[bug#38809] [PATCH] bootloader: grub: Add resolution override.

[Jan Nieuwenhuizen]

Tobias Geerinckx-Rice writes:

> Jan Nieuwenhuizen 写道：
>> With this patch I finally have a readable GRUB menu.
>
> Thanks!  Perhaps it will help solve my EFI framebuffer woes (probably
> not but who knows.
>
>> I am not sure about the name and semantics of `resolution':
>> Better to use `gfxmode', and/or use a list of strings
>> '("1024x768x32" "auto"), ... WDYT?
>
> Yes please, on both counts.  Grub-theme should expose the GRUB
> variable, not a lossy abstraction.

Okay, I think I just wished the GRUB name would be more meaningful for
casual users (such as myself).  I'm terrible with TLAwords, and very
happy I found and fixed this ;-)

Greetings,
janneke

>From 333ba3ee53e1c359a01aed80c24d17ece39ad975 Mon Sep 17 00:00:00 2001
From: Jan Nieuwenhuizen <address@hidden>
Date: Mon, 30 Dec 2019 11:25:40 +0100
Subject: [PATCH] bootloader: grub: Add gfxmode (resolution) override.

* gnu/bootloader/grub.scm (<grub-theme>): Add `gfxmode' entry.
(eye-candy): Use it.
* doc/guix.texi (Bootloader Configuration): Document it.
---
 doc/guix.texi           | 27 +++++++++++++++++++++++++--
 gnu/bootloader/grub.scm | 13 +++++++++----
 2 files changed, 34 insertions(+), 6 deletions(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index 70e3dfea6a..eaa4e7ab97 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -25923,9 +25923,21 @@ 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{gfxmode} (default: @code{'("auto")})
+The GRUB @code{gfxmode} to set (a list of screen resolution strings, see
+@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 +25948,17 @@ 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)
+         (gfxmode '("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 adcdbdbab0..229bba96ad 100644
--- a/gnu/bootloader/grub.scm
+++ b/gnu/bootloader/grub.scm
@@ -3,6 +3,7 @@
 ;;; Copyright © 2016 Chris Marusich <address@hidden>
 ;;; Copyright © 2017 Leo Famulari <address@hidden>
 ;;; Copyright © 2017 Mathieu Othacehe <address@hidden>
+;;; Copyright © 2019 Jan (janneke) Nieuwenhuizen <address@hidden>
 ;;;
 ;;; 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))))
+  (gfxmode         grub-gfxmode
+                   (default '("auto"))))          ;list of string
 
 (define %background-image
   (grub-image
@@ -149,8 +152,10 @@ 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=" (string-join
+                 (grub-gfxmode (bootloader-configuration-theme config))
+                 ";") "
   insmod video_bochs
   insmod video_cirrus
   insmod gfxterm
@@ -166,7 +171,7 @@ system string---e.g., \"x86_64-linux\"."
     insmod vbe
     insmod vga
   fi
-"
+")
         ""))
 
   (define (setup-gfxterm config font-file)
-- 
2.24.0

-- 
Jan Nieuwenhuizen <address@hidden> | GNU LilyPond http://lilypond.org
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