IFB Power Management
16-4
Intel® 460GX Chipset Software Developer’s Manual
16.2.5
ACPI Bits Not Implemented by IFB
Many ACPI registers and bits are optional, and do not have to be implemented for a standard
desktop design.
Table 16-4
shows which bits are not implemented by IFB.
16.2.6
Entry/Exit for the S4 and S5 States
As part of the ACPI spec, as well as PC’97 specs, all new desktop systems must support the SOFT
OFF (ACPI S5) state. The state will have the following characteristics:
•
No system context preserved.
•
Power shut to all subsystems except RTC and wake logic (typically just the power button).
•
All system clocks shut except 32.768 kHz internal to the RTC logic.
There are two ways to enter the Soft-Off state:
1. The CPU will write a value of 100 to the SLP_TYP field and set the SLP_EN bit to 1.
2. The power button is pressed for 4 seconds. This is known as a power-button override event.
In either case, the entry to the Soft-Off state is done by asserting the SUSB and SUSC signals. This
will cause the power to be shut and the PWROK signal is assumed to go low.
Note also that there is no need to enter the Soft-Off state gracefully. The STPCLK# and
SUS_STAT# signals don’t have to be asserted in any particular order, since the CPU and memory
controller will be reset after the system is rebooted.
Table 16-4. ACPI Bits Not Implemented in IFB
Offset
Register Name/Function
Comment
00-01h
PM1 Status
4
BM_STS
Not needed for standard desktop.
04-05h
PM1 Control
1
BM_RLD
Stopping CPU clock not supported.
0C-0Dh
General Purpose Status
9
GPI_STS
GPI not needed for desktop
11
LID_STS
Lid not needed for desktop
OE-0Fh
General Purpose Enables
9
GPI_EN
GPI not needed for desktop
11
LID_EN
Lid not needed for desktop
15h
Level 3 Register
Power state not needed for desktop
Summary of Contents for 460GX
Page 1: ...Intel 460GX Chipset System Software Developer s Manual June 2001 Document Number 248704 001 ...
Page 20: ...Introduction 1 8 Intel 460GX Chipset Software Developer s Manual ...
Page 80: ...System Architecture 3 8 Intel 460GX Chipset Software Developer s Manual ...
Page 90: ...System Address Map 4 10 Intel 460GX Chipset Software Developer s Manual ...
Page 98: ...Memory Subsystem 5 8 Intel 460GX Chipset Software Developer s Manual ...
Page 146: ...AGP Subsystem 7 16 Intel 460GX Chipset Software Developer s Manual ...
Page 170: ...IFB Register Mapping 9 6 Intel 460GX Chipset Software Developer s Manual ...
Page 190: ...IFB Usage Considerations 10 20 Intel 460GX Chipset Software Developer s Manual ...
Page 232: ...LPC FWH Interface Configuration 11 42 Intel 460GX Chipset Software Developer s Manual ...
Page 244: ...IDE Configuration 12 12 Intel 460GX Chipset Software Developer s Manual ...
Page 258: ...Universal Serial Bus USB Configuration 13 14 Intel 460GX Chipset Software Developer s Manual ...
Page 270: ...SM Bus Controller Configuration 14 12 Intel 460GX Chipset Software Developer s Manual ...
Page 288: ...PCI LPC Bridge Description 15 18 Intel 460GX Chipset Software Developer s Manual ...
Page 294: ...IFB Power Management 16 6 Intel 460GX Chipset Software Developer s Manual ...