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- Kernel driver pkgtemp
- ======================
- Supported chips:
- * Intel family
- Prefix: 'pkgtemp'
- CPUID:
- Datasheet: Intel 64 and IA-32 Architectures Software Developer's Manual
- Volume 3A: System Programming Guide
- Author: Fenghua Yu
- Description
- -----------
- This driver permits reading package level temperature sensor embedded inside
- Intel CPU package. The sensors can be in core, uncore, memory controller, or
- other components in a package. The feature is first implemented in Intel Sandy
- Bridge platform.
- Temperature is measured in degrees Celsius and measurement resolution is
- 1 degree C. Valid temperatures are from 0 to TjMax degrees C, because the actual
- value of temperature register is in fact a delta from TjMax.
- Temperature known as TjMax is the maximum junction temperature of package.
- We get this from MSR_IA32_TEMPERATURE_TARGET. If the MSR is not accessible,
- we define TjMax as 100 degrees Celsius. At this temperature, protection
- mechanism will perform actions to forcibly cool down the package. Alarm
- may be raised, if the temperature grows enough (more than TjMax) to trigger
- the Out-Of-Spec bit. Following table summarizes the exported sysfs files:
- temp1_input - Package temperature (in millidegrees Celsius).
- temp1_max - All cooling devices should be turned on.
- temp1_crit - Maximum junction temperature (in millidegrees Celsius).
- temp1_crit_alarm - Set when Out-of-spec bit is set, never clears.
- Correct CPU operation is no longer guaranteed.
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