In article <200001281805.KAA00381@lestat.nas.nasa.gov>,
Jason Thorpe  <thorpej@nas.nasa.gov> wrote:
>  Hal Murray <murray@pa.dec.com> wrote:
>  > I was thinking of an entry in the kernel where the display driver 
>  > could call in and register a procedure to be called on the way to/from 
>  > DDB.  If nobody calls in to register then nothing happens. 
> 
> My point is that even the VGA driver wouldn't know how to do this, right
> now, because the method is different for every VGA card on the market.

But the X server knows, and could tell the VGA driver.