The
Android
Compatibility Definition Document (CDD) Updatable Software
requires devices to implement the
SystemUpdatePolicy
class. SystemUpdatePolicy lets the device owner (DO) app, if
present, control the installation of system updates.
Notify device owners
The over-the-air (OTA) client must notify device owner apps about
incoming OTA updates using a system API. The OTA client must also
include a timestamp recording when the OTA update first became
available. OTA clients can call
DevicePolicyManager.notifyPendingSystemUpdate(long updateReceivedTime, boolean isSecurityPatch)
to notify device owner apps. If the OTA client doesn’t know if an update
is a security patch, the OTA client can fall back to using
DevicePolicyManager.notifyPendingSystemUpdate(long updateReceivedTime).
If an update isn’t currently available, the OTA client reports this by
setting the updateReceivedTime argument to -1.
We recommend sending notifications whenever the OTA client polls the
OTA server, or when an OTA is pushed to the client. You can also send
out notifications more frequently.
System update policy
Android 9 enhances the ability for device owners to control updates by allowing device owners to postpone OTA updates for up to 90 days. Focusing on dedicated device (previously called COSU) solutions, this feature lets owners pause the OS version running on devices over critical periods, such as holidays.
To comply with the CDD, the OTA client must implement behavioral policies. The DO can set the following policies, which must be respected by the device system update subsystems:
Device owners can also
set
freeze periods (in Android 9 or later) that freeze the OS version
over critical periods, such as holidays or other busy times. The system
doesn't install OTA updates during a freeze period. We recommend using
SystemUpdatePolicy.InstallationOption (see
following section), however the OTA client can also call
SystemUpdatePolicy.getFreezePeriods()
to check if the device is in a freeze period.