Boot loader refactoring

- Renamed system.build.menuBuilder to system.build.installBootLoader.

- ‘install-grub.pl’ (formerly grub-menu-builder.pl) now generates the
  GRUB menu *and* installs GRUB (if necessary).

- ‘switch-to-configuration.sh’ has no boot loader specific knowledge
  anymore.  It just calls installBootLoader.

modules/installer/cd-dvd/iso-image.nix

@@ -168,7 +168,6 @@ in
   boot.loader.grub.enable = false;
 
   # !!! Hack - attributes expected by other modules.
-  system.build.menuBuilder = "true";
   system.boot.loader.kernelFile = "bzImage";
   environment.systemPackages = [ pkgs.grub2 ];
 

modules/installer/cd-dvd/system-tarball-fuloong2f.nix

@@ -170,9 +170,6 @@ in
   boot.loader.generationsDir.enable = false;
   system.boot.loader.kernelFile = "vmlinux";
 
-  # Needed for nixos to evaluate
-  system.build.menuBuilder = "true";
-
   nixpkgs.config = {
     platform = pkgs.platforms.fuloong2f_n32;
   };

modules/installer/cd-dvd/system-tarball-sheevaplug.nix

@@ -177,9 +177,6 @@ in
   services.ttyBackgrounds.enable = false;
   jobs.openssh.startOn = pkgs.lib.mkOverrideTemplate 50 {} "";
 
-  # Needed for nixos to evaluate
-  system.build.menuBuilder = "true";
-
   nixpkgs.config = {
     platform = pkgs.platforms.sheevaplug;
   };

modules/installer/efi-boot-stub/efi-boot-stub.nix

@@ -123,9 +123,7 @@ in
   system = mkIf (config.boot.loader.efiBootStub.enable && (assert
     (config.boot.kernelPackages.kernel.features ? efiBootStub &&
     config.boot.kernelPackages.kernel.features.efiBootStub); true)) {
-    build = {
-      menuBuilder = efiBootStubBuilder;
-    };
+    build.installBootLoader = efiBootStubBuilder;
     boot.loader.id = "efiBootStub";
     boot.loader.kernelFile = platform.kernelTarget;
   };

modules/installer/generations-dir/generations-dir.nix

@@ -63,9 +63,7 @@ in
   ];
 
   system = mkIf config.boot.loader.generationsDir.enable {
-    build = {
-      menuBuilder = generationsDirBuilder;
-    };
+    build.installBootLoader = generationsDirBuilder;
     boot.loader.id = "generationsDir";
     boot.loader.kernelFile = platform.kernelTarget;
   };

modules/installer/grub/grub.nix

@@ -13,10 +13,11 @@ let
   grubConfig = pkgs.writeText "grub-config.xml" (builtins.toXML
     { splashImage = f config.boot.loader.grub.splashImage;
       grub = f grub;
+      fullVersion = (builtins.parseDrvName config.system.build.grub.name).version;
       inherit (config.boot.loader.grub)
         version extraConfig extraPerEntryConfig extraEntries
         extraEntriesBeforeNixOS configurationLimit copyKernels timeout
-        default;
+        default devices;
     });
 
 in
@@ -199,9 +200,9 @@ in
 
     system.build = mkAssert (cfg.devices != [])
       "You must set the ‘boot.loader.grub.device’ option to make the system bootable."
-      { menuBuilder =
+      { installBootLoader =
           "PERL5LIB=${makePerlPath [ pkgs.perlPackages.XMLLibXML pkgs.perlPackages.XMLSAX ]} " +
-          "${pkgs.perl}/bin/perl ${./grub-menu-builder.pl} ${grubConfig}";
+          "${pkgs.perl}/bin/perl ${./install-grub.pl} ${grubConfig}";
         inherit grub;
       };
 

modules/installer/grub/install-grub.pl

@@ -5,7 +5,6 @@ use File::Basename;
 use File::Path;
 use File::stat;
 use File::Copy;
-use IO::File;
 use POSIX;
 use Cwd;
 
@@ -15,6 +14,19 @@ my $dom = XML::LibXML->load_xml(location => $ARGV[0]);
 
 sub get { my ($name) = @_; return $dom->findvalue("/expr/attrs/attr[\@name = '$name']/*/\@value"); }
 
+sub readFile {
+    my ($fn) = @_; local $/ = undef;
+    open FILE, "<$fn" or return undef; my $s = <FILE>; close FILE;
+    local $/ = "\n"; chomp $s; return $s;
+}
+
+sub writeFile {
+    my ($fn, $s) = @_;
+    open FILE, ">$fn" or die "cannot create $fn: $!\n";
+    print FILE $s or die;
+    close FILE or die;
+}
+
 my $grub = get("grub");
 my $grubVersion = int(get("version"));
 my $extraConfig = get("extraConfig");
@@ -151,8 +163,8 @@ sub addEntry {
     my $kernelParams =
         "systemConfig=" . Cwd::abs_path($path) . " " .
         "init=" . Cwd::abs_path("$path/init") . " " .
-        join " ", IO::File->new("$path/kernel-params")->getlines;
-    my $xenParams = $xen && -e "$path/xen-params" ? join " ", IO::File->new("$path/xen-params")->getlines : "";
+        readFile("$path/kernel-params");
+    my $xenParams = $xen && -e "$path/xen-params" ? readFile("$path/xen-params") : "";
 
