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| author | Mattijs Korpershoek | 2024-07-10 10:40:05 +0200 |
|---|---|---|
| committer | Tom Rini | 2024-07-18 13:51:30 -0600 |
| commit | 125d9f3306ea4bc8888dc991ae3aa87327b0d522 (patch) | |
| tree | 1070bcb520507e4c549a68cbb81e0018fecdaa8d /doc | |
| parent | a525656c5ba69d307864c4de14e911384cc7dc0c (diff) | |
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>
Diffstat (limited to 'doc')
| -rw-r--r-- | doc/develop/bootstd.rst | 6 |
1 files changed, 6 insertions, 0 deletions
diff --git a/doc/develop/bootstd.rst b/doc/develop/bootstd.rst index 34631089ae0..bdda90fae3f 100644 --- a/doc/develop/bootstd.rst +++ b/doc/develop/bootstd.rst @@ -95,6 +95,7 @@ bootflows. Note: it is possible to have a bootmeth that uses a partition or a whole device directly, but it is more common to use a filesystem. +For example, the Android bootmeth uses a whole device. Note that some bootmeths are 'global', meaning that they select the bootdev themselves. Examples include VBE and EFI boot manager. In this case, they @@ -277,6 +278,9 @@ script_offset_f script_size_f Size of the script to load, e.g. 0x2000 +vendor_boot_comp_addr_r + Address to which to load the vendor_boot Android image, e.g. 0xe0000000 + Some variables are set by script bootmeth: devtype @@ -418,6 +422,7 @@ Bootmeth drivers are provided for: - EFI boot using bootefi from disk - VBE - EFI boot using boot manager + - Android bootflow (boot image v4) Command interface @@ -786,6 +791,7 @@ To do Some things that need to be done to completely replace the distro-boot scripts: - implement extensions (devicetree overlays with add-on boards) +- implement legacy (boot image v2) android boot flow Other ideas: |