S0iX Ultra Low Power States

[Dennis Wassenberg <dennis.wassenberg@secunet.com>]

Hi,

I would like to know more about the Linux power management in
correlation to the Intel S0iX Ultra Low Power States.

Systems which have a Windows 8 Logo must support Connected Standby (or
InstantGo, however it is called). One of the requirements getting this
logo is that the ACPI firmware must not provide an S3 object in the root
of the namespace. This means that Linux can not use the S3 mode.

To archive a very low power consumption Microsoft uses the Ultra Low
Power States S0i1 and S0i3. Is there a way to use these low power states
in linux for Haswell/LynxPoint or Broadwell/Skylake platforms?

I read something about these states. Such that they can be activated
automatically but there are some preconditions (e.g. certain IO devices
have to put into a low power state, graphics off, only one CPU online,
...). If I enter the S1 Low Power State (with additional
disable_nonboot_cpus) all of these preconditions should be fulfilled?!
But I can not observe that the there is a power consumption less than 1
Watt.

Thank you & Best regards,

Dennis