Existing values of color_normal/color_highlight are ignored when new video driver is loaded.

[Andrey Borzenkov]

All video drivers hardcode default text colors, so they ignore any value
set before module was loaded. This could be quite confusing if you are
looking for issues with colors during boot.

Unfortunately fixing this appears somewhat not trivial. Is there any way
in GRUB2 to conditionally execute function from another module,
something like

if module-foo-is-loaded
  call function-from-foo
else
  do nothing

?

Or at least is it possible to test whether specific module is currently
loaded?

Thank you

-andrey