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cfig 提交于 2023-01-16 00:28 . Issue #109: support vendor_boot.img w/o dtb

layout of [vendor_]boot.img

1. boot.img v0-v2

2. boot.img v3-v4

3. vendor_boot.img v3-v4

4. signature part

5. boot in memory

1. boot.img v0-v2

header

Value at 0x28 is one of {0x00,0x01,0x02,0x03,0x04}, this filed should be read first to identify header version.

          item                        size in bytes             position
+-----------------------------------------------------------+    --> 0
|<MAGIC HEADER>                  |     8 (value=ANDROID!)   |
|--------------------------------+--------------------------|    --> 8
|<kernel length>                 |     4                    |
|--------------------------------+--------------------------|    --> 12
|<kernel offset>                 |     4                    |
|--------------------------------+--------------------------|    --> 16 (0x10)
|<ramdisk length>                |     4                    |
|--------------------------------+--------------------------|    --> 20
|<ramdisk offset>                |     4                    |
|--------------------------------+--------------------------|    --> 24
|<second bootloader length>      |     4                    |
|--------------------------------+--------------------------|    --> 28
|<second bootloader offset>      |     4                    |
|--------------------------------+--------------------------|    --> 32 (0x20)
|<tags offset>                   |     4                    |
|--------------------------------+--------------------------|    --> 36
|<page size>                     |     4                    |
|--------------------------------+--------------------------|    --> 40 (0x28)
|<header version>                |     4 (value in [0,1,2]) |
|--------------------------------+--------------------------|    --> 44
|<os version & os patch level>   |     4                    |
|--------------------------------+--------------------------|    --> 48 (0x30)
|<board name>                    |     16                   |
|--------------------------------+--------------------------|    --> 64 (0x40)
|<cmdline part 1>                |     512                  |
|--------------------------------+--------------------------|    --> 576 (0x240)
|<hash digest>                   |     32                   |
|--------------------------------+--------------------------|    --> 608 (0x260)
|<cmdline part 2>                |     1024                 |
|--------------------------------+--------------------------|    --> 1632 (0x660)
|<recovery dtbo length>   [v1]   |     4                    |
|--------------------------------+--------------------------|    --> 1636
|<recovery dtbo offset>   [v1]   |     8                    |
|--------------------------------+--------------------------|    --> 1644
|<header size>            [v1]   |     4 (v1: value=1648)   |
|                                |       (v2: value=1660)   |
|--------------------------------+--------------------------|    --> 1648 (0x670)
|<dtb  length>            [v2]   |     4                    |
|--------------------------------+--------------------------|    --> 1652
|<dtb  offset>            [v2]   |     8                    |
|--------------------------------+--------------------------|    --> 1660 (0x67c)
|<padding>                       | min(n * page_size        |
|                                |           - header_size) |
+--------------------------------+--------------------------+    --> pagesize

data

+-----------------------------------------------------------+    --> pagesize
|<kernel>                        |   kernel length          |
|--------------------------------+--------------------------|
|<padding>                       | min(n * page_size - len) |
+-----------------------------------------------------------+

+-----------------------------------------------------------+
|<ramdisk>                       |   ramdisk length         |
|--------------------------------+--------------------------|
|<padding>                       | min(n * page_size - len) |
+-----------------------------------------------------------+

+-----------------------------------------------------------+
|<second bootloader>             | second bootloader length |
|--------------------------------+--------------------------|
|<padding>                       | min(n * page_size - len) |
+-----------------------------------------------------------+

+-----------------------------------------------------------+
|<recovery dtbo>          [v1]   | recovery dtbo length     |
|--------------------------------+--------------------------|
|<padding>                [v1]   | min(n * page_size - len) |
+-----------------------------------------------------------+

+-----------------------------------------------------------+
|<dtb>                    [v2]   | dtb length               |
|--------------------------------+--------------------------|
|<padding>                [v2]   | min(n * page_size - len) |
+-----------------------------------------------------------+    --> end of data part

2. boot.img v3-v4

For partitions: /boot, /init_boot or /recovery.

