint.inf for X64 or ArmPkg/Library/ArmStandaloneMmCoreEntryPoint/ArmStandaloneMmCoreEntryPoint.inf for AARCH64.
• ManageabilityPkg
  • ManageabilityPkg now exists in mu_basecore. Platforms are encouraged to switch to this over mu_feature_ipmi.

See EDK II Breaking Changes for complete descriptions, affected consumers, and migration guidance.

MU Overrides on EDK2

• At the start of 202608, mu_basecore contains 267 commits on top of edk2-stable202608. Full MU changes list can be viewed in the changelog.

Platform Integration Reference

Reference platforms which consume release/202608 are available in mu_tiano_platforms.

Please note that this version of EDK2 has specific requirements when it comes to TF-A support. Platforms that consume this version of EDK2 must ensure their TF-A contains this set of patches. Failure to contain the appropriate patches will result in a failure to boot.

Code of Conduct

This project has adopted the Microsoft Open Source Code of Conduct https://opensource.microsoft.com/codeofconduct/

For more information see the Code of Conduct FAQ https://opensource.microsoft.com/codeofconduct/faq/ or contact opencode@microsoft.com with any additional questions or comments.

Contributions

Contributions are always welcome and encouraged! Please open any issues in the Project Mu GitHub tracker and read https://microsoft.github.io/mu/How/contributing/

For documentation:

Copyright & License

Copyright (c) Microsoft Corporation

SPDX-License-Identifier: BSD-2-Clause-Patent

Upstream License (TianoCore)

Copyright (c) 2019, TianoCore and contributors. All rights reserved.

SPDX-License-Identifier: BSD-2-Clause-Patent

Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met:

1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
2. Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following disclaimer in the documentation and/or other materials provided with the distribution.

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1. their Contribution(s) (the licensed copyrights of copyright holders and non-copyrightable additions of contributors, in source or binary form) alone; or
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Except as expressly stated above, no rights or licenses from any copyright holder or contributor is granted under this license, whether expressly, by implication, estoppel or otherwise.

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