build: reset-timestamps: Include directories.

* guix/build/install.scm (reset-timestamps): Reset timestamps of
  directories as well.

vm: Only pass "-enable-kvm" to qemu if /dev/kvm is present.

Fixes <http://bugs.gnu.org/22633>.

* gnu/build/vm.scm (load-in-linux-vm): Only pass "-enable-kvm" flag to qemu
  if "/dev/kvm" is present.
* gnu/system/vm.scm (common-kvm-options): Same as above.

linux-modules: Use normalized module names for 'modprobe.blacklist'.

* gnu/build/linux-modules.scm (normalize-module-name): New procedure.
(file-name->module-name): Use it.
(module-black-list): Expound docstring.

file-systems: Spawn a Bournish REPL upon fsck failure.

Fixes <http://bugs.gnu.org/22588>.
Reported by Mark H Weaver <mhw@netris.org>.

* gnu/build/file-systems.scm (check-file-system): Pass
%BOURNISH-LANGUAGE as the argument to 'start-repl'.
* gnu/services.scm (activation-script): Add (guix build bournish).
* gnu/services/base.scm (file-system-shepherd-service)[imported-modules]:
Likewise.
* gnu/system/linux-container.scm (container-script): Likewise.
* gnu/system/vm.scm (expression->derivation-in-linux-vm): Likewise.

Rename 'dmd' to 'shepherd' in comments and strings.

* build-aux/hydra/demo-os.scm (operating-system)[issue]: Point to
  shepherd instead of dmd.
* ROADMAP: Likewise.
* gnu/build/install.scm (directives): Adjust comment.

Rename '/root/etc/dmd' directory and 'do-not-kill' file.

* gnu/services/base.scm (%do-not-kill-file): Rename to
  "/etc/shepherd/do-not-kill".
* gnu/build/linux-boot.scm (mount-root-file-system): Rename
  "/root/etc/dmd" to "/root/etc/shepherd".

Merge branch 'master' into core-updates

build: container: Make 'unprivileged-user-namespace-supported?' more robust.

* gnu/build/linux-container.scm (unprivileged-user-namespace-supported?): Only
  read and check the first character, to cope with a possible newline in the
  (pseudo-)file.

Merge branch 'master' into core-updates

linux-modules: Support 'modprobe.blacklist' on the command line.

* gnu/build/linux-modules.scm (file-name->module-name)
(module-black-list): New procedure.
* gnu/build/linux-modules.scm (load-linux-module*): Add #:black-list
parameter.
[black-listed?, load-dependencies]: New procedures.
Use them.

Merge branch 'master' into core-updates

linux-boot: Remove verbose output for module loads.

* gnu/build/linux-boot.scm (boot-system): Leave
'current-module-debugging-port' unchanged.
* gnu/build/linux-modules.scm (load-linux-module*): Update comment about
'mmap'.

Merge branch 'master' into core-updates

system: Allow the root file system to be named by UUID.

* gnu/build/file-systems.scm (canonicalize-device-spec)[canonical-title]:
Use 'string->uuid' to check whether SPEC is a UUID.
When SPEC is a string and CANONICAL-TITLE is 'uuid, call 'string->uuid'.
* gnu/system.scm (operating-system-grub.cfg): Add 'root-device'
variable and use it for the "--root=" argument.

file-systems: Move 'string->uuid' to the build side.

* gnu/system/file-systems.scm (%uuid-rx, string->uuid): Move to...
* gnu/build/file-systems.scm (%uuid-rx, string->uuid): ... here.  New
variables.

Merge branch 'master' into core-updates

build: container: Add feature test predicates.

* gnu/build/linux-container.scm (user-namespace-supported?,
  unprivileged-user-namespace-supported?, setgroups-supported?): New
  procedures.
* tests/container.scm: Use predicates.
* tests/syscalls.scm: Likewise.

Merge branch 'master' into dbus-update

container: Remove unnecessary CLONE_CHILD_* flags.

* gnu/build/linux-container.scm (namespaces->bit-mask): Remove
  CLONE_CHILD_CLEARTID and CLONE_CHILD_SETTID, which are unneeded.
  Discussed at <http://bugs.gnu.org/21694>.

Merge branch 'master' into dbus-update