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-rw-r--r--gnu/system/file-systems.scm72
-rw-r--r--gnu/system/grub.scm84
-rw-r--r--gnu/system/linux-initrd.scm347
-rw-r--r--gnu/system/linux.scm89
-rw-r--r--gnu/system/shadow.scm117
-rw-r--r--gnu/system/vm.scm478
6 files changed, 667 insertions, 520 deletions
diff --git a/gnu/system/file-systems.scm b/gnu/system/file-systems.scm
new file mode 100644
index 0000000000..485150ea51
--- /dev/null
+++ b/gnu/system/file-systems.scm
@@ -0,0 +1,72 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (gnu system file-systems)
+  #:use-module (guix records)
+  #:export (<file-system>
+            file-system
+            file-system?
+            file-system-device
+            file-system-mount-point
+            file-system-type
+            file-system-needed-for-boot?
+            file-system-flags
+            file-system-options
+
+            %fuse-control-file-system
+            %binary-format-file-system))
+
+;;; Commentary:
+;;;
+;;; Declaring file systems to be mounted.
+;;;
+;;; Code:
+
+;; File system declaration.
+(define-record-type* <file-system> file-system
+  make-file-system
+  file-system?
+  (device           file-system-device)           ; string
+  (mount-point      file-system-mount-point)      ; string
+  (type             file-system-type)             ; string
+  (flags            file-system-flags             ; list of symbols
+                    (default '()))
+  (options          file-system-options           ; string or #f
+                    (default #f))
+  (needed-for-boot? file-system-needed-for-boot?  ; Boolean
+                    (default #f))
+  (check?           file-system-check?            ; Boolean
+                    (default #t)))
+
+(define %fuse-control-file-system
+  ;; Control file system for Linux' file systems in user-space (FUSE).
+  (file-system
+    (device "fusectl")
+    (mount-point "/sys/fs/fuse/connections")
+    (type "fusectl")
+    (check? #f)))
+
+(define %binary-format-file-system
+  ;; Support for arbitrary executable binary format.
+  (file-system
+    (device "binfmt_misc")
+    (mount-point "/proc/sys/fs/binfmt_misc")
+    (type "binfmt_misc")
+    (check? #f)))
+
+;;; file-systems.scm ends here
diff --git a/gnu/system/grub.scm b/gnu/system/grub.scm
index 5dc0b85ff2..e789e4c591 100644
--- a/gnu/system/grub.scm
+++ b/gnu/system/grub.scm
@@ -22,10 +22,16 @@
   #:use-module (guix derivations)
   #:use-module (guix records)
   #:use-module (guix monads)
+  #:use-module (guix gexp)
   #:use-module (ice-9 match)
   #:use-module (srfi srfi-1)
-  #:export (menu-entry
+  #:export (grub-configuration
+            grub-configuration?
+            grub-configuration-device
+
+            menu-entry
             menu-entry?
+
             grub-configuration-file))
 
 ;;; Commentary:
@@ -34,51 +40,61 @@
 ;;;
 ;;; Code:
 
+(define-record-type* <grub-configuration>
+  grub-configuration make-grub-configuration
+  grub-configuration?
+  (grub            grub-configuration-grub           ; package
+                   (default (@ (gnu packages grub) grub)))
+  (device          grub-configuration-device)        ; string
+  (menu-entries    grub-configuration-menu-entries   ; list
+                   (default '()))
+  (default-entry   grub-configuration-default-entry  ; integer
+                   (default 1))
+  (timeout         grub-configuration-timeout        ; integer
+                   (default 5)))
+
 (define-record-type* <menu-entry>
   menu-entry make-menu-entry
   menu-entry?
   (label           menu-entry-label)
   (linux           menu-entry-linux)
   (linux-arguments menu-entry-linux-arguments
-                   (default '()))
-  (initrd          menu-entry-initrd))            ; file name of the initrd
+                   (default '()))          ; list of string-valued gexps
+  (initrd          menu-entry-initrd))     ; file name of the initrd as a gexp
 
-(define* (grub-configuration-file entries
-                                  #:key (default-entry 1) (timeout 5)
-                                  (system (%current-system)))
-  "Return the GRUB configuration file for ENTRIES, a list of
-<menu-entry> objects, defaulting to DEFAULT-ENTRY and with the given TIMEOUT."
-  (define (prologue kernel)
-    (format #f "
-set default=~a
-set timeout=~a
-search.file ~a~%"
-            default-entry timeout kernel))
-
-  (define (bzImage)
-    (any (match-lambda
-          (($ <menu-entry> _ linux)
-           (package-file linux "bzImage"
-                         #:system system)))
-         entries))
+(define* (grub-configuration-file config entries
+                                  #:key (system (%current-system)))
+  "Return the GRUB configuration file corresponding to CONFIG, a
+<grub-configuration> object."
+  (define all-entries
+    (append entries (grub-configuration-menu-entries config)))
 
-  (define entry->text
+  (define entry->gexp
     (match-lambda
      (($ <menu-entry> label linux arguments initrd)
-      (mlet %store-monad ((linux  (package-file linux "bzImage"
-                                                #:system system)))
-        (return (format #f "menuentry ~s {
-  linux ~a ~a
+      #~(format port "menuentry ~s {
+  linux ~a/bzImage ~a
   initrd ~a
 }~%"
-                        label
-                        linux (string-join arguments) initrd))))))
+                #$label
+                #$linux (string-join (list #$@arguments))
+                #$initrd))))
+
+  (define builder
+    #~(call-with-output-file #$output
+        (lambda (port)
+          (format port "
+set default=~a
+set timeout=~a
+search.file ~a/bzImage~%"
+                  #$(grub-configuration-default-entry config)
+                  #$(grub-configuration-timeout config)
+                  #$(any (match-lambda
+                          (($ <menu-entry> _ linux)
+                           linux))
+                         all-entries))
+          #$@(map entry->gexp all-entries))))
 
-  (mlet %store-monad ((kernel (bzImage))
-                      (body   (sequence %store-monad
-                                        (map entry->text entries))))
-    (text-file "grub.cfg"
-               (string-append (prologue kernel)
-                              (string-concatenate body)))))
+  (gexp->derivation "grub.cfg" builder))
 
 ;;; grub.scm ends here
diff --git a/gnu/system/linux-initrd.scm b/gnu/system/linux-initrd.scm
index 42ca29cb58..b80ff10f1e 100644
--- a/gnu/system/linux-initrd.scm
+++ b/gnu/system/linux-initrd.scm
@@ -18,19 +18,24 @@
 
 (define-module (gnu system linux-initrd)
   #:use-module (guix monads)
+  #:use-module (guix gexp)
   #:use-module (guix utils)
   #:use-module ((guix store)
                 #:select (%store-prefix))
+  #:use-module ((guix derivations)
+                #:select (derivation->output-path))
   #:use-module (gnu packages cpio)
   #:use-module (gnu packages compression)
   #:use-module (gnu packages linux)
   #:use-module (gnu packages guile)
   #:use-module ((gnu packages make-bootstrap)
                 #:select (%guile-static-stripped))
+  #:use-module (gnu system file-systems)
+  #:use-module (ice-9 match)
   #:use-module (ice-9 regex)
+  #:use-module (srfi srfi-1)
   #:export (expression->initrd
-            qemu-initrd
-            gnu-system-initrd))
+            qemu-initrd))
 
 
 ;;; Commentary:
@@ -49,12 +54,14 @@
                              (name "guile-initrd")
                              (system (%current-system))
                              (modules '())
+                             (to-copy '())
                              (linux #f)
                              (linux-modules '()))
   "Return a package that contains a Linux initrd (a gzipped cpio archive)
 containing GUILE and that evaluates EXP upon booting.  LINUX-MODULES is a list
-of `.ko' file names to be copied from LINUX into the initrd.  MODULES is a
-list of Guile module names to be embedded in the initrd."
+of `.ko' file names to be copied from LINUX into the initrd.  TO-COPY is a
+list of additional derivations or packages to copy to the initrd.  MODULES is
+a list of Guile module names to be embedded in the initrd."
 
