diff --git a/doc/config-examples/root-on-lvm.nix b/doc/config-examples/root-on-lvm.nix
index 4fd4ca3a65c..2ea1e547921 100644
--- a/doc/config-examples/root-on-lvm.nix
+++ b/doc/config-examples/root-on-lvm.nix
@@ -1,9 +1,6 @@
 # This configuration has / on a LVM volume.  Since Grub
 # doesn't know about LVM, a separate /boot is therefore
-# needed.  In particular you need to set "copyKernels"
-# to tell NixOS to copy kernels and initrds from /nix/store
-# to /boot, and "bootMount" to tell Grub the /boot device
-# in Grub syntax (e.g. (hd0,0) for /dev/sda1).
+# needed.
 #
 # In this example, labels are used for file systems and
 # swap devices: "boot" might be /dev/sda1, "root" might be
@@ -12,12 +9,8 @@
 # that / is on LVM; that's figured out automatically.
 
 {
-  boot = {
-    grubDevice = "/dev/sda";
-    initrd.kernelModules = ["ata_piix"];
-    copyKernels = true;
-    bootMount = "(hd0,0)";
-  };
+  boot.loader.grub.device = "/dev/sda";
+  boot.initrd.kernelModules = ["ata_piix"];
 
   fileSystems = [
     { mountPoint = "/";
diff --git a/modules/installer/grub/grub-menu-builder.sh b/modules/installer/grub/grub-menu-builder.sh
index 1cce302fdf0..72ea17875c5 100644
--- a/modules/installer/grub/grub-menu-builder.sh
+++ b/modules/installer/grub/grub-menu-builder.sh
@@ -12,8 +12,6 @@ fi
 
 grubVersion="@version@"
 defaultConfig="$1"
-bootDevice="@bootDevice@"
-if test -z "$bootDevice"; then bootDevice=/boot; fi
 
 case "$grubVersion" in
     1|2)
@@ -27,6 +25,20 @@ case "$grubVersion" in
 esac
 
 
+# Discover whether /boot is on the same filesystem as /.  If not, then
+# all kernels and initrds must be copied to /boot, and all paths in
+# the GRUB config file must be relative to the root of the /boot
+# filesystem.  `$bootRoot' is the path to be prepended to paths under
+# /boot.
+if [ "$(stat -f -c '%i' /)" = "$(stat -f -c '%i' /boot)" ]; then
+    bootRoot=/boot
+    copyKernels="@copyKernels@" # user can override in the NixOS config
+else
+    bootRoot=
+    copyKernels=1
+fi
+
+
 prologue() {
     case "$grubVersion" in
 	1)
@@ -37,7 +49,7 @@ default @default@
 timeout @timeout@
 GRUBEND
 	    if test -n "@splashImage@"; then
-		echo "splashimage $bootDevice/background.xpm.gz" >> "$1"
+		echo "splashimage $bootRoot/background.xpm.gz" >> "$1"
 	    fi
 	    ;;
 	2)
@@ -46,7 +58,7 @@ GRUBEND
 # Automatically generated.  DO NOT EDIT THIS FILE!
 set default=@default@
 set timeout=@timeout@
-if loadfont $bootDevice/grub/unicode.pf2; then
+if loadfont $bootRoot/grub/unicode.pf2; then
   set gfxmode=640x480
   insmod gfxterm
   insmod vbe
@@ -59,7 +71,7 @@ EOF
 		# if it doesn't match the video resolution.
 		cat >> "$1" <<EOF
 insmod png
-if background_image $bootDevice/background.png; then
+if background_image $bootRoot/background.png; then
   set color_normal=white/black
   set color_highlight=black/white
 else
@@ -106,7 +118,8 @@ declare -A filesCopied
 
 copyToKernelsDir() {
     local src="$1"
-    local dst="/boot/kernels/$(cleanName $src)"
+    local p="kernels/$(cleanName $src)"
+    local dst="/boot/$p"
     # Don't copy the file if $dst already exists.  This means that we
     # have to create $dst atomically to prevent partially copied
     # kernels or initrd if this script is ever interrupted.
@@ -116,7 +129,7 @@ copyToKernelsDir() {
         mv $dstTmp $dst
     fi
     filesCopied[$dst]=1
-    result=$dst
+    result="$bootRoot/$p"
 }
 
