bug#26875: [v2] system: grub: Expose GRUB's interactive interface settings.

[ludo@gnu.org (Ludovic Courtès)]

Hi Leo,

Leo Famulari <leo@famulari.name> skribis:

> * 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.

Overall LGTM.  Nice to see it taking shape!

Some minor comments and suggestions:

> +@item @code{terminal-outputs} (default: @code{'gfxterm})
> +The output terminals used for the GRUB boot menu, as a list of symbols.
> +These values are accepted: console, serial, serial_@{0-3@}, gfxterm,
> +vga_text, mda_text, morse, spkmodem

Please use @code for the possible, add a final period, and a
cross-reference to the relevant part of the GRUB manual with
“(@pxref{…})” if possible.

> +@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.  These values are accepted: console, serial, serial_@{0-3@},
> +at_keyboard, usb_keyboard.
> +
> +@item @code{serial-unit} (default: @code{#f})
> +The serial unit used by GRUB, as an integer from 0 to 3.  The default
> +value is chosen by GRUB at run-time; currently GRUB chooses 0, which
> +corresponds to COM1.

Likewise.

> +@item @code{serial-speed} (default: @code{#f})
> +The speed of the serial interface, as an integer.  The default value is
> +chosen by GRUB at run-time; currently GRUB chooses 9600bps.

9,600@tie{}bps.  :-)

Apart from that, as long as “make check-system TESTS=basic” and similar
pass, that’s all good for me!

Mathieu: is it OK to apply this before the patch series on non-GRUB
bootloaders?

Thanks,
Ludo’.