include/bootimg/bootimg.h - LeafOS-Project/android_system_tools_mkbootimg - Gitiles

 /*
  * Copyright (C) 2007 The Android Open Source Project
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
  *
  *      http://www.apache.org/licenses/LICENSE-2.0
  *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
  * See the License for the specific language governing permissions and
  * limitations under the License.
  */

 #pragma once

 #include <stdint.h>

 #define BOOT_MAGIC "ANDROID!"
 #define BOOT_MAGIC_SIZE 8
 #define BOOT_NAME_SIZE 16
 #define BOOT_ARGS_SIZE 512
 #define BOOT_EXTRA_ARGS_SIZE 1024

 #define VENDOR_BOOT_MAGIC "VNDRBOOT"
 #define VENDOR_BOOT_MAGIC_SIZE 8
 #define VENDOR_BOOT_ARGS_SIZE 2048
 #define VENDOR_BOOT_NAME_SIZE 16

 #define VENDOR_RAMDISK_TYPE_NONE 0
 #define VENDOR_RAMDISK_TYPE_PLATFORM 1
 #define VENDOR_RAMDISK_TYPE_RECOVERY 2
 #define VENDOR_RAMDISK_TYPE_DLKM 3
 #define VENDOR_RAMDISK_NAME_SIZE 32
 #define VENDOR_RAMDISK_TABLE_ENTRY_BOARD_ID_SIZE 16

 /* When a boot header is of version 0, the structure of boot image is as
  * follows:
  *
  * +-----------------+
  * | boot header     | 1 page
  * +-----------------+
  * | kernel          | n pages
  * +-----------------+
  * | ramdisk         | m pages
  * +-----------------+
  * | second stage    | o pages
  * +-----------------+
  *
  * n = (kernel_size + page_size - 1) / page_size
  * m = (ramdisk_size + page_size - 1) / page_size
  * o = (second_size + page_size - 1) / page_size
  *
  * 0. all entities are page_size aligned in flash
  * 1. kernel and ramdisk are required (size != 0)
  * 2. second is optional (second_size == 0 -> no second)
  * 3. load each element (kernel, ramdisk, second) at
  *    the specified physical address (kernel_addr, etc)
  * 4. prepare tags at tag_addr.  kernel_args[] is
  *    appended to the kernel commandline in the tags.
  * 5. r0 = 0, r1 = MACHINE_TYPE, r2 = tags_addr
  * 6. if second_size != 0: jump to second_addr
  *    else: jump to kernel_addr
  */
 struct boot_img_hdr_v0 {
     // Must be BOOT_MAGIC.
     uint8_t magic[BOOT_MAGIC_SIZE];

     uint32_t kernel_size; /* size in bytes */
     uint32_t kernel_addr; /* physical load addr */

     uint32_t ramdisk_size; /* size in bytes */
     uint32_t ramdisk_addr; /* physical load addr */

     uint32_t second_size; /* size in bytes */
     uint32_t second_addr; /* physical load addr */

     uint32_t tags_addr; /* physical addr for kernel tags (if required) */
     uint32_t page_size; /* flash page size we assume */

     // Version of the boot image header.
     uint32_t header_version;

     // Operating system version and security patch level.
     // For version "A.B.C" and patch level "Y-M-D":
     //   (7 bits for each of A, B, C; 7 bits for (Y-2000), 4 bits for M)
     //   os_version = A[31:25] B[24:18] C[17:11] (Y-2000)[10:4] M[3:0]
     uint32_t os_version;

 #if __cplusplus
     void SetOsVersion(unsigned major, unsigned minor, unsigned patch) {
         os_version &= ((1 << 11) - 1);
         os_version |= (((major & 0x7f) << 25) | ((minor & 0x7f) << 18) | ((patch & 0x7f) << 11));
     }

     void SetOsPatchLevel(unsigned year, unsigned month) {
         os_version &= ~((1 << 11) - 1);
         os_version |= (((year - 2000) & 0x7f) << 4) | ((month & 0xf) << 0);
     }
 #endif

     uint8_t name[BOOT_NAME_SIZE]; /* asciiz product name */

     uint8_t cmdline[BOOT_ARGS_SIZE]; /* asciiz kernel commandline */

     uint32_t id[8]; /* timestamp / checksum / sha1 / etc */

     // Supplemental command line data; kept here to maintain
     // binary compatibility with older versions of mkbootimg.
     // Asciiz.
     uint8_t extra_cmdline[BOOT_EXTRA_ARGS_SIZE];
 } __attribute__((packed));

