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Mike Rapoport (Microsoft)
dd1e79ef6c
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>
74 lines
2.2 KiB
C
74 lines
2.2 KiB
C
/* SPDX-License-Identifier: GPL-2.0 */
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#ifndef _LINUX_KHO_ABI_MEMBLOCK_H
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#define _LINUX_KHO_ABI_MEMBLOCK_H
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/**
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* DOC: memblock kexec handover ABI
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*
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* Memblock can serialize its current memory reservations created with
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* reserve_mem command line option across kexec through KHO.
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* The post-KHO kernel can then consume these reservations and they are
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* guaranteed to have the same physical address.
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*
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* The state is serialized using Flattened Device Tree (FDT) format. Any
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* modification to the FDT structure, node properties, or the compatible
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* strings constitutes a breaking change. Such changes require incrementing the
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* version number in the relevant `_COMPATIBLE` string to prevent a new kernel
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* from misinterpreting data from an old kernel.
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*
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* Changes are allowed provided the compatibility version is incremented.
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* However, backward/forward compatibility is only guaranteed for kernels
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* supporting the same ABI version.
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*
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* FDT Structure Overview:
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* The entire memblock state is encapsulated within a single KHO entry named
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* "memblock".
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* This entry contains an FDT with the following layout:
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*
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* .. code-block:: none
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*
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* / {
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* compatible = "memblock-v1";
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*
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* n1 {
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* compatible = "reserve-mem-v1";
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* start = <0xc06b 0x4000000>;
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* size = <0x04 0x00>;
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* };
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* };
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*
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* Main memblock node (/):
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*
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* - compatible: "memblock-v1"
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* Identifies the overall memblock ABI version.
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*
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* reserved_mem node:
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* These nodes describe all reserve_mem regions. The node name is the name
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* defined by the user for a reserve_mem region.
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*
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* - compatible: "reserve-mem-v1"
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*
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* Identifies the ABI version of reserve_mem descriptions
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*
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* - start: u64
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*
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* Physical address of the reserved memory region.
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*
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* - size: u64
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*
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* size in bytes of the reserved memory region.
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*/
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/* Top level memblock FDT node name. */
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#define MEMBLOCK_KHO_FDT "memblock"
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/* The compatible string for the memblock FDT root node. */
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#define MEMBLOCK_KHO_NODE_COMPATIBLE "memblock-v1"
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/* The compatible string for the reserve_mem FDT nodes. */
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#define RESERVE_MEM_KHO_NODE_COMPATIBLE "reserve-mem-v1"
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#endif /* _LINUX_KHO_ABI_MEMBLOCK_H */
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