Thermal Management
62
Datasheet
Code execution is halted in C1-C6. Therefore temperature cannot be read via the
processor MSR without bringing a core back into C0. However, temperature can still be
monitored through PECI in lower C-states.
Unlike traditional thermal devices, the DTS outputs a temperature relative to the
maximum supported operating temperature of the processor (T
j,max
). It is the
responsibility of software to convert the relative temperature to an absolute
temperature. The absolute reference temperature is readable in an MSR. The
temperature returned by the DTS is an implied negative integer indicating the relative
offset from T
j,max
. The DTS does not report temperatures greater than T
j,max
.
The DTS-relative temperature readout directly impacts the Adaptive Thermal Monitor
trigger point. When a DTS indicates that the maximum processor core temperature has
been reached (a reading of 0x0 on any core), the TCC will activate and indicate a
Adaptive Thermal Monitor event.
Changes to the temperature can be detected via two programmable thresholds located
in the processor thermal MSRs. These thresholds have the capability of generating
interrupts via the core's local APIC. Refer to the
Intel® 64 and IA-32 Architectures
Software Developer's Manuals
for specific register and programming details.
5.2.1.3
PROCHOT# Signal
PROCHOT# (processor hot) is asserted when the processor core temperature has
reached its maximum operating temperature (T
j,max
). This will activate the TCC and
signal a thermal event which is then resolved by the Adaptive Thermal Monitor. See
(above) for a timing diagram of the PROCHOT# signal assertion relative to
the Adaptive Thermal Response.
Only a single PROCHOT# pin exists at a package level
of the processor. When any core arrives at the TCC activation point, the PROCHOT#
signal will be driven by the processor core. PROCHOT# assertion policies are
independent of Adaptive Thermal Monitor enabling.
Note:
Bus snooping and interrupt latching are active while the TCC is active.
5.2.1.3.1
Bi-Directional PROCHOT#
By default, the PROCHOT# signal is defined as an output only. However, the signal may
be configured as bi-directional. When configured as a bi-directional signal, PROCHOT#
can be used for thermally protecting other platform components should they overheat
as well. When PROCHOT# is signaled externally:
•
The processor core will immediately reduce processor power to the minimum
voltage and frequency supported. This is contrary to the internally-generated
Adaptive Thermal Monitor response.
•
Clock modulation is not activated.
The TCC will remain active until the system deasserts PROCHOT#. The processor can
be configured to generate an interrupt upon assertion and deassertion of the
PROCHOT# signal.
