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doc: android: add documentation for v3, v4 boot image header

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Update the Android documentation to describe version 3 and 4 of boot
image header.

Signed-off-by: Safae Ouajih <souajih@baylibre.com>
Reviewed-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Tested-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
This commit is contained in:
Safae Ouajih 2023-02-06 00:50:19 +01:00 • committed by Tom Rini
parent 57e405e1f4
commit 3e7b71c728
1 changed files with 12 additions and 1 deletions
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13
doc/android/boot-image.rst
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@ -27,11 +27,21 @@ next image headers:
* v2: used in devices launched with Android 10; adds ``dtb`` field, which * v2: used in devices launched with Android 10; adds ``dtb`` field, which
references payload containing DTB blobs (either concatenated one after the references payload containing DTB blobs (either concatenated one after the
other, or in Android DTBO image format) other, or in Android DTBO image format)
* v3: used in devices launched with Android 11; adds ``vendor_boot`` partition
and removes the second-stage bootloader and recovery image support. The new
``vendor_boot`` partition holds the device tree blob (DTB) and a vendor ramdisk.
The generic ramdisk in ``boot`` partition is loaded immediately following
the vendor ramdisk.
* v4: used in devices launched with Android 12; provides a boot signature in boot
image header, supports multiple vendor ramdisk fragments in ``vendor_boot``
partition. This version also adds a bootconfig section at the end of the vendor
boot image, this section contains boot configuration parameters known at build time
(see [9]_ for details).
v2, v1 and v0 formats are backward compatible. v2, v1 and v0 formats are backward compatible.
The Android Boot Image format is represented by The Android Boot Image format is represented by
:c:type:`struct andr_img_hdr <andr_img_hdr>` in U-Boot, and can be seen in :c:type:`struct andr_image_data <andr_image_data>` in U-Boot, and can be seen in
``include/android_image.h``. U-Boot supports booting Android Boot Image and also ``include/android_image.h``. U-Boot supports booting Android Boot Image and also
has associated command has associated command
@ -153,3 +163,4 @@ References
.. [6] :doc:`avb2` .. [6] :doc:`avb2`
.. [7] https://source.android.com/devices/bootloader .. [7] https://source.android.com/devices/bootloader
.. [8] https://connect.linaro.org/resources/san19/san19-217/ .. [8] https://connect.linaro.org/resources/san19/san19-217/
.. [9] https://source.android.com/docs/core/architecture/bootloader/implementing-bootconfig