image: Move hurd image definition to a dedicated file.

This moves hurd-disk-image to a dedicated file. It also defines a default
operating-system so that the image can be built standalone.

* gnu/system/images/hurd.scm: New file,
* gnu/local.mk (GNU_SYSTEM_MODULES): add it,
* gnu/system/image.scm (root-offset, root-label): Export it,
(hurd-disk-image): remove it as this is now defined in the new, Hurd dedicated
file above,
(find-image): adapt to avoid loop dependency.

gnu/image.scm

@@ -67,6 +67,8 @@
 (define-record-type* <image>
   image make-image
   image?
+  (name               image-name ;symbol
+                      (default #f))
   (format             image-format) ;symbol
   (target             image-target
                       (default #f))

gnu/local.mk

@@ -632,6 +632,8 @@ GNU_SYSTEM_MODULES =				\
   %D%/system/uuid.scm				\
   %D%/system/vm.scm				\
 						\
+  %D%/system/images/hurd.scm			\
+						\
   %D%/machine.scm				\
   %D%/machine/digital-ocean.scm			\
   %D%/machine/ssh.scm				\

gnu/system/image.scm

@@ -53,10 +53,12 @@
   #:use-module (srfi srfi-35)
   #:use-module (rnrs bytevectors)
   #:use-module (ice-9 match)
-  #:export (esp-partition
+  #:export (root-offset
+            root-label
+
+            esp-partition
             root-partition
 
-            hurd-disk-image
             efi-disk-image
             iso9660-image
 
@@ -101,20 +103,6 @@
                      (list #:make-device-nodes
                            make-hurd-device-nodes)))))
 
-(define hurd-disk-image
-  (image
-   (format 'disk-image)
-   (target "i586-pc-gnu")
-   (partitions
-    (list (partition
-           (size 'guess)
-           (offset root-offset)
-           (label root-label)
-           (file-system "ext2")
-           (file-system-options '("-o" "hurd" "-O" "ext_attr"))
-           (flags '(boot))
-           (initializer hurd-initialize-root-partition))))))
-
 (define efi-disk-image
   (image
    (format 'disk-image)
@@ -565,7 +553,8 @@ addition of the <image> record."
     (_ (cond
         ((and target
               (hurd-triplet? target))
-         hurd-disk-image)
+         (module-ref (resolve-interface '(gnu system images hurd))
+                     'hurd-disk-image))
         (else
          efi-disk-image)))))
 

gnu/system/images/hurd.scm

@@ -0,0 +1,76 @@
+;;; GNU Guix --- Functional package management for GNU
+;;; Copyright © 2020 Mathieu Othacehe <m.othacehe@gmail.com>
+;;;
+;;; This file is part of GNU Guix.
+;;;
+;;; GNU Guix is free software; you can redistribute it and/or modify it
+;;; under the terms of the GNU General Public License as published by
+;;; the Free Software Foundation; either version 3 of the License, or (at
+;;; your option) any later version.
+;;;
+;;; GNU Guix is distributed in the hope that it will be useful, but
+;;; WITHOUT ANY WARRANTY; without even the implied warranty of
+;;; MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+;;; GNU General Public License for more details.
+;;;
+;;; You should have received a copy of the GNU General Public License
+;;; along with GNU Guix.  If not, see <http://www.gnu.org/licenses/>.
+
+(define-module (gnu system images hurd)
+  #:use-module (guix gexp)
+  #:use-module (gnu bootloader)
+  #:use-module (gnu bootloader grub)
+  #:use-module (gnu image)
+  #:use-module (gnu packages ssh)
+  #:use-module (gnu services)
+  #:use-module (gnu services ssh)
+  #:use-module (gnu system)
+  #:use-module (gnu system file-systems)
+  #:use-module (gnu system hurd)
+  #:use-module (gnu system image)
+  #:export (hurd-barebones-os
+            hurd-disk-image
+            hurd-barebones-disk-image))
+
+(define hurd-barebones-os
+  (operating-system
+    (inherit %hurd-default-operating-system)
+    (bootloader (bootloader-configuration
+                 (bootloader grub-minimal-bootloader)
+                 (target "/dev/sdX")))
+    (file-systems (cons (file-system
+                          (device (file-system-label "my-root"))
+                          (mount-point "/")
+                          (type "ext2"))
+                        %base-file-systems))
+    (host-name "guixygnu")
+    (timezone "Europe/Amsterdam")
+    (packages (cons openssh-sans-x %base-packages/hurd))
+    (services (cons (service openssh-service-type
+                             (openssh-configuration
+                              (openssh openssh-sans-x)
+                              (use-pam? #f)
+                              (port-number 2222)
+                              (permit-root-login #t)
+                              (allow-empty-passwords? #t)
+                              (password-authentication? #t)))
+               %base-services/hurd))))
+
+(define hurd-disk-image
+  (image
+   (format 'disk-image)
+   (target "i586-pc-gnu")
+   (partitions
+    (list (partition
+           (size 'guess)
+           (offset root-offset)
+           (label root-label)
+           (file-system "ext2")
+           (flags '(boot))
+           (initializer (gexp initialize-root-partition)))))))
+
+(define hurd-barebones-disk-image
+  (image
+   (inherit hurd-disk-image)
+   (name 'hurd-barebones-disk-image)
+   (operating-system hurd-barebones-os)))