nixos/qemu-vm: add option to use a non-standard BIOS

I'd like to change the default on x86 platforms to qboot at some point, since it
saves a fair bit of startup time.

nixos/modules/virtualisation/qemu-vm.nix

@@ -441,6 +441,18 @@ in
           '';
       };
 
+    virtualisation.bios =
+      mkOption {
+        default = null;
+        type = types.nullOr types.package;
+        description =
+          ''
+            An alternate BIOS (such as <package>qboot</package>) with which to start the VM.
+            Should containin a file named <literal>bios.bin</literal>.
+            If <literal>null</literal>, QEMU's builtin SeaBIOS will be used.
+          '';
+      };
+
   };
 
   config = {
@@ -521,6 +533,9 @@ in
       (mkIf cfg.useEFIBoot [
         "-pflash $TMPDIR/bios.bin"
       ])
+      (mkIf (cfg.bios != null) [
+        "-bios ${cfg.bios}/bios.bin"
+      ])
       (mkIf (!cfg.graphics) [
         "-nographic"
       ])

nixos/tests/all-tests.nix

@@ -273,6 +273,7 @@ in
   prosody = handleTest ./xmpp/prosody.nix {};
   prosodyMysql = handleTest ./xmpp/prosody-mysql.nix {};
   proxy = handleTest ./proxy.nix {};
+  qboot = handleTestOn ["x86_64-linux" "i686-linux"] ./qboot.nix {};
   quagga = handleTest ./quagga.nix {};
   quorum = handleTest ./quorum.nix {};
   rabbitmq = handleTest ./rabbitmq.nix {};

nixos/tests/qboot.nix

@@ -0,0 +1,13 @@
+import ./make-test-python.nix ({ pkgs, ...} : {
+  name = "qboot";
+
+  machine = { ... }: {
+    virtualisation.bios = pkgs.qboot;
+  };
+
+  testScript =
+    ''
+      start_all()
+      machine.wait_for_unit("multi-user.target")
+    '';
+})

pkgs/applications/virtualization/qboot/default.nix

@@ -1,4 +1,4 @@
-{ stdenv, meson, ninja, fetchFromGitHub }:
+{ stdenv, meson, ninja, fetchFromGitHub, nixosTests }:
 
 stdenv.mkDerivation {
   name = "qboot-20200423";
@@ -19,6 +19,8 @@ stdenv.mkDerivation {
 
   hardeningDisable = [ "stackprotector" "pic" ];
 
+  passthru.tests = { qboot = nixosTests.qboot; };
+
   meta = {
     description = "A simple x86 firmware for booting Linux";
     homepage = "https://github.com/bonzini/qboot";