I'll have to poke with what the dev was mentioning. The only method I've found to reliably work is what the second poster was describing.
You can add metamodes that have a transformation function either based on a matrix for complex changes or ViewPortIn/Out for simple scaling. They are of the form:
Code:
Output: ScreenResolution { ViewPortIn=ProgramResolution, ViewPortOut=ScaledResolution+XOffset+YOffset }
For instance, say I want to play the original Linux verson of Cave Story (640x480) scaled up to monitor height (1920x1200) at the proper aspect ratio; I would then add a ViewPort metamode to my xorg.conf (in my case a separate one for fullscreen games) like so:
Code:
Option "metamodes" "DFP-1: 1920x1200; DFP-1: 1920x1200 { ViewPortIn=640x480, ViewPortOut=1600x1200+160+0 }"
This would scale an input of 640x480 to 1600x1200 and offset it 160 pixels from the left of my 1920x1200 screen. The GPU will handle all scaling; the monitor itself will only get a 1920x1200 output.
The good news is this system is ridiculously flexible (like I said, you could even use a matrix to specify the transformation needed). The bad news is you have to do this for every single input resolution you'll encounter. Hopefully what aplattner is hinting at can work so we can have a convenient scaling switch (or maybe nvidia can add one again --;), but otherwise adding metamodes as needed will work.