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→XELK 3.x.y series
At Linux level, a more sophisticated protection mechanism is implemented. Please refer to the following sections for more details.
=====XELK 12.x.y series=====Practically speaking, for [[Axel_Embedded_Linux_Kit_(XELK)#XELK_software_components|XELK 12.x.y series]] this mechanism makes use of two different thresholds, denoted as <code>trip_point0</code> (also known as ''passive threshold'') and <code>trip_point1</code>(also known as ''critical threshold''. When Tj reaches <code>trip_point0</code>, Linux kernel scales down processor frequency:
<pre>
System is too hot. GPU3D will work at 1/64 clock.
thermal thermal_zone0: critical temperature reached(100 C),shutting down
</pre>
By default, temperature thresholds are set up as follows:*<code>trip_point0</code>: 85°C*<code>trip_point1</code>: 100°C. Trip point thresholds can be accessed via <code>sysfs</code> interface from user space. The following example shows how to read the values of the trip points:
<pre>
root@axel-lite:~# cat /sys/devices/virtual/thermal/thermal_zone0/trip_point_0_temp
100000
</pre>
This example shows how to set trip points 0 and 1 to 95°C and 100°C respectively:
<pre>
echo 100000 > /sys/class/thermal/thermal_zone0/trip_point_1_temp
</pre>
{{ImportantMessage|text=Exceeding Please note that*it is possible to set up trip points greater than the maximum junction temperature indicated by manufacturer datasheet*exceeding maximum junction temperature indicated by manufacturer datasheet may cause permanent damage.}}
To read current processor temperature please issue this command (reported temperature is 36.676°C in the example):
For more details about this functionality, please refer to <code>Documentation/thermal/sysfs-api.txt</code> in the kernel sources.
=====XELK 23.x.y series=====TBDXELK 3.x.y kernels implement the same mechanism of XELK 2.x.y series. However a notable difference exists, that is default temperature thresholds depend on the silicon grade, as follows:*for commercial parts** passive threshold: 85°C** critical threshold: 90°C*for extended commercial and industrial parts** passive threshold: 95°C** critical threshold: 100°C*for automotive parts** passive threshold: 115°C** critical threshold: 120°C.
==Related links==
*[[Power_consumption_(AxelLite)|Power consumption of AxelLite SOM]]
*[[FAQs_(Axel)|SoC frequency management]]
*[[Power_management_(Axel)|Power management of Axel product family]].