 /*
  * It is expected that callers would explicitly specify which version of the
  * boot image header they need to use.
  */
 typedef struct boot_img_hdr_v0 boot_img_hdr;

 /* When a boot header is of version 1, the structure of boot image is as
  * follows:
  *
  * +---------------------+
  * | boot header         | 1 page
  * +---------------------+
  * | kernel              | n pages
  * +---------------------+
  * | ramdisk             | m pages
  * +---------------------+
  * | second stage        | o pages
  * +---------------------+
  * | recovery dtbo/acpio | p pages
  * +---------------------+
  *
  * n = (kernel_size + page_size - 1) / page_size
  * m = (ramdisk_size + page_size - 1) / page_size
  * o = (second_size + page_size - 1) / page_size
  * p = (recovery_dtbo_size + page_size - 1) / page_size
  *
  * 0. all entities are page_size aligned in flash
  * 1. kernel and ramdisk are required (size != 0)
  * 2. recovery_dtbo/recovery_acpio is required for recovery.img in non-A/B
  *    devices(recovery_dtbo_size != 0)
  * 3. second is optional (second_size == 0 -> no second)
  * 4. load each element (kernel, ramdisk, second) at
  *    the specified physical address (kernel_addr, etc)
  * 5. If booting to recovery mode in a non-A/B device, extract recovery
  *    dtbo/acpio and apply the correct set of overlays on the base device tree
  *    depending on the hardware/product revision.
  * 6. set up registers for kernel entry as required by your architecture
  * 7. if second_size != 0: jump to second_addr
  *    else: jump to kernel_addr
  */
 struct boot_img_hdr_v1 : public boot_img_hdr_v0 {
     uint32_t recovery_dtbo_size;   /* size in bytes for recovery DTBO/ACPIO image */
     uint64_t recovery_dtbo_offset; /* offset to recovery dtbo/acpio in boot image */
     uint32_t header_size;
 } __attribute__((packed));

 /* When the boot image header has a version of 2, the structure of the boot
  * image is as follows:
  *
  * +---------------------+
  * | boot header         | 1 page
  * +---------------------+
  * | kernel              | n pages
  * +---------------------+
  * | ramdisk             | m pages
  * +---------------------+
  * | second stage        | o pages
  * +---------------------+
  * | recovery dtbo/acpio | p pages
  * +---------------------+
  * | dtb                 | q pages
  * +---------------------+

  * n = (kernel_size + page_size - 1) / page_size
  * m = (ramdisk_size + page_size - 1) / page_size
  * o = (second_size + page_size - 1) / page_size
  * p = (recovery_dtbo_size + page_size - 1) / page_size
  * q = (dtb_size + page_size - 1) / page_size
  *
  * 0. all entities are page_size aligned in flash
  * 1. kernel, ramdisk and DTB are required (size != 0)
  * 2. recovery_dtbo/recovery_acpio is required for recovery.img in non-A/B
  *    devices(recovery_dtbo_size != 0)
  * 3. second is optional (second_size == 0 -> no second)
  * 4. load each element (kernel, ramdisk, second, dtb) at
  *    the specified physical address (kernel_addr, etc)
  * 5. If booting to recovery mode in a non-A/B device, extract recovery
  *    dtbo/acpio and apply the correct set of overlays on the base device tree
  *    depending on the hardware/product revision.
  * 6. set up registers for kernel entry as required by your architecture
  * 7. if second_size != 0: jump to second_addr
  *    else: jump to kernel_addr
  */
 struct boot_img_hdr_v2 : public boot_img_hdr_v1 {
     uint32_t dtb_size; /* size in bytes for DTB image */
     uint64_t dtb_addr; /* physical load address for DTB image */
 } __attribute__((packed));


 /* When the boot image header has a version of 3, the structure of the boot
  * image is as follows:
  *
  * +---------------------+
  * | boot header         | 4096 bytes
  * +---------------------+
  * | kernel              | m pages
  * +---------------------+
  * | ramdisk             | n pages
  * +---------------------+
  *
  * m = (kernel_size + 4096 - 1) / 4096
  * n = (ramdisk_size + 4096 - 1) / 4096
  *
  * Note that in version 3 of the boot image header, page size is fixed at 4096 bytes.
  *
  * The structure of the vendor boot image (introduced with version 3 and
  * required to be present when a v3 boot image is used) is as follows:
  *
  * +---------------------+
  * | vendor boot header  | o pages
  * +---------------------+
  * | vendor ramdisk      | p pages
  * +---------------------+
  * | dtb                 | q pages
  * +---------------------+

