Android AB分区OTA升级说明
1. 概述¶
OTA升级即Over-the-Air upgrade，本文会大致介绍Android标准的OTA包包括整包（full OTA）和差分包（incremental OTA）的制作方法以及本地验证OTA升级的方法。
2. OTA包的制作¶
2.1 编译配置¶
在编译OTA包时，BoardConfig.mk中的$(AB_OTA_PARTITIONS)设定来决定要对哪些分区做OTA升级。一般需要将AOSP的所有分区都填入到该变量中。
2.2 编译dist¶
不论是制作整包还是差分包，都需要先将制作OTA包所需的镜像文件先编译出来：
source build/envsetup.sh lunch <device name> make dist DIST_DIR=dist_output
在AOSP执行上述命令后，会得到一个目录dist_output，接下制作OTA包会需要基于该目录。
2.3 制作整包¶
执行命令：
ota_from_target_files \
dist_output/<device name>_target_files.zip \
ota_update.zip
会得到ota_update.zip。
2.4 制作差分包¶
制作差分包和制作整包类似，差异在要多喂一个'基础包'给ota_from_target_files以用于和新的target_files差分得到差分包，形如：
ota_from_target_files \
-i last_target_files.zip \
dist_output/<device name>_target_files.zip \
incremental_ota_update.zip
会得到incremental_ota_update.zip。
3. 无缝升级验证¶
无缝升级即在系统运行的状态下将OTA包烧录到另一个slot。需要通过update_engine来完成OTA升级，主要有两种方式呼叫到update_engine：
- 在shell通过调用update_engine_clinet完成从升级
- APP通过UpdateEngine的applyPayload方法完成升级
3.1 使用update_engine_clinet验证¶
a> 编译出整包ota_update.zip
b> 解压ota_update.zip获得payload.bin和payload_properties.txt
xxxxxx:~/workspace/AOSP$ unzip ota_update.zip -d ota_update_decompress Archive: ota_update.zip signed by SignApk extracting: ota_update_decompress/META-INF/com/android/metadata extracting: ota_update_decompress/META-INF/com/android/metadata.pb extracting: ota_update_decompress/apex_info.pb extracting: ota_update_decompress/payload.bin extracting: ota_update_decompress/payload_properties.txt inflating: ota_update_decompress/META-INF/com/android/otacert
c> 检查当前设备所在的slot
PS C:\xxx> adb shell getprop ro.boot.slot_suffix _a
d> 将payload.bin文件push到data分区
PS C:\xxx> adb root restarting adbd as root PS C:\xxx> adb shell mkdir /data/temp PS C:\xxx> adb push .\ota_update_decompress\payload.bin /data/temp .\ota_update_decompress\payload.bin: 1 file pushed, 0 skipped. 6.1 MB/s (422765615 bytes in 66.130s)
e> 从payload_properties.txt取参数，调用update_engine_clinet完成OTA升级
在调用update_engine_clinet之前可以再开一个命令行窗口执行adb logcat -s update_engine观察update_engine的升级进度。
PS C:\xxx>> adb shell pioneer5_sdp:/ # update_engine_client --payload=file:///data/temp/payload.bin \ > --update \ > --headers="\ > FILE_HASH=k1VYZqDgsB0DJUw5hG2Rj9vg96bzE9DtY/CiYYpCuYI= > FILE_SIZE=422765615 > METADATA_HASH=IfvrrWCRjbzJMI5za1VHgsaGqg12UnyTvf4usdTBdWA= > METADATA_SIZE=44468" pioneer5_sdp:/ #
注：对于开启seLinux的板子可能需要先执行setenforce 0将seLinux切到permissive模式。
在另一个窗口中可以看到update_engine会打印形如下log展示进度:
02-09 01:25:22.737 350 350 I update_engine: [INFO:delta_performer.cc(115)] Completed 123/789 operations (15%), 109920256/422765615 bytes downloaded (26%), overall progress 20% 02-09 01:25:43.724 350 350 I update_engine: [INFO:delta_performer.cc(115)] Completed 176/789 operations (22%), 160661504/422765615 bytes downloaded (38%), overall progress 30% 02-09 01:26:07.740 350 350 I update_engine: [INFO:delta_performer.cc(115)] Completed 248/789 operations (31%), 211386368/422765615 bytes downloaded (50%), overall progress 40% 02-09 01:26:31.479 350 350 I update_engine: [INFO:delta_performer.cc(115)] Completed 313/789 operations (39%), 262127616/422765615 bytes downloaded (62%), overall progress 50% 02-09 01:26:55.912 350 350 I update_engine: [INFO:delta_performer.cc(115)] Completed 379/789 operations (48%), 312213504/422765615 bytes downloaded (73%), overall progress 60% 02-09 01:27:09.672 350 350 I update_engine: [INFO:delta_performer.cc(115)] Completed 490/789 operations (62%), 332742656/422765615 bytes downloaded (78%), overall progress 70% 02-09 01:27:16.097 350 350 I update_engine: [INFO:delta_performer.cc(115)] Completed 647/789 operations (82%), 332759040/422765615 bytes downloaded (78%), overall progress 80%
最终会看到形如下成功的log：
