system: Extend .gdbinit to authorize extensions from /gnu/store/*/lib.

* gnu/system/shadow.scm (default-skeletons)["gdbinit"]: Add 'auto-load
safe-path' statement.

linux-boot: Add #:on-error for initrd error handling.

Suggested by Danny Milosavljevic <dannym@scratchpost.org>
in <https://bugs.gnu.org/29922>.

* gnu/build/linux-boot.scm (boot-system): Add #:on-error parameter and
pass it to 'call-with-error-handling'.
* gnu/system/linux-initrd.scm (raw-initrd): Add #:on-error and pass it.
(base-initrd): Likewise.

vm: 'vm-image' images refer to the root file system by UUID.

This avoids the hard-coded "/dev/sda1", which only made sense when the
image is run with "qemu-system-x86_64 -hda", not when it's passed to
Xen, etc.

Reported by Andreas Enge <andreas@enge.fr>.

* gnu/system/vm.scm (system-qemu-image): Define 'root-uuid', use it as
the 'device' field for "/", and pass it to 'qemu-image'.

file-systems: Move %control-groups from %base-file-systems to
%elogind-file-systems.

* gnu/system/file-systems.scm (%base-file-systems): Move %control-groups from
here, to ...
(%elogind-file-systems): ... here.

file-systems: Do not mount hugetlb cgroup filesystem.

On ARM32 without LPAE support, hugetlb control group is not supported.
As it is not needed by elogind, remove it for all platforms.

* gnu/system/file-systems.scm (%control-groups): Remove hugetlb from control
  groups platforms.

mapped-devices: 'luks-device-mapping' checks its source device.

* gnu/system/mapped-devices.scm (check-luks-device): New procedure.
(luks-device-mapping)[check]: New field.

mapped-devices: Add 'location' and 'check' fields.

* gnu/system/mapped-devices.scm (<mapped-device>)[location]: New field.
(<mapped-device-type>)[check]: New field.

system: examples: Add missing initrd to beaglebone-black.tmpl.

* gnu/system/examples/beaglebone-black.tmpl (operating-system): Add the
  initrd with "omap_hsmmc" as an extra-module.

system: examples: Add a template for BeagleBone Black.

* gnu/system/examples/beaglebone-black.tmpl: New file.
* Makefile.am (EXAMPLES): Add it.
* gnu/system/install.scm (/etc/configuration-files): Add it.

vm: Pass the host's /dev/urandom to the guest at /dev/hwrng.

* gnu/build/vm.scm (load-in-linux-vm): Use QEMU's virtio-rng-pci.
* gnu/system/vm.scm (common-qemu-options): Likewise.

gnu: system: vm: Use loose cache for 9p file system.

This improves the performance of the shared store for operations involving
lots of files, e.g. searching through the store.

* gnu/system/vm.scm (mapping->file-system): Add cache=loose to options.

system: Add BeagleBone Black installer.

* gnu/bootloader/u-boot.scm (u-boot-beaglebone-black-bootloader): New exported
  bootloader.
* gnu/system/install.scm (beaglebone-black-installation-os): New exported variable.

bootloader: Factorize write-file-on-device.

* gnu/bootloader/extlinux.scm (install-extlinux): Factorize bootloader
writing in a new procedure write-file-on-device defined in (gnu build
bootloader).
* gnu/build/bootloader.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add new file.
* gnu/system/vm.scm (qemu-img): Adapt to import and use (gnu build bootloader)
module during derivation building.
* gnu/scripts/system.scm (bootloader-installer-derivation): Ditto.

vm: Adapt qemu command to ARM.

* gnu/build/vm.scm (load-in-linux-vm): New argument #:target-arm32.
Use it to adapt command for qemu-system-arm.  This implies to choose a
machine ("virt"), use the correct console port "ttyAMA0", disable KVM use
that is buggy on some ARM boards (Odroid XU4 for example) and use user mode
network stack instead of NIC. Gather all those options in a new variable
"arch-specific-flags".
* gnu/system/vm.scm (expression->derivation-in-linux-vm): Pass
to load-in-linux-vm "#:target-arm32?" argument.

Merge branch 'version-0.14.0'

gnu, doc, tests: Use ‘bootloader-configuration’ everywhere.

* doc/guix.texi (Proceeding with the Installation): Replace the old-style
‘grub-configuration’ with the newer ‘bootloader-configuration’ syntax.
* gnu/system/examples/vm-image.tmpl: Likewise.
* gnu/system/install.scm (installation-os): Likewise.
* gnu/tests.scm (%simple-os): Likewise.
* gnu/tests/install.scm (%minimal-os, %minimal-os-on-vda, %separate-home-os)
(%separate-store-os, %raid-root-os, %encrypted-root-os, %btrfs-root-os):
Likewise.
* gnu/tests/nfs.scm (%base-os): Likewise.
* tests/guix-system.scm (OS_BASE, make_user_config): Likewise.
* tests/system.scm (%os, %os-with-mapped-device): Likewise.

install: Don't start sshd by default.

Reported by Christopher Baines <mail@cbaines.net>
at <https://lists.gnu.org/archive/html/guix-devel/2017-12/msg00058.html>.

* gnu/services/ssh.scm (<openssh-configuration>)[%auto-start?]: New
field.
(openssh-shepherd-service): Honor it.
* gnu/system/install.scm (%installation-services): Set '%auto-start?' to
 #f for openssh-service-type.

bootloader: extlinux: Stop using dd binary.

* gnu/bootloader/extlinux.scm (dd): Remove it,
(install-extlinux): replace dd call by Guile I/O procedures.
* gnu/system/vm.scm (qemu-image): Add (ice-9 binary-ports) to used-modules
list to provide "get-bytevector-n" and "put-bytevector".
* guix/scripts/system.scm (bootloader-installer-derivation): Ditto.

install: Add colors in 'motd' and 'issue'.

* gnu/system/install.scm (%installation-services)[motd]: Add colors.
[services]: Use the "lat9u-16" font.
(%issue): Add colors.

install: Add the prerequisites of 'profile-derivation' as GC roots.

* gnu/system/install.scm (%installation-services): Add
GLIBC-UTF8-LOCALES, TEXINFO, and GUILE-FINAL as GC roots.