X86 Power Management Support
X86 power management is based on the ACPI specification for the Windows operation environment. The specification defines specific timing requirements associated with STPCLK and SMI message cycles related to power management events. The specification also describes ACPI-defined system state transitions that relate to wakeup event signaling via LDTREQ#. See the specification for reference information related to these events.
Stop Clock Signal
The STPCLK# is one of the basic x86 power management signals. When power management logic asserts this signal, it places the CPU into its Stop Grant State, which has the following effects (Intel PIII example). The processor:
issues a Stop Grant Acknowledge transaction
stops driving ...
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