[PATCH v3 04/19] android: boot: add boot image header v3 and v4 structures

Safae Ouajih souajih at baylibre.com
Mon Feb 6 00:50:06 CET 2023


Add support for v3/v4 boot image format by adding
the following structures:

- andr_boot_img_hdr_v3 : describes boot image header
- andr_vnd_boot_img_hdr : describes vendor boot image header

These definitions have been copied over from the AOSP documentation at
[1] and [2]

Boot arg sizes are taken from [3]:
commit: 35fb6262bc3f (ANDROID: Support for vendor boot)

This also adds documentation for boot image header v3/v4 structure
that was imported from [4], file: include/bootimg/bootimg.h
commit: 8d0922bfb932 (Adding GKI signature in boot.img v4)

Link:[1] https://source.android.com/docs/core/architecture/bootloader/boot-image-header
Link:[2] https://source.android.com/docs/core/architecture/bootloader/partitions/vendor-boot-partitions#vendor-boot-header
Link:[3] https://android.googlesource.com/platform/external/u-boot
Link:[4] https://android.googlesource.com/platform/system/tools/mkbootimg

Signed-off-by: Safae Ouajih <souajih at baylibre.com>
Reviewed-by: Simon Glass <sjg at chromium.org>
Reviewed-by: Mattijs Korpershoek <mkorpershoek at baylibre.com>
---
 include/android_image.h | 183 +++++++++++++++++++++++++++++++++++++++-
 1 file changed, 182 insertions(+), 1 deletion(-)

diff --git a/include/android_image.h b/include/android_image.h
index 2bdcab9122..f054363001 100644
--- a/include/android_image.h
+++ b/include/android_image.h
@@ -3,7 +3,7 @@
  * This is from the Android Project,
  * Repository: https://android.googlesource.com/platform/system/tools/mkbootimg
  * File: include/bootimg/bootimg.h
- * Commit: e55998a0f2b61b685d5eb4a486ca3a0c680b1a2f
+ * Commit: cce5b1923e3cd2fcb765b512610bdc5c42bc501d
  *
  * Copyright (C) 2007 The Android Open Source Project
  */
@@ -14,11 +14,58 @@
 #include <linux/compiler.h>
 #include <linux/types.h>
 
+#define ANDR_GKI_PAGE_SIZE 4096
 #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
+#define VENDOR_BOOT_MAGIC "VNDRBOOT"
+#define ANDR_VENDOR_BOOT_MAGIC_SIZE 8
+#define ANDR_VENDOR_BOOT_ARGS_SIZE 2048
+#define ANDR_VENDOR_BOOT_NAME_SIZE 16
+
+struct andr_boot_img_hdr_v3 {
+	u8 magic[ANDR_BOOT_MAGIC_SIZE];
+
+	u32 kernel_size;    /* size in bytes */
+	u32 ramdisk_size;   /* size in bytes */
+
+	u32 os_version;
+
+	u32 header_size;    /* size of boot image header in bytes */
+	u32 reserved[4];
+	u32 header_version; /* offset remains constant for version check */
+
+	u8 cmdline[ANDR_BOOT_ARGS_SIZE + ANDR_BOOT_EXTRA_ARGS_SIZE];
+	/* for boot image header v4 only */
+	u32 signature_size; /* size in bytes */
+};
+
+struct andr_vnd_boot_img_hdr {
+	u8 magic[ANDR_VENDOR_BOOT_MAGIC_SIZE];
+	u32 header_version;
+	u32 page_size;           /* flash page size we assume */
+
+	u32 kernel_addr;         /* physical load addr */
+	u32 ramdisk_addr;        /* physical load addr */
+
+	u32 vendor_ramdisk_size; /* size in bytes */
+
+	u8 cmdline[ANDR_VENDOR_BOOT_ARGS_SIZE];
+
+	u32 tags_addr;           /* physical addr for kernel tags */
+
+	u8 name[ANDR_VENDOR_BOOT_NAME_SIZE]; /* asciiz product name */
+	u32 header_size;         /* size of vendor boot image header in bytes */
+	u32 dtb_size;            /* size of dtb image */
+	u64 dtb_addr;            /* physical load address */
+	/* for boot image header v4 only */
+	u32 vendor_ramdisk_table_size; /* size in bytes for the vendor ramdisk table */
+	u32 vendor_ramdisk_table_entry_num; /* number of entries in the vendor ramdisk table */
+	u32 vendor_ramdisk_table_entry_size; /* size in bytes for a vendor ramdisk table entry */
+	u32 bootconfig_size; /* size in bytes for the bootconfig section */
+};
 
 /* The bootloader expects the structure of andr_boot_img_hdr_v0 with header
  * version 0 to be as follows: */
@@ -136,4 +183,138 @@ struct andr_boot_img_hdr_v0 {
  *    else: jump to kernel_addr
  */
 
+/* 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
+ */
+
+/* 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
+ */
 #endif
-- 
2.34.1



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