  * o = (2112 + page_size - 1) / page_size
  * p = (vendor_ramdisk_size + page_size - 1) / page_size
  * q = (dtb_size + page_size - 1) / page_size
  *
  * 0. all entities in the boot image are 4096-byte aligned in flash, all
  *    entities in the vendor boot image are page_size (determined by the vendor
  *    and specified in the vendor boot image header) aligned in flash
  * 1. kernel, ramdisk, vendor ramdisk, and DTB are required (size != 0)
  * 2. load the kernel and DTB at the specified physical address (kernel_addr,
  *    dtb_addr)
  * 3. load the vendor ramdisk at ramdisk_addr
  * 4. load the generic ramdisk immediately following the vendor ramdisk in
  *    memory
  * 5. set up registers for kernel entry as required by your architecture
  * 6. if the platform has a second stage bootloader jump to it (must be
  *    contained outside boot and vendor boot partitions), otherwise
  *    jump to kernel_addr
  */
 struct boot_img_hdr_v3 {
     // Must be BOOT_MAGIC.
     uint8_t magic[BOOT_MAGIC_SIZE];

     uint32_t kernel_size; /* size in bytes */
     uint32_t ramdisk_size; /* size in bytes */

     // Operating system version and security patch level.
     // For version "A.B.C" and patch level "Y-M-D":
     //   (7 bits for each of A, B, C; 7 bits for (Y-2000), 4 bits for M)
     //   os_version = A[31:25] B[24:18] C[17:11] (Y-2000)[10:4] M[3:0]
     uint32_t os_version;

 #if __cplusplus
     void SetOsVersion(unsigned major, unsigned minor, unsigned patch) {
         os_version &= ((1 << 11) - 1);
         os_version |= (((major & 0x7f) << 25) | ((minor & 0x7f) << 18) | ((patch & 0x7f) << 11));
     }

     void SetOsPatchLevel(unsigned year, unsigned month) {
         os_version &= ~((1 << 11) - 1);
         os_version |= (((year - 2000) & 0x7f) << 4) | ((month & 0xf) << 0);
     }
 #endif

     uint32_t header_size;

     uint32_t reserved[4];

     // Version of the boot image header.
     uint32_t header_version;

     // Asciiz kernel commandline.
     uint8_t cmdline[BOOT_ARGS_SIZE + BOOT_EXTRA_ARGS_SIZE];
 } __attribute__((packed));

 struct vendor_boot_img_hdr_v3 {
     // Must be VENDOR_BOOT_MAGIC.
     uint8_t magic[VENDOR_BOOT_MAGIC_SIZE];

     // Version of the vendor boot image header.
     uint32_t header_version;

     uint32_t page_size; /* flash page size we assume */

     uint32_t kernel_addr; /* physical load addr */
     uint32_t ramdisk_addr; /* physical load addr */

     uint32_t vendor_ramdisk_size; /* size in bytes */

     uint8_t cmdline[VENDOR_BOOT_ARGS_SIZE]; /* asciiz kernel commandline */

     uint32_t tags_addr; /* physical addr for kernel tags (if required) */
     uint8_t name[VENDOR_BOOT_NAME_SIZE]; /* asciiz product name */

     uint32_t header_size;

     uint32_t dtb_size; /* size in bytes for DTB image */
     uint64_t dtb_addr; /* physical load address for DTB image */
 } __attribute__((packed));

