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clarification on system states RRS feed

  • Question

  • To my understanding there are six system power states defined as:

    S0 (fully on)

    S1, S2, S3, S4 (sleep)

    S5 (power off)

    within S0 (fully on) there are 2 subsets of S0 called S0ix (S0i1 and S0i3).

    S0i1 is a standby mode

    S0i3 is a sleep mode 

    So my question are:

    1) Why do you need a S0i1 and S0i3 power modes when you already have sleep modes S1-S4?

    2) Does S0, S0i1, S0i3, S2, S3, S4, S5 all coexist together in one system or does some systems support S0ix and some dont?

    3) Does S0i1 and S0i3 replace S1-S4?

    4) What power modes does a connected Standby system support?

    5) What power modes does a non compliant connected standby system support. 



    Monday, September 23, 2013 4:19 PM

Answers

  • S0i1 and S0i3 are Intel marketing terms. They don't have a defined meaning within Windows, nor within the ACPI specification, which is where S0 through S5 are defined.

    With that said, what Intel is trying to convey here is that the exact same hardware that they built for machines with a '90s era view of laptop use (the machine sleeps, hibernates, etc.) can be repurposed with a few tweaks to meet more modern views of machine usage, where the machine seems to be always on, even when the screen is off.  Microsoft calls this "Connected Standby."  The ACPI specification needs no particular name for it, as the machine just stays in S0 all the time, though sometimes the screen is off and other parts of the machine are in low-power states too.

    S0i1 puts the processor and the machine as a whole into a state very similar to S1 and S0i3 puts the machine into a state very similar to S3.

    The major difference in hardware relates to wake signals.  Devices like a wire-attached Ethernet NIC might trigger a wake signal in S0 when a cable is plugged in, and a wake signal in S3 when a particular packet arrives over that cable.

    In a Connected Standby machine, the expectation is that your e-mail will arrive while the system is sleeping (at least if you use Windows Mail instead of Outlook, which is a Win32 app which can't receive updates in CS) and your music will continue to play (at least if you use Xbox Music rather than Media Player, which is a Win32 app -- you get the pattern here.)  To accomplish the task of remaining connected enough to continue to receive e-mail, the WiFi NIC needs to support offloading of a few TCP connections to keep them alive while the rest of the machine dozes.  When data comes in over those, it triggers its wake signal and the machine runs code long enough to buffer the message.

    So, to directly answer your questions:

    1) If you want an always-connected usage pattern, S1 through S4 don't get that for you.

    2) Physically, these things can coexist and you'll see machines that support Connected Standby and also run Windows 7, which only supports S0 through S5.  In practice, the sorts of machine designs that can support long periods of Connected Standby also have bus architectures (like I2C-attached keyboards and touchscreens) that aren't well supported in Windows 7.  Windows 8 and 8.1 either support the CS mode of operation or the older laptop-style mode, but not both at the same time.  You'll find switches in the BIOS for machines that can go either way.

    4) CS systems support "on" and "off" where "on" means that it dozes when you're not using it.  "Off" means entirely off and you'll have to boot from scratch the next time you use the machine.  "On" is S0.  "Off" is S5.

    5) This question is a little absurd.  It's like asking "what laws does a criminal respect?"

    - Jake Oshins

    Windows Kernel Team

    Monday, September 23, 2013 5:17 PM

All replies

  • Windows traditionally had power states S0 to S5 see http://msdn.microsoft.com/en-us/library/windows/hardware/ff564571(v=vs.85).aspx   I've assumed that the S0i1 and S0i3 states that Intel has created will be mapped into the standard states, but until Microsoft says what they are doing you probably should not worry about it.


    Don Burn Windows Filesystem and Driver Consulting Website: http://www.windrvr.com Blog: http://msmvps.com/blogs/WinDrvr

    Monday, September 23, 2013 4:24 PM
  • S0i1 and S0i3 are Intel marketing terms. They don't have a defined meaning within Windows, nor within the ACPI specification, which is where S0 through S5 are defined.

    With that said, what Intel is trying to convey here is that the exact same hardware that they built for machines with a '90s era view of laptop use (the machine sleeps, hibernates, etc.) can be repurposed with a few tweaks to meet more modern views of machine usage, where the machine seems to be always on, even when the screen is off.  Microsoft calls this "Connected Standby."  The ACPI specification needs no particular name for it, as the machine just stays in S0 all the time, though sometimes the screen is off and other parts of the machine are in low-power states too.

    S0i1 puts the processor and the machine as a whole into a state very similar to S1 and S0i3 puts the machine into a state very similar to S3.

    The major difference in hardware relates to wake signals.  Devices like a wire-attached Ethernet NIC might trigger a wake signal in S0 when a cable is plugged in, and a wake signal in S3 when a particular packet arrives over that cable.

    In a Connected Standby machine, the expectation is that your e-mail will arrive while the system is sleeping (at least if you use Windows Mail instead of Outlook, which is a Win32 app which can't receive updates in CS) and your music will continue to play (at least if you use Xbox Music rather than Media Player, which is a Win32 app -- you get the pattern here.)  To accomplish the task of remaining connected enough to continue to receive e-mail, the WiFi NIC needs to support offloading of a few TCP connections to keep them alive while the rest of the machine dozes.  When data comes in over those, it triggers its wake signal and the machine runs code long enough to buffer the message.

    So, to directly answer your questions:

    1) If you want an always-connected usage pattern, S1 through S4 don't get that for you.

    2) Physically, these things can coexist and you'll see machines that support Connected Standby and also run Windows 7, which only supports S0 through S5.  In practice, the sorts of machine designs that can support long periods of Connected Standby also have bus architectures (like I2C-attached keyboards and touchscreens) that aren't well supported in Windows 7.  Windows 8 and 8.1 either support the CS mode of operation or the older laptop-style mode, but not both at the same time.  You'll find switches in the BIOS for machines that can go either way.

    4) CS systems support "on" and "off" where "on" means that it dozes when you're not using it.  "Off" means entirely off and you'll have to boot from scratch the next time you use the machine.  "On" is S0.  "Off" is S5.

    5) This question is a little absurd.  It's like asking "what laws does a criminal respect?"

    - Jake Oshins

    Windows Kernel Team

    Monday, September 23, 2013 5:17 PM

  • 4) CS systems support "on" and "off" where "on" means that it dozes when you're not using it.  "Off" means entirely off and you'll have to boot from scratch the next time you use the machine.  "On" is S0.  "Off" is S5.

    - Jake Oshins

    Windows Kernel Team

    It sounds like you are saying that in the Connected Standby world S0ix does not have any meaning. Please confirm.

    It also sounds like you are saying that Connected Standby does not follow the traditional ACPI system states of S0, S1, S2, S3, S4, S5 as well.  The Connected Standby system is:

    1) On while in use

    OR

    2) Dozes off while not in use but stays connected to the network

    OR

    3) OFF

    Please confirm

    Tuesday, September 24, 2013 2:18 PM