diff --git a/test/boot-stage-1-init.sh b/test/boot-stage-1-init.sh
index 1299599a94ee..3e93571ebdaf 100644
--- a/test/boot-stage-1-init.sh
+++ b/test/boot-stage-1-init.sh
@@ -83,9 +83,6 @@ else
     # Hard-coded root device.
     mount -o ro "@rootDevice@" /mnt/root
 
-    # Testing.
-    fail
-
 fi
 
 # Start stage 2.
@@ -96,6 +93,7 @@ cd /mnt/root
 mount --move . /
 umount /proc # cleanup
 umount /sys
-exec chroot . /init
+
+exec chroot . @stage2Init@
 
 fail
diff --git a/test/boot-stage-1.nix b/test/boot-stage-1.nix
index bb52b3f83545..ef1ebfc72255 100644
--- a/test/boot-stage-1.nix
+++ b/test/boot-stage-1.nix
@@ -15,6 +15,10 @@
 
   # If scanning, we need a disk label.
 , rootLabel
+
+, # The path of the stage 2 init to call once we've mounted the root
+  # device.
+  stage2Init ? "/init"
 }:
 
 assert !autoDetectRootDevice -> rootDevice != "";
@@ -31,4 +35,9 @@ genericSubstituter {
     extraUtils
   ];
   makeDevices = ./make-devices.sh;
+
+  # We only want the path of the stage 2 init, we don't want it as a
+  # dependency (since then it the stage 2 init would end up in the
+  # initrd).
+  stage2Init = toString stage2Init; # !!! doesn't work
 }
diff --git a/test/boot-stage-2-init.sh b/test/boot-stage-2-init.sh
index be54926aabce..edf3e9c0dbf7 100644
--- a/test/boot-stage-2-init.sh
+++ b/test/boot-stage-2-init.sh
@@ -2,11 +2,13 @@
 
 # !!! copied from stage 1; remove duplication
 
+
 # Print a greeting.
 echo
 echo "<<< NixOS Stage 2 >>>"
 echo
 
+
 # Set the PATH.
 export PATH=/empty
 for i in @path@; do
@@ -16,49 +18,70 @@ for i in @path@; do
     fi
 done
 
-# Mount special file systems.
-mount -t tmpfs none /etc -n # to shut up mount
-touch /etc/fstab # idem
+
+# Mount special file systems, initialise required directories.
+
+if test -z "@readOnlyRoot@"; then
+    #rootDev=$(grep "/dev/.* / " /proc/mounts | sed 's/^\([^ ]*\) .*/\1/')
+    mount -o remount,rw /dontcare / # !!! check for failure
+fi
+
+needWritableDir() {
+    if test -n "@readOnlyRoot@"; then
+        mount -t tmpfs none $1 $3
+        chmod $2 $1
+    else
+        mkdir -m $2 -p $1
+    fi
+}
+
+needWritableDir /etc 0755 -n # to shut up mount
+
+test -e /etc/fstab || touch /etc/fstab # idem
+
 mount -t proc none /proc
 mount -t sysfs none /sys
-mount -t tmpfs none /dev
-mount -t tmpfs none /tmp
-mount -t tmpfs none /var
-mount -t tmpfs none /nix/var
+needWritableDir /dev 0755
+needWritableDir /tmp 01777
+needWritableDir /var 0755
+needWritableDir /nix/var 0755
+
+mkdir -m 0755 -p /nix/var/nix/db
+mkdir -m 0755 -p /nix/var/nix/gcroots
+mkdir -m 0755 -p /nix/var/nix/temproots
 
-mkdir -p /nix/var/nix/db
-mkdir -p /nix/var/nix/gcroots
-mkdir -p /nix/var/nix/temproots
 
 # Ensure that the module tools can find the kernel modules.
 export MODULE_DIR=@kernel@/lib/modules/
 
-# Create device nodes in /dev.
-#source @makeDevices@
 
 # Start udev.
 udevd --daemon
 
+
 # Let udev create device nodes for all modules that have already been
 # loaded into the kernel (or for which support is built into the
 # kernel).
 udevtrigger
 udevsettle # wait for udev to finish
 
+
 # Start syslogd.
-mkdir -p /var/run
+mkdir -m 0755 -p /var/run
 #mkdir -p /var/log
 #touch /var/log/messages
 echo "*.* /dev/tty10" > /etc/syslog.conf
 echo "syslog 514/udp" > /etc/services # required, even if we don't use it
 @sysklogd@/sbin/syslogd &
 
