The grub terminal setup is divided into the setting for the output
and the input console. For both settings different parameters exists.
So far kiwi did not differentiate between the two parts of the
console setup and that could lead to a wrong setting if only one
value is provided in kiwi's console= attribute which lead to the
grub setting, GRUB_TERMINAL=value. If value is set to e.g gfxterm
grub takes this for both input and output and it's obviously
wrong for the input. To make this less error prune the kiwi code
changes with this commit to set GRUB_TERMINAL_INPUT and
GRUB_TERMINAL_OUTPUT rather than GRUB_TERMINAL and also runs sanity
checks on the provided values if they are applicable. The information
for setting up the console in the schema stays untouched though.
That's because it's used for all bootloaders and also because grub
supports multiple values for the console in/out setting in one
GRUB_TERMINAL variable even though kiwi does no longer use it.
To make this clear for the users also the documentation for the
console attribute setup has been updated. If we want to wish two
distinct attributes for input and output console settings a schema
change and also differentiation between bootloaders is needed and
that I only see for the kiwi-10 branch if at all. This Fixes#2419
c6d8235fa6