diff --git a/include/android_image.h b/include/android_image.h
index d78db9e..0519ece 100644
--- a/include/android_image.h
+++ b/include/android_image.h
@@ -1,59 +1,78 @@
-/* SPDX-License-Identifier: BSD-2-Clause */
+/* SPDX-License-Identifier: BSD-3-Clause */
 /*
  * This is from the Android Project,
- * Repository: https://android.googlesource.com/platform/system/core/
- * File: mkbootimg/bootimg.h
- * Commit: d162828814b08ada310846a33205befb69ef5799
+ * Repository: https://android.googlesource.com/platform/system/tools/mkbootimg
+ * File: include/bootimg/bootimg.h
+ * Commit: e55998a0f2b61b685d5eb4a486ca3a0c680b1a2f
  *
- * Copyright (C) 2008 The Android Open Source Project
+ * Copyright (C) 2007 The Android Open Source Project
  */
 
 #ifndef _ANDROID_IMAGE_H_
 #define _ANDROID_IMAGE_H_
 
-typedef struct andr_img_hdr andr_img_hdr;
-
 #define ANDR_BOOT_MAGIC "ANDROID!"
 #define ANDR_BOOT_MAGIC_SIZE 8
 #define ANDR_BOOT_NAME_SIZE 16
 #define ANDR_BOOT_ARGS_SIZE 512
 #define ANDR_BOOT_EXTRA_ARGS_SIZE 1024
 
+/*
+ * It is expected that callers would explicitly specify which version of the
+ * boot image header they need to use.
+ */
+typedef struct andr_img_hdr andr_img_hdr;
+
+/* The bootloader expects the structure of andr_img_hdr with header
+ * version 0 to be as follows: */
 struct andr_img_hdr {
-	char magic[ANDR_BOOT_MAGIC_SIZE];
+    /* Must be ANDR_BOOT_MAGIC. */
+    char magic[ANDR_BOOT_MAGIC_SIZE];
 
-	u32 kernel_size;	/* size in bytes */
-	u32 kernel_addr;	/* physical load addr */
+    u32 kernel_size; /* size in bytes */
+    u32 kernel_addr; /* physical load addr */
 
-	u32 ramdisk_size;	/* size in bytes */
-	u32 ramdisk_addr;	/* physical load addr */
+    u32 ramdisk_size; /* size in bytes */
+    u32 ramdisk_addr; /* physical load addr */
 
-	u32 second_size;	/* size in bytes */
-	u32 second_addr;	/* physical load addr */
+    u32 second_size; /* size in bytes */
+    u32 second_addr; /* physical load addr */
 
-	u32 tags_addr;		/* physical addr for kernel tags */
-	u32 page_size;		/* flash page size we assume */
-	u32 unused;		/* reserved for future expansion: MUST be 0 */
+    u32 tags_addr; /* physical addr for kernel tags */
+    u32 page_size; /* flash page size we assume */
 
-	/* operating system version and security patch level; for
-	 * version "A.B.C" and patch level "Y-M-D":
-	 * ver = A << 14 | B << 7 | C         (7 bits for each of A, B, C)
-	 * lvl = ((Y - 2000) & 127) << 4 | M  (7 bits for Y, 4 bits for M)
-	 * os_version = ver << 11 | lvl */
-	u32 os_version;
+    /* Version of the boot image header. */
+    u32 header_version;
 
-	char name[ANDR_BOOT_NAME_SIZE]; /* asciiz product name */
+    /* 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] */
+    u32 os_version;
 
-	char cmdline[ANDR_BOOT_ARGS_SIZE];
+    char name[ANDR_BOOT_NAME_SIZE]; /* asciiz product name */
 
-	u32 id[8]; /* timestamp / checksum / sha1 / etc */
+    char cmdline[ANDR_BOOT_ARGS_SIZE];
 
-	/* Supplemental command line data; kept here to maintain
-	 * binary compatibility with older versions of mkbootimg */
-	char extra_cmdline[ANDR_BOOT_EXTRA_ARGS_SIZE];
+    u32 id[8]; /* timestamp / checksum / sha1 / etc */
+
+    /* Supplemental command line data; kept here to maintain
+     * binary compatibility with older versions of mkbootimg. */
+    char extra_cmdline[ANDR_BOOT_EXTRA_ARGS_SIZE];
+
+    /* Fields in boot_img_hdr_v1 and newer. */
+    u32 recovery_dtbo_size;   /* size in bytes for recovery DTBO/ACPIO image */
+    u64 recovery_dtbo_offset; /* offset to recovery dtbo/acpio in boot image */
+    u32 header_size;
+
+    /* Fields in boot_img_hdr_v2 and newer. */
+    u32 dtb_size; /* size in bytes for DTB image */
+    u64 dtb_addr; /* physical load address for DTB image */
 } __attribute__((packed));
 
-/*
+/* When a boot header is of version 0, the structure of boot image is as
+ * follows:
+ *
  * +-----------------+
  * | boot header     | 1 page
  * +-----------------+
@@ -79,4 +98,45 @@
  * 6. if second_size != 0: jump to second_addr
  *    else: jump to kernel_addr
  */
+
+/* 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. prepare tags at tag_addr.  kernel_args[] is
+ *    appended to the kernel commandline in the tags.
+ * 7. r0 = 0, r1 = MACHINE_TYPE, r2 = tags_addr
+ * 8. if second_size != 0: jump to second_addr
+ *    else: jump to kernel_addr
+ */
+
 #endif