 /* When the boot image header has a version of 4, the structure of the boot
  * image is as follows:
  *
  * +---------------------+
  * | boot header         | 4096 bytes
  * +---------------------+
  * | kernel              | m pages
  * +---------------------+
  * | ramdisk             | n pages
  * +---------------------+
  * | boot signature      | g pages
  * +---------------------+
  *
  * m = (kernel_size + 4096 - 1) / 4096
  * n = (ramdisk_size + 4096 - 1) / 4096
  * g = (signature_size + 4096 - 1) / 4096
  *
  * Note that in version 4 of the boot image header, page size is fixed at 4096
  * bytes.
  *
  * The structure of the vendor boot image version 4, which is required to be
  * present when a version 4 boot image is used, is as follows:
  *
  * +------------------------+
  * | vendor boot header     | o pages
  * +------------------------+
  * | vendor ramdisk section | p pages
  * +------------------------+
  * | dtb                    | q pages
  * +------------------------+
  * | vendor ramdisk table   | r pages
  * +------------------------+
  * | bootconfig             | s pages
  * +------------------------+
  *
  * o = (2128 + page_size - 1) / page_size
  * p = (vendor_ramdisk_size + page_size - 1) / page_size
  * q = (dtb_size + page_size - 1) / page_size
  * r = (vendor_ramdisk_table_size + page_size - 1) / page_size
  * s = (vendor_bootconfig_size + page_size - 1) / page_size
  *
  * Note that in version 4 of the vendor boot image, multiple vendor ramdisks can
  * be included in the vendor boot image. The bootloader can select a subset of
  * ramdisks to load at runtime. To help the bootloader select the ramdisks, each
  * ramdisk is tagged with a type tag and a set of hardware identifiers
  * describing the board, soc or platform that this ramdisk is intended for.
  *
  * The vendor ramdisk section is consist of multiple ramdisk images concatenated
  * one after another, and vendor_ramdisk_size is the size of the section, which
  * is the total size of all the ramdisks included in the vendor boot image.
  *
  * The vendor ramdisk table holds the size, offset, type, name and hardware
  * identifiers of each ramdisk. The type field denotes the type of its content.
  * The vendor ramdisk names are unique. The hardware identifiers are specified
  * in the board_id field in each table entry. The board_id field is consist of a
  * vector of unsigned integer words, and the encoding scheme is defined by the
  * hardware vendor.
  *
  * For the different type of ramdisks, there are:
  *    - VENDOR_RAMDISK_TYPE_NONE indicates the value is unspecified.
  *    - VENDOR_RAMDISK_TYPE_PLATFORM ramdisks contain platform specific bits, so
  *      the bootloader should always load these into memory.
  *    - VENDOR_RAMDISK_TYPE_RECOVERY ramdisks contain recovery resources, so
  *      the bootloader should load these when booting into recovery.
  *    - VENDOR_RAMDISK_TYPE_DLKM ramdisks contain dynamic loadable kernel
  *      modules.
  *
  * Version 4 of the vendor boot image also adds a bootconfig section to the end
  * of the image. This section contains Boot Configuration parameters known at
  * build time. The bootloader is responsible for placing this section directly
  * after the generic ramdisk, followed by the bootconfig trailer, before
  * entering the kernel.
  *
  * 0. all entities in the boot image are 4096-byte aligned in flash, all
  *    entities in the vendor boot image are page_size (determined by the vendor
  *    and specified in the vendor boot image header) aligned in flash
  * 1. kernel, ramdisk, and DTB are required (size != 0)
  * 2. load the kernel and DTB at the specified physical address (kernel_addr,
  *    dtb_addr)
  * 3. load the vendor ramdisks at ramdisk_addr
  * 4. load the generic ramdisk immediately following the vendor ramdisk in
  *    memory
  * 5. load the bootconfig immediately following the generic ramdisk. Add
  *    additional bootconfig parameters followed by the bootconfig trailer.
  * 6. set up registers for kernel entry as required by your architecture
  * 7. if the platform has a second stage bootloader jump to it (must be
  *    contained outside boot and vendor boot partitions), otherwise
  *    jump to kernel_addr
  */
 struct boot_img_hdr_v4 : public boot_img_hdr_v3 {
     uint32_t signature_size; /* size in bytes */
 } __attribute__((packed));

 struct vendor_boot_img_hdr_v4 : public vendor_boot_img_hdr_v3 {
     uint32_t vendor_ramdisk_table_size; /* size in bytes for the vendor ramdisk table */
     uint32_t vendor_ramdisk_table_entry_num; /* number of entries in the vendor ramdisk table */
     uint32_t vendor_ramdisk_table_entry_size; /* size in bytes for a vendor ramdisk table entry */
     uint32_t bootconfig_size; /* size in bytes for the bootconfig section */
 } __attribute__((packed));

 struct vendor_ramdisk_table_entry_v4 {
     uint32_t ramdisk_size; /* size in bytes for the ramdisk image */
     uint32_t ramdisk_offset; /* offset to the ramdisk image in vendor ramdisk section */
     uint32_t ramdisk_type; /* type of the ramdisk */
     uint8_t ramdisk_name[VENDOR_RAMDISK_NAME_SIZE]; /* asciiz ramdisk name */

