From 323d269a24fd7ef1b3be009ae3550b346d57c562 Mon Sep 17 00:00:00 2001
From: edef <edef@anthropic.com>
Date: Sat, 10 Jan 2026 23:58:09 +0000
Subject: [PATCH] nixos/amazon: move nvme_core.io_timeout to runtime module

This kernel parameter was accidentally added to the image builder module
in 2018 (e4777ae2d84c) when it should have been in the runtime config.
This causes a mismatch between AMIs built with the builder and systems
configured with just the runtime module.

Move it to modules/virtualisation/amazon-image.nix so that all EC2
instances get the recommended NVMe timeout, regardless of how they
were provisioned.
---
 nixos/maintainers/scripts/ec2/amazon-image.nix | 11 -----------
 nixos/modules/virtualisation/amazon-image.nix  | 17 +++++++++++++----
 2 files changed, 13 insertions(+), 15 deletions(-)

diff --git a/nixos/maintainers/scripts/ec2/amazon-image.nix b/nixos/maintainers/scripts/ec2/amazon-image.nix
index 9ce667a30995..e117b1d28d52 100644
--- a/nixos/maintainers/scripts/ec2/amazon-image.nix
+++ b/nixos/maintainers/scripts/ec2/amazon-image.nix
@@ -11,7 +11,6 @@ let
     mkOption
     optionalString
     types
-    versionAtLeast
     ;
   inherit (lib.options) literalExpression;
   cfg = config.amazonImage;
@@ -46,16 +45,6 @@ in
     })
   ];
 
-  # Amazon recommends setting this to the highest possible value for a good EBS
-  # experience, which prior to 4.15 was 255.
-  # https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/nvme-ebs-volumes.html#timeout-nvme-ebs-volumes
-  config.boot.kernelParams =
-    let
-      timeout =
-        if versionAtLeast config.boot.kernelPackages.kernel.version "4.15" then "4294967295" else "255";
-    in
-    [ "nvme_core.io_timeout=${timeout}" ];
-
   options.amazonImage = {
     contents = mkOption {
       example = literalExpression ''
diff --git a/nixos/modules/virtualisation/amazon-image.nix b/nixos/modules/virtualisation/amazon-image.nix
index 1e267bfdad95..640c81cff474 100644
--- a/nixos/modules/virtualisation/amazon-image.nix
+++ b/nixos/modules/virtualisation/amazon-image.nix
@@ -59,10 +59,19 @@ in
     ];
     boot.initrd.kernelModules = [ "xen-blkfront" ];
     boot.initrd.availableKernelModules = [ "nvme" ];
-    boot.kernelParams = [
-      "console=ttyS0,115200n8"
-      "random.trust_cpu=on"
-    ];
+    boot.kernelParams =
+      let
+        # Amazon recommends setting this to the highest possible value for a good EBS
+        # experience, which prior to 4.15 was 255.
+        # https://docs.aws.amazon.com/AWSEC2/latest/UserGuide/nvme-ebs-volumes.html#timeout-nvme-ebs-volumes
+        nvmeTimeout =
+          if lib.versionAtLeast config.boot.kernelPackages.kernel.version "4.15" then "4294967295" else "255";
+      in
+      [
+        "console=ttyS0,115200n8"
+        "random.trust_cpu=on"
+        "nvme_core.io_timeout=${nvmeTimeout}"
+      ];
 
     # Prevent the nouveau kernel module from being loaded, as it
     # interferes with the nvidia/nvidia-uvm modules needed for CUDA.