From d0126c0508e46fff6b7560f60f2d9e9f1067b096 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?J=C3=B6rg=20Thalheim?= <joerg@thalheim.io>
Date: Wed, 12 Jun 2024 08:15:16 +0200
Subject: [PATCH] make-disk-image: fix build for systems that use
 boot.loader.grub.devices

config.boot.loader.grub.device is just an alias that gets assigned to config.boot.loader.grub.devices.
If config.boot.loader.grub.device is set to null, it will fail with the following error
as described in https://github.com/nix-community/nixos-generators/issues/339
---
 nixos/lib/make-disk-image.nix | 9 +++++----
 1 file changed, 5 insertions(+), 4 deletions(-)

diff --git a/nixos/lib/make-disk-image.nix b/nixos/lib/make-disk-image.nix
index 9bdbf4e0713d..1220bbfd5ed7 100644
--- a/nixos/lib/make-disk-image.nix
+++ b/nixos/lib/make-disk-image.nix
@@ -603,10 +603,11 @@ let format' = format; in let
       ${lib.optionalString installBootLoader ''
         # In this throwaway resource, we only have /dev/vda, but the actual VM may refer to another disk for bootloader, e.g. /dev/vdb
         # Use this option to create a symlink from vda to any arbitrary device you want.
-        ${optionalString (config.boot.loader.grub.enable && config.boot.loader.grub.device != "/dev/vda") ''
-            mkdir -p $(dirname ${config.boot.loader.grub.device})
-            ln -s /dev/vda ${config.boot.loader.grub.device}
-        ''}
+        ${optionalString (config.boot.loader.grub.enable) (lib.concatMapStringsSep " " (device:
+          lib.optionalString (device != "/dev/vda") ''
+            mkdir -p "$(dirname ${device})"
+            ln -s /dev/vda ${device}
+          '') config.boot.loader.grub.devices)}
 
         # Set up core system link, bootloader (sd-boot, GRUB, uboot, etc.), etc.