Datasheet

Thermal Specifications
120 Intel
®
Xeon
®
Processor 5500 Series Datasheet, Volume 1
managed only in the PECI domain. In-band software may not manipulate or read the
PECI T-state control setting. In the event that multiple agents are requesting T-state
throttling simultaneously, the CPU always gives priority to the lowest power setting, or
the numerically lowest duty cycle.
On Intel Xeon processor 5500 series, the only supported duty cycle is 12.5% (12.5%
clocks on, 87.5% clocks off). It is expected that T-state throttling will be engaged only
under emergency thermal or power conditions. Future products may support more duty
cycles, as defined in the following table:
The T-state control word is defined as follows:
\
6.3.2.7 MbxSend()
The MbxSend() command is utilized for sending requests to the generic Mailbox
interface. Those requests are in turn serviced by the processor with some nominal
latency and the result is deposited in the mailbox for reading. MbxGet() is used to
retrieve the response and details are documented in Section 6.3.2.8.
The details of processor mailbox capabilities are described in Section 6.3.2.6.1, and
many of the fundamental concepts of Mailbox ownership, release, and management are
discussed in Section 6.3.2.9.
6.3.2.7.1 Write Data
Regardless of the function of the mailbox command, a request type modifier and 4-byte
data payload must be sent. For Mailbox commands where the 4-byte data field is not
applicable (e.g., the command is a read), the data written should be all zeroes.
Table 6-22. ACPI T-state Duty Cycle Definition
Duty Cycle Code Definition
0x0 Undefined
0x1 12.5% clocks on / 87.5% clocks off
0x2 25% clocks on / 75% clocks off
0x3 37.5% clocks on / 62.5% clocks off
0x4 50% clocks on / 50% clocks off
0x5 62.5% clocks on / 37.5% clocks off
0x6 75% clocks on / 25% clocks off
0x7 87.5% clocks on / 12.5% clocks off
Figure 6-22. ACPI T-state Throttling Control Read / Write Definition
Enable
Duty Cycle
Reserved
70
0xB / 0xC
Request Type
Request Data
543 107
1 2 3 4Byte # 0
Data