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/84cceb912bccd7cdd...
[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_a... [5] https://lore.kernel.org/r/all/20230914165615.1058529-17-sjg@chromium.org/ [6] https://software-dl.ti.com/processor-sdk-android/esd/AM62X/09_02_00/docs/and...
Signed-off-by: Mattijs Korpershoek mkorpershoek@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-v1-0-0c69d4457cc5@baylib...
--- 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,