[Bug 1763151] Re: GRUB_TERMINAL=serial ignored

[Launchpad Bug Tracker]

Status changed to 'Confirmed' because the bug affects multiple users.

** Changed in: grub2 (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/1763151

Title:
  GRUB_TERMINAL=serial ignored

Status in grub2 package in Ubuntu:
  Confirmed

Bug description:
  apt-cache policy grub2-common
  grub2-common:
    Installed: 2.02-2ubuntu8
    Candidate: 2.02-2ubuntu8
    Version table:
   *** 2.02-2ubuntu8 500
          500 http://archive.ubuntu.com/ubuntu bionic/main amd64 Packages
          100 /var/lib/dpkg/status

  
  Setting /etc/default/grub

  GRUB_TERMINAL=serial
  GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"

  is ignored by /usr/sbin/update-grub and /usr/sbin/grub-mkconfig

  apparently due to /etc/grub.d/00_header only checking:

  for x in ${GRUB_TERMINAL_INPUT} ${GRUB_TERMINAL_OUTPUT}; do
      if [ xserial = "x$x" ]; then
          serial=1;

  and therefore the subsequent generation of the serial command not
  being performed:

  if [ "x$serial" = x1 ]; then
   ...
      echo "${GRUB_SERIAL_COMMAND}"

  and thus resulting in:

  $ grep -n terminal /boot/grub/grub.cfg
  62:terminal_input console
  63:terminal_output console

  
  In order to have it work correctly 2 additional assignments are required:

  GRUB_TERMINAL=serial
  GRUB_TERMINAL_INPUT=serial
  GRUB_TERMINAL_OUTPUT=serial
  GRUB_SERIAL_COMMAND="serial --speed=115200 --unit=0 --word=8 --parity=no --stop=1"

  GRUB_TERMINAL isn't exported to the scripts in /etc/grub.d/ but is
  used by /usr/sbin/grub-mkconfig

  Surely when it is set and the others aren't it should be copied to
  them? It seems ridiculous to require 3 variables be set when 1 will do
  for the default case of having both I/O redirected to a serial port.

  As an aside:

  Using a cloudimg derived rootfs (used by LXD and others) as the basis
  for a bootable image creates a file that isn't attributed to any
  package which forces 'console' even when 'serial' is set

  /etc/default/grub.d/50-cloudimg-settings.cfg:

  GRUB_TERMINAL=console

  This file has to be deleted.

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