This patch series adds support for Android A/B boot process [1].
Main steps of A/B boot process are:
- A/B metadata integrity check
- looking for the current slot (where the system should be
booting from)
- getting the name of the current boot partition (boot_a or boot_b)
and loading the corresponding Android boot image
- getting the name of the current system partition (system_a or
system_b) and passing of its full name via kernel command line
(like 'root=/dev/mmcblk1p11')
- passing current slot via kernel command line (like
'androidboot.slot_suffix=_a') and via A/B metadata (e.g. via
misc partition)
- A/B metadata processing: setting the boot success flag for
current slot, handling the retry counter, etc
A/B metadata is organized according to Android reference [2] and stored
on 'misc' partition. On the first A/B boot process, when 'misc'
partition doesn't contain required data, default A/B metadata will be
created and stored in 'misc' partition. In the end of the Android boot,
'update_verifier' and 'update_engine' services are processing the
A/B metadata through the Boot Control HAL. To confirm the boot was
successful using current slot, "boot success" flag must be set on
Android side.
To enable Android A/B support in U-Boot:
1. Set the following config options:
CONFIG_ANDROID_AB=y
CONFIG_CMD_ANDROID_AB_SELECT=y
2. Change the disk layout so that it has sloted boot partitions.
E.g. instead of 'boot' and 'system' partitions there should be
'boot_a', 'boot_b', 'system_a' and 'system_b' partitions.
To be able to actually test this patch series, the A/B features must
be implemented and enabled in Android as well (see [1] for details).
Documentation and corresponding test for A/B boot is present here. The
last patch in this series integrates A/B boot support on AM57xx based
boards (though it's not enabled by default). Future users of A/B boot
feature can use it as a reference.
This series is a part of previous submission [3] by Alex Deymo. It
contains only A/B feature that was stripped out from there with some
modifications for using with "bootm" command preferred in upstream.
[1] https://source.android.com/devices/tech/ota/ab/ab_implement
[2]
bootable/recovery/bootloader_message/include/bootloader_message/bootloader_message.h
[3] https://lists.denx.de/pipermail/u-boot/2017-April/285841.html
Ruslan Trofymenko (7):
cmd: part: Add 'number' sub-command
disk: part: Extend API to get partition info
common: Implement A/B metadata
cmd: Add 'android_ab_select' command
test/py: Add base test case for A/B updates
doc: android: Add simple guide for A/B updates
env: am57xx: Implement A/B boot process
cmd/Kconfig | 11 ++
cmd/Makefile | 1 +
cmd/android_ab_select.c | 53 +++++++
cmd/part.c | 16 +-
common/Kconfig | 10 ++
common/Makefile | 1 +
common/android_ab.c | 278 +++++++++++++++++++++++++++++++++++
configs/sandbox_defconfig | 2 +
disk/part.c | 68 +++++++++
doc/README.android-ab | 67 +++++++++
include/android_ab.h | 34 +++++
include/android_bootloader_message.h | 164 +++++++++++++++++++++
include/environment/ti/boot.h | 44 +++++-
include/part.h | 21 +++
test/py/tests/test_ab.py | 74 ++++++++++
15 files changed, 839 insertions(+), 5 deletions(-)
create mode 100644 cmd/android_ab_select.c
create mode 100644 common/android_ab.c
create mode 100644 doc/README.android-ab
create mode 100644 include/android_ab.h
create mode 100644 include/android_bootloader_message.h
create mode 100644 test/py/tests/test_ab.py
--
2.7.4
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