     // Hardware identifiers describing the board, soc or platform which this
     // ramdisk is intended to be loaded on.
     uint32_t board_id[VENDOR_RAMDISK_TABLE_ENTRY_BOARD_ID_SIZE];
 } __attribute__((packed));
	/*
	* Copyright (C) 2007 The Android Open Source Project
	*
	* Licensed under the Apache License, Version 2.0 (the "License");
	* you may not use this file except in compliance with the License.
	* You may obtain a copy of the License at
	*
	* http://www.apache.org/licenses/LICENSE-2.0
	*
	* Unless required by applicable law or agreed to in writing, software
	* distributed under the License is distributed on an "AS IS" BASIS,
	* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
	* See the License for the specific language governing permissions and
	* limitations under the License.
	*/

	#pragma once

	#include <stdint.h>

	#define BOOT_MAGIC "ANDROID!"
	#define BOOT_MAGIC_SIZE 8
	#define BOOT_NAME_SIZE 16
	#define BOOT_ARGS_SIZE 512
	#define BOOT_EXTRA_ARGS_SIZE 1024

	#define VENDOR_BOOT_MAGIC "VNDRBOOT"
	#define VENDOR_BOOT_MAGIC_SIZE 8
	#define VENDOR_BOOT_ARGS_SIZE 2048
	#define VENDOR_BOOT_NAME_SIZE 16

	#define VENDOR_RAMDISK_TYPE_NONE 0
	#define VENDOR_RAMDISK_TYPE_PLATFORM 1
	#define VENDOR_RAMDISK_TYPE_RECOVERY 2
	#define VENDOR_RAMDISK_TYPE_DLKM 3
	#define VENDOR_RAMDISK_NAME_SIZE 32
	#define VENDOR_RAMDISK_TABLE_ENTRY_BOARD_ID_SIZE 16

	/* When a boot header is of version 0, the structure of boot image is as
	* follows:
	*
	* +-----------------+
	* \| boot header \| 1 page
	* +-----------------+
	* \| kernel \| n pages
	* +-----------------+
	* \| ramdisk \| m pages
	* +-----------------+
	* \| second stage \| o pages
	* +-----------------+
	*
	* n = (kernel_size + page_size - 1) / page_size
	* m = (ramdisk_size + page_size - 1) / page_size
	* o = (second_size + page_size - 1) / page_size
	*
	* 0. all entities are page_size aligned in flash
	* 1. kernel and ramdisk are required (size != 0)
	* 2. second is optional (second_size == 0 -> no second)
	* 3. load each element (kernel, ramdisk, second) at
	* the specified physical address (kernel_addr, etc)
	* 4. prepare tags at tag_addr. kernel_args[] is
	* appended to the kernel commandline in the tags.
	* 5. r0 = 0, r1 = MACHINE_TYPE, r2 = tags_addr
	* 6. if second_size != 0: jump to second_addr
	* else: jump to kernel_addr
	*/
	struct boot_img_hdr_v0 {
	// Must be BOOT_MAGIC.
	uint8_t magic[BOOT_MAGIC_SIZE];

	uint32_t kernel_size; /* size in bytes */
	uint32_t kernel_addr; /* physical load addr */

	uint32_t ramdisk_size; /* size in bytes */
	uint32_t ramdisk_addr; /* physical load addr */

	uint32_t second_size; /* size in bytes */
	uint32_t second_addr; /* physical load addr */

	uint32_t tags_addr; /* physical addr for kernel tags (if required) */
	uint32_t page_size; /* flash page size we assume */

	// Version of the boot image header.
	uint32_t header_version;

	// Operating system version and security patch level.
	// For version "A.B.C" and patch level "Y-M-D":
	// (7 bits for each of A, B, C; 7 bits for (Y-2000), 4 bits for M)
	// os_version = A[31:25] B[24:18] C[17:11] (Y-2000)[10:4] M[3:0]
	uint32_t os_version;

	#if __cplusplus
	void SetOsVersion(unsigned major, unsigned minor, unsigned patch) {
	os_version &= ((1 << 11) - 1);
	os_version \|= (((major & 0x7f) << 25) \| ((minor & 0x7f) << 18) \| ((patch & 0x7f) << 11));
	}

	void SetOsPatchLevel(unsigned year, unsigned month) {
	os_version &= ~((1 << 11) - 1);
	os_version \|= (((year - 2000) & 0x7f) << 4) \| ((month & 0xf) << 0);
	}
	#endif

	uint8_t name[BOOT_NAME_SIZE]; /* asciiz product name */

	uint8_t cmdline[BOOT_ARGS_SIZE]; /* asciiz kernel commandline */

	uint32_t id[8]; /* timestamp / checksum / sha1 / etc */

	// Supplemental command line data; kept here to maintain
	// binary compatibility with older versions of mkbootimg.
	// Asciiz.
	uint8_t extra_cmdline[BOOT_EXTRA_ARGS_SIZE];
	} __attribute__((packed));

