
Intel Xeon Processor MP with up to 2MB L3 Cache
6-3
Features
BINIT# will be recognized while the processor is in Stop-Grant state. If STPCLK# is still asserted
at the completion of the BINIT# bus initialization, the processor will remain in Stop-Grant mode. If
the STPCLK# is not asserted at the completion of the BINIT# bus initialization, the processor will
return to Normal state.
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 deassertion of the
STPCLK# signal. When re-entering the Stop-Grant state from the sleep state, STPCLK# should
only be deasserted one or more bus clocks after the deassertion of SLP#.
A transition to the HALT/Grant Snoop state will occur when the processor detects a snoop on the
assertion of the SLP# signal.
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.
6.2.4
HALT/Grant Snoop State—State 4
The processor will respond to snoop transactions on the system bus while in Stop-Grant state or in
AutoHALT 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 system bus has been
serviced (whether by the processor or another agent on the system bus). After the snoop is serviced,
the processor will return to the Stop-Grant state or AutoHALT Power Down state, as appropriate.
6.2.5
Sleep State—State 5
The Sleep state is a very low power state in which each processor maintains its context, maintains
the phase-locked loop (PLL), and has stopped most of internal clocks. The Sleep state can only be
entered from Stop-Grant state. Once in the Stop-Grant state, the SLP# pin can be asserted, causing
the processor to enter the Sleep state. The SLP# pin is not recognized in the Normal or AutoHALT
states.
Snoop events that occur while in Sleep state or during a transition into or out of Sleep state will
cause unpredictable behavior.
In the Sleep state, the processor is incapable of responding to snoop transactions or latching
interrupt signals. No transitions or assertions of signals (with the exception of SLP# or RESET#)
are allowed on the system bus while the processor is in Sleep state. Any transition on an input
signal before the processor has returned to Stop-Grant state will result in unpredictable behavior.
If RESET# is driven active while the processor is in the Sleep state, and held active as specified in
the RESET# pin specification, then the processor will reset itself, ignoring the transition through
Stop-Grant state. If RESET# is driven active while the processor is in the Sleep state, the SLP# and
STPCLK# signals should be deasserted immediately after RESET# is asserted to ensure the
processor correctly executes the reset sequence.
Once in the Sleep state, the SLP# pin can be deasserted if another asynchronous system bus event
occurs. The SLP# pin should only be asserted when the processor is in the Stop-Grant state. For
Intel Xeon processor MP on the 0.13 micron process processors, the SLP# pin may only be
asserted when all logical processors are in the Stop-Grant state. SLP# assertions while the
processors are not in the Stop-Grant state is out of specification and may result in illegal operation.