I opened my /etc/default/grub file while fixing a bug with laptop suspending…
And I read
# For full documentation of the options in this file, see:
# info -f grub -n ‘Simple configuration’
then I did info -f grub -n ‘Simple configuration’
and I found that the difference between GRUB_CMDLINE_LINUX_DEFAULT and GRUB_CMDLINE_LINUX
is that the _DEFAULT entry is fot non-recovery kernel menu entries only… that’s it!
Command-line arguments to add to menu entries for the Linux kernel.
Unless `GRUB_DISABLE_RECOVERY’ is set to `true’, two menu entries
will be generated for each Linux kernel: one default entry and one
entry for recovery mode. This option lists command-line arguments
to add only to the default menu entry, after those listed in