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2026-01-26kho/abi: add memblock ABI headerMike Rapoport (Microsoft)
Introduce KHO ABI header describing preservation ABI for memblock's reserve_mem regions and link the relevant documentation to KHO docs. [lukas.bulwahn@redhat.com: MAINTAINERS: adjust file entry in MEMBLOCK AND MEMORY MANAGEMENT INITIALIZATION] Link: https://lkml.kernel.org/r/20260107090438.22901-1-lukas.bulwahn@redhat.com [rppt@kernel.org: update reserved_mem node description, per Pratyush] Link: https://lkml.kernel.org/r/aW_M-HYZzx5SkbnZ@kernel.org Link: https://lkml.kernel.org/r/20260105165839.285270-7-rppt@kernel.org Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Reviewed-by: Pratyush Yadav <pratyush@kernel.org> Cc: Alexander Graf <graf@amazon.com> Cc: Jason Miu <jasonmiu@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-01-26kho: relocate vmalloc preservation structure to KHO ABI headerJason Miu
The `struct kho_vmalloc` defines the in-memory layout for preserving vmalloc regions across kexec. This layout is a contract between kernels and part of the KHO ABI. To reflect this relationship, the related structs and helper macros are relocated to the ABI header, `include/linux/kho/abi/kexec_handover.h`. This move places the structure's definition under the protection of the KHO_FDT_COMPATIBLE version string. The structure and its components are now also documented within the ABI header to describe the contract and prevent ABI breaks. [rppt@kernel.org: update comment, per Pratyush] Link: https://lkml.kernel.org/r/aW_Mqp6HcqLwQImS@kernel.org Link: https://lkml.kernel.org/r/20260105165839.285270-6-rppt@kernel.org Signed-off-by: Jason Miu <jasonmiu@google.com> Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Cc: Alexander Graf <graf@amazon.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Pratyush Yadav <pratyush@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-01-26kho: introduce KHO FDT ABI headerJason Miu
Introduce the `include/linux/kho/abi/kexec_handover.h` header file, which defines the stable ABI for the KHO mechanism. This header specifies how preserved data is passed between kernels using an FDT. The ABI contract includes the FDT structure, node properties, and the "kho-v1" compatible string. By centralizing these definitions, this header serves as the foundational agreement for inter-kernel communication of preserved states, ensuring forward compatibility and preventing misinterpretation of data across kexec transitions. Since the ABI definitions are now centralized in the header files, the YAML files that previously described the FDT interfaces are redundant. These redundant files have therefore been removed. Link: https://lkml.kernel.org/r/20260105165839.285270-5-rppt@kernel.org Signed-off-by: Jason Miu <jasonmiu@google.com> Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Reviewed-by: Pratyush Yadav <pratyush@kernel.org> Cc: Alexander Graf <graf@amazon.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2026-01-26kho: docs: combine concepts and FDT documentationMike Rapoport (Microsoft)
Currently index.rst in KHO documentation looks empty and sad as it only contains links to "Kexec Handover Concepts" and "KHO FDT" chapters. Inline contents of these chapters into index.rst to provide a single coherent chapter describing KHO. While on it, drop parts of the KHO FDT description that will be superseded by addition of KHO ABI documentation. [rppt@kernel.org: fix Documentation/core-api/kho/index.rst] Link: https://lkml.kernel.org/r/aV4bnHlBXGpT_FMc@kernel.org Link: https://lkml.kernel.org/r/20260105165839.285270-4-rppt@kernel.org Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Reviewed-by: Pratyush Yadav <pratyush@kernel.org> Cc: Alexander Graf <graf@amazon.com> Cc: Jason Miu <jasonmiu@google.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Pratyush Yadav <pratyush@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-11-27liveupdate: kho: move to kernel/liveupdatePasha Tatashin
