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After the OTA update is successful, AOSP marks the target slot B to active. Now, when the next boot happens, the device boots from slot B. Now my question is how does the bootloader or android come to know it has to boot from that active slot? Does it read from any ro property or from something else?

srjhnd
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swetabh suman
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1 Answers1

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This is manufacturer/vendor specific and not specified by Android. A vendor has to provide an implementation of the android.hardware.boot@1.0 HAL in which he has to decide how to implement the setActiveBootSlot call coming from the update_engine.

The bootloader (also provided by the vendor) then has to implement means to get the active boot slot.

A vendor could for example decide to store the current active boot slot in the /misc partition

See https://source.android.com/devices/tech/ota/ab/ab_implement.html

Simpl
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  • This ro.boot.slot_suffix is only be modified by kernel cmdline argument.and its value is set by kernel cmdline property ie androidboot.slot_suffix – swetabh suman Jul 29 '19 at 10:54