[...] > > > There is another mode, where a single buffer forms a big desktop, > > > of which each RAMDAC displays a part. Seems like stupid driver > > > limitations restrict this mode to using the same resolution for > > > both heads, but I'm not sure. > > > > It is to be expected that a single rendering context has only one > > framebuffer configuration. "Consumer" hardware does not have a per > > pixel framebuffer configuration stored in the framebuffer together > > with the color (and possibly clipping) data; a rendering operation > > expects a single config. > > Right, but resolution is just a matter of RAMDAC parameters. All I > want is a 3856x1536 framebuffer with one RAMDAC displaying a > 2048x1536 window and the other displaying a 1808x1356 window. I don't > care about one tiny MB of VRAM being invisible.
True, this should be possible as long as the pixel format is the same; I misunderstood before, this is indeed a driver limitation. > BTW, the 8800 is limited to 2048x2048 for OpenGL contexts, but that > seems to be per context, and I'm not inderested in stretching a > single context over both screens anyway. (I'm not interested in > stretching *anything* over both screens; just moving windows across > them, which is not possible with independent desktops.) That is a problem since there is no way an application can know about this limitation and I don't think X has a way of returning "window too large" on a window config request. --ms