Support for Platform Standby (S0i3) Entry and Exit

Linux system can be forced to a low power state by writing a state value to /sys/power/state entry. Ref-OS-IoT supports “freeze” state where the system is put into S0ix state and all OS timer activities are suspended. The system wakes up from this state only for certain wake signals like keyboard/mouse event, RTC event, uSD card connection/disconnection, etc.

To force the system into suspend state:

echo freeze > /sys/power/state

In case all runtime pm conditions are met (for instance, all CPUs are in deepest power save state) and all gating devices are in D3 state, the system can also enter the S0ix state automatically between wake events (e.g. timer events).

For more complete information about compiler optimizations, see our Optimization Notice.