   ;; General Linux overview in `Documentation/early-userspace/README' and
   ;; `Documentation/filesystems/ramfs-rootfs-initramfs.txt'.
@@ -63,150 +70,157 @@ list of Guile module names to be embedded in the initrd."
     ;; Return a regexp that matches STR exactly.
     (string-append "^" (regexp-quote str) "$"))
 
-  (define builder
-    `(begin
-       (use-modules (guix build utils)
-                    (ice-9 pretty-print)
-                    (ice-9 popen)
-                    (ice-9 match)
-                    (ice-9 ftw)
-                    (srfi srfi-26)
-                    (system base compile)
-                    (rnrs bytevectors)
-                    ((system foreign) #:select (sizeof)))
-
-       (let ((guile   (assoc-ref %build-inputs "guile"))
-             (cpio    (string-append (assoc-ref %build-inputs "cpio")
-                                     "/bin/cpio"))
-             (gzip    (string-append (assoc-ref %build-inputs "gzip")
-                                     "/bin/gzip"))
-             (modules (assoc-ref %build-inputs "modules"))
-             (gos     (assoc-ref %build-inputs "modules/compiled"))
-             (scm-dir (string-append "share/guile/" (effective-version)))
-             (go-dir  (format #f ".cache/guile/ccache/~a-~a-~a-~a"
-                              (effective-version)
-                              (if (eq? (native-endianness) (endianness little))
-                                  "LE"
-                                  "BE")
-                              (sizeof '*)
-                              (effective-version)))
-             (out     (assoc-ref %outputs "out")))
-         (mkdir out)
-         (mkdir "contents")
-         (with-directory-excursion "contents"
-           (copy-recursively guile ".")
-           (call-with-output-file "init"
-             (lambda (p)
-               (format p "#!/bin/guile -ds~%!#~%" guile)
-               (pretty-print ',exp p)))
-           (chmod "init" #o555)
-           (chmod "bin/guile" #o555)
-
-           ;; Copy Guile modules.
-           (chmod scm-dir #o777)
-           (copy-recursively modules scm-dir
-                             #:follow-symlinks? #t)
-           (copy-recursively gos (string-append "lib/guile/"
-                                                (effective-version) "/ccache")
-                             #:follow-symlinks? #t)
-
-           ;; Compile `init'.
-           (mkdir-p go-dir)
-           (set! %load-path (cons modules %load-path))
-           (set! %load-compiled-path (cons gos %load-compiled-path))
-           (compile-file "init"
-                         #:opts %auto-compilation-options
-                         #:output-file (string-append go-dir "/init.go"))
-
-           ;; Copy Linux modules.
-           (let* ((linux      (assoc-ref %build-inputs "linux"))
-                  (module-dir (and linux
-                                   (string-append linux "/lib/modules"))))
-             (mkdir "modules")
-             ,@(map (lambda (module)
-                      `(match (find-files module-dir
-                                          ,(string->regexp module))
-                         ((file)
-                          (format #t "copying '~a'...~%" file)
-                          (copy-file file (string-append "modules/"
-                                                         ,module)))
-                         (()
-                          (error "module not found" ,module module-dir))
-                         ((_ ...)
-                          (error "several modules by that name"
-                                 ,module module-dir))))
-                    linux-modules))
-
-           ;; Reset the timestamps of all the files that will make it in the
-           ;; initrd.
-           (for-each (cut utime <> 0 0 0 0)
-                     (find-files "." ".*"))
-
-           (system* cpio "--version")
-           (let ((pipe (open-pipe* OPEN_WRITE cpio "-o"
-                                   "-O" (string-append out "/initrd")
-                                   "-H" "newc" "--null")))
-             (define print0
-               (let ((len (string-length "./")))
-                 (lambda (file)
-                   (format pipe "~a\0" (string-drop file len)))))
-
-             ;; Note: as per `ramfs-rootfs-initramfs.txt', always add
-             ;; directory entries before the files that are inside of it: "The
-             ;; Linux kernel cpio extractor won't create files in a directory
-             ;; that doesn't exist, so the directory entries must go before
-             ;; the files that go in those directories."
-             (file-system-fold (const #t)
-                               (lambda (file stat result) ; leaf
-                                 (print0 file))
-                               (lambda (dir stat result) ; down
-                                 (unless (string=? dir ".")
-                                   (print0 dir)))
-                               (const #f)         ; up
-                               (const #f)         ; skip
-                               (const #f)
-                               #f
-                               ".")
-
-             (and (zero? (close-pipe pipe))
-                  (with-directory-excursion out
-                    (and (zero? (system* gzip "--best" "initrd"))
-                         (rename-file "initrd.gz" "initrd")))))))))
-
-  (mlet* %store-monad
-      ((source   (imported-modules modules))
-       (compiled (compiled-modules modules))
-       (inputs   (lower-inputs
-                  `(("guile" ,guile)
-                    ("cpio" ,cpio)
-                    ("gzip" ,gzip)
-                    ("modules" ,source)
-                    ("modules/compiled" ,compiled)
-                    ,@(if linux
-                          `(("linux" ,linux))
-                          '())))))
-   (derivation-expression name builder
-                          #:modules '((guix build utils))
-                          #:inputs inputs)))
-
-(define* (qemu-initrd #:key
+  (mlet* %store-monad ((source   (imported-modules modules))
+                       (compiled (compiled-modules modules)))
+    (define builder
+      ;; TODO: Move most of this code to (guix build linux-initrd).
+      #~(begin
+          (use-modules (guix build utils)
+                       (ice-9 pretty-print)
+                       (ice-9 popen)
+                       (ice-9 match)
+                       (ice-9 ftw)
+                       (srfi srfi-26)
+                       (system base compile)
+                       (rnrs bytevectors)
+                       ((system foreign) #:select (sizeof)))
+
+          (let ((cpio    (string-append #$cpio "/bin/cpio"))
+                (gzip    (string-append #$gzip "/bin/gzip"))
+                (modules #$source)
+                (gos     #$compiled)
+                (scm-dir (string-append "share/guile/" (effective-version)))
+                (go-dir  (format #f ".cache/guile/ccache/~a-~a-~a-~a"
+                                 (effective-version)
+                                 (if (eq? (native-endianness) (endianness little))
+                                     "LE"
+                                     "BE")
+                                 (sizeof '*)
+                                 (effective-version))))
+            (mkdir #$output)
+            (mkdir "contents")
+            (with-directory-excursion "contents"
+              (copy-recursively #$guile ".")
+              (call-with-output-file "init"
+                (lambda (p)
+                  (format p "#!/bin/guile -ds~%!#~%" #$guile)
+                  (pretty-print '#$exp p)))
+              (chmod "init" #o555)
+              (chmod "bin/guile" #o555)
+
+              ;; Copy Guile modules.
+              (chmod scm-dir #o777)
+              (copy-recursively modules scm-dir
+                                #:follow-symlinks? #t)
+              (copy-recursively gos (string-append "lib/guile/"
+                                                   (effective-version) "/ccache")
+                                #:follow-symlinks? #t)
+
+              ;; Compile `init'.
+              (mkdir-p go-dir)
+              (set! %load-path (cons modules %load-path))
+              (set! %load-compiled-path (cons gos %load-compiled-path))
+              (compile-file "init"
+                            #:opts %auto-compilation-options
+                            #:output-file (string-append go-dir "/init.go"))
+
+              ;; Copy Linux modules.
+              (let* ((linux      #$linux)
+                     (module-dir (and linux
+                                      (string-append linux "/lib/modules"))))
+                (mkdir "modules")
+                #$@(map (lambda (module)
+                          #~(match (find-files module-dir
+                                               #$(string->regexp module))
+                              ((file)
+                               (format #t "copying '~a'...~%" file)
+                               (copy-file file (string-append "modules/"
+                                                              #$module)))
+                              (()
+                               (error "module not found" #$module module-dir))
+                              ((_ ...)
+                               (error "several modules by that name"
+                                      #$module module-dir))))
+                        linux-modules))
+
+              (let ((store   #$(string-append "." (%store-prefix)))
+                    (to-copy '#$to-copy))
+                (unless (null? to-copy)
+                  (mkdir-p store))
+                ;; XXX: Should we do export-references-graph?
+                (for-each (lambda (input)
+                            (let ((target
+                                   (string-append store "/"
+                                                  (basename input))))
+                              (copy-recursively input target)))
+                          to-copy))
+
+              ;; Reset the timestamps of all the files that will make it in the
+              ;; initrd.
+              (for-each (cut utime <> 0 0 0 0)
+                        (find-files "." ".*"))
+
+              (system* cpio "--version")
+              (let ((pipe (open-pipe* OPEN_WRITE cpio "-o"
+                                      "-O" (string-append #$output "/initrd")
+                                      "-H" "newc" "--null")))
+                (define print0
+                  (let ((len (string-length "./")))
+                    (lambda (file)
+                      (format pipe "~a\0" (string-drop file len)))))
+
+                ;; Note: as per `ramfs-rootfs-initramfs.txt', always add
+                ;; directory entries before the files that are inside of it: "The
+                ;; Linux kernel cpio extractor won't create files in a directory
+                ;; that doesn't exist, so the directory entries must go before
+                ;; the files that go in those directories."
+                (file-system-fold (const #t)
+                                  (lambda (file stat result) ; leaf
+                                    (print0 file))
+                                  (lambda (dir stat result) ; down
+                                    (unless (string=? dir ".")
+                                      (print0 dir)))
+                                  (const #f)         ; up
+                                  (const #f)         ; skip
+                                  (const #f)
+                                  #f
+                                  ".")
+
+                (and (zero? (close-pipe pipe))
+                     (with-directory-excursion #$output
+                       (and (zero? (system* gzip "--best" "initrd"))
+                            (rename-file "initrd.gz" "initrd")))))))))
+
+   (gexp->derivation name builder
+                     #:modules '((guix build utils)))))
+
+(define (file-system->spec fs)
+  "Return a list corresponding to file-system FS that can be passed to the
+initrd code."
+  (match fs
+    (($ <file-system> device mount-point type flags options _ check?)
+     (list device mount-point type flags options check?))))
+
+(define* (qemu-initrd file-systems
+                      #:key
                       guile-modules-in-chroot?
-                      volatile-root?
-                      (mounts `((cifs "/store" ,(%store-prefix))
-                                (cifs "/xchg" "/xchg"))))
+                      (qemu-networking? #t)
+                      volatile-root?)
   "Return a monadic derivation that builds an initrd for use in a QEMU guest
-where the store is shared with the host.  MOUNTS is a list of file systems to
-be mounted atop the root file system, where each item has the form:
+where the store is shared with the host.  FILE-SYSTEMS is a list of
+file-systems to be mounted by the initrd, possibly in addition to the root
+file system specified on the kernel command line via '--root'.
 
