==================================
ϡ
linux-2.6.13/Documentation/power/states.txt 
Ǥ
Ρ JF ץ < http://www.linux.or.jp/JF/ >
  2005/9/2
  Hiroshi.Suzuki < setter at reset dot jp >
  Masanori Kobayasi <zap03216 at nifty dot ne dot jp>
==================================

System Power Management States

ƥŸ

The kernel supports three power management states generically, though
each is dependent on platform support code to implement the low-level
details for each state. This file describes each state, what they are
commonly called, what ACPI state they map to, and what string to write
to /sys/power/state to enter that state

ͥϰŪ3ĤŸ֤򥵥ݡȤޤ
줾졢ƾ֤ؤκץåȥեॵݡȥɤ
¸ƤޤΥեϡƾ֤ǡ̤ǸƤӽФɤ ACPI 
֤ξ֤ˤʤ뤿ᡢɤʸ󤬡/sys/power/state ˽񤭹ޤ
Ƥޤ

State:		Standby / Power-On Suspend
ACPI State:	S1
String:		"standby"

:		Ե(Standby) / ž֤ǰ(Power-On Suspend)
ACPI :	S1
ʸ:		"standby"

This state offers minimal, though real, power savings, while providing
a very low-latency transition back to a working system. No operating
state is lost (the CPU retains power), so the system easily starts up
again where it left off. 

ξ֤ϡºݤˤϺǾ¤ξϤ󶡤ޤȤƤûԤ֤ǥƥ
ư֤᤹Ǥޤ֤ϼʤ (CPU Ÿ뤵Ƥ)
Τǡƥϡ߾֤ñ˺Ƶưޤ

We try to put devices in a low-power state equivalent to D1, which
also offers low power savings, but low resume latency. Not all devices
support D1, and those that don't are left on. 

ǥХ D1 Ͼ֤ˤ褦ȤޤޤϤˤʤޤ󤬡
֤ûǤ٤ƤΥǥХ D1 򥵥ݡȤƤʤΤǡ
Τ褦ʥǥХŸڤޤ

A transition from Standby to the On state should take about 1-2
seconds. 

Х֤顢Ư֤˰ܤޤǤˡ1-2äޤ

State:		Suspend-to-RAM
ACPI State:	S3
String:		"mem"

:		RAM ¸ư(Suspend-to-RAM)
ACPI :	S3
ʸ:		"mem"

This state offers significant power savings as everything in the
system is put into a low-power state, except for memory, which is
placed in self-refresh mode to retain its contents. 

ξ֤ϡƤ¸뤿Ἣʥեå⡼ɤˤʤäƤ
ƥह٤ƤϾ֤ˤϤ󶡤ޤ

System and device state is saved and kept in memory. All devices are
suspended and put into D3. In many cases, all peripheral buses lose
power when entering STR, so devices must be able to handle the
transition back to the On state. 

ƥȥǥХξ֤ϡݸ¸ޤ٤ƤΥǥХ
ϡߤD3 ˤʤޤ¿ξ硢٤ƤμեХ STR ˤʤȤ
ˡŸ򼺤ΤǡƯ֤ؤǽǤʤƤϤʤޤ

For at least ACPI, STR requires some minimal boot-strapping code to
resume the system from STR. This may be true on other platforms. 

ʤȤ ACPI ĶǤϡSTRϡƥब STR 뤿ᡢĤ
Ǿ¤Υ֡ȥȥåԥ󥰥ɤɬפȤޤϡ¾Υץåȥե
Ǥ⤢ƤϤޤǤ礦

A transition from Suspend-to-RAM to the On state should take about
3-5 seconds. 

Suspend-to-RAM 顢Ư֤˰ܤޤǤˡ3-5äޤ

State:		Suspend-to-disk
ACPI State:	S4
String:		"disk"

:		ǥ¸ư(Suspend-to-disk)
ACPI :	S4
ʸ:		"disk"


This state offers the greatest power savings, and can be used even in
the absence of low-level platform support for power management. This
state operates similarly to Suspend-to-RAM, but includes a final step
of writing memory contents to disk. On resume, this is read and memory
is restored to its pre-suspend state. 

ξ֤ϺǹξϤ󶡤ŸΤؤΥץåȥեॵݡ
ʤƤȤޤξ֤ϡSuspend-to-RAM Ȥ褯Ԥޤ
Ƥ򡢥ǥ˽񤭹ǽʳޤǤޤϡȤ
ɤ߹ޤ졢ϡξ֤ޤ

STD can be handled by the firmware or the kernel. If it is handled by
the firmware, it usually requires a dedicated partition that must be
setup via another operating system for it to use. Despite the
inconvenience, this method requires minimal work by the kernel, since
the firmware will also handle restoring memory contents on resume. 

ե०ޤϡͥϡSTD Ǥޤե०
ʤ顢̾¾Υڥ졼ƥ󥰥ƥबȤꤷϤΡѤΥѡ
ƥɬפȤޤǤ褽ˡե०ϡˡ
ƤⰷΤǡˡϥͥˤǾ¤νɬפȤޤ

If the kernel is responsible for persistently saving state, a mechanism 
called 'swsusp' (Swap Suspend) is used to write memory contents to
free swap space. swsusp has some restrictive requirements, but should
work in most cases. Some, albeit outdated, documentation can be found
in Documentation/power/swsusp.txt. 

ͥ뤬³ŪʾϾ֤ˤԤʤ顢å׶֤˥
񤭹िᡢ'swsusp' (åפ¸ư(Swap Suspend)) ȸƤֵ
Ȥޤswsusp ˤϡĤθŪ׵बޤۤȤɤξ
ưϤǤŤǤDocumentation/power/swsusp.txt 


Once memory state is written to disk, the system may either enter a
low-power state (like ACPI S4), or it may simply power down. Powering
down offers greater savings, and allows this mechanism to work on any
system. However, entering a real low-power state allows the user to
trigger wake up events (e.g. pressing a key or opening a laptop lid). 

٥֤ϥǥ˽񤭹ޤȡƥϡϾ (ACPI S4 Τ
) 뤫ñŸڤ뤫Τɤ餫ˤʤޤŸڤϡ
¿ˤʤ塢ɤʥƥǤ⤳εưޤ
ºݤϾ֤äƤȤϡ桼٥(㤨С
򲡤ȤåץȥåפΥե򳫤)ȯ뤳ȤǤޤ

A transition from Suspend-to-Disk to the On state should take about 30
seconds, though it's typically a bit more with the current
implementation. 

Suspend-to-Disk 顢ư֤˰ܤΤ 30äޤ
Ǥ⡢ߤμǤ̾⤦ޤ
