AMD-761 Datasheet, PDF (197/264 Pages) Advanced Micro Devices – AMD-761-TM System Controller Software/BIOS Design Guide

24081D—February 2002
Preliminary Information
AMD-761™ System Controller Software/BIOS Design Guide
4 Power Management
This chapter provides the BIOS requirements for the
AMD-761™ system controller’s various power management
states. The AMD-761 system controller includes logic
specifically for the support of the following Advanced
Configuration and Power Interface (ACPI) states:
„ C2 Stop Grant (probed)
„ S1 Power-On Suspend
„ S3 Suspend to RAM
This chapter discusses the BIOS requirements for the AMD-761
system controller only, and does not include special
requirements for the processor, Southbridge, or the operating
system support of each power management state.
Note: To accommodate the S3 state, some of the AMD-761 system
controller register bits are not initialized to a known value
at power-on with the RESET# signal. The BIOS must
initialize all of these bits for proper operation, especially
when enabling power management features as described in
this section. BIOS must also perform a save and restore of
all relevant configuration bits in the processor and chipset
to support the Suspend to RAM feature.
Table 31 on page 186 summarizes the various features required
by the AMD-761 system controller to support the different
power management states.
Note: ACPI C3 state is not supported by the AMD-761 system
controller, and the BIOS must not declare C3 support to the
operating system through the Fixed ACPI Description Table.
The BIOS should declare the following values:
• A value of 0 in the PM2_CNT_BLK field in the Fixed
ACPI Description Table (FADT)
• A value of 0 in the PM2_CNT_LEN field of the FADT
• A value of 0 in the X_PM2_CNT_BLK field of the FADT
if this ACPI 2.0 extension is supported by the operating
system.
Chapter 4
Power Management
185