On Tue, 2005-03-15 at 12:30 +0100, Roland Scheidegger wrote:

Ville Syrjälä wrote:
  > I think that making the assumption that all memory is preserved when 
the

quoted

memory layout (virtual resolution and depth) doesn't change is perfectly 
valid too. That would allow X to do it's Ctrl-Alt-+ and - things without 
repainting the whole screen.

I'm not sure I agree here, as it's not always true. For instance, the 
radeon has some restrictions whether it can use tiling or not with a 
certain mode (interlace/double scan) thus you need to redraw everything 
anyway (which is exactly why I implemented a driver workaround to 
repaint everything when that happens - in fact the workaround also gets 
rid of the offscreen contents, which is not necessary, but was much 
easier to implement, since I couldn't find an easy way to "invalidate 
the framebuffer"). What's the big deal with repainting everything? It's 
not like you would do 100 mode changes per second so it would be 
performance-critical...

It's ugly, but that's not the point. The point is that all deployed
versions of X (and even current X.org CVS head still, in fact) make this
assumption.


-- 
Earthling Michel Dänzer      |     Debian (powerpc), X and DRI developer
Libre software enthusiast    |   http://svcs.affero.net/rm.php?r=daenzer