Low Power Features; Clock Control And Low-Power States - Intel P8700 - Core 2 Duo Processor Datasheet

Low Power Features

2 Low Power Features
2.1

Clock Control and Low-Power States

The processor supports low-power states both at the individual core level and the
package level for optimal power management.
A core may independently enter the C1/AutoHALT, C1/MWAIT, C2, C3, C4, Intel®
Enhanced Deeper Sleep and Intel® Deep Power Down Technology low-power states.
When both cores coincide in a common core low-power state, the central power
management logic ensures the entire processor enters the respective package low-
power state by initiating a P_LVLx (P_LVL2, P_LVL3, P_LVL4, P_LVL5,P_LVL6) I/O read
to the GMCH.
The processor implements two software interfaces for requesting low-power states:
MWAIT instruction extensions with sub-state hints and P_LVLx reads to the ACPI P_BLK
register block mapped in the processor's I/O address space. The P_LVLx I/O reads are
converted to equivalent MWAIT C-state requests inside the processor and do not
directly result in I/O reads on the processor FSB. The P_LVLx I/O Monitor address does
not need to be set up before using the P_LVLx I/O read interface. The sub-state hints
used for each P_LVLx read can be configured through the IA32_MISC_ENABLES model
specific register (MSR).
If a core encounters a GMCH break event while STPCLK# is asserted, it asserts the
PBE# output signal. Assertion of PBE# when STPCLK# is asserted indicates to system
logic that individual cores should return to the C0 state and the processor should return
to the Normal state.
Figure 1
states for the processor.
states.
Datasheet
shows the core low-power states and
Table 1
Figure 2
maps the core low-power states to package low-power
shows the package low-power
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