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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: 3.a. Get slot (A/B) from BCB 3.b. Run AVB (Android Verified Boot) on boot partitions 3.c. Load boot and vendor_boot partitions 3.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. [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-sjg@chromium.org/ Reviewed-by: Simon Glass <sjg@chromium.org> Reviewed-by: Julien Masson <jmasson@baylibre.com> Tested-by: Guillaume La Roque <glaroque@baylibre.com> Signed-off-by: Mattijs Korpershoek <mkorpershoek@baylibre.com>
29 lines
822 B
C
29 lines
822 B
C
/* SPDX-License-Identifier: GPL-2.0+ */
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/*
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* Bootmethod for Android
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*
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* Copyright (C) 2024 BayLibre, SAS
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* Written by Mattijs Korpershoek <mkorpershoek@baylibre.com>
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*/
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enum android_boot_mode {
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ANDROID_BOOT_MODE_NORMAL = 0,
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/*
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* Android "recovery" is a special boot mode that uses another ramdisk.
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* It can be used to "factory reset" a board or to flash logical partitions
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* It operates in 2 modes: adb or fastbootd
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* To enter recovery from Android, we can do:
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* $ adb reboot recovery
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* $ adb reboot fastboot
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*/
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ANDROID_BOOT_MODE_RECOVERY,
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/*
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* Android "bootloader" is for accessing/reflashing physical partitions
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* Typically, this will launch a fastboot process in U-Boot.
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* To enter "bootloader" from Android, we can do:
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* $ adb reboot bootloader
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*/
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ANDROID_BOOT_MODE_BOOTLOADER,
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};
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