From dfceb5702b0de5787f79e1098b4787e9d3adbe4e Mon Sep 17 00:00:00 2001
From: Jan Nieuwenhuizen <janneke@gnu.org>
Date: Mon, 30 Dec 2019 11:25:40 +0100
Subject: [PATCH] bootloader: grub: Add resolution override.

* gnu/bootloader/grub.scm (<grub-theme>): Add `resolution' entry.
(eye-candy): Use it.
* doc/guix.texi (Bootloader Configuration): Document it.
---
 doc/guix.texi           | 26 ++++++++++++++++++++++++--
 gnu/bootloader/grub.scm | 11 +++++++----
 2 files changed, 31 insertions(+), 6 deletions(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index efc59c1aaf..02cecae043 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -25923,9 +25923,20 @@ must @emph{not} be an OS device name such as @file{/dev/sda1}.
 @end table
 @end deftp
 
+@cindex HDPI
+@cindex resolution
 @c FIXME: Write documentation once it's stable.
-For now only GRUB has theme support. GRUB themes are created using
-the @code{grub-theme} form, which is not documented yet.
+For now only GRUB has theme support.  GRUB themes are created using
+the @code{grub-theme} form, which is not fully documented yet.
+
+@deftp {Data Type} grub-theme
+Data type representing the configuration of the GRUB theme.
+
+@table @asis
+@item @code{resolution} (default: @code{"auto"})
+The @code{gfxmode} to set (@pxref{gfxmode,,, grub, GNU GRUB manual}).
+@end table
+@end deftp
 
 @defvr {Scheme Variable} %default-theme
 This is the default GRUB theme used by the operating system if no
@@ -25936,6 +25947,17 @@ It comes with a fancy background image displaying the GNU and Guix
 logos.
 @end defvr
 
+For example, to override the default resolution, you may use something
+like
+
+@lisp
+(bootloader
+ (grub-configuration
+ ;; @dots{}
+ (theme (grub-theme
+         (inherit %default-theme)
+         (resolution "1024x786x32;auto")))))
+@end lisp
 
 @node Invoking guix system
 @section Invoking @code{guix system}
diff --git a/gnu/bootloader/grub.scm b/gnu/bootloader/grub.scm
index fd62f627a0..70de3edeb5 100644
--- a/gnu/bootloader/grub.scm
+++ b/gnu/bootloader/grub.scm
@@ -3,6 +3,7 @@
 ;;; Copyright © 2016 Chris Marusich <cmmarusich@gmail.com>
 ;;; Copyright © 2017 Leo Famulari <leo@famulari.name>
 ;;; Copyright © 2017 Mathieu Othacehe <m.othacehe@gmail.com>
+;;; Copyright © 2019 Jan (janneke) Nieuwenhuizen <janneke@gnu.org>
 ;;;
 ;;; This file is part of GNU Guix.
 ;;;
@@ -88,7 +89,9 @@ denoting a file name."
   (color-normal    grub-theme-color-normal
                    (default '((fg . cyan) (bg . blue))))
   (color-highlight grub-theme-color-highlight
-                   (default '((fg . white) (bg . blue)))))
+                   (default '((fg . white) (bg . blue))))
+  (resolution      grub-resolution
+                   (default "auto")))
 
 (define %background-image
   (grub-image
@@ -149,8 +152,8 @@ system string---e.g., \"x86_64-linux\"."
     ;; most other modern architectures have no other mode and therefore don't
     ;; need to be switched.
     (if (string-match "^(x86_64|i[3-6]86)-" system)
-        "
-  # Leave 'gfxmode' to 'auto'.
+        (string-append "
+  set gfxmode=" (grub-resolution (bootloader-configuration-theme config)) "
   insmod video_bochs
   insmod video_cirrus
   insmod gfxterm
@@ -166,7 +169,7 @@ system string---e.g., \"x86_64-linux\"."
     insmod vbe
     insmod vga
   fi
-"
+")
         ""))
 
   (define (setup-gfxterm config font-file)
-- 
2.24.0