bootstd: Add a bootmeth for Android
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>
diff --git a/boot/Kconfig b/boot/Kconfig
index ffcae84..4a17dea 100644
--- a/boot/Kconfig
+++ b/boot/Kconfig
@@ -494,6 +494,23 @@
EFI bootmgr, since they take full control over which bootdevs are
selected to boot.
+config BOOTMETH_ANDROID
+ bool "Bootdev support for Android"
+ depends on X86 || ARM || SANDBOX
+ depends on CMDLINE
+ select ANDROID_AB
+ select ANDROID_BOOT_IMAGE
+ select CMD_BCB
+ select CMD_FASTBOOT
+ select PARTITION_TYPE_GUID
+ select PARTITION_UUIDS
+ help
+ Enables support for booting Android using bootstd. Android requires
+ multiple partitions (misc, boot, vbmeta, ...) in storage for booting.
+
+ Note that only MMC bootdevs are supported at present. This is caused
+ by AVB being limited to MMC devices only.
+
config BOOTMETH_CROS
bool "Bootdev support for Chromium OS"
depends on X86 || ARM || SANDBOX