system: vm: Remove -net user flag.

* gnu/system/vm.scm (common-qemu-options): Remove -net user flag.

system: Use 'source-module-closure' where needed.

* gnu/system/vm.scm (%vm-module-closure): Remove.
(expression->derivation-in-linux-vm): Use 'source-module-closure'
instead of %VM-MODULE-CLOSURE.
(qemu-image): Likewise.
* gnu/system/linux-initrd.scm (expression->initrd): Likewise.
(flat-linux-module-directory, base-initrd): Likewise.
* gnu/system/mapped-devices.scm (open-luks-device): Likewise.

Reinstate "services: elogind: Provide '%elogind-file-systems' by extension."

This reverts commit 17073dafc59d62fb8cbb8b94d61d3ecc488ac59f.

system: Do not create the home directory of "nobody".

Fixes <http://bugs.gnu.org/24275>.
Reported by John Darrington <john@darrington.wattle.id.au>.

* gnu/system/shadow.scm (%base-user-accounts):
Add (create-home-directory? #f) for "nobody".

system: Add 'create-home-directory?' field to <user-account>.

* gnu/system/shadow.scm (<user-account>)[create-home-directory?]: New
field.
(user-account->gexp): Serialize it.
* gnu/build/activation.scm (activate-users+groups)[activate-user]:
Update 'match-lambda' pattern accordingly.  Pass #:create-home? to
'ensure-user'.
(add-user, modify-user, ensure-user): Add #:create-home? parameter and
honor it.
* doc/guix.texi (User Accounts): Document it.

Revert "services: elogind: Provide '%elogind-file-systems' by extension."

This reverts commit 3cf319a3f8e23831960a0f1320122cc514188a37.

services: elogind: Provide '%elogind-file-systems' by extension.

* gnu/system/file-systems.scm (%base-file-systems): Remove
%ELOGIND-FILE-SYSTEMS.
* gnu/services/desktop.scm (elogind-service-type): Extend
FILE-SYSTEM-SERVICE-TYPE to provide %ELOGIND-FILE-SYSTEMS.

ui: Remove dependency on (gnu system file-systems).

* guix/ui.scm (specification->file-system-mapping): Move to...
* gnu/system/file-systems.scm (specification->file-system-mapping):
... here.

Merge branch 'core-updates'

Revert "Merge branch 'core-updates'"

This reverts commit 455859a50f88f625d13fc2f304111f02369b366b.

mapped-devices: raid-device-mapping: Avoid non-top-level 'use-modules'.

Fixes <http://bugs.gnu.org/24135>.
Reported by myglc2 <myglc2@gmail.com>.

* gnu/system/mapped-devices.scm (open-raid-device): Avoid non-top-level
'use-modules' form.

mapped-devices: Bail out when RAID sources don't show up.

* gnu/system/mapped-devices.scm (open-raid-device): Bail out after 20
loop iterations.

mapped-devices: Make RAID device opening message clearer.

* gnu/system/mapped-devices.scm (open-raid-device): Rename 'source' to
'sources'.  Make 'waiting' message more informative.
(close-raid-device): Rename 'source' to 'sources'.

mapped-devices: Do not always use (gnu build file-systems).

Fixes <http://bugs.gnu.org/24129>.
Reported by myglc2 <myglc2@gmail.com>.

* gnu/system/mapped-devices.scm (device-mapping-service-type): Remove
'modules' field from 'shepherd-service' form.
(open-luks-device): Add 'use-modules' form.

Merge branch 'core-updates'

install: Add nvi to the image.

* gnu/system/install.scm (installation-os)[packages]: Add NVI.
* doc/guix.texi (Proceeding with the Installation): Mention it.

Merge remote-tracking branch 'origin/master' into core-updates

system: Add mapped devices for RAID.

* gnu/system/mapped-devices.scm (raid-device-mapping, open-raid-device,
close-raid-device): New variables.
* doc/guix.texi (Mapped Devices): Add documentation for RAID devices,
reorganize documentation for LUKS devices.

Co-authored-by: Ludovic Courtès <ludo@gnu.org>

Merge branch 'master' into core-updates

services: Add pam-limits-service.

* gnu/system/pam.scm (<pam-limits-entry>): New record type.
(pam-limits-entry, pam-limits-entry->string): New procedures.
* gnu/services/base.scm (pam-limits-service-type): New variable.
(pam-limits-service): New procedure.
* doc/guix.texi (Base Services): Document it.