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H. Peter Anvin
H. Peter Anvin
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x86, hwmon: Package Level Thermal/Power: pkgtemp documentation
Document for package level thermal hwmon driver. Signed-off-by: Fenghua Yu <fenghua.yu@intel.com> LKML-Reference: <1280448826-12004-6-git-send-email-fenghua.yu@intel.com> Reviewed-by: Len Brown <len.brown@intel.com> Signed-off-by: H. Peter Anvin <hpa@linux.intel.com>
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Documentation/hwmon/pkgtemp
| File was created | 1 | Kernel driver pkgtemp | |
| 2 | ====================== | ||
| 3 | |||
| 4 | Supported chips: | ||
| 5 | * Intel family | ||
| 6 | Prefix: 'pkgtemp' | ||
| 7 | CPUID: | ||
| 8 | Datasheet: Intel 64 and IA-32 Architectures Software Developer's Manual | ||
| 9 | Volume 3A: System Programming Guide | ||
| 10 | |||
| 11 | Author: Fenghua Yu | ||
| 12 | |||
| 13 | Description | ||
| 14 | ----------- | ||
| 15 | |||
| 16 | This driver permits reading package level temperature sensor embedded inside | ||
| 17 | Intel CPU package. The sensors can be in core, uncore, memory controller, or | ||
| 18 | other components in a package. The feature is first implemented in Intel Sandy | ||
| 19 | Bridge platform. | ||
| 20 | |||
| 21 | Temperature is measured in degrees Celsius and measurement resolution is | ||
| 22 | 1 degree C. Valid temperatures are from 0 to TjMax degrees C, because the actual | ||
| 23 | value of temperature register is in fact a delta from TjMax. | ||
| 24 | |||
| 25 | Temperature known as TjMax is the maximum junction temperature of package. | ||
| 26 | We get this from MSR_IA32_TEMPERATURE_TARGET. If the MSR is not accessible, | ||
| 27 | we define TjMax as 100 degrees Celsius. At this temperature, protection | ||
| 28 | mechanism will perform actions to forcibly cool down the package. Alarm | ||
| 29 | may be raised, if the temperature grows enough (more than TjMax) to trigger | ||
| 30 | the Out-Of-Spec bit. Following table summarizes the exported sysfs files: | ||
| 31 | |||
| 32 | temp1_input - Package temperature (in millidegrees Celsius). | ||
| 33 | temp1_max - All cooling devices should be turned on. | ||
| 34 | temp1_crit - Maximum junction temperature (in millidegrees Celsius). | ||
| 35 | temp1_crit_alarm - Set when Out-of-spec bit is set, never clears. | ||
| 36 | Correct CPU operation is no longer guaranteed. | ||
| 37 |