LinuxQuestions.org - ACPI sleep states

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ACPI sleep states

i'm trying to get my acpi sleep states working, but i'm not sure exactly how they're supposed to behave, so i dont know if what happens when i do an "echo "disk" > /sys/power/state", for example. so, i'm going to list the states that i have available, what happens when i try to use them. i'm hoping somebody can tell me if it's working and what is supposed to happen when i enter these states.

screen blanking:
i've heard you can do this: "xset +dpms and then $ xset dpms force off" to turn a laptop's backlight off, but mine doesnt seem to actually go off. the screen goes blank, but i can kind of tell that there's a light on behind it. there's definitely a difference between this and when it's been shutdown.

S1: I "echo "standby" > /sys/power/state".
if i'm in X, the screen goes black and then goes right back to normal.
if i'm in the console, nothing happens, shouldnt something happen?

S3: I "echo "mem" > /sys/power/state".
It goes to the console, says some stuff about saving state, then the the screen goes blank. sometimes the "power" led light sometimes it stays on, sometimes it goes off and comes back on when i press a button. it's not supposed to shut it down, right? so why is my light going off? also, it doesn't actually wake up. i'm not sure how i would wake it up though. would pressing a keyboard button, the mouse buttons, or the power button do it? none of that has worked.

S4: I "echo "disk" > /sys/power/state".
It goes to console, saves the state to disk, then shuts down. my power led actually goes off and it's totally shut down. when i resume, i have to hit the power button and it goes through the startup process again. is that supposed to happen? from the description of S4, it's supposed to be pretty much like S3 except it saves the state to disk, right? "hibernation" in windows never turned my power led off. if this is what S4 is supposed to do, whats the difference between S4 and "Software Suspend"?

S5:

Quote:

S5 - "Soft Off"

System is shut down, however some power may be supplied to certain devices to generate a wake event, for example to support automatic startup from a LAN or USB device. In Microsoft Windows, the "Shut down" command is associated with this state. Mechanical power can usually be removed or restored with no ill effects.

My computer doesn't seem to support it, but it sounds very similar to what happens when i try to use S4. When you use S5, do you have to go thru the whole startup process(lilo and stuff) when you resume? would it be possible to wake my computer up from S4 remotely over my lan? that would be so cool.

Re: ACPI sleep states

Quote:

Originally posted by slinky2004
screen blanking:
i've heard you can do this: "xset +dpms and then $ xset dpms force off" to turn a laptop's backlight off, but mine doesnt seem to actually go off. the screen goes blank, but i can kind of tell that there's a light on behind it. there's definitely a difference between this and when it's been shutdown.

When the backlight on a notebook burns out you'll get exactly what you seem to be describing - a faint image of the desktop on the screen. It seems to me that this is doing exactly what it's supposed to - just turn off the backlight, nothing else.

Quote:

S1: I "echo "standby" > /sys/power/state".
if i'm in X, the screen goes black and then goes right back to normal.
if i'm in the console, nothing happens, shouldnt something happen?

As I understand it you have to add the parameter '-n' with the string "standby", so the command would be:

Code:

echo -n "standby" > /sys/power/state

Same with S3 and S4.

Quote:

S5:
My computer doesn't seem to support it, but it sounds very similar to what happens when i try to use S4. When you use S5, do you have to go thru the whole startup process(lilo and stuff) when you resume? would it be possible to wake my computer up from S4 remotely over my lan? that would be so cool.

S5 is just like a shutdown except it maintains minimal power in order to read wake-on-lan type signals. I'm not sure that it's possible to enable this state with a 2.6 kernel, unless a regular shutdown is now the same as S5. You ought to be able to wake the computer up from state S4 without actually restarting, and would be a nice way to suspend every night - restarting would be very quick.

How do you wake it up? I can't for some reason

Thanks

It would depend on hardware support.