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diff --git a/doc/android/ab.txt b/doc/android/ab.txt deleted file mode 100644 index 9f37ed5c586..00000000000 --- a/doc/android/ab.txt +++ /dev/null @@ -1,67 +0,0 @@ -Android A/B updates -=================== - -Overview --------- - -A/B system updates ensures modern approach for system update. This feature -allows one to use two sets (or more) of partitions referred to as slots -(normally slot A and slot B). The system runs from the current slot while the -partitions in the unused slot can be updated [1]. - -A/B enablement --------------- - -The A/B updates support can be activated by specifying next options in -your board configuration file: - - CONFIG_ANDROID_AB=y - CONFIG_CMD_AB_SELECT=y - -The disk space on target device must be partitioned in a way so that each -partition which needs to be updated has two or more instances. The name of -each instance must be formed by adding suffixes: _a, _b, _c, etc. -For example: boot_a, boot_b, system_a, system_b, vendor_a, vendor_b. - -As a result you can use 'ab_select' command to ensure A/B boot process in your -boot script. This command analyzes and processes A/B metadata stored on a -special partition (e.g. "misc") and determines which slot should be used for -booting up. - -Command usage -------------- - - ab_select <slot_var_name> <interface> <dev[:part_number|#part_name]> - -for example: - - => ab_select slot_name mmc 1:4 - -or - - => ab_select slot_name mmc 1#misc - -Result: - - => printenv slot_name - slot_name=a - -Based on this slot information, the current boot partition should be defined, -and next kernel command line parameters should be generated: - - - androidboot.slot_suffix= - - root= - -For example: - - androidboot.slot_suffix=_a root=/dev/mmcblk1p12 - -A/B metadata is organized according to AOSP reference [2]. On the first system -start with A/B enabled, when 'misc' partition doesn't contain required data, -the default A/B metadata will be created and written to 'misc' partition. - -References ----------- - -[1] https://source.android.com/devices/tech/ota/ab -[2] bootable/recovery/bootloader_message/include/bootloader_message/bootloader_message.h |