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, 3 insertions, 3 deletions

diff --git a/tests/guix-system.sh b/tests/guix-system.sh
index 7e992e7bdbc..6aab1f380a9 100644
--- a/tests/guix-system.sh
+++ b/tests/guix-system.sh
@@ -115,7 +115,7 @@ cat > "$tmpfile" <<EOF
   (timezone "Europe/Paris")                           ; 6
   (locale "en_US.UTF-8")                              ; 7
 
-  (bootloader (GRUB-config (target "/dev/sdX")))      ; 9
+  (bootloader (GRUB-config (targets (list "/dev/sdX"))))        ; 9
   (file-systems (cons (file-system
                         (device (file-system-label "root"))
                         (mount-point "/")
@@ -168,7 +168,7 @@ OS_BASE='
 
   (bootloader (bootloader-configuration
                (bootloader grub-bootloader)
-               (target "/dev/sdX")))
+               (targets (list "/dev/sdX"))))
   (file-systems (cons (file-system
                         (device (file-system-label "root"))
                         (mount-point "/")
@@ -241,7 +241,7 @@ make_user_config ()
 
   (bootloader (bootloader-configuration
                 (bootloader grub-bootloader)
-                (target "/dev/sdX")))
+                (targets (list "/dev/sdX"))))
   (file-systems (cons (file-system
                         (device (file-system-label "root"))
                         (mount-point "/")