     if ($grubVersion == 1) {
         $conf .= "title $name\n";
@@ -192,7 +204,7 @@ foreach my $link (@links) {
     my $date = strftime("%F", localtime(lstat($link)->mtime));
     my $version =
         -e "$link/nixos-version"
-        ? IO::File->new("$link/nixos-version")->getline
+        ? readFile("$link/nixos-version")
         : basename((glob(dirname(Cwd::abs_path("$link/kernel")) . "/lib/modules/*"))[0]);
     addEntry("NixOS - Configuration " . nrFromGen($link) . " ($date - $version)", $link);
 }
@@ -203,9 +215,7 @@ $conf .= "}\n" if $grubVersion == 2;
 # Atomically update the GRUB config.
 my $confFile = $grubVersion == 1 ? "/boot/grub/menu.lst" : "/boot/grub/grub.cfg";
 my $tmpFile = $confFile . ".tmp";
-open CONF, ">$tmpFile" or die "cannot open $tmpFile for writing\n";
-print CONF $conf or die;
-close CONF;
+writeFile($tmpFile, $conf);
 rename $tmpFile, $confFile or die "cannot rename $tmpFile to $confFile\n";
 
 
@@ -215,3 +225,18 @@ foreach my $fn (glob "/boot/kernels/*") {
     print STDERR "removing obsolete file $fn\n";
     unlink $fn;
 }
+
+
+# Install GRUB if the version changed from the last time we installed
+# it.  FIXME: shouldn't we reinstall if ‘devices’ changed?
+my $prevVersion = readFile("/boot/grub/version") // "";
+if (($ENV{'NIXOS_INSTALL_GRUB'} // "") eq "1" || get("fullVersion") ne $prevVersion) {
+    foreach my $dev ($dom->findnodes('/expr/attrs/attr[@name = "devices"]/list/string/@value')) {
+        $dev = $dev->findvalue(".") or die;
+        next if $dev eq "nodev";
+        print STDERR "installing the GRUB $grubVersion boot loader on $dev...\n";
+        system("$grub/sbin/grub-install", "--recheck", Cwd::abs_path($dev)) == 0
+            or die "$0: installation of GRUB on $dev failed\n";
+    }
+    writeFile("/boot/grub/version", get("fullVersion"));
+}

modules/system/activation/switch-to-configuration.sh

@@ -23,32 +23,8 @@ fi
 
 # Install or update the bootloader.
 if [ "$action" = "switch" -o "$action" = "boot" ]; then
-
-    if [ "@bootLoader@" = "grub" ]; then
-        
-        @menuBuilder@ @out@
-
-        # If the GRUB version has changed, then force a reinstall.
-        oldGrubVersion="$(cat /boot/grub/version 2>/dev/null || true)"
-        newGrubVersion="@grubVersion@"
-
-        if [ "$NIXOS_INSTALL_GRUB" = 1 -o "$oldGrubVersion" != "$newGrubVersion" ]; then
-            for dev in @grubDevices@; do
-                if [ "$dev" != nodev ]; then
-                    echo "installing the GRUB bootloader on $dev..."
-                    @grub@/sbin/grub-install --recheck "$(readlink -f "$dev")" --no-floppy
-                fi
-            done
-            echo "$newGrubVersion" > /boot/grub/version
-        fi
-          
-    elif [ "@bootLoader@" = "generationsDir" ]; then
-        @menuBuilder@ @out@
-    elif [ "@bootLoader@" = "efiBootStub" ]; then
-        @menuBuilder@ @out@
-    else
-        echo "Warning: don't know how to make this configuration bootable; please enable a boot loader." 1>&2
-    fi
+    
+    @installBootLoader@ @out@
 
     if [ -n "@initScriptBuilder@" ]; then
         @initScriptBuilder@ @out@

modules/system/activation/top-level.nix

@@ -101,9 +101,6 @@ let
 
       ln -s ${kernelPath} $out/kernel
       ln -s ${config.system.modulesTree} $out/kernel-modules
-      if [ -n "$grub" ]; then
-        ln -s $grub $out/grub
-      fi
 
       ln -s ${config.system.build.initialRamdisk}/initrd $out/initrd
 
@@ -152,7 +149,9 @@ let
     inherit children;
     kernelParams =
       config.boot.kernelParams ++ config.boot.extraKernelParams;
-    menuBuilder = config.system.build.menuBuilder or "true";
+    installBootLoader =
+      config.system.build.installBootLoader
+      or "echo 'Warning: don't know how to make this configuration bootable; please enable a boot loader.' 1>&2; true";
     initScriptBuilder = config.system.build.initScriptBuilder;
     activationScript = config.system.activationScripts.script;
     nixosVersion = config.system.nixosVersion;
@@ -176,20 +175,6 @@ let
         config.system.build.upstart # for initctl
       ];
 
-    # Boot loaders
-    bootLoader = config.system.boot.loader.id;
-    grub =
-      if config.boot.loader.grub.enable
-      then config.system.build.grub
-      else null;
-    grubVersion =
-      if config.boot.loader.grub.enable
-      then (builtins.parseDrvName config.system.build.grub.name).version
-      else "";
-    grubDevices =
-      let
-        wrapQuotes = s: "\"" + s + "\"";
-      in map wrapQuotes config.boot.loader.grub.devices;
     configurationName = config.boot.loader.grub.configurationName;
   };