Re: Non-graphical GRUB configuration

[Leo Famulari <leo@famulari.name>]

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On Sun, Apr 02, 2017 at 05:06:20PM -0400, Leo Famulari wrote:
> Based on the GRUB manual [0], how about this plan?
> 
> We'd add these fields to (grub-configuration): 
> 
> terminal-outputs: One or more symbols: console, serial, gfxterm,
> ofconsole, vga_text. Default gfxterm.
> 
> terminal-inputs: One or more symbols: console, serial, ofconsole,
> at_keyboard,usb_keyboard. Default unset.
> 
> If 'terminal-inputs' or 'serial-*' are unset, we do what we do now:
> nothing. If 'terminal-outputs' is unset, we also do the same thing we
> now, which is set it to gfxterm.
> 
> If any of them are set, we'd insert the corresponding text into the
> generated grub.cfg.
> 
> If terminal-outputs does not include the symbol 'gfxterm', we'd disable
> the "setup_gfxterm" function.

Here's a WIP patch that I'd like some advice about. It does insert the
relevant text into grub.cfg, although I recommend testing it in a
virtual machine for now.

Questions:

1) In general, is this approach okay?

2) I think that (grub-setup-io) should be used in
(grub-configuration-file) instead of (eye-candy). But, when I try
calling it there, in the builder, it has no effect on grub.cfg. Any
suggestions for debugging this?

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From c1d081d111fb4778b6a0625abbdd8cc540ae630f Mon Sep 17 00:00:00 2001
From: Leo Famulari <leo@famulari.name>
Date: Sun, 2 Apr 2017 22:18:00 -0400
Subject: [PATCH] system: grub: Expose GRUB settings for interactive
 interfaces.

WIP: Does not validate input and setup-io is used in the wrong place

* gnu/system/grub.scm (<grub-configuration>): Add new fields
terminal-outputs, terminal-inputs, serial-unit, and serial-speed.
(grub-setup-io, setup-gfxterm): New procedures.
* doc/guix.texi (GRUB Configuration): Document the new fields.
---
 doc/guix.texi       | 17 ++++++++++++
 gnu/system/grub.scm | 75 +++++++++++++++++++++++++++++++++++++++++------------
 2 files changed, 75 insertions(+), 17 deletions(-)

diff --git a/doc/guix.texi b/doc/guix.texi
index aa779e38e..8107872bc 100644
--- a/doc/guix.texi
+++ b/doc/guix.texi
@@ -14920,6 +14920,23 @@ The @code{grub-theme} object describing the theme to use.
 
 @item @code{grub} (default: @code{grub})
 The GRUB package to use.
+
+@item @code{terminal-outputs} (default: @code{'gfxterm})
+The output terminals used for the GRUB boot menu, as a list of symbols.
+
+@item @code{terminal-inputs} (default: @code{'()})
+The input terminals used for the GRUB boot menu, as a list of symbols.
+The default is the native platform terminal as determined by GRUB at
+run-time.
+
+@item @code{serial-unit} (default: @code{#f})
+The serial unit used by GRUB, as an integer from 0 to 3.  The default
+value is deferred to GRUB; currently GRUB choosese 0, which corresponds
+to COM1.
+
+@item @code{serial-speed} (default: @code{#f})
+The speed of the serial interface, as an integer.  The default value is
+deferred to GRUB; currently GRUB chooses 9600bps.
 @end table
 
