Lines Matching +full:use +full:- +full:ram +full:- +full:code
1 .. SPDX-License-Identifier: GPL-2.0
13 Sleep states are global low-power states of the entire system in which user
14 space code cannot be executed and the overall system activity is significantly
28 Suspend-to-Idle
29 ---------------
31 This is a generic, pure software, light-weight variant of system suspend (also
34 I/O devices into low-power states (possibly lower-power than available in the
38 The system is woken up from this state by in-band interrupts, so theoretically
43 or :ref:`suspend-to-RAM <s2ram>`, or it can be used in addition to any of the
50 -------
58 I/O devices into low-power states, which is done for :ref:`suspend-to-idle
59 <s2idle>` too, nonboot CPUs are taken offline and all low-level system functions
61 allow more energy to be saved relative to :ref:`suspend-to-idle <s2idle>`, but
65 reduced relative to :ref:`suspend-to-idle <s2idle>` and it may be necessary to
70 core system suspend subsystem. On ACPI-based systems this state is mapped to
75 Suspend-to-RAM
76 --------------
79 energy savings as everything in the system is put into a low-power state, except
80 for memory, which should be placed into the self-refresh mode to retain its
83 take place depending on the platform capabilities. In particular, on ACPI-based
86 more low-level components that are not directly controlled by the kernel.
89 suspended and put into low-power states. In many cases, all peripheral buses
93 On ACPI-based systems S2RAM requires some minimal boot-strapping code in the
98 relative to :ref:`suspend-to-idle <s2idle>` and :ref:`standby <standby>` and it
104 suspend subsystem. On ACPI-based systems it is mapped to the S3 system state
110 -----------
112 This state (also referred to as Suspend-to-Disk or STD) offers the greatest
113 energy savings and can be used even in the absence of low-level platform support
114 for system suspend. However, it requires some low-level code for resuming the
124 is written out and finally the system goes into the target low-power state in
129 special low-power state (like ACPI S4), or it may simply power down itself.
131 any system. However, entering a special low-power state may allow additional
144 the special architecture-specific low-level code is needed. Finally, the
145 image kernel restores the system to the pre-hibernation state and allows user
150 for the given CPU architecture includes the low-level code for system resume.
169 :ref:`hibernation <hibernation>`, :ref:`suspend-to-idle <s2idle>` and
183 and "deep". The "s2idle" string always represents :ref:`suspend-to-idle
185 :ref:`standby <standby>` and :ref:`suspend-to-RAM <s2ram>`,
197 This file controls the operating mode of hibernation (Suspend-to-Disk).
204 Put the system into a special low-power state (e.g. ACPI S4) to
224 the hibernation image and continue. Otherwise, use the image
248 It can be written a string representing a non-negative integer that will
249 be used as a best-effort upper limit of the image size, in bytes. The
257 around 2/5 of the available RAM size by default.
275 :ref:`suspend-to-idle <s2idle>` state. The first one is to write "freeze"
282 system go into the :ref:`suspend-to-RAM <s2ram>` state (write "deep" into
287 supporting :ref:`suspend-to-RAM <s2ram>`) or "s2idle", but it can be overridden
290 default may be "s2idle" even if :ref:`suspend-to-RAM <s2ram>` is supported in