-    (FILE-SYSTEM-TYPE SOURCE TARGET)
+When QEMU-NETWORKING? is true, set up networking with the standard QEMU
+parameters.
+
+When VOLATILE-ROOT? is true, the root file system is writable but any changes
+to it are lost.
 
 When GUILE-MODULES-IN-CHROOT? is true, make core Guile modules available in
 the new root.  This is necessary is the file specified as '--load' needs
 access to these modules (which is the case if it wants to even just print an
-exception and backtrace!).
-
-When VOLATILE-ROOT? is true, the root file system is writable but any changes
-to it are lost."
+exception and backtrace!)."
   (define cifs-modules
     ;; Modules needed to mount CIFS file systems.
     '("md4.ko" "ecb.ko" "cifs.ko"))
@@ -215,35 +229,56 @@ to it are lost."
     ;; Modules for the 9p paravirtualized file system.
     '("9pnet.ko" "9p.ko" "9pnet_virtio.ko"))
 
+  (define (file-system-type-predicate type)
+    (lambda (fs)
+      (string=? (file-system-type fs) type)))
+
   (define linux-modules
     ;; Modules added to the initrd and loaded from the initrd.
     `("virtio.ko" "virtio_ring.ko" "virtio_pci.ko"
       "virtio_balloon.ko" "virtio_blk.ko" "virtio_net.ko"
-      ,@(if (assoc-ref mounts 'cifs)
+      ,@(if (find (file-system-type-predicate "cifs") file-systems)
             cifs-modules
             '())
-      ,@(if (assoc-ref mounts '9p)
+      ,@(if (find (file-system-type-predicate "9p") file-systems)
             virtio-9p-modules
+            '())
+      ,@(if volatile-root?
+            '("fuse.ko")
+            '())))
+
+  (define helper-packages
+    ;; Packages to be copied on the initrd.
+    `(,@(if (find (lambda (fs)
+                    (string-prefix? "ext" (file-system-type fs)))
+                  file-systems)
+            (list e2fsck/static)
+            '())
+      ,@(if volatile-root?
+            (list unionfs-fuse/static)
             '())))
 
   (expression->initrd
-   `(begin
-      (use-modules (guix build linux-initrd))
-
-      (boot-system #:mounts ',mounts
-                   #:linux-modules ',linux-modules
-                   #:qemu-guest-networking? #t
-                   #:guile-modules-in-chroot? ',guile-modules-in-chroot?
-                   #:volatile-root? ',volatile-root?))
+   #~(begin
+       (use-modules (guix build linux-initrd)
+                    (guix build utils)
+                    (srfi srfi-26))
+
+       (with-output-to-port (%make-void-port "w")
+         (lambda ()
+           (set-path-environment-variable "PATH" '("bin" "sbin")
+                                          '#$helper-packages)))
+
+       (boot-system #:mounts '#$(map file-system->spec file-systems)
+                    #:linux-modules '#$linux-modules
+                    #:qemu-guest-networking? #$qemu-networking?
+                    #:guile-modules-in-chroot? '#$guile-modules-in-chroot?
+                    #:volatile-root? '#$volatile-root?))
    #:name "qemu-initrd"
    #:modules '((guix build utils)
                (guix build linux-initrd))
+   #:to-copy helper-packages
    #:linux linux-libre
    #:linux-modules linux-modules))
 