	/*
	* It is expected that callers would explicitly specify which version of the
	* boot image header they need to use.
	*/
	typedef struct boot_img_hdr_v0 boot_img_hdr;

	/* When a boot header is of version 1, the structure of boot image is as
	* follows:
	*
	* +---------------------+
	* \| boot header \| 1 page
	* +---------------------+
	* \| kernel \| n pages
	* +---------------------+
	* \| ramdisk \| m pages
	* +---------------------+
	* \| second stage \| o pages
	* +---------------------+
	* \| recovery dtbo/acpio \| p pages
	* +---------------------+
	*
	* n = (kernel_size + page_size - 1) / page_size
	* m = (ramdisk_size + page_size - 1) / page_size
	* o = (second_size + page_size - 1) / page_size
	* p = (recovery_dtbo_size + page_size - 1) / page_size
	*
	* 0. all entities are page_size aligned in flash
	* 1. kernel and ramdisk are required (size != 0)
	* 2. recovery_dtbo/recovery_acpio is required for recovery.img in non-A/B
	* devices(recovery_dtbo_size != 0)
	* 3. second is optional (second_size == 0 -> no second)
	* 4. load each element (kernel, ramdisk, second) at
	* the specified physical address (kernel_addr, etc)
	* 5. If booting to recovery mode in a non-A/B device, extract recovery
	* dtbo/acpio and apply the correct set of overlays on the base device tree
	* depending on the hardware/product revision.
	* 6. set up registers for kernel entry as required by your architecture
	* 7. if second_size != 0: jump to second_addr
	* else: jump to kernel_addr
	*/
	struct boot_img_hdr_v1 : public boot_img_hdr_v0 {
	uint32_t recovery_dtbo_size; /* size in bytes for recovery DTBO/ACPIO image */
	uint64_t recovery_dtbo_offset; /* offset to recovery dtbo/acpio in boot image */
	uint32_t header_size;
	} __attribute__((packed));

	/* When the boot image header has a version of 2, the structure of the boot
	* image is as follows:
	*
	* +---------------------+
	* \| boot header \| 1 page
	* +---------------------+
	* \| kernel \| n pages
	* +---------------------+
	* \| ramdisk \| m pages
	* +---------------------+
	* \| second stage \| o pages
	* +---------------------+
	* \| recovery dtbo/acpio \| p pages
	* +---------------------+
	* \| dtb \| q pages
	* +---------------------+

	* n = (kernel_size + page_size - 1) / page_size
	* m = (ramdisk_size + page_size - 1) / page_size
	* o = (second_size + page_size - 1) / page_size
	* p = (recovery_dtbo_size + page_size - 1) / page_size
	* q = (dtb_size + page_size - 1) / page_size
	*
	* 0. all entities are page_size aligned in flash
	* 1. kernel, ramdisk and DTB are required (size != 0)
	* 2. recovery_dtbo/recovery_acpio is required for recovery.img in non-A/B
	* devices(recovery_dtbo_size != 0)
	* 3. second is optional (second_size == 0 -> no second)
	* 4. load each element (kernel, ramdisk, second, dtb) at
	* the specified physical address (kernel_addr, etc)
	* 5. If booting to recovery mode in a non-A/B device, extract recovery
	* dtbo/acpio and apply the correct set of overlays on the base device tree
	* depending on the hardware/product revision.
	* 6. set up registers for kernel entry as required by your architecture
	* 7. if second_size != 0: jump to second_addr
	* else: jump to kernel_addr
	*/
	struct boot_img_hdr_v2 : public boot_img_hdr_v1 {
	uint32_t dtb_size; /* size in bytes for DTB image */
	uint64_t dtb_addr; /* physical load address for DTB image */
	} __attribute__((packed));


	/* When the boot image header has a version of 3, the structure of the boot
	* image is as follows:
	*
	* +---------------------+
	* \| boot header \| 4096 bytes
	* +---------------------+
	* \| kernel \| m pages
	* +---------------------+
	* \| ramdisk \| n pages
	* +---------------------+
	*
	* m = (kernel_size + 4096 - 1) / 4096
	* n = (ramdisk_size + 4096 - 1) / 4096
	*
	* Note that in version 3 of the boot image header, page size is fixed at 4096 bytes.
	*
	* The structure of the vendor boot image (introduced with version 3 and
	* required to be present when a v3 boot image is used) is as follows:
	*
	* +---------------------+
	* \| vendor boot header \| o pages
	* +---------------------+
	* \| vendor ramdisk \| p pages
	* +---------------------+
	* \| dtb \| q pages
	* +---------------------+

