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