-(define (gnu-system-initrd)
-  "Initrd for the GNU system itself, with nothing QEMU-specific."
-  (qemu-initrd #:guile-modules-in-chroot? #f
-               #:mounts '()))
-
 ;;; linux-initrd.scm ends here
diff --git a/gnu/system/linux.scm b/gnu/system/linux.scm
index 65868ce9bf..5440f5852f 100644
--- a/gnu/system/linux.scm
+++ b/gnu/system/linux.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2013 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -21,6 +21,7 @@
   #:use-module (guix records)
   #:use-module (guix derivations)
   #:use-module (guix monads)
+  #:use-module (guix gexp)
   #:use-module (ice-9 match)
   #:use-module (srfi srfi-1)
   #:use-module (srfi srfi-26)
@@ -28,8 +29,8 @@
   #:export (pam-service
             pam-entry
             pam-services->directory
-            %pam-other-services
-            unix-pam-service))
+            unix-pam-service
+            base-pam-services))
 
 ;;; Commentary:
 ;;;
@@ -58,58 +59,56 @@
 (define-record-type* <pam-entry> pam-entry
   make-pam-entry
   pam-entry?
-  (control    pam-entry-control)                  ; string
-  (module     pam-entry-module)                   ; file name
-  (arguments  pam-entry-arguments                 ; list of strings
+  (control    pam-entry-control)         ; string
+  (module     pam-entry-module)          ; file name
+  (arguments  pam-entry-arguments        ; list of string-valued g-expressions
               (default '())))
 
 (define (pam-service->configuration service)
-  "Return the configuration string for SERVICE, to be dumped in
-/etc/pam.d/NAME, where NAME is the name of SERVICE."
-  (define (entry->string type entry)
+  "Return the derivation building the configuration file for SERVICE, to be
+dumped in /etc/pam.d/NAME, where NAME is the name of SERVICE."
+  (define (entry->gexp type entry)
     (match entry
       (($ <pam-entry> control module (arguments ...))
-       (string-append type "  "
-                      control " " module " "
-                      (string-join arguments)
-                      "\n"))))
+       #~(format #t "~a ~a ~a ~a~%"
+                 #$type #$control #$module
+                 (string-join (list #$@arguments))))))
 
   (match service
     (($ <pam-service> name account auth password session)
-     (string-concatenate
-      (append (map (cut entry->string "account" <>) account)
-              (map (cut entry->string "auth" <>) auth)
-              (map (cut entry->string "password" <>) password)
-              (map (cut entry->string "session" <>) session))))))
+     (define builder
+       #~(begin
+           (with-output-to-file #$output
+             (lambda ()
+               #$@(append (map (cut entry->gexp "account" <>) account)
+                          (map (cut entry->gexp "auth" <>) auth)
+                          (map (cut entry->gexp "password" <>) password)
+                          (map (cut entry->gexp "session" <>) session))
+               #t))))
+
+     (gexp->derivation name builder))))
 
 (define (pam-services->directory services)
   "Return the derivation to build the configuration directory to be used as
 /etc/pam.d for SERVICES."
   (mlet %store-monad
       ((names -> (map pam-service-name services))
-       (files (mapm %store-monad
-                    (match-lambda
-                     ((and service ($ <pam-service> name))
-                      (let ((config (pam-service->configuration service)))
-                        (text-file (string-append name ".pam") config))))
-
-                    ;; XXX: Eventually, SERVICES may be a list of monadic
-                    ;; values instead of plain values.
-                    (map return services))))
+       (files (sequence %store-monad
+                        (map pam-service->configuration
+                             ;; XXX: Eventually, SERVICES may be a list of
+                             ;; monadic values instead of plain values.
+                             services))))
     (define builder
-      '(begin
-         (use-modules (ice-9 match))
+      #~(begin
+          (use-modules (ice-9 match))
 
-         (let ((out (assoc-ref %outputs "out")))
-           (mkdir out)
-           (for-each (match-lambda
-                      ((name . file)
-                       (symlink file (string-append out "/" name))))
-                     %build-inputs)
-           #t)))
+          (mkdir #$output)
+          (for-each (match-lambda
+                     ((name file)
+                      (symlink file (string-append #$output "/" name))))
+                    '#$(zip names files))))
 
-    (derivation-expression "pam.d" builder
-                           #:inputs (zip names files))))
+    (gexp->derivation "pam.d" builder)))
 
 (define %pam-other-services
   ;; The "other" PAM configuration, which denies everything (see
@@ -149,7 +148,19 @@ should be the name of a file used as the message-of-the-day."
                             (pam-entry
                              (control "optional")
                              (module "pam_motd.so")
-                             (arguments (list (string-append "motd=" motd)))))
+                             (arguments
+                              (list #~(string-append "motd=" #$motd)))))
                       (list unix))))))))
 
+(define* (base-pam-services #:key allow-empty-passwords?)
+  "Return the list of basic PAM services everyone would want."
+  (cons %pam-other-services
+        (map (cut unix-pam-service <>
+                  #:allow-empty-passwords? allow-empty-passwords?)
+             '("su" "passwd" "sudo"
+               "useradd" "userdel" "usermod"
+               "groupadd" "groupdel" "groupmod"
+               ;; TODO: Add other Shadow programs?
+               ))))
+
 ;;; linux.scm ends here
diff --git a/gnu/system/shadow.scm b/gnu/system/shadow.scm
index 2a85a20ebb..738816b78f 100644
--- a/gnu/system/shadow.scm
+++ b/gnu/system/shadow.scm
@@ -1,5 +1,5 @@
 ;;; GNU Guix --- Functional package management for GNU
-;;; Copyright © 2013 Ludovic Courtès <ludo@gnu.org>
+;;; Copyright © 2013, 2014 Ludovic Courtès <ludo@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -17,25 +17,23 @@
 ;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
 
 (define-module (gnu system shadow)
-  #:use-module (guix store)
   #:use-module (guix records)
-  #:use-module (guix packages)
+  #:use-module (guix gexp)
   #:use-module (guix monads)
   #:use-module ((gnu packages admin)
                 #:select (shadow))
   #:use-module (gnu packages bash)
-  #:use-module (srfi srfi-1)
-  #:use-module (ice-9 match)
+  #:use-module (gnu packages guile-wm)
   #:export (user-account
             user-account?
             user-account-name
-            user-account-pass
+            user-account-password
             user-account-uid
-            user-account-gid
+            user-account-group
+            user-account-supplementary-groups
             user-account-comment
             user-account-home-directory
             user-account-shell
-            user-account-inputs
 
             user-group
             user-group?
@@ -44,9 +42,8 @@
             user-group-id
             user-group-members
 