	* o = (2112 + page_size - 1) / page_size
	* p = (vendor_ramdisk_size + page_size - 1) / page_size
	* q = (dtb_size + page_size - 1) / page_size
	*
	* 0. all entities in the boot image are 4096-byte aligned in flash, all
	* entities in the vendor boot image are page_size (determined by the vendor
	* and specified in the vendor boot image header) aligned in flash
	* 1. kernel, ramdisk, vendor ramdisk, and DTB are required (size != 0)
	* 2. load the kernel and DTB at the specified physical address (kernel_addr,
	* dtb_addr)
	* 3. load the vendor ramdisk at ramdisk_addr
	* 4. load the generic ramdisk immediately following the vendor ramdisk in
	* memory
	* 5. set up registers for kernel entry as required by your architecture
	* 6. if the platform has a second stage bootloader jump to it (must be
	* contained outside boot and vendor boot partitions), otherwise
	* jump to kernel_addr
	*/
	struct boot_img_hdr_v3 {
	// Must be BOOT_MAGIC.
	uint8_t magic[BOOT_MAGIC_SIZE];

	uint32_t kernel_size; /* size in bytes */
	uint32_t ramdisk_size; /* size in bytes */

	// Operating system version and security patch level.
	// For version "A.B.C" and patch level "Y-M-D":
	// (7 bits for each of A, B, C; 7 bits for (Y-2000), 4 bits for M)
	// os_version = A[31:25] B[24:18] C[17:11] (Y-2000)[10:4] M[3:0]
	uint32_t os_version;

	#if __cplusplus
	void SetOsVersion(unsigned major, unsigned minor, unsigned patch) {
	os_version &= ((1 << 11) - 1);
	os_version \|= (((major & 0x7f) << 25) \| ((minor & 0x7f) << 18) \| ((patch & 0x7f) << 11));
	}

	void SetOsPatchLevel(unsigned year, unsigned month) {
	os_version &= ~((1 << 11) - 1);
	os_version \|= (((year - 2000) & 0x7f) << 4) \| ((month & 0xf) << 0);
	}
	#endif

	uint32_t header_size;

	uint32_t reserved[4];

	// Version of the boot image header.
	uint32_t header_version;

	// Asciiz kernel commandline.
	uint8_t cmdline[BOOT_ARGS_SIZE + BOOT_EXTRA_ARGS_SIZE];
	} __attribute__((packed));

	struct vendor_boot_img_hdr_v3 {
	// Must be VENDOR_BOOT_MAGIC.
	uint8_t magic[VENDOR_BOOT_MAGIC_SIZE];

	// Version of the vendor boot image header.
	uint32_t header_version;

	uint32_t page_size; /* flash page size we assume */

	uint32_t kernel_addr; /* physical load addr */
	uint32_t ramdisk_addr; /* physical load addr */

	uint32_t vendor_ramdisk_size; /* size in bytes */

	uint8_t cmdline[VENDOR_BOOT_ARGS_SIZE]; /* asciiz kernel commandline */

	uint32_t tags_addr; /* physical addr for kernel tags (if required) */
	uint8_t name[VENDOR_BOOT_NAME_SIZE]; /* asciiz product name */

	uint32_t header_size;

	uint32_t dtb_size; /* size in bytes for DTB image */
	uint64_t dtb_addr; /* physical load address for DTB image */
	} __attribute__((packed));

