gnu: Move root's home directory to /root.

* gnu/system.scm (operating-system-derivation): Change root's
  'home-directory' to "/root".
* gnu/system/vm.scm (operating-system-default-contents): Add /root.

gnu: dmd: Use 'text-file*' when building Xorg's config file.

* gnu/system/dmd.scm (xorg-service)[xserver.conf]: Change to use
  'text-file*' instead of 'text-file'.
  Adjust body accordingly.  Remove now extraneous packages from the
  service's 'inputs' field.

gnu: vm: Create all the user directories.

* gnu/system/vm.scm (operating-system-default-contents)[user-directories]:
  New procedure.  Use it to create each user's home and GC root
  directories.

gnu: vm: Add /run/current-system and /bin/sh.

* gnu/system/vm.scm (operating-system-default-contents): Populate
  /run/current-system and create /bin/sh.
* gnu/system.scm (operating-system-profile-derivation,
  operating-system-profile-directory): New procedures.
  (operating-system-derivation): Use it.

gnu: Add preliminary Xorg service.

* gnu/system/dmd.scm (xorg-service): New procedure.

gnu: vm: Add support for running a VM that shares its store with the host.

* gnu/system/vm.scm (qemu-image): Check whether GUIX is #f.
  (operating-system-build-gid, operating-system-default-contents): New
  procedures.
  (system-qemu-image): Use 'operating-system-build-gid'.
  (system-qemu-image/shared-store,
  system-qemu-image/shared-store-script): New procedures.
* gnu/system.scm: Add missing exports.

gnu: linux-initrd: Allow the root file system to be volatile.

* gnu/system/linux-initrd.scm (qemu-initrd): Add 'volatile-root?'
  parameter.
* guix/build/linux-initrd.scm (boot-system): Likewise.  Honor it.

gnu: linux-initrd: Recognize 9p file systems.

* gnu/system/linux-initrd.scm (qemu-initrd)[virtio-9p-modules]: New
  variable.
  [linux-modules]: Append VIRTIO-9P-MODULES when a 9p file system is in
  MOUNTS.
* guix/build/linux-initrd.scm (mount-qemu-9p): New procedure.
  (boot-system): Recognize '9p' in MOUNTS, and use 'mount-qemu-9p'.

gnu: linux-initrd: Match kernel module file names exactly.

* gnu/system/linux-initrd.scm (expression->initrd)[string->regexp]: New
  procedure.  Use it in the call to 'find-files'.

gnu: linux-initrd: Properly distinguish between /dev/sda* and /dev/vda*.

* guix/build/linux-initrd.scm (make-essential-device-nodes): Rename
  devices with major = 8 to /dev/sda*.  Make /dev/vda* devices.
* gnu/system/vm.scm (qemu-image): Change '/dev/vda' to '/dev/sda'.
* gnu/system.scm (operating-system-derivation): Likewise.

gnu: vm: Run QEMU with '-enable-kvm'.

* gnu/system/vm.scm (expression->derivation-in-linux-vm): Pass QEMU
  '-enable-kvm'.

gnu: linux-initrd: Factorize boot code.

* guix/build/linux-initrd.scm (boot-system): New procedure.
* gnu/system/linux-initrd.scm (qemu-initrd): Add keyword parameters
  'guile-modules-in-chroot?' and 'mounts'.  Change builder to simply
  call 'boot-system'.
  (gnu-system-initrd): Change to a simple call to 'qemu-initrd'.
* gnu/system/vm.scm (expression->derivation-in-linux-vm): Call
  'qemu-initrd' with #:guile-modules-in-chroot?.

gnu: Lower initrd makers from packages to monadic procedures.

* gnu/packages/linux-initrd.scm: Remove.
* gnu/system/linux-initrd.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Adjust accordingly.
* gnu/system.scm (<operating-system>): Change default 'initrd' value
  to (gnu-system-initrd).
  (operating-system-derivation): Bind 'operating-system-initrd'.  Pass
  'menu-entry' an initrd file name instead of a package.
* gnu/system/grub.scm (grub-configuration-file): Expect 'initrd' to be
  file name.

gnu: Changes references to (gnu packages admin).

* gnu/packages/version-control.scm, gnu/packages/vim.scm,
  gnu/system.scm, gnu/system/dmd.scm, gnu/system/shadow.scm,
  gnu/system/vm.scm: Change references to (gnu packages system) to (gnu
  packages admin).
  This is a followup to commit 4aeea89.

gnu: vm: Increase size of VM image.

* gnu/system/vm.scm (system-qemu-image): Add 'disk-image-size'
  parameter; increase it.

gnu: Honor the operating system's locale and timezone.

* gnu/system.scm (etc-directory): Add 'locale' and 'timezone'
  parameters.  Set 'LC_ALL', 'TZ', and 'TZDIR' in /etc/profile.
  (operating-system-derivation): Adjust call accordingly.
* gnu/system/vm.scm (%demo-operating-system): Change locale to
  'en_US.UTF-8'.  Add TZDATA to 'packages'.

gnu: Allow a plain list of packages in 'operating-system'.

* gnu/system.scm (union): Allow (PACKAGE OUTPUT), (PACKAGE), and
  PACKAGE.
  (<operating-system>)[packages]: Make the default a list of package?
  objects.
* gnu/system/vm.scm (%demo-operating-system): Likewise.  Add a few
  packages.

gnu: Add 'inputs' field to <user-account>; make 'shell' a monadic value.

* gnu/system/shadow.scm (<user-account>)[inputs]: New field.
  (passwd-file): Bind the 'shell' field of each account.
* gnu/system/vm.scm (%demo-operating-system): Remove 'shell' field.
* gnu/system/dmd.scm (guix-build-accounts): Store a monadic value in
  'shell'.  Add 'inputs' field.
* gnu/system.scm (operating-system-derivation): Remove 'shell' field for
  'root' account.  Add all the 'user-account-inputs' to EXTRAS.

gnu: dmd: Avoid "already exists" error on startup.

* gnu/system/dmd.scm (dmd-configuration-file)[config]: Remove
  "/var/nix/gcroots/etc-directory" before trying to recreate it.

gnu: Add (gnu system).

* gnu/system/vm.scm (lower-inputs): Move to monads.scm.
  (qemu-image): Don't add GRUB-CONFIGURATION to the INPUTS-TO-COPY.
  (union, file-union, etc-directory): Move to gnu/system.scm.
  (%demo-operating-system): New variable.
  (system-qemu-image): Add 'os' parameter.  Rewrite in terms of
  'operating-system-derivation'.
* guix/monads.scm (lower-inputs): New procedure.
* gnu/system/grub.scm (grub-configuration-file): Change 'entries' to be
  a plain list instead of a list of monadic values.
* gnu/system.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.