Merge branch 'master' into core-updates

linux-boot: Make /etc/mtab a symlink to /proc/self/mounts.

Fixes <http://bugs.gnu.org/19491>.

* gnu/build/linux-boot.scm (mount-root-file-system): Make /root/etc/mtab
  a symlink to /proc/self/mounts.
* gnu/build/file-systems.scm (mount-file-system): Don't update /etc/mtab.
* guix/build/syscalls.scm (mount, umount): Have #:update-mtab? default to
  #f.

Merge branch 'master' into 'core-updates'.

activation: Copy the account skeletons when creating the 'root' account.

* gnu/build/activation.scm (%skeleton-directory): New variable.
  (dot-or-dot-dot?, copy-account-skeletons): New procedure.
  (add-user): Use 'copy-account-skeletons'.
  (activate-etc): Use 'dot-or-dot-dot?'.

system: Don't make /boot/grub/grub.cfg a symlink to the store.

This would not work when /boot is a separate partition, as reported by
Nikita Karetnikov <nikita@karetnikov.org> in <http://bugs.gnu.org/19220>.
This fixes a regression introduced in 39d1f82.

* gnu/build/install.scm (install-grub): Copy GRUB.CFG instead of
  symlinking it, as was the case before 39d1f82.
* gnu/build/vm.scm (register-grub.cfg-root): Add 'grub.cfg' parameter.
  Make it a permanent GC root instead of an indirect GC root.
  (initialize-hard-disk): Adjust accordingly.
* guix/scripts/system.scm (install-grub*): Replace use of
  'add-indirect-root' by the addition of a permanent GC root in
  %GC-ROOTS-DIRECTORY.

activation: Don't create unneeded "/var/guix/gcroots/etc-directory".

* gnu/build/activation.scm (activate-etc): Don't create
  "/var/guix/gcroots/etc-directory".

system: Make /boot/grub/grub.cfg an indirect GC root.

Fixes <http://bugs.gnu.org/19160>.

* guix/scripts/system.scm (install-grub*): Make /boot/grub/grub.cfg an
  indirect GC root.
* gnu/build/install.scm (install-grub): Make TARGET a symlink.
* gnu/build/vm.scm (register-grub.cfg-root): New procedure.
  (initialize-hard-disk): Use it.

linux-modules: Correctly propagate error code from 'init_module'.

* gnu/packages/patches/guile-linux-syscalls.patch (scm_load_linux_module):
  Leave 'errno' unchanged when ERR != 0.
* gnu/build/linux-modules.scm (load-linux-module*): Check for the errno
  value of ARGS to determine whether the module was already loaded.

linux-boot: Load modules and their dependencies, à la 'modprobe'.

* gnu/build/linux-boot.scm: Use (gnu build linux-modules).
  (load-linux-module*): Remove.
  (boot-system): Add #:linux-module-directory parameter.
  [lookup-module]: New procedure.
  Call 'current-module-debugging-port'.  Pass #:lookup-module to
  'load-linux-module*'.  Map LOOKUP-MODULE on LINUX-MODULES.
* gnu/system/linux-initrd.scm (base-initrd): Adjust 'boot-system' call
  accordingly.  Adjust #:modules argument as well.
* gnu/system.scm (operating-system-activation-script)[%modules]: Likewise.
* gnu/system/vm.scm (expression->derivation-in-linux-vm): Likewise.

system: Add (gnu build linux-modules).

* gnu/build/linux-modules.scm: New file.
* gnu-system.am (GNU_SYSTEM_MODULES): Add it.

linux-boot: Call 'pre-mount' before 'mount-root-file-system'.

Partly fixes <http://bugs.gnu.org/19190>.
Reported by Nikita Karetnikov <nikita@karetnikov.org>.

* gnu/build/linux-boot.scm (boot-system): Move PRE-MOUNT call before
  'mount-root-file-system' is called.

linux-boot: Error out when 'pre-mount' returns #f.

* gnu/build/linux-boot.scm (boot-system): Call 'error' when PRE-MOUNT
  returns #f.

linux-boot: Don't catch exceptions thrown by 'mount-root-file-system'.

* gnu/build/linux-boot.scm (mount-root-file-system): Remove 'catch #t'
  around body.  This was unneeded and even inconvenient because this
  procedure is called from within 'call-with-error-handling' already.

file-systems: Always write the options field in /etc/mtab.

* gnu/build/file-systems.scm (mount-file-system): When OPTIONS is false,
  write "rw" to /etc/mtab.  This fixes a bug whereby 'remove-from-mtab'
  in (guix syscalls) would otherwise raise a 'match-error' because of
  the missing field.  This affected file systems mounted from the
  initrd, such as devtmpfs, which has options == #f.

vm: Set the boot flag on the root partition.

Reported by nebuli on #guix.

* gnu/build/vm.scm (initialize-partition-table): Add #:bootable?
  parameter and honor it.
  (initialize-hard-disk): Likewise.

linux-boot: Make more disk partition block devices.

Reported by nebuli on #guix.

* gnu/build/linux-boot.scm (make-disk-device-nodes): Make 16 block
  devices for disk partitions.

activation: Set the firmware search path.

* gnu/build/activation.scm (activate-firmware): New procedure.
* gnu/system.scm (<operating-system>)[firmware]: New field.
  (directory-union): New procedure.
  (%base-firmware): New variable.
  (operating-system-activation-script): Use 'directory-union', and call
  'activate-firmware'.
* doc/guix.texi (operating-system Reference): Document 'firmware'.

system: Allow Linux-libre to find our 'modprobe' command.

Fixes <http://bugs.gnu.org/18525>.
Reported by Mark H Weaver <mhw@netris.org>.

* gnu/build/activation.scm (activate-modprobe): New procedure.
* gnu/system.scm (modprobe-wrapper): New procedure.
  (operating-system-activation-script): Use both.

system: Add support for boot-time mapped devices.

* gnu/build/linux-boot.scm (boot-system): Add #:pre-mount parameter and
  honor it.
* gnu/system/linux-initrd.scm (base-initrd): Add #:mapped-devices
  parameter.  Add 'device-mapping-commands' variable, and use it to
  build the #:pre-mount argument of 'boot-system'.
* gnu/system.scm (mapped-device-user,
  operating-system-user-mapped-devices,
  operating-system-boot-mapped-devices): New procedures.
  (device-mapping-services): Use 'operating-system-user-mapped-devices'
  instead of 'operating-system-mapped-devices'.
  (operating-system-initrd-file): Call the initrd with #:mapped-devices.

activation: Ensure existing user accounts have the right settings.

* gnu/build/activation.scm (modify-user, ensure-user): New procedures.
  (activate-users+groups): Systematically call 'ensure-user'.