T2447: add configurable kernel boot option 'disable-power-saving'

Lower available CPU C states to a minimum if this option set. This will set
Kernel commandline options "intel_idle.max_cstate=0 processor.max_cstate=1".

Author: c-po

docs/configuration/system/option.rst

@@ -24,7 +24,7 @@ General
 
 .. cfgcmd:: set system option root-partition-auto-resize
 
-    Enables the root partition auto-extension and resizes to the maximum 
+    Enables the root partition auto-extension and resizes to the maximum
     available space on system boot.
 
 Kernel
@@ -35,6 +35,23 @@ Kernel
     Disable all optional CPU mitigations. This improves system performance,
     but it may also expose users to several CPU vulnerabilities.
 
+    This will add the following option to the Kernel commandline:
+
+    * ``mitigations=off``
+
+    .. note:: Setting will only become active with the next reboot!
+
+.. cfgcmd:: set system option kernel disable-power-saving
+
+    Disable CPU power saving mechanisms also known as C states.
+
+    This will add the following two options to the Kernel commandline:
+
+    * ``intel_idle.max_cstate=0`` Disable intel_idle and fall back on acpi_idle
+    * ``processor.max_cstate=1`` Limit processor to maximum C-state 1
+
+    .. note:: Setting will only become active with the next reboot!
+
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