system: <boot-parameters> does not use "/dev" device names.

Fixes <https://bugs.gnu.org/28445>.
Reported by Mark H Weaver and Roel Janssen.

* gnu/system.scm (read-boot-parameters)[ensure-not-/dev]: New procedure.
Use it.

gnu: system: Fix computation of boot parameters for LUKS devices.

* gnu/system.scm (read-boot-parameters): Fix store-device computation for root
devices of type "device", like the LUKS partition described in the manual.
From a patch from https://debbugs.gnu.org/cgi/bugreport.cgi?bug=28445#23.

Signed-off-by: Andy Wingo <wingo@igalia.com>

system: Create "/etc/hostname".

* gnu/system.scm (operating-system-etc-service): Add a plain-file with the
  operating-system-host-name.

system: Define 'DICPATH' in /etc/profile.

* gnu/system.scm (operating-system-etc-service) <profile>: Define
'DICPATH'.

system: Add gexp compiler for <operating-system>.

* gnu/system.scm (operating-system-compiler): New procedure.

system: Fix typo in 'read-boot-parameters'.

Fixes a regression introduced in
commit 075681d3501082c6e22df8abf29dfe89d85effc1.

* gnu/system.scm (read-boot-parameters): For 'root-device', use
'device-sexp->device', not 'device->sexp'.

system: Serialize the UUID type in the "parameters" file.

* gnu/system.scm (read-boot-parameters)[device->sexp]: New procedure.
Use it for 'root-device' and 'store-device'.
(device->sexp): Serialize the UUID type in addition to its bytevector.

system: Introduce a disjoint UUID type.

Conceptually a UUID is just a bytevector.  However, there's software out
there such as GRUB that relies on the string representation of different
UUID types (e.g., the string representation of DCE UUIDs differs from
that of ISO-9660 UUIDs, even if they are actually bytevectors of the
same length).  This new <uuid> record type allows us to preserve
information about the type of UUID so we can eventually convert it to a
string using the right representation.

* gnu/system/uuid.scm (<uuid>): New record type.
(bytevector->uuid): New procedure.
(uuid): Return calls to 'make-uuid'.
(uuid->string): Rewrite using 'match-lambda*' to accept a single 'uuid?'
argument.
* gnu/bootloader/grub.scm (grub-root-search): Check for 'uuid?' instead
of 'bytevector?'.
* gnu/system.scm (bootable-kernel-arguments): Check whether ROOT-DEVICE
is 'uuid?'.
(read-boot-parameters): Use 'bytevector->uuid' when the
store device is a bytevector.
(read-boot-parameters-file): Check for 'uuid?' instead of 'bytevector?'.
(device->sexp): New procedure.
(operating-system-boot-parameters-file): Use it for 'root-device' and
'store'.
(operating-system-bootcfg): Remove conditional in definition of
'root-device'.
* gnu/system/file-systems.scm (file-system->spec): Check for 'uuid?' on
DEVICE and take its bytevector.
* gnu/system/mapped-devices.scm (open-luks-device): Likewise.
* gnu/system/vm.scm (iso9660-image): Call 'uuid-bytevector' for the
 #:volume-uuid argument.

Merge branch 'core-updates'

Merge branch 'master' into core-updates

bootloader: Use <menu-entry> for the bootloader side.

* gnu/bootloader.scm (menu-entry-device-mount-point): New variable.  Export it.
(<menu-entry>: New field "device".
* gnu/bootloader/grub.scm (grub-confgiuration-file): Handle <menu-entry>
entries.
* gnu/bootloader/extlinux.scm (extlinux-configuration-file): Handle
<menu-entry> entries.
* gnu/system.scm (menu->entry->boot-parameters): Delete variable.
(boot-parameters->menu-entry): New variable.  Export it.
(operating-system-bootcfg): Make OLD-ENTRIES a list of <menu-entry>.
* guix/script/system.scm (reinstall-bootloader): Fix bootcfg usage.
(perform-action): Fix bootcfg usage.

Merge branch 'master' into core-updates

gnu: Add support for aarch64's compiled kernel.

* gnu/packages/linux.scm (linux-libre)[arguments]: Add to the regex to
find and install the aarch64-linux kernel.
* gnu/system.scm (system-linux-image-file-name): Add entry for aarch64.

Merge branch 'master' into core-updates

system: Add 'newuidmap' and 'newgidmap' to %SETUID-PROGRAMS.

* gnu/system.scm (%setuid-programs): Add 'newuidmap' and 'newgidmap'.

locale: Demonadify the locale creation API.

* gnu/system/locale.scm (single-locale-directory): Use 'computed-file'
instead of 'gexp->derivation'.
(locale-directory): Adjust accordingly and do the same.
* gnu/system.scm (operating-system-directory-base-entries): Adjust
accordingly.

system: Avoid collision between GMP variants in the global profile.

* gnu/system.scm (%base-packages): Move GUILE-2.2 out of the list passed
to 'canonical-package'.

Merge branch 'master' into core-updates

system: Use "@" to refer to the 'shadow' package.

Reported by Mark H Weaver
at <https://lists.gnu.org/archive/html/guix-devel/2017-06/msg00349.html>.

* gnu/system.scm (%base-packages): Use '@' for shadow.  This fixes an
error on Guile 2.0 where 'shadow' alone resolves to the (gnu system
shadow) module.

Merge branch 'master' into core-updates