mreow: power stuff

system/system-mreow.nix

@@ -24,6 +24,29 @@
   # if I move to another lock screen program, i will have to replace `swaylock`
   security.pam.services.swaylock = { };
 
+  # Kernel-level power tuning. These are boot-time / module-load-time settings
+  # that power-profiles-daemon (in common.nix) does not manage. ppd handles
+  # governor and EPP at runtime; these cover everything else.
+  boot.kernelParams = [
+    # Disable NMI watchdog. Eliminates periodic perf-counter interrupts
+    # across all cores (~1 W). Kernel softlockup watchdog remains active.
+    "nmi_watchdog=0"
+
+    # Route kernel work items to already-busy CPUs rather than waking idle
+    # ones. Reduces C-state exit frequency -- significant on battery where
+    # cores idle often.
+    "workqueue.power_efficient=1"
+  ];
+
+  boot.kernel.sysctl."kernel.nmi_watchdog" = 0;
+
+  # Power-gate the HDA codec between audio activity. 1-second inactivity
+  # timeout; controller powers down fully. Wakes transparently on next
+  # audio event -- no audible artifacts on Framework 13 AMD.
+  boot.extraModprobeConfig = ''
+    options snd_hda_intel power_save=1 power_save_controller=Y
+  '';
+
   # Greetd display manager
   services.greetd = {
     enable = true;