Features
RESET# will cause the processor to immediately initialize itself, but the processor will
stay in Stop-Grant state. A transition back to the Normal state will occur with the de-
assertion of the STPCLK# signal.
A transition to the Grant Snoop state will occur when the processor detects a snoop on
the front side bus (see Section 7.2.4.1).
While in the Stop-Grant state, SMI#, INIT#, BINIT# and LINT[1:0] will be latched by
the processor, and only serviced when the processor returns to the Normal state. Only
one occurrence of each event will be recognized upon return to the Normal state.
While in Stop-Grant state, the processor will process snoops on the front side bus and it
will latch interrupts delivered on the front side bus.
The PBE# signal can be driven when the processor is in Stop-Grant state. PBE# will be
asserted if there is any pending interrupt latched within the processor. Pending
interrupts that are blocked by the EFLAGS.IF bit being clear will still cause assertion of
PBE#. Assertion of PBE# indicates to system logic that it should return the processor to
the Normal state.
7.2.4
Enhanced HALT Snoop or HALT Snoop State,
Stop Grant Snoop State
The Enhanced HALT Snoop state is used in conjunction with the Enhanced HALT state.
If the 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, Stop Grant Snoop state and Enhanced HALT Snoop state.
7.2.4.1
HALT Snoop State, Stop Grant Snoop State
The processor will respond to snoop or interrupt transactions on the front side bus
while in Stop-Grant state or in HALT Power Down state. During a snoop or interrupt
transaction, the processor enters the HALT/Grant Snoop state. The processor will stay
in this state until the snoop on the front side bus has been serviced (whether by the
processor or another agent on the front side bus) or the interrupt has been latched.
After the snoop is serviced or the interrupt is latched, the processor will return to the
Stop-Grant state or HALT Power Down state, as appropriate.
7.2.4.2
7.3
86
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 and interrupt transactions are
handled the same way as in the HALT Snoop state. After the snoop is serviced or the
interrupt is latched, the processor will return to the Enhanced HALT state.
Enhanced Intel SpeedStep® Technology
The Dual-Core Intel Xeon Processor 5000 series support Enhanced Intel SpeedStep
Technology. This technology enables the processor to switch between multiple
frequency and voltage points, which results in platform power savings. Enhanced Intel
SpeedStep Technology requires support for dynamic VID transitions in the platform.
Switching between voltage/frequency states is software controlled.
Dual-Core Intel® Xeon® Processor 5000 Series Datasheet
INTEL [ INTEL ]
