doc: Add note to 'udisks-service'.

* doc/guix.texi (Desktop Services): Specify how to add file-systems
utilities to 'udisks-service'.

services: Add `hurd-getty-service-type'.

* gnu/services/hurd.scm (<hurd-gettty-configuration>): New record.
(hurd-ttys-shepherd-service): New procedure.
(hurd-getty-service-type): New variable.
* doc/guix.texi (Hurd Services): Document it.

services: Add `hurd-console-service-type'.

* gnu/services/hurd.scm: New file.
* gnu/local.mk (GNU_SYSTEM_MODULES): Add it.
* doc/guix.texi (Hurd Services): Document it.

bootloader: Extend `<menu-entry>' for multiboot.

* gnu/bootloader.scm (<menu-entry>)[multiboot-kernel,multiboot-arguments,
multiboot-modules]: New fields.
[linux,initrd]: Add default value '#f'.
(menu-entry->sexp, sexp->menu-entry): Support multiboot entry.
* doc/guix.texi (Bootloader Configuration): Document them.

system: Add 'hurd' field to <operating-system>.

* gnu/system.scm (<operating-system>)[hurd]: New field.
* doc/guix.texi (operating-system Reference): Document 'hurd'.

doc: cookbook: Add entry about getting substitutes through Tor.

* doc/guix-cookbook.texi (Getting substitutes from Tor): New section.

doc: Mention Btrfs compression.

Suggested by Pierre Neidhardt <mail@ambrevar.xyz>.

* doc/guix.texi (Keyboard Layout and Networking and Partitioning):
Mention Btrfs compression.

gnu: services: docker: Add a debug? parameter.

* gnu/services/docker.scm (docker-configuration): Add a debug? field.
(containerd-shepherd-service): Pass the "--log-level=debug" argument when
DEBUG? is true.
(docker-shepherd-service): Pass the "--debug" and "--log-level=debug"
arguments when DEBUG? is true.
* doc/guix.texi (Miscellaneous Services): Update doc.

doc: cookbook: Add entry about Wireguard VPN.

Co-authored-by: Brice Waegeneire <brice@waegenei.re>

* doc/guix-cookbook.texi (Connect to Wireguard VPN): New section.

services: nfs: Expose configuration options for TCP and UDP.

* gnu/services/nfs.scm (<nfs-configuration>)[nfsd-tcp?, nfsd-udp?]: New
fields.
(nfs-shepherd-services)[rpc.nfsd]: Populate the --{no-,}tcp and --{no-,}udp
command line options based on the values of the nfsd-tcp? and nfsd-upd?
fields.
* doc/guix.texi (Network File System): Add doc.

doc: Add example to calculate the size a system.

* doc/guix.texi (Invoking `guix size'): Add guix size example for store item.

doc: Remove explicit support for mips64el-linux.

It's been a good run, but no one is maintaining the architecture.
So long, and thanks for all the fish.

* doc/guix.texi (GNU Distribution): Change text for mips64el-linux
to denote it is deprecated.
(Daemon Offload Setup): Change occurrences of mips64el-linux to
aarch64-linux and adjust local code snippets.
(Guix Environment)[cross-compilation]: Change mips64el-linux-gnu to
aarch64-linux-gnu.
(GNU Build System)(package-cross-derivation]: Same.
(G-Expressions)[cross compilation]: Same.
(Additional Build Options)[cross-compilation, build logs]: Same.
(qemu-binfmt-service-type): Remove mips64el.
* doc/contributing.texi (Submitting Patches): Same.
* m4/guix.m4: (GUIX_ASSERT_SUPPORTED_SYSTEM): Remove mips64el-linux.

doc: Use existing URLs and file names in installation instructions.

Some users are confused that these URLs and file names don't work, so
change them to the most popular architecture, while still mentioning
alternatives.

* doc/guix.texi (USB Stick and DVD Installation, Binary Installation): Use
x86_64-linux URLs by default.

doc: Remove one use of 'file-append*'.

* doc/build.scm (texinfo-manual-source)[build]: Use 'file-append', not
'file-append*', for 'htmlxref.cnf', to ensure it has the right basename.

doc: Fix typos.

* doc/guix.texi: Fix typos.
* doc/contributing.texi: Fix typos.

Signed-off-by: Julien Lepiller <julien@lepiller.eu>

pull: Protect against downgrade attacks.

* guix/scripts/pull.scm (%default-options): Add 'validate-pull'.
(%options, show-help): Add '--allow-downgrades'.
(warn-about-backward-updates): New procedure.
(guix-pull): Pass #:current-channels and #:validate-pull to
'latest-channel-instances'.
* guix/channels.scm (ensure-forward-channel-update): Add hint for
when (channel-commit channel) is true.
* doc/guix.texi (Invoking guix pull): Document '--allow-downgrades'.

doc: cookbook: Add subsection about session locking with xss-lock.

* doc/guix-cookbook.texi (Session lock): New node.

Signed-off-by: Ludovic Courtès <ludo@gnu.org>

doc: Update to the new 'grub-theme' procedure.

This is a follow-up commit to 9cdb10d52e34f7e8fa3b6238fe268646a4bbb877:
gnu: grub: Allow a PNG image and replace "aspect-ratio" with "resolution".

* doc/guix.texi (Bootloader Configuration): Describe and use the 'grub-theme'
procedure instead of the removed '%default-theme' variable.

doc: Update 'Bootstrapping' for further binary seed reduction.

* doc/images/gcc-core-mesboot0-graph.dot: New image, replacing
* doc/images/gcc-mesboot0-bag-graph.dot: ... remove file.
* doc/local.mk (DOT_FILES): Update for new image file.
* doc/guix.texi (Reduced Binary Seed Bootstrap): Use it in updated description
of further reduction of the trusted computing base.

packages: Introduce <content-hash> and use it in <origin>.

* guix/packages.scm (<content-hash>): New record type.
(define-content-hash-constructor, build-content-hash)
(content-hash): New macros.
(print-content-hash): New procedure.
(<origin>): Rename constructor to '%origin'.
[sha256]: Remove field.
[hash]: New field.  Adjust users.
(origin-compatibility-helper, origin): New macros.
(origin-sha256): New deprecated procedure.
(origin->derivation): Adjust accordingly.
* tests/packages.scm ("package-source-derivation, origin, sha512"): New
test.
* guix/tests.scm: Hide (gcrypt hash) 'sha256' for proper syntax
matching.
* tests/challenge.scm: Add #:prefix for (gcrypt hash) and adjust users.
* tests/derivations.scm: Likewise.
* tests/store.scm: Likewise.
* tests/graph.scm ("bag DAG, including origins"): Provide 'sha256' field
with the right length.
* gnu/packages/aspell.scm (aspell-dictionary)
(aspell-dict-ca, aspell-dict-it): Use 'hash' and 'content-hash' for
proper syntax matching.
* gnu/packages/bash.scm (bash-patch): Rename 'sha256' to 'sha256-bv'.
* gnu/packages/bootstrap.scm (bootstrap-executable): Rename 'sha256' to 'bv'.
* gnu/packages/readline.scm (readline-patch): Likewise.
* gnu/packages/virtualization.scm (qemu-patch): Rename 'sha256' to
'sha256-bv'.
* guix/import/utils.scm: Hide (gcrypt hash) 'sha256'.