	/* When the boot image header has a version of 4, the structure of the boot
	* image is as follows:
	*
	* +---------------------+
	* \| boot header \| 4096 bytes
	* +---------------------+
	* \| kernel \| m pages
	* +---------------------+
	* \| ramdisk \| n pages
	* +---------------------+
	* \| boot signature \| g pages
	* +---------------------+
	*
	* m = (kernel_size + 4096 - 1) / 4096
	* n = (ramdisk_size + 4096 - 1) / 4096
	* g = (signature_size + 4096 - 1) / 4096
	*
	* Note that in version 4 of the boot image header, page size is fixed at 4096
	* bytes.
	*
	* The structure of the vendor boot image version 4, which is required to be
	* present when a version 4 boot image is used, is as follows:
	*
	* +------------------------+
	* \| vendor boot header \| o pages
	* +------------------------+
	* \| vendor ramdisk section \| p pages
	* +------------------------+
	* \| dtb \| q pages
	* +------------------------+
	* \| vendor ramdisk table \| r pages
	* +------------------------+
	* \| bootconfig \| s pages
	* +------------------------+
	*
	* o = (2128 + page_size - 1) / page_size
	* p = (vendor_ramdisk_size + page_size - 1) / page_size
	* q = (dtb_size + page_size - 1) / page_size
	* r = (vendor_ramdisk_table_size + page_size - 1) / page_size
	* s = (vendor_bootconfig_size + page_size - 1) / page_size
	*
	* Note that in version 4 of the vendor boot image, multiple vendor ramdisks can
	* be included in the vendor boot image. The bootloader can select a subset of
	* ramdisks to load at runtime. To help the bootloader select the ramdisks, each
	* ramdisk is tagged with a type tag and a set of hardware identifiers
	* describing the board, soc or platform that this ramdisk is intended for.
	*
	* The vendor ramdisk section is consist of multiple ramdisk images concatenated
	* one after another, and vendor_ramdisk_size is the size of the section, which
	* is the total size of all the ramdisks included in the vendor boot image.
	*
	* The vendor ramdisk table holds the size, offset, type, name and hardware
	* identifiers of each ramdisk. The type field denotes the type of its content.
	* The vendor ramdisk names are unique. The hardware identifiers are specified
	* in the board_id field in each table entry. The board_id field is consist of a
	* vector of unsigned integer words, and the encoding scheme is defined by the
	* hardware vendor.
	*
	* For the different type of ramdisks, there are:
	* - VENDOR_RAMDISK_TYPE_NONE indicates the value is unspecified.
	* - VENDOR_RAMDISK_TYPE_PLATFORM ramdisks contain platform specific bits, so
	* the bootloader should always load these into memory.
	* - VENDOR_RAMDISK_TYPE_RECOVERY ramdisks contain recovery resources, so
	* the bootloader should load these when booting into recovery.
	* - VENDOR_RAMDISK_TYPE_DLKM ramdisks contain dynamic loadable kernel
	* modules.
	*
	* Version 4 of the vendor boot image also adds a bootconfig section to the end
	* of the image. This section contains Boot Configuration parameters known at
	* build time. The bootloader is responsible for placing this section directly
	* after the generic ramdisk, followed by the bootconfig trailer, before
	* entering the kernel.
	*
	* 0. all entities in the boot image are 4096-byte aligned in flash, all
	* entities in the vendor boot image are page_size (determined by the vendor
	* and specified in the vendor boot image header) aligned in flash
	* 1. kernel, ramdisk, and DTB are required (size != 0)
	* 2. load the kernel and DTB at the specified physical address (kernel_addr,
	* dtb_addr)
	* 3. load the vendor ramdisks at ramdisk_addr
	* 4. load the generic ramdisk immediately following the vendor ramdisk in
	* memory
	* 5. load the bootconfig immediately following the generic ramdisk. Add
	* additional bootconfig parameters followed by the bootconfig trailer.
	* 6. set up registers for kernel entry as required by your architecture
	* 7. if the platform has a second stage bootloader jump to it (must be
	* contained outside boot and vendor boot partitions), otherwise
	* jump to kernel_addr
	*/
	struct boot_img_hdr_v4 : public boot_img_hdr_v3 {
	uint32_t signature_size; /* size in bytes */
	} __attribute__((packed));

	struct vendor_boot_img_hdr_v4 : public vendor_boot_img_hdr_v3 {
	uint32_t vendor_ramdisk_table_size; /* size in bytes for the vendor ramdisk table */
	uint32_t vendor_ramdisk_table_entry_num; /* number of entries in the vendor ramdisk table */
	uint32_t vendor_ramdisk_table_entry_size; /* size in bytes for a vendor ramdisk table entry */
	uint32_t bootconfig_size; /* size in bytes for the bootconfig section */
	} __attribute__((packed));

	struct vendor_ramdisk_table_entry_v4 {
	uint32_t ramdisk_size; /* size in bytes for the ramdisk image */
	uint32_t ramdisk_offset; /* offset to the ramdisk image in vendor ramdisk section */
	uint32_t ramdisk_type; /* type of the ramdisk */
	uint8_t ramdisk_name[VENDOR_RAMDISK_NAME_SIZE]; /* asciiz ramdisk name */

	// Hardware identifiers describing the board, soc or platform which this
	// ramdisk is intended to be loaded on.
	uint32_t board_id[VENDOR_RAMDISK_TABLE_ENTRY_BOARD_ID_SIZE];
	} __attribute__((packed));