-            passwd-file
-            group-file
-            guix-build-accounts))
+            default-skeletons
+            skeleton-directory))
 
 ;;; Commentary:
 ;;;
@@ -58,68 +55,66 @@
   user-account make-user-account
   user-account?
   (name           user-account-name)
-  (password       user-account-pass (default ""))
-  (uid            user-account-uid)
-  (gid            user-account-gid)
+  (password       user-account-password (default #f))
+  (uid            user-account-uid (default #f))
+  (group          user-account-group)             ; number | string
+  (supplementary-groups user-account-supplementary-groups
+                        (default '()))            ; list of strings
   (comment        user-account-comment (default ""))
   (home-directory user-account-home-directory)
-  (shell          user-account-shell              ; monadic value
-                  (default (package-file bash "bin/bash")))
-  (inputs         user-account-inputs (default `(("bash" ,bash)))))
+  (shell          user-account-shell              ; gexp
+                  (default #~(string-append #$bash "/bin/bash"))))
 
 (define-record-type* <user-group>
   user-group make-user-group
   user-group?
   (name           user-group-name)
   (password       user-group-password (default #f))
-  (id             user-group-id)
+  (id             user-group-id (default #f))
   (members        user-group-members (default '())))
 
-(define (group-file groups)
-  "Return a /etc/group file for GROUPS, a list of <user-group> objects."
-  (define contents
-    (let loop ((groups groups)
-               (result '()))
-      (match groups
-        ((($ <user-group> name _ gid (users ...)) rest ...)
-         ;; XXX: Ignore the group password.
-         (loop rest
-               (cons (string-append name "::" (number->string gid)
-                                    ":" (string-join users ","))
-                     result)))
-        (()
-         (string-join (reverse result) "\n" 'suffix)))))
+(define (default-skeletons)
+  "Return the default skeleton files for /etc/skel.  These files are copied by
+'useradd' in the home directory of newly created user accounts."
+  (define copy-guile-wm
+    #~(begin
+        (use-modules (guix build utils))
+        (copy-file (car (find-files #$guile-wm "wm-init-sample.scm"))
+                   #$output)))
 
-  (text-file "group" contents))
+  (mlet %store-monad ((bashrc (text-file "bashrc" "\
+# Allow non-login shells such as an xterm to get things right.
+test -f /etc/profile && source /etc/profile\n"))
+                      (guile-wm (gexp->derivation "guile-wm" copy-guile-wm
+                                                  #:modules
+                                                  '((guix build utils))))
+                      (xdefaults (text-file "Xdefaults" "\
+XTerm*utf8: always
+XTerm*metaSendsEscape: true\n"))
+                      (gdbinit   (text-file "gdbinit" "\
+# Tell GDB where to look for separate debugging files.
+set debug-file-directory ~/.guix-profile/lib/debug\n")))
+    (return `((".bashrc" ,bashrc)
+              (".Xdefaults" ,xdefaults)
+              (".guile-wm" ,guile-wm)
+              (".gdbinit" ,gdbinit)))))
 
-(define* (passwd-file accounts #:key shadow?)
-  "Return a password file for ACCOUNTS, a list of <user-account> objects.  If
-SHADOW? is true, then it is a /etc/shadow file, otherwise it is a /etc/passwd
-file."
-  ;; XXX: The resulting file is world-readable, so beware when SHADOW? is #t!
-  (define (contents)
-    (with-monad %store-monad
-      (let loop ((accounts accounts)
-                 (result   '()))
-        (match accounts
-          ((($ <user-account> name pass uid gid comment home-dir mshell)
-            rest ...)
-           (mlet %store-monad ((shell mshell))
-             (loop rest
-                   (cons (if shadow?
-                             (string-append name
-                                            ":"    ; XXX: use (crypt PASS …)?
-                                            ":::::::")
-                             (string-append name
-                                            ":" "x"
-                                            ":" (number->string uid)
-                                            ":" (number->string gid)
-                                            ":" comment ":" home-dir ":" shell))
-                         result))))
-          (()
-           (return (string-join (reverse result) "\n" 'suffix)))))))
+(define (skeleton-directory skeletons)
+  "Return a directory containing SKELETONS, a list of name/derivation pairs."
+  (gexp->derivation "skel"
+                    #~(begin
+                        (use-modules (ice-9 match))
 
-  (mlet %store-monad ((contents (contents)))
-    (text-file (if shadow? "shadow" "passwd") contents)))
+                        (mkdir #$output)
+                        (chdir #$output)
+
+                        ;; Note: copy the skeletons instead of symlinking
+                        ;; them like 'file-union' does, because 'useradd'
+                        ;; would just copy the symlinks as is.
+                        (for-each (match-lambda
+                                   ((target source)
+                                    (copy-file source target)))
+                                  '#$skeletons)
+                        #t)))
 
 ;;; shadow.scm ends here
diff --git a/gnu/system/vm.scm b/gnu/system/vm.scm
index 069ac3093a..a15c4c358b 100644
--- a/gnu/system/vm.scm
+++ b/gnu/system/vm.scm
@@ -19,6 +19,7 @@
 (define-module (gnu system vm)
   #:use-module (guix config)
   #:use-module (guix store)
+  #:use-module (guix gexp)
   #:use-module (guix derivations)
   #:use-module (guix packages)
   #:use-module (guix monads)
@@ -41,6 +42,7 @@
   #:use-module (gnu system linux)
   #:use-module (gnu system linux-initrd)
   #:use-module (gnu system grub)
+  #:use-module (gnu system file-systems)
   #:use-module (gnu system)
   #:use-module (gnu services)
 
@@ -52,7 +54,8 @@
             qemu-image
             system-qemu-image
             system-qemu-image/shared-store
-            system-qemu-image/shared-store-script))
+            system-qemu-image/shared-store-script
+            system-disk-image))
 
 
 ;;; Commentary:
@@ -81,19 +84,34 @@ input tuple.  The output file name is when building for SYSTEM."
       ((input (and (? string?) (? store-path?) file))
        (return `(,input . ,file))))))
 
-;; An alias to circumvent name clashes.
-(define %imported-modules imported-modules)
+(define %linux-vm-file-systems
+  ;; File systems mounted for 'derivation-in-linux-vm'.  The store and /xchg
+  ;; directory are shared with the host over 9p.
+  (list (file-system
+          (mount-point (%store-prefix))
+          (device "store")
+          (type "9p")
+          (needed-for-boot? #t)
+          (options "trans=virtio")
+          (check? #f))
+        (file-system
+          (mount-point "/xchg")
+          (device "xchg")
+          (type "9p")
+          (needed-for-boot? #t)
+          (options "trans=virtio")
+          (check? #f))))
 
 (define* (expression->derivation-in-linux-vm name exp
                                              #:key
                                              (system (%current-system))
-                                             (inputs '())
                                              (linux linux-libre)
                                              initrd
                                              (qemu qemu-headless)
                                              (env-vars '())
-                                             (imported-modules
+                                             (modules
                                               '((guix build vm)
+                                                (guix build install)
                                                 (guix build linux-initrd)
                                                 (guix build utils)))
                                              (guile-for-build
@@ -102,222 +120,240 @@ input tuple.  The output file name is when building for SYSTEM."
                                              (make-disk-image? #f)
                                              (references-graphs #f)
                                              (memory-size 256)
+                                             (disk-image-format "qcow2")
                                              (disk-image-size
                                               (* 100 (expt 2 20))))
   "Evaluate EXP in a QEMU virtual machine running LINUX with INITRD (a
-derivation).  In the virtual machine, EXP has access to all of INPUTS from the
+derivation).  In the virtual machine, EXP has access to all its inputs from the
 store; it should put its output files in the `/xchg' directory, which is
 copied to the derivation's output when the VM terminates.  The virtual machine
 runs with MEMORY-SIZE MiB of memory.
 
