521 datasheet(88/96 Pages) INTEL

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Datasheet

Features

6.2.4

Enhanced HALT Snoop or HALT Snoop State, Grant Snoop

State

The Enhanced HALT Snoop State is used in conjunction with the new Enhanced HALT state. If

Enhanced HALT state is not enabled in the BIOS, the default Snoop State entered will be the

HALT Snoop State. Refer to the sections below for details on HALT Snoop State, Grant Snoop

State and Enhanced HALT Snoop State.

6.2.4.1

HALT Snoop State, Grant Snoop State

The processor will respond to snoop transactions on the FSB while in Stop-Grant state or in HALT

Power Down state. During a snoop transaction, the processor enters the HALT:Grant Snoop state.

The processor will stay in this state until the snoop on the FSB has been serviced (whether by the

processor or another agent on the FSB). After the snoop is serviced, the processor will return to the

Stop-Grant state or HALT Power Down state, as appropriate.

6.2.4.2

Enhanced HALT Snoop State

The Enhanced HALT Snoop State is the default Snoop State when the Enhanced HALT state is

enabled via the BIOS. The processor will remain in the lower bus ratio and VID operating point of

the Enhanced HALT state.

While in the Enhanced HALT Snoop State, snoops are handled the same way as in the HALT

Snoop State. After the snoop is serviced the processor will return to the Enhanced HALT Power

Down state.

521 Datasheet(PDF) 88 Page - Intel Corporation