From e09eea204910700fb9720cadf671991dbf39652b Mon Sep 17 00:00:00 2001
From: Tom Alexander <tom@fizz.buzz>
Date: Mon, 23 Dec 2024 10:00:01 -0500
Subject: [PATCH] Switch to zen kernel optimized for znver4.

---
 nix/configuration/configuration.nix           |  2 +-
 nix/configuration/hosts/odo/default.nix       |  1 +
 .../hosts/odo/optimized_build.nix             | 30 +++++++++++++++++++
 3 files changed, 32 insertions(+), 1 deletion(-)
 create mode 100644 nix/configuration/hosts/odo/optimized_build.nix

diff --git a/nix/configuration/configuration.nix b/nix/configuration/configuration.nix
index bd623fd..c8fe1c8 100644
--- a/nix/configuration/configuration.nix
+++ b/nix/configuration/configuration.nix
@@ -42,7 +42,7 @@
   ];
   nix.settings.trusted-users = [ "@wheel" ];
 
-  boot.kernelPackages = pkgs.linuxPackages_6_11;
+  # boot.kernelPackages = pkgs.linuxPackages_6_11;
   hardware.enableRedistributableFirmware = true;
 
   services.getty = {
diff --git a/nix/configuration/hosts/odo/default.nix b/nix/configuration/hosts/odo/default.nix
index 79ef251..723a854 100644
--- a/nix/configuration/hosts/odo/default.nix
+++ b/nix/configuration/hosts/odo/default.nix
@@ -3,6 +3,7 @@
   imports = [
     ./hardware-configuration.nix
     ./disk-config.nix
+    ./optimized_build.nix
   ];
 
   # Generate with `head -c4 /dev/urandom | od -A none -t x4`
diff --git a/nix/configuration/hosts/odo/optimized_build.nix b/nix/configuration/hosts/odo/optimized_build.nix
new file mode 100644
index 0000000..22c0ba3
--- /dev/null
+++ b/nix/configuration/hosts/odo/optimized_build.nix
@@ -0,0 +1,30 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+{
+  imports = [ ];
+
+  nixpkgs.overlays = [
+    (
+      self: super:
+      let
+        optimizeWithFlags =
+          pkg: flags:
+          pkg.overrideAttrs (old: {
+            NIX_CFLAGS_COMPILE = [ (old.NIX_CFLAGS_COMPILE or "") ] ++ flags;
+          });
+      in
+      {
+        linux_znver4 = optimizeWithFlags super.linux_zen [
+          "-march=znver4"
+          "-mtune=znver4"
+        ];
+      }
+    )
+  ];
+
+  boot.kernelPackages = lib.mkIf (!config.me.buildingIso) (pkgs.linuxPackagesFor pkgs.linux_znver4);
+}