+
 # Try to load modules for all PCI devices.
 for i in /sys/bus/pci/devices/*/modalias; do
     echo "Trying to load a module for $(basename $(dirname $i))..."
     modprobe $(cat $i)
 done
 
+
 # Bring up the network devices.
 modprobe af_packet
 for i in $(cd /sys/class/net && ls -d *); do
@@ -71,18 +94,26 @@ for i in $(cd /sys/class/net && ls -d *); do
     fi
 done
 
+
 # login/su absolutely need this.
-touch /etc/login.defs 
+test -e /etc/login.defs || touch /etc/login.defs 
+
 
 # Enable a password-less root login.
-echo "root::0:0:root:/:@shell@" > /etc/passwd
-echo "root:*:0" > /etc/group
+if ! test -e /etc/passwd; then
+    echo "root::0:0:root:/:@shell@" > /etc/passwd
+fi
+if ! test -e /etc/group; then
+    echo "root:*:0" > /etc/group
+fi
+
 
 # Set up inittab.
 for i in $(seq 1 6); do 
     echo "$i:2345:respawn:@mingetty@/sbin/mingetty --noclear tty$i" >> /etc/inittab
 done
 
+
 # Show a nice greeting on each terminal.
 cat > /etc/issue <<EOF
 
@@ -93,6 +124,7 @@ You can log in as \`root'.
 
 EOF
 
+
 # Additional path for the interactive shell.
 for i in @extraPath@; do
     PATH=$PATH:$i/bin
@@ -106,11 +138,14 @@ export PATH=$PATH
 export MODULE_DIR=$MODULE_DIR
 EOF
 
+
 # Set the host name.
 hostname nixos
 
+
 # Start an interactive shell.
 #exec @shell@
 
+
 # Start init.
 exec init 2
diff --git a/test/boot-stage-2.nix b/test/boot-stage-2.nix
index 4514d1779ad4..51420554500d 100644
--- a/test/boot-stage-2.nix
+++ b/test/boot-stage-2.nix
@@ -2,12 +2,16 @@
 , utillinux, kernel, sysklogd, mingetty, udev
 , module_init_tools, nettools, dhcp
 , path ? []
+
+, # Whether the root device is root only.  If so, we'll mount a
+  # ramdisk on /etc, /var and so on.
+  readOnlyRoot
 }:
 
 genericSubstituter {
   src = ./boot-stage-2-init.sh;
   isExecutable = true;
-  inherit shell kernel sysklogd mingetty;
+  inherit shell kernel sysklogd mingetty readOnlyRoot;
   path = [
     coreutils
     findutils
@@ -18,5 +22,4 @@ genericSubstituter {
     dhcp
   ];
   extraPath = path;
-  makeDevices = ./make-devices.sh;
 }
diff --git a/test/installer.nix b/test/installer.nix
index d960bab1bb14..4b3ec85939ca 100644
--- a/test/installer.nix
+++ b/test/installer.nix
@@ -10,7 +10,8 @@ genericSubstituter {
   nixClosure = stdenv.mkDerivation {
     name = "closure";
     builder = builtins.toFile "builder.sh"
-      "source $stdenv/setup; /nix/bin/nix-store -qR $nix > $out";
+      "source $stdenv/setup; nix-store -qR $nix > $out";
+    buildInputs = [nix];
     inherit nix;
   };
 }
diff --git a/test/make-iso9660-image.nix b/test/make-iso9660-image.nix
index f08aac3abc5d..861b229b8a4d 100644
--- a/test/make-iso9660-image.nix
+++ b/test/make-iso9660-image.nix
@@ -1,4 +1,4 @@
-{ stdenv, cdrtools
+{ stdenv, cdrtools, nix
 
   # The file name of the resulting ISO image.
 , isoName ? "cd.iso"
@@ -31,7 +31,7 @@ assert bootable -> bootImage != "";
 stdenv.mkDerivation {
   name = "iso9660-image";
   builder = ./make-iso9660-image.sh;
-  buildInputs = [cdrtools];
+  buildInputs = [cdrtools nix];
   inherit isoName packages init bootable bootImage;
   sources = map ({source, target}: source) contents;
   targets = map ({source, target}: target) contents;
diff --git a/test/make-iso9660-image.sh b/test/make-iso9660-image.sh
index 17f44e78ff01..774fbb8a90ec 100644
--- a/test/make-iso9660-image.sh
+++ b/test/make-iso9660-image.sh
@@ -13,7 +13,7 @@ done
 
