1Kernel driver pkgtemp 2====================== 3 4Supported 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 11Author: Fenghua Yu 12 13Description 14----------- 15 16This driver permits reading package level temperature sensor embedded inside 17Intel CPU package. The sensors can be in core, uncore, memory controller, or 18other components in a package. The feature is first implemented in Intel Sandy 19Bridge platform. 20 21Temperature is measured in degrees Celsius and measurement resolution is 221 degree C. Valid temperatures are from 0 to TjMax degrees C, because the actual 23value of temperature register is in fact a delta from TjMax. 24 25Temperature known as TjMax is the maximum junction temperature of package. 26We get this from MSR_IA32_TEMPERATURE_TARGET. If the MSR is not accessible, 27we define TjMax as 100 degrees Celsius. At this temperature, protection 28mechanism will perform actions to forcibly cool down the package. Alarm 29may be raised, if the temperature grows enough (more than TjMax) to trigger 30the Out-Of-Spec bit. Following table summarizes the exported sysfs files: 31 32temp1_input - Package temperature (in millidegrees Celsius). 33temp1_max - All cooling devices should be turned on. 34temp1_crit - Maximum junction temperature (in millidegrees Celsius). 35temp1_crit_alarm - Set when Out-of-spec bit is set, never clears. 36 Correct CPU operation is no longer guaranteed. 37