Fixes <https://bugs.gnu.org/22883>.

* guix/channels.scm (<channel>)[introduction]: New field.
(<channel-introduction>): New record type.
(%guix-channel-introduction): New variable.
(%default-channels): Use it.
(<channel-metadata>)[keyring-reference]: New field.
(%default-keyring-reference): New variable.
(read-channel-metadata, read-channel-metadata-from-source): Initialize
the 'keyring-reference' field.
(commit-short-id, verify-introductory-commit)
(authenticate-channel): New procedures.
(latest-channel-instance): Call 'authenticate-channel' when CHANNEL has
an introduction.
* tests/channels.scm (gpg+git-available?, commit-id-string): New
procedures.
("authenticate-channel, wrong first commit signer"):
("authenticate-channel, .guix-authorizations"): New tests.
* doc/guix.texi (Invoking guix pull): Mention authentication.

* doc/contributing.texi (Building from Git): Move "make authenticate"
instructions below.

* guix/scripts/pack.scm (%compressors): Add zstd.
* doc/guix.texi (Invoking guix pack): Document it.

Suggested by Maxim Cournoyer via IRC.

* doc/guix.texi (The Hurd in a Virtual Machine): Explicitly mention that
hurd-vm and childhurd are two names for this service.

The amount of packages has more than tripled since this section was written.
Adjust the rebuild limits and cycle lengths based on current practices.

* doc/contributing.texi (Submitting Patches): Increase 'staging' rebuild limit
to 1800 packages, and adjust the cycle to six weeks.  Increase 'core-updates'
cycle to six months.

* guix/scripts/repl.scm: Add filename options for script execution.
* doc/guix.texi (Invoking guix repl): Document it.
* tests/guix-repl.sh: Test it.
* Makefile.am: (SH_TESTS): Add it.

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

* gnu/services/virtualization.scm (hurd-vm-shepherd-service,
hurd-vm-disk-image): New procedures.
(%hurd-vm-operating-system, hurd-vm-service-type): New variables.
(<hurd-vm-configuration>): New record type.
* doc/guix.texi (Virtualization Services): Document it.
* gnu/services/shepherd.scm (scm->go): Use let-system, remove FIXME.  Fixes
fixes cross-building of shepherd modules for the Hurd image.

Suggested by Edouard Klein <edk@beaver-labs.com>.

* guix/profiles.scm (check-for-collisions): Export.
* guix/lint.scm (check-profile-collisions): New procedure.
(%local-checkers): Add 'profile-collisions' checker.
* tests/lint.scm ("profile-collisions: no warnings")
("profile-collisions: propagated inputs collide")
("profile-collisions: propagated inputs collide, store items"): New tests.
* doc/guix.texi (Invoking guix lint): Document it.

* doc/guix.texi (Invoking guix lint): Mention the 'derivation' checker.

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

* 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.

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

* 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.

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

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

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

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

* 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.

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

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

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

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.

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

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

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

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

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

This is a follow-up commit to 9cdb10d5:
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/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.

* 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'.

* guix/scripts/download.scm (show-help, %options): Support "base64"
format.
* guix/scripts/hash.scm (show-help, %options): Likewise.
* tests/guix-hash.sh: Test it.
* doc/guix.texi (Invoking guix hash): Document it.

* guix/scripts/download.scm (%default-options): Add 'hash-algorithm'.
(show-help, %options): Add "--hash".
(guix-download): Honor it.
* guix/scripts/hash.scm (%default-options): Add 'hash-algorithm'.
(show-help, %options): Add "--hash".
(guix-hash): Honor it.
* tests/guix-hash.sh: Test '-H sha512'.
* doc/guix.texi (Invoking guix download): Document it.
(Invoking guix hash): Document it.

* build-aux/check-channel-news.scm: New file.
* Makefile.am (EXTRA_DIST): Add it.
(check-channel-news): New phony rule.
* doc/contributing.texi (Commit Access): Mention "make check-channel-news".

These two words have different meanings and we really meant
"alternatively" here.

* doc/guix.texi (System Installation):
(Preparing for Installation):
(Invoking guix refresh):
(Invoking guix challenge):
(Networking Services): "Alternatively", not "Alternately".

* gnu/bootloader/grub.scm (strip-mount-point): Remove procedure.
(normalize-file): Add procedure.
(grub-configuration-file): New BTRFS-SUBVOLUME-FILE-NAME parameter.  When
defined, prepend its value to the kernel and initrd file names, using the
NORMALIZE-FILE procedure.  Adjust the call to EYE-CANDY to pass the
BTRFS-SUBVOLUME-FILE-NAME argument.  Normalize the KEYMAP file as well.
(eye-candy): Add a BTRFS-SUBVOLUME-FILE-NAME parameter, and use it, along with
the NORMALIZE-FILE procedure, to normalize the FONT-FILE and IMAGE nested
variables.  Adjust doc.
* gnu/bootloader/depthcharge.scm (depthcharge-configuration-file): Adapt.
* gnu/bootloader/extlinux.scm (extlinux-configuration-file): Likewise.
* gnu/system/file-systems.scm (btrfs-subvolume?)
(btrfs-store-subvolume-file-name): New procedures.
* gnu/system.scm (operating-system-bootcfg): Specify the Btrfs
subvolume file name the store resides on to the
`operating-system-bootcfg' procedure, using the new
BTRFS-SUBVOLUME-FILE-NAME argument.
* doc/guix.texi (File Systems): Add a Btrfs subsection to document the use of
subvolumes.
* gnu/tests/install.scm (%btrfs-root-on-subvolume-os)
(%btrfs-root-on-subvolume-os-source)
(%btrfs-root-on-subvolume-installation-script)
(%test-btrfs-root-on-subvolume-os): New variables.

* gnu/system/file-systems.scm (file-system-options->alist)
(alist->file-system-options): New procedures.
* tests/file-systems.scm: New tests.
* doc/guix.texi (File Systems): Add note about the newly added procedures.

The --root option can now be omitted, and inferred from the root file system
declaration instead.

* gnu/build/file-systems.scm (canonicalize-device-spec): Extend to support NFS
directly, and...
* gnu/build/linux-boot.scm (boot-system): ...remove NFS special casing from
here.  Remove nested definitions for root-fs-type, root-fs-flags and
root-fs-options, and bind those inside the let* instead.  Make "--root" take
precedence over the device field string representation of the root file
system.
* doc/guix.texi (Initial RAM Disk): Document that "--root" can be left
unspecified.

* guix/scripts/describe.scm (%available-formats): New variable.
(list-formats): New procedure.
(%options, show-help): Add --list-formats
* doc/guix.texi: Add --list-formats

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

* doc/build.scm (guile-lib/htmlprag-fixed)[source]: Remove.
[arguments]: Add 'fix-htmlprag' phase.

* doc/guix.texi (Build Systems): Fix meson build system description.

Fix commit 1f14e25c
as discussed in <https://bugs.gnu.org/41038

>.

* doc/guix.texi (Packages for C Development): Rename to...
(The GCC toolchain): ...this. Add gfortran-toolchain.
(Invoking guix package): Add guix-search anchor.
(Application Setup)[The GCC toolchain]: Remove.

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