doc: Give an example with an encrypted root partition.

* gnu/system/examples/desktop.tmpl: Add 'mapped-devices' field.
  Use it in 'file-systems'.
* doc/guix.texi (System Installation): Suggest encrypted partitions.
  Give an example of a command sequence.

1 files changed, 10 insertions, 2 deletions

diff --git a/gnu/system/examples/desktop.tmpl b/gnu/system/examples/desktop.tmpl
index 988b8f937f..41f66f693a 100644
--- a/gnu/system/examples/desktop.tmpl
+++ b/gnu/system/examples/desktop.tmpl
@@ -13,9 +13,17 @@
   ;; Assuming /dev/sdX is the target hard disk, and "root" is
   ;; the label of the target root file system.
   (bootloader (grub-configuration (device "/dev/sdX")))
+
+  ;; Here we assume that /dev/sdX1 contains a LUKS-encrypted
+  ;; root partition created with 'cryptsetup luksFormat'.
+  (mapped-devices (list (mapped-device
+                          (source "/dev/sdX1")
+                          (target "root-partition")
+                          (type luks-device-mapping))))
+
+  ;; Mount said encrypted partition.
   (file-systems (cons (file-system
-                        (device "root")
-                        (title 'label)
+                        (device "/dev/mapper/root-partition")
                         (mount-point "/")
                         (type "ext4"))
                       %base-file-systems))