-When MAKE-DISK-IMAGE? is true, then create a QEMU disk image of
-DISK-IMAGE-SIZE bytes and return it.
+When MAKE-DISK-IMAGE? is true, then create a QEMU disk image of type
+DISK-IMAGE-FORMAT (e.g., 'qcow2' or 'raw'), of DISK-IMAGE-SIZE bytes and
+return it.
 
-IMPORTED-MODULES is the set of modules imported in the execution environment
-of EXP.
+MODULES is the set of modules imported in the execution environment of EXP.
 
 When REFERENCES-GRAPHS is true, it must be a list of file name/store path
 pairs, as for `derivation'.  The files containing the reference graphs are
 made available under the /xchg CIFS share."
-  ;; FIXME: Add #:modules parameter, for the 'use-modules' form.
-
-  (define input-alist
-    (map input->name+output inputs))
-
-  (define builder
-    ;; Code that launches the VM that evaluates EXP.
-    `(let ()
-       (use-modules (guix build utils)
-                    (guix build vm))
-
-       (let ((linux   (string-append (assoc-ref %build-inputs "linux")
-                                     "/bzImage"))
-             (initrd  (string-append (assoc-ref %build-inputs "initrd")
-                                     "/initrd"))
-             (loader  (assoc-ref %build-inputs "loader"))
-             (graphs  ',(match references-graphs
-                          (((graph-files . _) ...) graph-files)
-                          (_ #f))))
-
-         (set-path-environment-variable "PATH" '("bin")
-                                        (map cdr %build-inputs))
-
-         (load-in-linux-vm loader
-                           #:output (assoc-ref %outputs "out")
-                           #:linux linux #:initrd initrd
-                           #:memory-size ,memory-size
-                           #:make-disk-image? ,make-disk-image?
-                           #:disk-image-size ,disk-image-size
-                           #:references-graphs graphs))))
-
   (mlet* %store-monad
-      ((input-alist  (sequence %store-monad input-alist))
-       (module-dir   (%imported-modules imported-modules))
-       (compiled     (compiled-modules imported-modules))
-       (exp* ->      `(let ((%build-inputs ',input-alist))
-                        ,exp))
-       (user-builder (text-file "builder-in-linux-vm"
-                                (object->string exp*)))
-       (loader       (text-file* "linux-vm-loader" ; XXX: use 'sexp-file'
-                                 "(begin (set! %load-path (cons \""
-                                 module-dir "\" %load-path)) "
-                                 "(set! %load-compiled-path (cons \""
-                                 compiled "\" %load-compiled-path))"
-                                 "(primitive-load \"" user-builder "\"))"))
+      ((module-dir   (imported-modules modules))
+       (compiled     (compiled-modules modules))
+       (user-builder (gexp->file "builder-in-linux-vm" exp))
+       (loader       (gexp->file "linux-vm-loader"
+                                 #~(begin
+                                     (set! %load-path
+                                           (cons #$module-dir %load-path))
+                                     (set! %load-compiled-path
+                                           (cons #$compiled
+                                                 %load-compiled-path))
+                                     (primitive-load #$user-builder))))
        (coreutils -> (car (assoc-ref %final-inputs "coreutils")))
        (initrd       (if initrd                   ; use the default initrd?
                          (return initrd)
-                         (qemu-initrd #:guile-modules-in-chroot? #t
-                                      #:mounts `((9p "store" ,(%store-prefix))
-                                                 (9p "xchg" "/xchg")))))
-       (inputs       (lower-inputs `(("qemu" ,qemu)
-                                     ("linux" ,linux)
-                                     ("initrd" ,initrd)
-                                     ("coreutils" ,coreutils)
-                                     ("builder" ,user-builder)
-                                     ("loader" ,loader)
-                                     ,@inputs))))
-    (derivation-expression name builder
-                           ;; TODO: Require the "kvm" feature.
-                           #:system system
-                           #:inputs inputs
-                           #:env-vars env-vars
-                           #:modules (delete-duplicates
-                                      `((guix build utils)
-                                        (guix build vm)
-                                        (guix build linux-initrd)
-                                        ,@imported-modules))
-                           #:guile-for-build guile-for-build
-                           #:references-graphs references-graphs)))
+                         (qemu-initrd %linux-vm-file-systems
+                                      #:guile-modules-in-chroot? #t))))
+
+    (define builder
+      ;; Code that launches the VM that evaluates EXP.
+      #~(begin
+          (use-modules (guix build utils)
+                       (guix build vm))
+
+          (let ((inputs  '#$(list qemu coreutils))
+                (linux   (string-append #$linux "/bzImage"))
+                (initrd  (string-append #$initrd "/initrd"))
+                (loader  #$loader)
+                (graphs  '#$(match references-graphs
+                              (((graph-files . _) ...) graph-files)
+                              (_ #f))))
+
+            (set-path-environment-variable "PATH" '("bin") inputs)
+
+            (load-in-linux-vm loader
+                              #:output #$output
+                              #:linux linux #:initrd initrd
+                              #:memory-size #$memory-size
+                              #:make-disk-image? #$make-disk-image?
+                              #:disk-image-format #$disk-image-format
+                              #:disk-image-size #$disk-image-size
+                              #:references-graphs graphs))))
+
+    (gexp->derivation name builder
+                      ;; TODO: Require the "kvm" feature.
+                      #:system system
+                      #:env-vars env-vars
+                      #:modules modules
+                      #:guile-for-build guile-for-build
+                      #:references-graphs references-graphs)))
 