02-09 01:27:50.421 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(330)] Hashing partition 0 (boot) on device /dev/block/platform/soc/soc:emmc/by-name/boot_b 02-09 01:27:50.427 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(380)] Verity writes disabled on partition boot 02-09 01:27:50.734 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(436)] Hash of boot: qPqEV09LNCXxbgCuBZLiGRM8KFy+IGqvxqWGzJ/1mDk= 02-09 01:27:50.749 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(330)] Hashing partition 1 (dtbo) on device /dev/block/platform/soc/soc:emmc/by-name/dtbo_b 02-09 01:27:50.755 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(380)] Verity writes disabled on partition dtbo 02-09 01:27:50.762 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(436)] Hash of dtbo: AvTCoA5SNMaDcvFBEgLrlckITdd6yR5R9qFreokowI4= 02-09 01:27:50.768 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(330)] Hashing partition 2 (odm) on device /dev/block/platform/soc/soc:emmc/by-name/odm_b 02-09 01:27:50.774 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(380)] Verity writes disabled on partition odm 02-09 01:27:50.932 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(436)] Hash of odm: 9FZ3WRMTUcsn7iSWv/1FekiY65WvykZ89YeRZdRtMcQ= 02-09 01:27:50.942 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(330)] Hashing partition 3 (system) on device /dev/block/platform/soc/soc:emmc/by-name/system_b 02-09 01:27:50.948 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(380)] Verity writes disabled on partition system 02-09 01:28:14.876 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(436)] Hash of system: 5s+2+UIPmwSdJ9Nzm4197qkcqHlu6r6UX8cdAJQv544= 02-09 01:28:15.378 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(330)] Hashing partition 4 (vendor) on device /dev/block/platform/soc/soc:emmc/by-name/vendor_b 02-09 01:28:15.385 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(380)] Verity writes disabled on partition vendor 02-09 01:28:20.167 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(436)] Hash of vendor: O6/WFp4iXJDfGycYnAYUzyIfYWfxlPlpdAIGdl2K4Ao= 02-09 01:28:20.313 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(330)] Hashing partition 5 (vendor_boot) on device /dev/block/platform/soc/soc:emmc/by-name/vendor_boot_b 02-09 01:28:20.320 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(380)] Verity writes disabled on partition vendor_boot 02-09 01:28:20.569 350 350 I update_engine: [INFO:filesystem_verifier_action.cc(436)] Hash of vendor_boot: kLJ2SzMyS+Io/K+Vlo/+8WUOf8gIW17cwdINmc86sIk= 02-09 01:28:20.584 350 350 I update_engine: [INFO:action_processor.cc(116)] ActionProcessor: finished FilesystemVerifierAction with code ErrorCode::kSuccess 02-09 01:28:20.591 350 350 I update_engine: [INFO:action_processor.cc(143)] ActionProcessor: starting PostinstallRunnerAction 02-09 01:28:20.598 350 350 I update_engine: [INFO:dynamic_partition_control_android.cc(1057)] Skip FinishedSnapshotWrites() because /metadata is not mounted 02-09 01:28:20.619 350 350 I update_engine: [INFO:hardware_android.cc(291)] Device doesn't use avb, skipping setting vbmeta digest 02-09 01:28:20.628 350 350 E update_engine: UnmapAllSnapshots should never be called. 02-09 01:28:20.634 350 350 I update_engine: [INFO:postinstall_runner_action.cc(389)] Unmapped all partitions. 02-09 01:28:20.640 350 350 I update_engine: [INFO:postinstall_runner_action.cc(405)] All post-install commands succeeded 02-09 01:28:20.646 350 350 I update_engine: [INFO:action_processor.cc(116)] ActionProcessor: finished last action PostinstallRunnerAction with code ErrorCode::kSuccess 02-09 01:28:20.652 350 350 I update_engine: [INFO:update_attempter_android.cc(546)] Processing Done. 02-09 01:28:20.659 350 350 I update_engine: [INFO:update_attempter_android.cc(559)] Update successfully applied, waiting to reboot. 02-09 01:28:20.665 350 350 E update_engine: UnmapAllSnapshots should never be called. 02-09 01:28:20.674 350 350 I update_engine: [INFO:metrics_reporter_android.cc(159)] Current update attempt downloads 403 bytes data 02-09 01:28:20.685 350 350 I update_engine: [INFO:metrics_utils.cc(335)] Updated Marker = 1/1/1970 0:39:21 GMT
f> reboot重启，查看设备是否正常开机，和c步骤一样的方法查看设备当前是否处在另一个slot。