Hi Mattijs,

On Thu, 13 Jun 2024 at 04:13, Mattijs Korpershoek
<mkorpersh...@baylibre.com> wrote:
>
> Android boot flow is a bit different than a regular Linux distro.
> Android relies on multiple partitions in order to boot.
>
> A typical boot flow would be:
> 1. Parse the Bootloader Control Block (BCB, misc partition)
> 2. If BCB requested bootonce-bootloader, start fastboot and wait.
> 3. If BCB requested recovery or normal android, run the following:
>    a. Get slot (A/B) from BCB
>    b. Run AVB (Android Verified Boot) on boot partitions
>    c. Load boot and vendor_boot partitions
>    d. Load device-tree, ramdisk and boot
>
> The AOSP documentation has more details at [1], [2], [3]
>
> This has been implemented via complex boot scripts such as [4].
> However, these boot script are neither very maintainable nor generic.
> Moreover, DISTRO_DEFAULTS is being deprecated [5].
>
> Add a generic Android bootflow implementation for bootstd.
>
> For this initial version, only boot image v4 is supported.
>
> This has been tested on sandbox using:
> $ ./test/py/test.py --bd sandbox --build -k test_ut
>
> This has also been tested on the AM62X SK EVM using TI's Android SDK[6]
> To test on TI board, the following (WIP) patch is needed as well:
> https://gitlab.baylibre.com/baylibre/ti/ti-u-boot/-/commit/84cceb912bccd7cdd7f9dd69bca0e5d987a1fd04
>
> [1] https://source.android.com/docs/core/architecture/bootloader
> [2] https://source.android.com/docs/core/architecture/partitions
> [3] https://source.android.com/docs/core/architecture/partitions/generic-boot
> [4] 
> https://source.denx.de/u-boot/u-boot/-/blob/master/include/configs/meson64_android.h
> [5] https://lore.kernel.org/r/all/20230914165615.1058529-17-...@chromium.org/
> [6] 
> https://software-dl.ti.com/processor-sdk-android/esd/AM62X/09_02_00/docs/android/Overview.html
>
> Signed-off-by: Mattijs Korpershoek <mkorpersh...@baylibre.com>
> ---
> Changes in v2:
> - Dropped patch 2/6 boot: android: Add image_android_get_version() (Igor)
> - Fixed multi-line comment style (Igor, Simon)
> - Added dependency on CMD_FASTBOOT for BOOTMETH_ANDROID (Igor)
> - Fixed various resource leaks (Igor)
> - Fixed bootmeth_priv dangling pointer on error cases (Igor)
> - Updated test instructions in commit message for patch 6/6
> - Added __weak impl of get_avendor_bootimg_addr() in patch 1 (dropped
>   Igor's review because of this change)
> - Added extra info in Kconfig to detail MMC limitation (Simon)
> - Fixed typo Bootmethod->Bootmeth (Simon)
> - Documented android_priv structure (Simon)
> - Demoted various messages from printf() to log_debug (Simon)
> - Fixed some lines too long (Simon)
> - Added function documentation to read_slotted_partition() (Simon)
> - Added some doc about avb extra_args being modified (Simon)
> - Link to v1: 
> https://lore.kernel.org/r/20240606-bootmeth-android-v1-0-0c69d4457...@baylibre.com
>
> ---
> Mattijs Korpershoek (5):
>       boot: android: Provide vendor_bootimg_addr in boot_get_fdt()
>       bootstd: Add bootflow_iter_check_mmc() helper
>       android: boot: Add set_abootimg_addr() and set_avendor_bootimg_addr()
>       bootstd: Add a bootmeth for Android
>       bootstd: Add test for bootmeth_android
>
>  MAINTAINERS               |   7 +
>  arch/sandbox/dts/test.dts |   8 +
>  boot/Kconfig              |  16 ++
>  boot/Makefile             |   2 +
>  boot/bootflow.c           |  12 +
>  boot/bootmeth_android.c   | 553 
> ++++++++++++++++++++++++++++++++++++++++++++++
>  boot/bootmeth_android.h   |  29 +++
>  boot/image-android.c      |   5 +
>  boot/image-fdt.c          |   2 +-
>  cmd/abootimg.c            |  10 +
>  configs/sandbox_defconfig |   2 +-
>  doc/develop/bootstd.rst   |   6 +
>  include/bootflow.h        |   9 +
>  include/image.h           |  14 ++
>  test/boot/bootflow.c      |  65 +++++-
>  test/py/tests/test_ut.py  |  76 +++++++
>  16 files changed, 811 insertions(+), 5 deletions(-)
> ---
> base-commit: f9886bc60f42d5bcfcfa4e474af7dc230400b6be
> change-id: 20240605-bootmeth-android-bfc8596e9367
>
> Best regards,
> --
> Mattijs Korpershoek <mkorpersh...@baylibre.com>
>

Thinking about this, I believe we should start having docs about the
individual bootmeths themselves.

Can you add a section about your new bootmeth? I will come up with a
patch for the others that I know about. Perhaps
doc/develop/bootstd.rst would be a suitable place for now?

Regards,
Simon

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