Functional Description
10.7
Thermal Sensor
There are several registers that need to be configured to support the GMCH thermal
sensor functionality and SMI# generation. Customers must enable the Catastrophic
Trip Point at 115 °C as protection for the GMCH. If the Catastrophic Trip Point is
crossed, then the GMCH will instantly turn off all clocks inside the device. Customers
may optionally enable the Hot Trip Point between 85 °C and 105 °C to generate SMI#.
Customers will be required to then write their own SMI# handler in BIOS that will
speed up the GMCH (or system) fan to cool the part.
10.7.1
PCI Device 0, Function 0
The SMICMD register requires that a bit be set to generate an SMI# when the Hot trip
point is crossed. The ERRSTS register can be inspected for the SMI alert.
Address
Offset
Symbol
Register Name
Default
Value
Access
C8–C9h
CC–CDh
ERRSTS
SMICMD
Error Status
SMI Command
0000h
0000h
RO, RWC/S
RO, RW
10.7.2
MCHBAR Thermal Sensor Registers
The Digital Thermometer Configuration Registers reside in the MCHBAR configuration
space.
Address
Offset
Symbol
Register Name
Default
Value
Access
CD8h
TSC1
Thermal Sensor Control 1
00h
RW/L, RW,
RS/WC
CD9h
CDAh
TSC2
TSS
Thermal Sensor Control 2
Thermal Sensor Status
00h
00h
RW/L, RO
RO
CDC–CDFh
TSTTP
Thermal Sensor Temperature Trip
Point
00000000h
RO, RW,
RW/L
CE2h
CE4h
TCO
Thermal Calibration Offset
00h
00h
RW/L/K,
RW/L
THERM1
Hardware Protection
RW/L, RO,
RW/L/K
CE6h
CEA–CEBh
CF1h
THERM3
TIS
TCO Fuses
00h
0000h
00h
RS/WC, RO
RO, RWC
RO, RW
Thermal Interrupt Status
Thermal SMI Command
TSMICMD
304
Datasheet
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