 (define* (qemu-image #:key
                      (name "qemu-image")
                      (system (%current-system))
+                     (qemu qemu-headless)
                      (disk-image-size (* 100 (expt 2 20)))
+                     (disk-image-format "qcow2")
+                     (file-system-type "ext4")
                      grub-configuration
-                     (initialize-store? #f)
-                     (populate #f)
+                     (register-closures? #t)
                      (inputs '())
-                     (inputs-to-copy '()))
-  "Return a bootable, stand-alone QEMU image.  The returned image is a full
-disk image, with a GRUB installation that uses GRUB-CONFIGURATION as its
-configuration file (GRUB-CONFIGURATION must be the name of a file in the VM.)
-
-INPUTS-TO-COPY is a list of inputs (as for packages) whose closure is copied
-into the image being built.  When INITIALIZE-STORE? is true, initialize the
-store database in the image so that Guix can be used in the image.
-
-POPULATE is a list of directives stating directories or symlinks to be created
-in the disk image partition.  It is evaluated once the image has been
-populated with INPUTS-TO-COPY.  It can be used to provide additional files,
-such as /etc files."
+                     copy-inputs?)
+  "Return a bootable, stand-alone QEMU image of type DISK-IMAGE-FORMAT (e.g.,
+'qcow2' or 'raw'), with a root partition of type FILE-SYSTEM-TYPE.  The
+returned image is a full disk image, with a GRUB installation that uses
+GRUB-CONFIGURATION as its configuration file (GRUB-CONFIGURATION must be the
+name of a file in the VM.)
+
+INPUTS is a list of inputs (as for packages).  When COPY-INPUTS? is true, copy
+all of INPUTS into the image being built.  When REGISTER-CLOSURES? is true,
+register INPUTS in the store database of the image so that Guix can be used in
+the image."
   (mlet %store-monad
-      ((graph (sequence %store-monad
-                        (map input->name+output inputs-to-copy))))
+      ((graph (sequence %store-monad (map input->name+output inputs))))
    (expression->derivation-in-linux-vm
-    "qemu-image"
-    `(let ()
-       (use-modules (guix build vm)
-                    (guix build utils))
-
-       (set-path-environment-variable "PATH" '("bin" "sbin")
-                                      (map cdr %build-inputs))
-
-       (let ((graphs ',(match inputs-to-copy
-                         (((names . _) ...)
-                          names))))
-         (initialize-hard-disk #:grub.cfg ,grub-configuration
-                               #:closures-to-copy graphs
-                               #:disk-image-size ,disk-image-size
-                               #:initialize-store? ,initialize-store?
-                               #:directives ',populate)
-         (reboot)))
+    name
+    #~(begin
+        (use-modules (guix build vm)
+                     (guix build utils))
+
+        (let ((inputs
+               '#$(append (list qemu parted grub e2fsprogs util-linux)
+                          (map (compose car (cut assoc-ref %final-inputs <>))
+                               '("sed" "grep" "coreutils" "findutils" "gawk"))
+                          (if register-closures? (list guix) '())))
+
+              ;; This variable is unused but allows us to add INPUTS-TO-COPY
+              ;; as inputs.
+              (to-register
+                '#$(map (match-lambda
+                         ((name thing) thing)
+                         ((name thing output) `(,thing ,output)))
+                        inputs)))
+
+          (set-path-environment-variable "PATH" '("bin" "sbin") inputs)
+
+          (let ((graphs '#$(match inputs
+                             (((names . _) ...)
+                              names))))
+            (initialize-hard-disk "/dev/vda"
+                                  #:grub.cfg #$grub-configuration
+                                  #:closures graphs
+                                  #:copy-closures? #$copy-inputs?
+                                  #:register-closures? #$register-closures?
+                                  #:disk-image-size #$disk-image-size
+                                  #:file-system-type #$file-system-type)
+            (reboot))))
     #:system system
-    #:inputs `(("parted" ,parted)
-               ("grub" ,grub)
-               ("e2fsprogs" ,e2fsprogs)
-
-               ;; For shell scripts.
-               ("sed" ,(car (assoc-ref %final-inputs "sed")))
-               ("grep" ,(car (assoc-ref %final-inputs "grep")))
-               ("coreutils" ,(car (assoc-ref %final-inputs "coreutils")))
-               ("findutils" ,(car (assoc-ref %final-inputs "findutils")))
-               ("gawk" ,(car (assoc-ref %final-inputs "gawk")))
-               ("util-linux" ,util-linux)
-
-               ,@(if initialize-store?
-                     `(("guix" ,guix))
-                     '())
-
-               ,@inputs-to-copy)
     #:make-disk-image? #t
     #:disk-image-size disk-image-size
+    #:disk-image-format disk-image-format
     #:references-graphs graph)))
 
 
 ;;;
-;;; Stand-alone VM image.
+;;; VM and disk images.
 ;;;
 
-(define (operating-system-build-gid os)
-  "Return as a monadic value the group id for build users of OS, or #f."
-  (anym %store-monad
-        (lambda (service)
-          (and (equal? '(guix-daemon)
-                       (service-provision service))
-               (match (service-user-groups service)
-                 ((group)
-                  (user-group-id group)))))
-        (operating-system-services os)))
-
-(define (operating-system-default-contents os)
-  "Return a list of directives suitable for 'system-qemu-image' describing the
-basic contents of the root file system of OS."
-  (define (user-directories user)
-    (let ((home (user-account-home-directory user))
-          ;; XXX: Deal with automatically allocated ids.
-          (uid  (or (user-account-uid user) 0))
-          (gid  (or (user-account-gid user) 0))
-          (root (string-append "/var/guix/profiles/per-user/"
-                               (user-account-name user))))
-      `((directory ,root ,uid ,gid)
-        (directory ,home ,uid ,gid))))
-
-  (mlet* %store-monad ((os-drv    (operating-system-derivation os))
-                       (os-dir -> (derivation->output-path os-drv))
-                       (build-gid (operating-system-build-gid os))
-                       (profile   (operating-system-profile-directory os)))
-    (return `((directory ,(%store-prefix) 0 ,(or build-gid 0))
-              (directory "/etc")
-              (directory "/var/log")                     ; for dmd
-              (directory "/var/run/nscd")
-              (directory "/var/guix/gcroots")
-              ("/var/guix/gcroots/system" -> ,os-dir)
-              (directory "/run")
-              ("/run/current-system" -> ,profile)
-              (directory "/bin")
-              ("/bin/sh" -> "/run/current-system/bin/bash")
-              (directory "/tmp")
-              (directory "/var/guix/profiles/per-user/root" 0 0)
-
-              (directory "/root" 0 0)             ; an exception
-              ,@(append-map user-directories
-                            (operating-system-users os))))))
+(define* (system-disk-image os
+                            #:key
+                            (file-system-type "ext4")
+                            (disk-image-size (* 900 (expt 2 20)))
+                            (volatile? #t))
+  "Return the derivation of a disk image of DISK-IMAGE-SIZE bytes of the
+system described by OS.  Said image can be copied on a USB stick as is.  When
+VOLATILE? is true, the root file system is made volatile; this is useful
+to USB sticks meant to be read-only."
+  (define file-systems-to-keep
+    (remove (lambda (fs)
+              (string=? (file-system-mount-point fs) "/"))
+            (operating-system-file-systems os)))
+
+  (let ((os (operating-system (inherit os)
+              ;; Since this is meant to be used on real hardware, don't set up
+              ;; QEMU networking.
+              (initrd (cut qemu-initrd <>
+                           #:volatile-root? volatile?
+                           #:qemu-networking? #f))
+
+              ;; Force our own root file system.
+              (file-systems (cons (file-system
+                                    (mount-point "/")
+                                    (device "/dev/sda1")
+                                    (type file-system-type))
+                                  file-systems-to-keep)))))
+
+    (mlet* %store-monad ((os-drv   (operating-system-derivation os))
+                         (grub.cfg (operating-system-grub.cfg os)))
+      (qemu-image #:grub-configuration grub.cfg
+                  #:disk-image-size disk-image-size
+                  #:disk-image-format "raw"
+                  #:file-system-type file-system-type
+                  #:copy-inputs? #t
+                  #:register-closures? #t
+                  #:inputs `(("system" ,os-drv)
+                             ("grub.cfg" ,grub.cfg))))))
 
