From 5bc1b01a403e071500a3b0659364fb6ee20391e1 Mon Sep 17 00:00:00 2001
From: Markus Partheymueller <markus.partheymueller@cyberus-technology.de>
Date: Mon, 14 Nov 2022 14:20:58 +0100
Subject: [PATCH] boot.loader.systemd-boot: add extraInstallCommands option
 (#200715)

---
 .../boot/loader/systemd-boot/systemd-boot.nix | 24 ++++++++++++++++++-
 1 file changed, 23 insertions(+), 1 deletion(-)

diff --git a/nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix b/nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix
index a9d43d027e01..8cb7c7b8e47b 100644
--- a/nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix
+++ b/nixos/modules/system/boot/loader/systemd-boot/systemd-boot.nix
@@ -57,6 +57,12 @@ let
       --disallow-untyped-defs \
       $out
   '';
+
+  finalSystemdBootBuilder = pkgs.writeScript "install-systemd-boot.sh" ''
+    #!${pkgs.runtimeShell}
+    ${checkedSystemdBootBuilder} "$@"
+    ${cfg.extraInstallCommands}
+  '';
 in {
 
   imports =
@@ -99,6 +105,22 @@ in {
       '';
     };
 
+    extraInstallCommands = mkOption {
+      default = "";
+      example = ''
+        default_cfg=$(cat /boot/loader/loader.conf | grep default | awk '{print $2}')
+        init_value=$(cat /boot/loader/entries/$default_cfg | grep init= | awk '{print $2}')
+        sed -i "s|@INIT@|$init_value|g" /boot/custom/config_with_placeholder.conf
+      '';
+      type = types.lines;
+      description = lib.mdDoc ''
+        Additional shell commands inserted in the bootloader installer
+        script after generating menu entries. It can be used to expand
+        on extra boot entries that cannot incorporate certain pieces of
+        information (such as the resulting `init=` kernel parameter).
+      '';
+    };
+
     consoleMode = mkOption {
       default = "keep";
 
@@ -277,7 +299,7 @@ in {
     ];
 
     system = {
-      build.installBootLoader = checkedSystemdBootBuilder;
+      build.installBootLoader = finalSystemdBootBuilder;
 
       boot.loader.id = "systemd-boot";