3-24 Software Functional Overview
Global System State Definitions
Global system states (Gx states) apply to the entire system and are visible to the
user. The following are various system states:
G2/S5 – Soft Off
Power is removed from most of system components except Suspend wakeup
logic in PIC and RTC. Refer to the next section on wake up events.
G1 – Sleeping
n
CPU is in stop clock mode (core logic in stop clock mode also).
n
Clock chip is in Power down Mode.
n
VGA chip is in suspend mode, LCD power is removed.
n
PCMCIA chip is in sleep mode.
n
Hard disk is in sleep mode.
n
CD-ROM is in sleep mode.
n
Modem is in power down mode.
G0 – Working
This is a computer's state where the system dispatches user mode (application)
threads for execution. In this state, the devices (peripherals) power states are
dynamically changed. The user selects (through some user interface) various
performance/power characteristics of the system for optimal software
performance or battery life. The system responds to external events in real time.
It is neither safe nor recommended to disassemble the machine in this state.
Sleeping State Definitions
Sleeping states (Sx states) are types of sleeping states within the global sleeping
state, G1. The Sx states are briefly defined:
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) while the hardware maintains all system
context.
S2 – Sleeping State
The S2 sleeping state is a low wake-up latency sleeping state. This state is
similar to the S1 sleeping state except that the CPU and system cache context is
lost. The OS is responsible for maintaining the caches and CPU context. Control
starts from the processor's reset vector after the wake-up event.
