From bbe86a57e5a1dbc74a2d84f9da1a0ee8b8d4474f Mon Sep 17 00:00:00 2001
From: Alexander Fritsch <git@afritsch.dev>
Date: Fri, 19 Jun 2026 14:59:11 +0200
Subject: [PATCH] raspberry-pi/common/kernel: fix preempt config on kernel
 >=6.18

---
 raspberry-pi/common/kernel.nix | 11 +++++++++--
 1 file changed, 9 insertions(+), 2 deletions(-)

diff --git a/raspberry-pi/common/kernel.nix b/raspberry-pi/common/kernel.nix
index 203aabbe..c335b5ff 100644
--- a/raspberry-pi/common/kernel.nix
+++ b/raspberry-pi/common/kernel.nix
@@ -72,11 +72,18 @@ in
       NLS_CODEPAGE_437 = lib.mkForce yes;
       FB_SIMPLE = yes;
     }
-    # arm64 vendor defconfigs (bcm2711, bcm2712) use full preempt;
-    # arm32 ones (bcmrpi, bcm2709) use voluntary preempt (nixpkgs default)
+    # nixpkgs defaults to lazy preempt on kernel version >=6.18
+    # arm64 vendor defconfigs (bcm2711, bcm2712) use full preempt
     // lib.optionalAttrs (rpiVersion >= 3) {
       PREEMPT = lib.mkForce yes;
+      PREEMPT_LAZY = lib.mkForce no;
       PREEMPT_VOLUNTARY = lib.mkForce no;
+    }
+    # arm32 ones (bcmrpi, bcm2709) use voluntary preempt
+    // lib.optionalAttrs (rpiVersion < 3) {
+      PREEMPT = lib.mkForce no;
+      PREEMPT_LAZY = lib.mkForce no;
+      PREEMPT_VOLUNTARY = lib.mkForce yes;
     };
 
     extraMeta =