header

          item                        size in bytes             position
+-----------------------------------------------------------+    --> 0
|<MAGIC HEADER>                  |   8 (value=ANDROID!)     |
|--------------------------------+--------------------------|    --> 8
|<kernel size>                   |   4                      |
|--------------------------------+--------------------------|    --> 12
|<ramdisk size>                  |   4                      |
|--------------------------------+--------------------------|    --> 16
|<os version & os patch level>   |   4                      |
|--------------------------------+--------------------------|    --> 20
|<header size>                   |   4                      |
|--------------------------------+--------------------------|    --> 24
|<reserved>                      |   4 * 4                  |
|--------------------------------+--------------------------|    --> 40 (0x28)
|<header version>                |   4 (value in [3|4])     |
|--------------------------------+--------------------------|    --> 44
|<cmdline>                       |   1024+512=1536          |
|--------------------------------+--------------------------|    --> 1580
|<signature_size>   (v4 only)    |   4 (values in [4096|0]) |
|--------------------------------+--------------------------|    --> 1584
|<padding>                       | min(n * page_size        |
|                                |           - header_size) |
+--------------------------------+--------------------------+    --> pagesize=4096

data

+-----------------------------------------------------------+    --> pagesize
|<kernel>                        |   kernel length          |
+-----------------------------------------------------------+    --> + kernel len
|<ramdisk>                       |   ramdisk length         |
+-----------------------------------------------------------+    --> + ramdisk len
|<boot signature>   (v4 only)    |   boot signature length  |
|                                |   GKI 1.0 : 4K           |
|                                |   GKI 2.0 : 16K          |
+--------------------------------+--------------------------+    --> + boot sig len
|<padding>                       | min(n * page_size - len) |
+-----------------------------------------------------------+

3. vendor_boot.img v3-v4

For partitions: /vendor_boot or /vendor_kernel_boot.

header

          item                        size in bytes             position
+-----------------------------------------------------------+    --> 0
|<MAGIC HEADER>                  |     8 (vaue=VNDRBOOT)    |
|--------------------------------+--------------------------|    --> 8
|<header version>                |     4 (value=3)          |
|--------------------------------+--------------------------|    --> 12
|<page size>                     |     4                    |
|--------------------------------+--------------------------|    --> 16
|<kernel load addr>              |     4                    |
|--------------------------------+--------------------------|    --> 20
|<ramdisk load addr>             |     4                    |
|--------------------------------+--------------------------|    --> 24
|<vendor ramdisk total size>     |     4                    |
|--------------------------------+--------------------------|    --> 28
|<vendor cmdline>                |     2048                 |
|--------------------------------+--------------------------|    --> 2076
|<tags offset>                   |     4                    |
|--------------------------------+--------------------------|    --> 2080
|<board name>                    |     16                   |
|--------------------------------+--------------------------|    --> 2096
|<header size>                   |     4 (v3: value=2112)   |
|                                |     4 (v4: value=2128)   |
|--------------------------------+--------------------------|    --> 2100
|<dtb size>                      |     4                    |
|--------------------------------+--------------------------|    --> 2104
|<dtb load addr>                 |     8                    |
|--------------------------------+--------------------------|    --> 2112
|<vendor ramdisk table size>     |     4   (v4 only)        |
|--------------------------------+--------------------------|    --> 2116
|<vendor ramdisk table entry num>|     4   (v4 only)        |
|--------------------------------+--------------------------|    --> 2120
|<vendor ramdisk table entry size|     4   (v4 only)        |
|--------------------------------+--------------------------|    --> 2124
|<bootconfig size>               |     4   (v4 only)        |
|--------------------------------+--------------------------|    --> 2128
|<padding>                       | min(n * page_size        |
|                                |           - header_size) |
+--------------------------------+--------------------------+    --> pagesize

data

+------------------+-------------+--------------------------+    --> pagesize
|                  | ramdisk 1   |                          |
|                  |-------------+                          |
|                  | ramdisk 2   |                          |
|<vendor ramdisks> |-------------+   padded len             |
|                  | ramdisk n   |                          |
|                  |-------------+                          |    --> pagesize + vendor_ramdisk_total_size
|                  | padding     |                          |
+------------------+-------------+--------------------------+    --> pagesize + vendor_ramdisk_total_size + padding
|                  |   dtb       |                          |
|<dtb>             |-------------+   padded len             |
|                  | padding     |                          |
+------------------+-------------+--------------------------+    --> dtb offset + dtb size + padding
|<vendor ramdisk > | entry 1     |                          |
|     table>       |-------------+                          |
|                  | entry 2     |   padded len             |
|                  |-------------+                          |
|                  | entry n     |                          |
|      (v4)        |-------------+                          |
|                  | padding     |                          |
+------------------+----------------------------------------+    --> vrt offset + vrt size + padding
|<bootconfig>            (v4)    |   padded len             |
+--------------------------------+--------------------------+

