Re: GRUB and installer invisible on serial console

[Brice Waegeneire <brice@waegenei.re>]

On 2019-12-21 18:31, Ricardo Wurmus wrote:
> Hi Guix,
> 
> I just wanted to install Guix System on a server where I currently only
> have remote access via serial console — and which happens to have a 
> Guix
> USB stick stuck in its USB port.  I can see the system’s UEFI output 
> and
> see that it boots from USB, but “Welcome to GRUB!” is the very last
> thing I see.  There is no further output.
> 
> Our GRUB is using fancy graphics, so I wonder if that means that it has
> switched to a mode that I simply can’t see over my serial connection.
> 
> Is there a way to make it start GRUB in text mode — and stay in text
> mode throughout the installation?
> 
> --
> Ricardo

Hello Ricardo,

I got the same setup as you working some weeks ago with the following 
config.
I also had to tweak my BIOS settings to have a reliable serial 
connection.

--8<---------------cut here---------------start------------->8---
    (kernel-arguments
      '("quiet" "console=tty0" "console=ttyS0,115200"))

   (bootloader
     (bootloader-configuration
       (bootloader grub-efi-bootloader)
       (target "/boot/efi")
       (keyboard-layout keyboard-layout)
       (terminal-outputs '(gfxterm serial))
       (terminal-inputs '(console serial))
       (serial-unit 0)
       (serial-speed 115200)))
--8<---------------cut here---------------end--------------->8---

The order of the kernel argument "console=" is important because
« The last device will be used when you open /dev/console » [1].
And note that my baudrate is not 9600, the default value, because it's 
too slow
when displaying files. If you have a low quality serial link use the 
default.

I was wondering about writing a patch to make this kind of setup the 
default for
the image installer to allow installing Guix through a serial connection 
only.
Unfortunately such a setup will remove the current eye-candy GRUB theme.

#38580 may also interest you, it adds access to the BIOS settings from 
GRUB when
using UEFI.

[1]: 
https://www.kernel.org/doc/html/latest/admin-guide/serial-console.html
[2]: https://debbugs.gnu.org/cgi/bugreport.cgi?bug=38580