 (define* (system-qemu-image os
-                            #:key (disk-image-size (* 900 (expt 2 20))))
-  "Return the derivation of a QEMU image of DISK-IMAGE-SIZE bytes of the GNU
-system as described by OS."
-  (mlet* %store-monad
-      ((os-drv      (operating-system-derivation os))
-       (os-dir   -> (derivation->output-path os-drv))
-       (grub.cfg -> (string-append os-dir "/grub.cfg"))
-       (populate    (operating-system-default-contents os)))
-    (qemu-image  #:grub-configuration grub.cfg
-                 #:populate populate
-                 #:disk-image-size disk-image-size
-                 #:initialize-store? #t
-                 #:inputs-to-copy `(("system" ,os-drv)))))
+                            #:key
+                            (file-system-type "ext4")
+                            (disk-image-size (* 900 (expt 2 20))))
+  "Return the derivation of a freestanding QEMU image of DISK-IMAGE-SIZE bytes
+of the GNU system as described by OS."
+  (define file-systems-to-keep
+    ;; Keep only file systems other than root and not normally bound to real
+    ;; devices.
+    (remove (lambda (fs)
+              (let ((target (file-system-mount-point fs))
+                    (source (file-system-device fs)))
+                (or (string=? target "/")
+                    (string-prefix? "/dev/" source))))
+            (operating-system-file-systems os)))
+
+  (let ((os (operating-system (inherit os)
+              ;; Force our own root file system.
+              (file-systems (cons (file-system
+                                    (mount-point "/")
+                                    (device "/dev/sda1")
+                                    (type file-system-type))
+                                  file-systems-to-keep)))))
+    (mlet* %store-monad
+        ((os-drv      (operating-system-derivation os))
+         (grub.cfg    (operating-system-grub.cfg os)))
+      (qemu-image  #:grub-configuration grub.cfg
+                   #:disk-image-size disk-image-size
+                   #:file-system-type file-system-type
+                   #:inputs `(("system" ,os-drv)
+                              ("grub.cfg" ,grub.cfg))
+                   #:copy-inputs? #t))))
+
+(define (virtualized-operating-system os)
+  "Return an operating system based on OS suitable for use in a virtualized
+environment with the store shared with the host."
+  (operating-system (inherit os)
+    (initrd (cut qemu-initrd <> #:volatile-root? #t))
+    (file-systems (cons* (file-system
+                           (mount-point "/")
+                           (device "/dev/vda1")
+                           (type "ext4"))
+                         (file-system
+                           (mount-point (%store-prefix))
+                           (device "store")
+                           (type "9p")
+                           (needed-for-boot? #t)
+                           (options "trans=virtio")
+                           (check? #f))
+
+                         ;; Remove file systems that conflict with those
+                         ;; above, or that are normally bound to real devices.
+                         (remove (lambda (fs)
+                                   (let ((target (file-system-mount-point fs))
+                                         (source (file-system-device fs)))
+                                     (or (string=? target (%store-prefix))
+                                         (string=? target "/")
+                                         (string-prefix? "/dev/" source))))
+                                 (operating-system-file-systems os))))))
 
 (define* (system-qemu-image/shared-store
           os
@@ -326,13 +362,14 @@ system as described by OS."
 with the host."
   (mlet* %store-monad
       ((os-drv      (operating-system-derivation os))
-       (os-dir   -> (derivation->output-path os-drv))
-       (grub.cfg -> (string-append os-dir "/grub.cfg"))
-       (populate    (operating-system-default-contents os)))
-    ;; TODO: Initialize the database so Guix can be used in the guest.
+       (grub.cfg    (operating-system-grub.cfg os)))
     (qemu-image #:grub-configuration grub.cfg
-                #:populate populate
-                #:disk-image-size disk-image-size)))
+                #:disk-image-size disk-image-size
+                #:inputs `(("system" ,os-drv))
+
+                ;; XXX: Passing #t here is too slow, so let it off by default.
+                #:register-closures? #f
+                #:copy-inputs? #f)))
 
 (define* (system-qemu-image/shared-store-script
           os
@@ -341,47 +378,28 @@ with the host."
           (graphic? #t))
   "Return a derivation that builds a script to run a virtual machine image of
 OS that shares its store with the host."
-  (let* ((initrd (qemu-initrd #:mounts `((9p "store" ,(%store-prefix)))
-                              #:volatile-root? #t))
-         (os     (operating-system (inherit os) (initrd initrd))))
+  (mlet* %store-monad
+      ((os ->  (virtualized-operating-system os))
+       (os-drv (operating-system-derivation os))
+       (image  (system-qemu-image/shared-store os)))
     (define builder
-      (mlet %store-monad ((image  (system-qemu-image/shared-store os))
-                          (qemu   (package-file qemu
-                                                "bin/qemu-system-x86_64"))
-                          (bash   (package-file bash "bin/sh"))
-                          (kernel (package-file (operating-system-kernel os)
-                                                "bzImage"))
-                          (initrd initrd)
-                          (os-drv (operating-system-derivation os)))
-        (return `(let ((out (assoc-ref %outputs "out")))
-                   (call-with-output-file out
-                     (lambda (port)
-                       (display
-                        (string-append "#!" ,bash "
-exec " ,qemu " -enable-kvm -no-reboot -net nic,model=virtio \
-  -virtfs local,path=" ,(%store-prefix) ",security_model=none,mount_tag=store \
+      #~(call-with-output-file #$output
+          (lambda (port)
+            (display
+             (string-append "#!" #$bash "/bin/sh
+exec " #$qemu "/bin/qemu-system-x86_64 -enable-kvm -no-reboot -net nic,model=virtio \
+  -virtfs local,path=" #$(%store-prefix) ",security_model=none,mount_tag=store \
   -net user \
-  -kernel " ,kernel " -initrd "
-  ,(string-append (derivation->output-path initrd) "/initrd") " \
--append \"" ,(if graphic? "" "console=ttyS0 ")
-"--load=" ,(derivation->output-path os-drv) "/boot --root=/dev/vda1\" \
-  -drive file=" ,(derivation->output-path image)
+  -kernel " #$(operating-system-kernel os) "/bzImage \
+  -initrd " #$os-drv "/initrd \
+-append \"" #$(if graphic? "" "console=ttyS0 ")
+  "--system=" #$os-drv " --load=" #$os-drv "/boot --root=/dev/vda1\" \
+  -serial stdio \
+  -drive file=" #$image
   ",if=virtio,cache=writeback,werror=report,readonly\n")
-                        port)))
-                   (chmod out #o555)
-                   #t))))
-
-    (mlet %store-monad ((image   (system-qemu-image/shared-store os))
-                        (initrd  initrd)
-                        (qemu    (package->derivation qemu))
-                        (bash    (package->derivation bash))
-                        (os      (operating-system-derivation os))
-                        (builder builder))
-      (derivation-expression "run-vm.sh" builder
-                             #:inputs `(("qemu" ,qemu)
-                                        ("image" ,image)
-                                        ("bash" ,bash)
-                                        ("initrd" ,initrd)
-                                        ("os" ,os))))))
+             port)
+            (chmod port #o555))))
+
+    (gexp->derivation "run-vm.sh" builder)))
 
 ;;; vm.scm ends here