From 216d98ab97fbec49a213e4b5a6df0c6e771aef3d Mon Sep 17 00:00:00 2001
From: andre4ik3 <andre4ik3@fastmail.com>
Date: Mon, 11 Aug 2025 05:34:33 +0000
Subject: [PATCH] nixos/systemd-initrd: silence various warnings

Silences 2 warning messages that appear when using the systemd initrd:

1. "System tainted (var-run-bad)": occurs because `/var/run` isn't a
   symlink to `/run`. Fixed by making /run and linking /var/run to it.

2. "Failed to make /usr a mountpoint": occurs because ProtectSystem
   defaults to true in the initrd, which makes systemd try to remount
   `/usr` as read-only, which doesn't exist in the initrd. Fixed by
   linking `/usr/bin` and `/usr/sbin` to the initrd bin directories.

Also moves the `/tmp` creation from the initrd module to make-initrd-ng,
to avoid making an unnecessary `/tmp/.keep`, saving a store path and a
few bytes in the initrd image.
---
 nixos/modules/system/boot/systemd/initrd.nix | 3 ++-
 pkgs/build-support/kernel/make-initrd-ng.nix | 3 ++-
 2 files changed, 4 insertions(+), 2 deletions(-)

diff --git a/nixos/modules/system/boot/systemd/initrd.nix b/nixos/modules/system/boot/systemd/initrd.nix
index c2b1b1ab005c..ffce5e7e0dfa 100644
--- a/nixos/modules/system/boot/systemd/initrd.nix
+++ b/nixos/modules/system/boot/systemd/initrd.nix
@@ -481,7 +481,6 @@ in
       settings.Manager.DefaultEnvironment = "PATH=/bin:/sbin";
 
       contents = {
-        "/tmp/.keep".text = "systemd requires the /tmp mount point in the initrd cpio archive";
         "/init".source = "${cfg.package}/lib/systemd/systemd";
         "/etc/systemd/system".source = stage1Units;
 
@@ -507,6 +506,8 @@ in
 
         "/bin".source = "${initrdBinEnv}/bin";
         "/sbin".source = "${initrdBinEnv}/sbin";
+        "/usr/bin".source = "${initrdBinEnv}/bin";
+        "/usr/sbin".source = "${initrdBinEnv}/sbin";
 
         "/etc/sysctl.d/nixos.conf".text = "kernel.modprobe = /sbin/modprobe";
         "/etc/modprobe.d/systemd.conf".source = "${cfg.package}/lib/modprobe.d/systemd.conf";
diff --git a/pkgs/build-support/kernel/make-initrd-ng.nix b/pkgs/build-support/kernel/make-initrd-ng.nix
index b5cfc55c695e..35fd66e89db7 100644
--- a/pkgs/build-support/kernel/make-initrd-ng.nix
+++ b/pkgs/build-support/kernel/make-initrd-ng.nix
@@ -100,7 +100,8 @@ runCommand name
     ++ lib.optional makeUInitrd ubootTools;
   })
   ''
-    mkdir -p ./root/var/empty
+    mkdir -p ./root/{run,tmp,var/empty}
+    ln -s ../run ./root/var/run
     make-initrd-ng "$contentsPath" ./root
     mkdir "$out"
     (cd root && find . -exec touch -h -d '@1' '{}' +)