 
@@ -147,34 +160,27 @@ addEntry() {
 	    1)
 		cat > /boot/nixos-grub-config <<EOF
 	title Emergency boot
-	kernel ${bootDevice:-/boot}/nixos-kernel systemConfig=$(readlink -f "$path") init=/boot/nixos-init $(cat "$path/kernel-params")
-	initrd ${bootDevice:-/boot}/nixos-initrd
+	kernel $bootRoot/nixos-kernel systemConfig=$(readlink -f "$path") init=/boot/nixos-init $(cat "$path/kernel-params")
+	initrd $bootRoot/nixos-initrd
 EOF
 		;;
 	    2)
 		cat > /boot/nixos-grub-config <<EOF
         menuentry "Emergency boot" {
-          linux  ${bootDevice:-/boot}/nixos-kernel systemConfig=$(readlink -f "$path") init=/boot/nixos-init $(cat "$path/kernel-params")
-          initrd ${bootDevice:-/boot}/initrd
+          linux  $bootRoot/nixos-kernel systemConfig=$(readlink -f "$path") init=/boot/nixos-init $(cat "$path/kernel-params")
+          initrd $bootRoot/initrd
         }
 EOF
 		;;
 	esac
     fi
 
-    if test -n "@copyKernels@"; then
+    if test -n "$copyKernels"; then
         copyToKernelsDir $kernel; kernel=$result
         copyToKernelsDir $initrd; initrd=$result
     fi
     
-    if test -n "$bootDevice"; then
-        kernel=$(echo $kernel | sed -e "s^/boot^$bootDevice^")
-        initrd=$(echo $initrd | sed -e "s^/boot^$bootDevice^")
-    fi
-    
-    local confName=$(if test -e $path/configuration-name; then 
-	cat $path/configuration-name; 
-    fi)
+    local confName=$(cat $path/configuration-name 2>/dev/null)
     if test -n "$confName"; then
 	name="$confName $3"
     fi
@@ -199,7 +205,7 @@ GRUBEND
 }
 
 
-if test -n "@copyKernels@"; then
+if test -n "$copyKernels"; then
     mkdir -p /boot/kernels
 fi
 
diff --git a/modules/installer/grub/grub.nix b/modules/installer/grub/grub.nix
index 0939abd6e18..e3df1593e71 100644
--- a/modules/installer/grub/grub.nix
+++ b/modules/installer/grub/grub.nix
@@ -13,7 +13,7 @@ let
     inherit (pkgs) bash;
     path = [pkgs.coreutils pkgs.gnused pkgs.gnugrep];
     inherit (config.boot.loader.grub) copyKernels extraEntries extraEntriesBeforeNixOS
-      splashImage bootDevice configurationLimit version default timeout;
+      splashImage configurationLimit version default timeout;
   };
   
 in
@@ -53,15 +53,10 @@ in
         '';
       };
 
+      # !!! How can we mark options as obsolete?
       bootDevice = mkOption {
         default = "";
-        example = "(hd0,0)";
-        description = ''
-          If the system partition may be wiped on reinstall, it is better
-          to have /boot on a small partition. To do it, we need to explain
-          to GRUB where the kernels live. Specify the partition here (in 
-          GRUB notation).
-        '';
+        description = "Obsolete.";
       };
 
       configurationName = mkOption {
@@ -121,8 +116,8 @@ in
         default = false;
         description = ''
           Whether the GRUB menu builder should copy kernels and initial
-          ramdisks to /boot.  This is necessary when /nix is on a
-          different file system than /boot.
+          ramdisks to /boot.  This is done automatically if /boot is
+          on a different partition than /.
         '';
       };