Move KHO to kernel/liveupdate/ in preparation of placing all Live Update core kernel related files to the same place. [pasha.tatashin@soleen.com: disable the menu when DEFERRED_STRUCT_PAGE_INIT] Link: https://lkml.kernel.org/r/CA+CK2bAvh9Oa2SLfsbJ8zztpEjrgr_hr-uGgF1coy8yoibT39A@mail.gmail.com Link: https://lkml.kernel.org/r/20251101142325.1326536-8-pasha.tatashin@soleen.com Signed-off-by: Pasha Tatashin <pasha.tatashin@soleen.com> Reviewed-by: Jason Gunthorpe <jgg@nvidia.com> Reviewed-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Cc: Alexander Graf <graf@amazon.com> Cc: Changyuan Lyu <changyuanl@google.com> Cc: Christian Brauner <brauner@kernel.org> Cc: Jason Gunthorpe <jgg@ziepe.ca> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Masahiro Yamada <masahiroy@kernel.org> Cc: Miguel Ojeda <ojeda@kernel.org> Cc: Pratyush Yadav <pratyush@kernel.org> Cc: Randy Dunlap <rdunlap@infradead.org> Cc: Simon Horman <horms@kernel.org> Cc: Tejun Heo <tj@kernel.org> Cc: Zhu Yanjun <yanjun.zhu@linux.dev> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-05-12Documentation: KHO: add memblock bindingsMike Rapoport (Microsoft)
We introduced KHO into Linux: A framework that allows Linux to pass metadata and memory across kexec from Linux to Linux. KHO reuses fdt as file format and shares a lot of the same properties of firmware-to- Linux boot formats: It needs a stable, documented ABI that allows for forward and backward compatibility as well as versioning. As first user of KHO, we introduced memblock which can now preserve memory ranges reserved with reserve_mem command line options contents across kexec, so you can use the post-kexec kernel to read traces from the pre-kexec kernel. This patch adds memblock schemas similar to "device" device tree ones to a new kho bindings directory. This allows us to force contributors to document the data that moves across KHO kexecs and catch breaking change during review. Link: https://lkml.kernel.org/r/20250509074635.3187114-18-changyuanl@google.com Co-developed-by: Alexander Graf <graf@amazon.com> Signed-off-by: Alexander Graf <graf@amazon.com> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Signed-off-by: Changyuan Lyu <changyuanl@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anthony Yznaga <anthony.yznaga@oracle.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Ashish Kalra <ashish.kalra@amd.com> Cc: Ben Herrenschmidt <benh@kernel.crashing.org> Cc: Borislav Betkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Eric Biederman <ebiederm@xmission.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Gowans <jgowans@amazon.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Krzysztof Kozlowski <krzk@kernel.org> Cc: Marc Rutland <mark.rutland@arm.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Pratyush Yadav <ptyadav@amazon.de> Cc: Rob Herring <robh@kernel.org> Cc: Saravana Kannan <saravanak@google.com> Cc: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleinxer <tglx@linutronix.de> Cc: Thomas Lendacky <thomas.lendacky@amd.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
2025-05-12Documentation: add documentation for KHOAlexander Graf
With KHO in place, let's add documentation that describes what it is and how to use it. Link: https://lkml.kernel.org/r/20250509074635.3187114-17-changyuanl@google.com Signed-off-by: Alexander Graf <graf@amazon.com> Co-developed-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org> Co-developed-by: Changyuan Lyu <changyuanl@google.com> Signed-off-by: Changyuan Lyu <changyuanl@google.com> Cc: Andy Lutomirski <luto@kernel.org> Cc: Anthony Yznaga <anthony.yznaga@oracle.com> Cc: Arnd Bergmann <arnd@arndb.de> Cc: Ashish Kalra <ashish.kalra@amd.com> Cc: Ben Herrenschmidt <benh@kernel.crashing.org> Cc: Borislav Betkov <bp@alien8.de> Cc: Catalin Marinas <catalin.marinas@arm.com> Cc: Dave Hansen <dave.hansen@linux.intel.com> Cc: David Woodhouse <dwmw2@infradead.org> Cc: Eric Biederman <ebiederm@xmission.com> Cc: "H. Peter Anvin" <hpa@zytor.com> Cc: Ingo Molnar <mingo@redhat.com> Cc: James Gowans <jgowans@amazon.com> Cc: Jason Gunthorpe <jgg@nvidia.com> Cc: Jonathan Corbet <corbet@lwn.net> Cc: Krzysztof Kozlowski <krzk@kernel.org> Cc: Marc Rutland <mark.rutland@arm.com> Cc: Paolo Bonzini <pbonzini@redhat.com> Cc: Pasha Tatashin <pasha.tatashin@soleen.com> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Pratyush Yadav <ptyadav@amazon.de> Cc: Rob Herring <robh@kernel.org> Cc: Saravana Kannan <saravanak@google.com> Cc: Stanislav Kinsburskii <skinsburskii@linux.microsoft.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Thomas Gleinxer <tglx@linutronix.de> Cc: Thomas Lendacky <thomas.lendacky@amd.com> Cc: Will Deacon <will@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>