diff --git a/modules/installer/cd-dvd/system-tarball-pc-readme.txt b/modules/installer/cd-dvd/system-tarball-pc-readme.txt
new file mode 100644
index 00000000000..c4a0a111cd3
--- /dev/null
+++ b/modules/installer/cd-dvd/system-tarball-pc-readme.txt
@@ -0,0 +1,89 @@
+Let all the files in the system tarball sit in a directory served by NFS (the
+NFS root) like this in exportfs:
+  /home/pcroot    192.168.1.0/24(rw,no_root_squash,no_all_squash)
+
+Run "exportfs -a" after editing /etc/exportfs, for the nfs server to be aware
+of the changes.
+
+Use a tftp server serving the root of boot/ (from the system tarball).
+
+In order to have PXE boot, use the boot/dhcpd.conf-example file for your dhcpd
+server, as it will point your PXE clients to pxelinux.0 from the tftp server.
+Adapt the configuration to your network.
+
+Adapt the pxelinux configuration (boot/pxelinux.cfg/default) to set the path to
+your nfrroot. If you use ip=dhcp in the kernel, the nfs server ip will be taken
+from dhcp and so you don't have to specify it.
+
+The linux in bzImage includes network drivers for some usual cards.
+
+
+QEMU Testing
+---------------
+
+You can test qemu pxe boot without having a DHCP server adapted, but having
+nfsroot, like this:
+  qemu-system-x86_64 -tftp /home/pcroot/boot -net nic -net user,bootfile=pxelinux.0 -boot n
+
+I don't know how to use NFS through the qemu '-net user' though.
+
+
+QEMU Testing with NFS root and bridged network
+-------------------------------------------------
+
+This allows testing with qemu as any other host in your LAN.
+
+Testing with the real dhcpd server requires setting up a bridge and having a
+tap device.
+  tunctl -t tap0
+  brctl addbr br0
+  brctl addif br0 eth0
+  brctl addif tap0 eth0
+  ifconfig eth0 0.0.0.0 up
+  ifconfig tap0 0.0.0.0 up
+  ifconfig br0 up # With your ip configuration
+
+Then you can run qemu:
+  qemu-system-x86_64 -boot n -net tap,ifname=tap0,script=no -net nic,model=e1000
+
+
+Using the system-tarball-pc in a chroot
+--------------------------------------------------
+
+Installation:
+  mkdir nixos-chroot && cd nixos-chroot
+  tar xf your-system-tarball.tar.xz
+  mkdir sys dev proc tmp root var run
+  mount --bind /sys sys
+  mount --bind /dev dev
+  mount --bind /proc proc
+
+Activate the system: look for a directory in nix/store similar to:
+    "/nix/store/y0d1lcj9fppli0hl3x0m0ba5g1ndjv2j-nixos-feb97bx-53f008"
+Having found it, activate that nixos system *twice*:
+  chroot . /nix/store/SOMETHING-nixos-SOMETHING/activate
+  chroot . /nix/store/SOMETHING-nixos-SOMETHING/activate
+  
+This runs a 'hostname' command. Restore your old hostname with:
+  hostname OLDHOSTNAME
+
+Copy your system resolv.conf to the /etc/resolv.conf inside the chroot:
+  cp /etc/resolv.conf etc
+
+Then you can get an interactive shell in the nixos chroot. '*' means
+to run inside the chroot interactive shell
+  chroot . /bin/sh
+*  source /etc/profile
+
+Populate the nix database: that should be done in the init script if you
+had booted this nixos. Run:
+*  `grep local-cmds run/current-system/init`
+
+Then you can proceed normally subscribing to a nixos channel:
+  nix-channel --add http://nixos.org/releases/nixos/channels/nixos-unstable
+  nix-channel --update
+
+Testing:
+  nix-env -i hello
+  which hello
+  hello
diff --git a/modules/installer/cd-dvd/system-tarball-pc.nix b/modules/installer/cd-dvd/system-tarball-pc.nix
index 2bc6ce78d94..e98a8c215f9 100644
--- a/modules/installer/cd-dvd/system-tarball-pc.nix
+++ b/modules/installer/cd-dvd/system-tarball-pc.nix
@@ -60,54 +60,7 @@ let
     }
   '';
 
-  readme = pkgs.writeText "readme.txt" ''
-    Let all the files in the system tarball sit in a directory served by NFS (the NFS root)
-    like this in exportfs:
-      /home/pcroot    192.168.1.0/24(rw,no_root_squash,no_all_squash)
-
-    Run "exportfs -a" after editing /etc/exportfs, for the nfs server to be aware of the
-    changes.
-
-    Use a tftp server serving the root of boot/ (from the system tarball).
-
-    In order to have PXE boot, use the boot/dhcpd.conf-example file for your dhcpd server,
-    as it will point your PXE clients to pxelinux.0 from the tftp server. Adapt the
-    configuration to your network.
-
-    Adapt the pxelinux configuration (boot/pxelinux.cfg/default) to set the path to your
-    nfrroot. If you use ip=dhcp in the kernel, the nfs server ip will be taken from
-    dhcp and so you don't have to specify it.
-
-    The linux in bzImage includes network drivers for some usual cards.
-
-
-    QEMU Testing
-    ---------------
-
-    You can test qemu pxe boot without having a DHCP server adapted, but having nfsroot,
-    like this:
-      qemu-system-x86_64 -tftp /home/pcroot/boot -net nic -net user,bootfile=pxelinux.0 -boot n
-
-    I don't know how to use NFS through the qemu '-net user' though.
-
-
-    QEMU Testing with NFS root and bridged network
-    -------------------------------------------------
-
-    This allows testing with qemu as any other host in your LAN.
-
-    Testing with the real dhcpd server requires setting up a bridge and having a tap device.
-      tunctl -t tap0
-      brctl addbr br0
-      brctl addif br0 eth0
-      brctl addif tap0 eth0
-      ifconfig eth0 0.0.0.0 up
-      ifconfig tap0 0.0.0.0 up
-      ifconfig br0 up # With your ip configuration
-
-    Then you can run qemu:
-      qemu-system-x86_64 -boot n -net tap,ifname=tap0,script=no -net nic,model=e1000
-  '';
+  readme = builtins.readFile ./system-tarball-pc-readme.txt;
 
 in