From fd2a16c66b5b521ff071835909b770acc0d0981e Mon Sep 17 00:00:00 2001
From: Christian Breunig <christian@breunig.cc>
Date: Tue, 5 Mar 2024 20:23:14 +0100
Subject: 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".

(cherry picked from commit 3a3e0dff4ff1f80835eca6b2362d792e3ecacc8e)
---
 interface-definitions/system_option.xml.in | 6 ++++++
 src/conf_mode/system_option.py             | 2 ++
 2 files changed, 8 insertions(+)

diff --git a/interface-definitions/system_option.xml.in b/interface-definitions/system_option.xml.in
index 602d7d100..fe517d17d 100644
--- a/interface-definitions/system_option.xml.in
+++ b/interface-definitions/system_option.xml.in
@@ -43,6 +43,12 @@
                    <valueless/>
                  </properties>
                </leafNode>
+               <leafNode name="disable-power-saving">
+                <properties>
+                  <help>Disable CPU power saving mechanisms also known as C states</help>
+                  <valueless/>
+                </properties>
+              </leafNode>
              </children>
            </node>
            <leafNode name="keyboard-layout">
diff --git a/src/conf_mode/system_option.py b/src/conf_mode/system_option.py
index 3b5b67437..7ed451e16 100755
--- a/src/conf_mode/system_option.py
+++ b/src/conf_mode/system_option.py
@@ -92,6 +92,8 @@ def generate(options):
     if 'kernel' in options:
         if 'disable_mitigations' in options['kernel']:
             cmdline_options.append('mitigations=off')
+        if 'disable_power_saving' in options['kernel']:
+            cmdline_options.append('intel_idle.max_cstate=0 processor.max_cstate=1')
     grub_util.update_kernel_cmdline_options(' '.join(cmdline_options))
 
     return None
-- 
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