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/* SPDX-License-Identifier: GPL-2.0 */
/*
* Copyright (c) 2026, Google LLC.
* Pasha Tatashin <pasha.tatashin@soleen.com>
*/
/**
* DOC: KHO Serialization Blocks ABI
*
* Subsystems using the KHO Serialization Blocks framework rely on the stable
* Application Binary Interface defined below to pass serialized state from a
* pre-update kernel to a post-update kernel.
*
* This interface is a contract. Any modification to the structure fields,
* compatible strings, or the layout of the `__packed` serialization
* structures defined here constitutes a breaking change. Such changes require
* incrementing the version number in the `KHO_FDT_COMPATIBLE` string to
* prevent a new kernel from misinterpreting data from an old kernel.
*
* Changes are allowed provided the compatibility version is incremented;
* however, backward/forward compatibility is only guaranteed for kernels
* supporting the same ABI version.
*/
#ifndef _LINUX_KHO_ABI_BLOCK_H
#define _LINUX_KHO_ABI_BLOCK_H
#include <asm/page.h>
#include <linux/types.h>
/**
* KHO_BLOCK_SIZE - The size of each serialization block.
*
* This is defined as PAGE_SIZE. PAGE_SIZE is ABI compliant because live
* update between kernels with different page sizes is not supported by KHO.
*/
#define KHO_BLOCK_SIZE PAGE_SIZE
/**
* struct kho_block_header_ser - Header for the serialized data block.
* @next: Physical address of the next struct kho_block_header_ser.
* @count: The number of entries that immediately follow this header in the
* memory block.
*
* This structure is located at the beginning of a block of physical memory
* preserved across a kexec. It provides the necessary metadata to interpret
* the array of entries that follow.
*/
struct kho_block_header_ser {
u64 next;
u64 count;
} __packed;
#endif /* _LINUX_KHO_ABI_BLOCK_H */
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