 @end deftp
diff --git a/gnu/system/grub.scm b/gnu/system/grub.scm
index 4f9bde6a6..8a516f05f 100644
--- a/gnu/system/grub.scm
+++ b/gnu/system/grub.scm
@@ -107,17 +107,25 @@ denoting a file name."
 (define-record-type* <grub-configuration>
   grub-configuration make-grub-configuration
   grub-configuration?
-  (grub            grub-configuration-grub           ; package
-                   (default (@ (gnu packages bootloaders) grub)))
-  (device          grub-configuration-device)        ; string
-  (menu-entries    grub-configuration-menu-entries   ; list
-                   (default '()))
-  (default-entry   grub-configuration-default-entry  ; integer
-                   (default 0))
-  (timeout         grub-configuration-timeout        ; integer
-                   (default 5))
-  (theme           grub-configuration-theme          ; <grub-theme>
-                   (default %default-theme)))
+  (grub             grub-configuration-grub             ; package
+                    (default (@ (gnu packages bootloaders) grub)))
+  (device           grub-configuration-device)          ; string
+  (menu-entries     grub-configuration-menu-entries     ; list
+                    (default '()))
+  (default-entry    grub-configuration-default-entry    ; integer
+                    (default 0))
+  (timeout          grub-configuration-timeout          ; integer
+                    (default 5))
+  (theme            grub-configuration-theme            ; <grub-theme>
+                    (default %default-theme))
+  (terminal-outputs grub-configuration-terminal-outputs ; list of symbols
+                    (default '(gfxterm)))
+  (terminal-inputs  grub-configuration-terminal-inputs  ; list of symbols
+                    (default '()))
+  (serial-unit      grub-configuration-serial-unit      ; integer | #f
+                    (default #f))
+  (serial-speed     grub-configuration-serial-speed     ; integer | #f
+                    (default #f)))
 
 (define-record-type* <menu-entry>
   menu-entry make-menu-entry
@@ -198,11 +206,16 @@ system string---e.g., \"x86_64-linux\"."
     insmod vbe
     insmod vga
   fi
-
-  terminal_output gfxterm
 "
         ""))
 
+  (define (setup-gfxterm config font-file)
+    (if (memq 'gfxterm (grub-configuration-terminal-outputs config))
+      #~(format #f "if loadfont ~a; then
+  setup_gfxterm
+fi~%" #$font-file)
+      ""))
+
   (define (theme-colors type)
     (let* ((theme  (grub-configuration-theme config))
            (colors (type theme)))
@@ -221,9 +234,8 @@ function setup_gfxterm {~a}
 # Set 'root' to the partition that contains /gnu/store.
 ~a
 
-if loadfont ~a; then
-  setup_gfxterm
-fi
+~a
+~a
 
 insmod png
 if background_image ~a; then
@@ -235,7 +247,8 @@ else
 fi~%"
                            #$setup-gfxterm-body
                            #$(grub-root-search store-device font-file)
-                           #$font-file
+                           #$(grub-setup-io config)
+                           #$(setup-gfxterm config font-file)
 
                            #$(strip-mount-point store-mount-point image)
                            #$(theme-colors grub-theme-color-normal)
@@ -246,6 +259,34 @@ fi~%"
 ;;; Configuration file.
 ;;;
 
+(define (grub-setup-io config)
+  "Return GRUB commands to configure the input / output interfaces.  The result
+is a string that can be inserted in grub.cfg.
+TODO Check the bounds of unit, and compare outputs and inputs to a list of
+valid interfaces taken from the GRUB manual."
+  (let* ((symbols->string (lambda (list)
+                           (string-join (map symbol->string list) " ")))
+         (outputs (grub-configuration-terminal-outputs config))
+         (inputs (grub-configuration-terminal-inputs config))
+         (unit (grub-configuration-serial-unit config))
+         (speed (grub-configuration-serial-speed config))
+         (io (string-append
+               "terminal_output " (symbols->string outputs) "\n"
+               (if (null? inputs)
+                 ""
+                 (string-append "terminal_input "
+                                (symbols->string inputs) "\n"))
+               (if (or unit speed)
+                 (string-append "serial"
+                                (if unit
+                                  (string-append " --unit="
+                                                 (number->string unit)) "")
+                                (if speed
+                                  (string-append " --speed="
+                                                 (number->string speed)) ""))
+                 ""))))
+    (format #f "~a" io)))
+
 (define (grub-root-search device file)
   "Return the GRUB 'search' command to look for DEVICE, which contains FILE,
 a gexp.  The result is a gexp that can be inserted in the grub.cfg-generation
-- 
2.12.2


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