graphical console: limit resolution?

[Thomas Klausner <wiz%NetBSD.org@localhost>]

Hi!

Some time ago I upgraded my monitor to one supporting 3840x2160. This
broke the graphical console with my old, but supported radeon card.

The card's limit is 2560x1440 (I think), but the graphical console
code doesn't care and tries to switch to 3840x2160 and the screen is
just black afterwards.

Is there a way to limit the resolution for the graphical console
(e.g., a kernel config parameter)?
 Thomas