Comment 23 for bug 1763144

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AaronMa (mapengyu) wrote :

Hi,
TDP Intel U CPU family is defined as 25w.
Please refer to:
https://www.intel.com/content/www/us/en/products/processors/core/i5-processors/i5-8250u.html

CPU is not meant to go to 44W that is far away as Intel designed.

To allow the optimal operation and long-term reliability of Intel processor-based
systems, the component temperature specification is the applicable Tjmax which defined in MSR 0x1a2h[23:16];
Tj MAX is factory calibrated and is not user configurable.
TCC Activation Offset is set in TEMPERATURE_TARGET (0x1A2) MSR,bits [29:24];
the offset value will be subtracted from the value TjMAX.
Please try it if you like overclock.

When temperature is retrieved by the processor MSR, it is the instantaneous
temperature of the given DTS.
thermal interrupt in Linux depends on reading MSR to warn the system like:
temperature above threshold
Then EC will make CPU be full speed to cool down system, when CPU temperature is stable like 80C, CPU can work at the defined freq.

This is designed to make system reliable to work at the standard performance no matter with OS.