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PowerEdge T310 Technical Guide 45
9.3 Power Management
Power management features come in two flavors: fixed or generic. Fixed features use bits defined
in the ACPI specification for specific capabilities. The fixed feature bits give the OS complete control
over the power management of a device since the location of the bits is given to the OS in the FACP
table. Thus, a driver can directly access bits to control a device’s power management. Generic
features have defined enable and status bits, but the functionality is not fully visible to the OS. Dell
provides ASL code to handle the details of generic features, allowing the OS to intelligently
communicate with system-specific hardware.
Table 16. Power Management Features
Feature Type
Enable/Status/
Ctrl bit
location Description
ACPI mode
switch
Fixed PCH The OS uses the SCI_EN bit to switch from
legacy mode to ACPI mode.
Sleep
states
Fixed PCH Supported states: S0 (Working), S4-OS
(‘Hibernation’ in W2K), and S5 (Soft-off).
S1 (also called ‘standby’ or ‘suspend’) and
S3 are not supported.
Power
Button
Fixed PCH In ACPI mode, OS has control of the
power button. In non-ACPI mode, SMI
handler owns power button events.
Real-Time
Clock
Fixed PCH The OS is able to configure the system to
wake on the RTC alarm.
Power
Mgmt.
Timer
Fixed PCH 24-bit power management timer is used.
Power
Mgmt.
Event
(PME)
Generic PCH Each host bus’s PME# signal is routed to a
separate general-purpose event pin in the
chipset. When a device signals PME#, the
system wakes (if necessary), the OS
detects the event, and a Dell-defined ASL
routine handles the event. Wake-on-LAN
is one example of a PME.
USB wake Generic N/A This feature is not supported on this
system since the S1 state is not
supported.
DBS N/A Processor
MSRs
This feature does P state transition under
Windows
C State
Support
N/A
Processor and
PCH registers
This feature allows multiple C state
support for Processor. This feature will
work under Windows and ACPI OS that
understand C states.