Chapter 6: Power Management And Acpi; Acpi Power Management Implementation; Figure 6-1 Linked List For Capabilities; Table 6-1 Acpi States Supported By The Rx881 - AMD RX881 Data Book

6.1

ACPI Power Management Implementation

This chapter describes the support for ACPI power management provided by the RX881. The RX881 Northbridge
supports ACPI Revision 2.0. The hardware, system BIOS, video BIOS, and drivers of the RX881 have all the logic
required for meeting the power management specifications of PC2001, OnNow, and the Windows Logo Program and
Device Requirements version 2.1.
supported by the RX881.
management scheme of the RX881.

Table 6-1 ACPI States Supported by the RX881

ACPI State
Processor States:
S0/C0: Working State
S0/C1: Halt
S0/C2: Stop Grant
Caches Snoopable
S0/C3/C1e: Stop Grant
Caches Snoopable
System States:
S3: Standby
Suspend to RAM
S4: Hibernate
Suspend to Disk
S5: Soft Off
G3: Mechanical Off
Note: Also supported are additional processor power states that are not part of the ACPI specification, e.g. C1E (C1
Enhanced) and C3 pop-up. Please refer to the and the RS880 ASIC Family Register Programming Requirements, order#
46141, for more information.

Table 6-2 ACPI Signal Definitions

Signal Name
ALLOW_LDTSTOP
LDTSTOP#
POWERON#
RESET#
© 2011 Advanced Micro Devices, Inc.
Proprietary
Table 6-1, "ACPI States Supported by the RX881,"
Table 6-2, "ACPI Signal Definitions,"
Working State. The processor is executing instructions.
CPU Halt state. No instructions are executed. This state has the lowest latency on resume and contributes
minimum power savings.
Stop Grant or Cache Snoopable CPU state. This state offers more power savings but has a higher latency
on resume than the C1 state.
Processor is put into Stop Grant state. Caches are still snoopable. The HyperTransport™ link may be
disconnected and put into a low power state. System memory may be put into self-refresh.
System is off but context is saved to RAM. OEM support of this state is optional. System memory is put
into self-refresh.
System is off but context is saved to disk. When the system transitions to the working state, the OS is
resumed without a system re-boot.
System is off. OS re-boots when the system transitions to the working state.
Occurs when system power (AC or battery) is not present or is unable to keep the system in one of the
other states.
Description
Output to the Southbridge to allow LDTSTOP# assertion.
HyperTransport™ Technology Stop: Enables and disables links during
system state transitions.
Power On
Global Reset

Figure 6-1 Linked List for Capabilities

Power Management and ACPI
describes the signals used in the ACPI power
Description
Chapter 6
describes the ACPI states
Source
Northbridge
Southbridge
Power switch
Southbridge
46136 AMD RX881 Databook 1.40
6-1