 # !!! Just as with make-initrd.nix, the call to Nix here needs to be
 # fixed.
-packagesClosure=$(/nix/bin/nix-store -qR $packages $init)
+packagesClosure=$(nix-store -qR $packages $init)
 
 for i in $packagesClosure; do
     graftList="$graftList ${i:1}=$i"
diff --git a/test/rescue-cd.nix b/test/rescue-cd.nix
index 002288bea870..ddb6a7cb6772 100644
--- a/test/rescue-cd.nix
+++ b/test/rescue-cd.nix
@@ -9,12 +9,14 @@ in
   with import ./rescue-system.nix {
     autoDetectRootDevice = true;
     rootLabel = cdromLabel;
+    stage2Init = "/init";
+    readOnlyRoot = true;
   };
 
   
 rec {
 
-  inherit nixosInstaller; # !!! debug
+  inherit nixosInstaller bootStage1; # !!! debug
 
 
   # Since the CD is read-only, the mount points must be on disk.
@@ -34,7 +36,7 @@ rec {
   # kernel, the initrd produced above, and the closure of the stage 2
   # init.
   rescueCD = import ./make-iso9660-image.nix {
-    inherit (pkgs) stdenv cdrtools;
+    inherit (pkgs) stdenv cdrtools nix;
     isoName = "nixos.iso";
     
     contents = [
diff --git a/test/rescue-system.nix b/test/rescue-system.nix
index 40ec535c6b17..b2050fb14aee 100644
--- a/test/rescue-system.nix
+++ b/test/rescue-system.nix
@@ -2,6 +2,8 @@
 , autoDetectRootDevice ? false
 , rootDevice ? ""
 , rootLabel ? ""
+, stage2Init
+, readOnlyRoot
 }:
 
 rec {
@@ -50,6 +52,7 @@ rec {
     inherit (pkgsDiet) module_init_tools;
     inherit extraUtils;
     inherit autoDetectRootDevice rootDevice rootLabel;
+    inherit stage2Init;
     modules = modulesClosure;
     shell = stdenvLinuxStuff.bootstrapTools.bash;
     staticTools = stdenvLinuxStuff.staticTools;
@@ -110,6 +113,8 @@ rec {
     ];
 
     mingetty = pkgs.mingettyWrapper;
+
+    inherit readOnlyRoot;
   };
 
 
diff --git a/test/system-configuration.nix b/test/system-configuration.nix
index ef04dc1badc9..531dc0d5cb85 100644
--- a/test/system-configuration.nix
+++ b/test/system-configuration.nix
@@ -7,14 +7,17 @@ let
   # don't want GRUB to be installed).
   grubDevice = "/dev/hda";
 
-in
-
-  # Build boot scripts for the CD that find the CD-ROM automatically.
-  with import ./rescue-system.nix {
+  # Build boot scripts.
+  bootEnv = import ./rescue-system.nix {
     autoDetectRootDevice = false;
     inherit rootDevice;
+    stage2Init = "/init"; # !!! should be bootEnv.bootStage2;
+    readOnlyRoot = false;
   };
 
+in
+
+with bootEnv;
   
 rec {
 
@@ -24,6 +27,7 @@ rec {
     builder = ./system-configuration.sh;
     inherit (pkgs) grub coreutils gnused gnugrep diffutils;
     inherit grubDevice;
+    inherit bootStage2;
     kernel = pkgs.kernel + "/vmlinuz";
     initrd = initialRamdisk + "/initrd";
   };
diff --git a/test/system-configuration.sh b/test/system-configuration.sh
index 17d58f4d0cbe..d35811a84da5 100644
--- a/test/system-configuration.sh
+++ b/test/system-configuration.sh
@@ -23,6 +23,7 @@ export PATH=$coreutils/bin:$gnused/bin:$gnugrep/bin:$diffutils/bin
 if test -n "$grubDevice"; then
     $grub/sbin/grub-install "$grubDevice" --no-floppy --recheck
     cp -f $out/menu.lst /boot/grub/menu.lst
+    ln -sf $bootStage2 /init # !!! fix?
 fi
 EOF