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.
By default, temperature thresholds are set up as follows:
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:
For more details about this functionality, please refer to <code>Documentation/thermal/sysfs-api.txt</code> in the kernel sources.
=====XELK 3.x.y series=====
XELK 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: