gnu: bootloader: Support multiple targets.

Fixes <https://issues.guix.gnu.org/40997>.

* gnu/bootloader.scm (<bootloader-configuration>): New 'targets' field.
(%bootloader-configuration-target): New procedure.
(bootloader-configuration-target): Add deprecation warning.
(bootloader-configuration-targets): New procedure.
* guix/scripts/system.scm (install): Access targets via
bootloader-configuration-targets.
(perform-action)[bootloader-target]: Remove unused argument and update doc.
Access targets via bootloader-configuration-targets and fix indentation.
(process-action): Access targets via bootloader-configuration-targets.
Do not provide the unused BOOTLOADER-TARGET argument when applying
`perform-action'.
* guix/scripts/system/reconfigure.scm (install-bootloader-program): Rename
DEVICE argument to DEVICES.  Adjust doc and comment.  Apply `installer' and
`disk-installer' for every DEVICES.
(install-bootloader): Access targets via bootloader-configuration-targets and
rename variable from DEVICE to DEVICES.
* gnu/tests/install.scm: Adjust accordingly.
* tests/guix-system.sh: Likewise.
* gnu/tests/reconfigure.scm (run-install-bootloader-test): Adjust the DEVICES
argument so that it is a list.
* doc/guix.texi: Update doc.

1 files changed, 20 insertions, 2 deletions

diff --git a/gnu/bootloader.scm b/gnu/bootloader.scm
index 6d7352ddd21..98807a4810b 100644
--- a/gnu/bootloader.scm
+++ b/gnu/bootloader.scm
@@ -55,7 +55,8 @@
             bootloader-configuration
             bootloader-configuration?
             bootloader-configuration-bootloader
-            bootloader-configuration-target
+            bootloader-configuration-target ;deprecated
+            bootloader-configuration-targets
             bootloader-configuration-menu-entries
             bootloader-configuration-default-entry
             bootloader-configuration-timeout
@@ -183,7 +184,9 @@ record."
   bootloader-configuration make-bootloader-configuration
   bootloader-configuration?
   (bootloader         bootloader-configuration-bootloader) ;<bootloader>
-  (target             bootloader-configuration-target      ;string
+  (targets            %bootloader-configuration-targets    ;list of strings
+                      (default #f))
+  (target             %bootloader-configuration-target ;deprecated
                       (default #f))
   (menu-entries       bootloader-configuration-menu-entries ;list of <menu-entry>
                       (default '()))
@@ -204,6 +207,21 @@ record."
   (serial-speed       bootloader-configuration-serial-speed ;integer | #f
                       (default #f)))
 
+;;; Deprecated.
+(define (bootloader-configuration-target config)
+  (warning (G_ "the 'target' field is deprecated, please use 'targets' \
+instead~%"))
+  (%bootloader-configuration-target config))
+
+(define (bootloader-configuration-targets config)
+  (or (%bootloader-configuration-targets config)
+      ;; TODO: Remove after the deprecated 'target' field is removed.
+      (list (bootloader-configuration-target config))
+      ;; XXX: At least the GRUB installer (see (gnu bootloader grub)) has this
+      ;; peculiar behavior of installing fonts and GRUB modules when DEVICE is #f,
+      ;; hence the default value of '(#f) rather than '().
+      (list #f)))
+
 
 ;;;
 ;;; Bootloaders.