User Guide

Software Functional Overview
3-12 FIC MD02 Service Manual
Global System State Definitions
Global system states (Gx states) apply to the entire system and are visible to the user.
Following is a list of the system states:
G0/S0 - Working:
A computer state where the system dispatches user mode (application) threads and they
execute. In this state, devices (peripherals) are dynamically having their power state
changed. The user will be able to select (through some user interface) various
performance/power characteristics of the system to have the software optimize for
performance or battery life. The system responds to external events in real time. It is not safe
to disassemble the machine in this state.
G1 - Sleeping:
A computer state where the computer consumes a small amount of power, user mode
threads are not being executed, and the system “appears” to be off (from an end user’s
perspective, the display is off, etc.). Latency for returning to the Working state varies on the
wakeup environment selected prior to entry of this state (for example, should the system
answer phone calls, etc.). Work can be resumed without rebooting the OS because large
elements of system context are saved by the hardware and the rest by system software. It is
not safe to disassemble the machine in this state.
G2/S5 - Soft Off:
A computer state where the computer consumes a minimal amount of power. No user
mode or system mode code is run. This state requires a large latency in order to return to
the Working state. The system’s context will not be preserved by the hardware. The system
must be restarted to return to the Working state. It is not safe to disassemble the machine.
G3 – Mechanical Off:
A computer state that is entered and left by a mechanical means. It is implied by the entry
of this off state through a mechanical means that the no electrical current is running through
the circuitry and it can be worked on without damaging the hardware or endangering the
service personnel. The OS must be restarted to return to the Working state. No hardware
context is retained. Except for the real time clock, power consumption is zero.
Sleeping State Definitions
Sleeping states (Sx states) are types of sleeping states within the global sleeping state, G1.
The Sx states are briefly defined below. For a detailed definition of the system behavior within
each Sx state, refer to ACPI specification section 7.5.2. For a detailed definition of the
transitions between each of the Sx states, refer to ACPI specification section 9.1.
S1 Sleeping State:
The S1 sleeping state is a low wake-up latency sleeping state. In this state, no system
context is lost (CPU or chip set) and hardware maintains all system context.
S3 Sleeping State:
The S3 sleeping state is a low wake-up latency sleeping state where all system context is
lost except system memory. CPU, cache, and chip set context are lost in this state.
Hardware maintains memory context and restores some CPU and L2 configuration context.
Control starts from the processor’s reset vector after the wake-up event.
S4 Sleeping State:
The S4 sleeping state is the lowest power, longest wake-up latency sleeping state
supported by ACPI. In order to reduce power to a minimum, it is assumed that the hardware
platform has powered off all devices. Platform context is saved in disk.
S5 Soft Off State:
The S5 state is similar to the S4 state except the OS does not save any context nor
enable any devices to wake the system. The system is in the “SOFT” off state and requires a
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