Features
Figure 22.
Processor Low Power State Machine
6.2.1
6.2.2
Normal State
This is the normal operating state for the processor.
HALT and Extended HALT Powerdown States
The processor supports the HALT or Extended HALT powerdown state. The Extended
HALT Powerdown must be enabled via the BIOS for the processor to remain within its
specification.
The Extended HALT state is a lower power state as compared to the Stop Grant State.
If Extended HALT is not enabled, the default Powerdown state entered will be HALT.
Refer to the sections below for details about the HALT and Extended HALT states.
6.2.2.1
HALT Powerdown State
HALT is a low power state entered when all the processor cores have executed the HALT
or MWAIT instructions. When one of the processor cores executes the HALT instruction,
that processor core is halted, however, the other processor continues normal operation.
The processor will transition to the Normal state upon the occurrence of SMI#, INIT#,
or LINT[1:0] (NMI, INTR). RESET# will cause the processor to immediately initialize
itself.
The return from a System Management Interrupt (SMI) handler can be to either
Normal Mode or the HALT Power Down state. See the Intel Architecture Software
Developer's Manual, Volume III: System Programmer's Guide for more information.
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Datasheet
INTEL [ INTEL ]