4. signature part

4.1 Boot Image Signature (VBoot 1.0)

+--------------------------------+--------------------------+    --> end of data part
|<signature>                     | signature length         |
|--------------------------------+--------------------------+
|<padding>                       | defined by boot_signer   |
+--------------------------------+--------------------------+

4.2 AVB Footer (VBoot 2.0)

                     item                        size in bytes             position
+------+--------------------------------+-------------------------+ --> end of data part (say locaton +0)
|      | VBMeta Header                  | total 256               |
|      |                                |                         |
|      |   - Header Magic "AVB0"        |     4                   |
|      |   - avb_version Major          |     4                   |
|      |   - avb_version Minor          |     4                   |
|      |   - authentication_blob_size   |     8                   |
|      |   - auxiliary blob size        |     8                   |
|      |   - algorithm type             |     4                   |
|      |   - hash_offset                |     8                   |
|      |   - hash_size                  |     8                   |
|      |   - signature_offset           |     8                   |
|      |   - signature_size             |     8                   |
|      |   - pub_key_offset             |     8                   |
|VBMeta|   - pub_key_size               |     8                   |
| Blob |   - pub_key_metadata_offset    |     8                   |
|      |   - pub_key_metadata_size      |     8                   |
|      |   - descriptors_offset         |     8                   |
|      |   - descriptors_size           |     8                   |
|      |   - rollback_index             |     8                   |
|      |   - flags                      |     4                   |
|      |   - RESERVED                   |     4                   |
|      |   - release string             |     47                  |
|      |   - NULL                       |     1                   |
|      |   - RESERVED                   |     80                  |
|      |--------------------------------+-------------------------+ --> + 256
|      | Authentication Blob            |                         |
|      |   - Hash of Header & Aux Blob  | alg.hash_num_bytes      | --> + 256 + hash_offset
|      |   - Signature of Hash          | alg.signature_num_bytes | --> + 256 + signature_offset
|      |   - Padding                    | align by 64             |
|      +--------------------------------+-------------------------+
|      | Auxiliary Blob                 |                         |
|      |   - descriptors                |                         | --> + 256 + authentication_blob_size + descriptors_offset
|      |   - pub key                    |                         | --> + 256 + authentication_blob_size + pub_key_offset
|      |   - pub key meta data          |                         | --> + 256 + authentication_blob_size + pub_key_metadata_offset
|      |   - padding                    | align by 64             |
|      +--------------------------------+-------------------------+
|      | Padding                        | align by block_size     |
+------+--------------------------------+-------------------------+ --> + (block_size * n)

+---------------------------------------+-------------------------+
|                                       |                         |
|                                       |                         |
| DONOT CARE CHUNK                      |                         |
|                                       |                         |
|                                       |                         |
+---------------------------------------+-------------------------+

+---------------------------------------+-------------------------+ --> partition_size - block_size
| Padding                               | block_size - 64         |
+---------------------------------------+-------------------------+ --> partition_size - 64
| AVB Footer                            | total 64                |
|                                       |                         |
|   - Footer Magic "AVBf"               |     4                   |
|   - Footer Major Version              |     4                   |
|   - Footer Minor Version              |     4                   |
|   - Original image size               |     8                   |
|   - VBMeta offset                     |     8                   |
|   - VBMeta size                       |     8                   |
|   - Padding                           |     28                  |
+---------------------------------------+-------------------------+ --> partition_size

5. boot in memory

       ┌────────────────────────────────────────┐
       │           kernel                       │
       ├──────────────────┬─────────────────────┤
       │                  │ vendor ramdisk 1    │
       │                  ├─────────────────────┤
       │                  │ vendor ramdisk 2    │
       │  vendor ramdisks ├─────────────────────┤
       │                  │   ...               │
       │                  ├─────────────────────┤
       │                  │ vendor ramdisk n    │
       ├──────────────────┴─────────────────────┤
       │  generic ramdisk (from init_boot/boot) │
       ├──────────────────┬─────────────────────┤
       │                  │parameters           │
       │                  ├─────────────────────┤
       │                  │param size  (4)      │
       │   bootconfig     ├─────────────────────┤
       │                  │param checksum (4)   │
       │                  ├─────────────────────┤
       │                  │bootconfig magic(12) │ --> "#BOOTCONFIG\n"
       └──────────────────┴─────────────────────┘
Kotlin
1
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Android_boot_image_editor
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