[PATCH] Reorder visuals reported by the intel driver

Jesse Barnes jbarnes at virtuousgeek.org
Wed Jul 30 13:05:06 PDT 2008


On Wednesday, July 30, 2008 12:13 pm Tomas Carnecky wrote:
> Jesse Barnes wrote:
> > On Sunday, June 15, 2008 5:27 am Tomas Carnecky wrote:
> >> The root window visual can not be changed. Neither at runtime nor
> >> through the configuration file. The xserver simply selects the first one
> >> that matches the class (usually TrueColor). I need a root window visual
> >> with stencil buffer because my compiz plugin uses the it for some
> >> operations. This patch reorders the visuals that the 3D driver reports
> >> and puts the one with stencil (and depth) bits as first.
> >
> > So until we have private back buffers etc. we'll need to make sure the
> > root window's visual is as featureful as possible because the X server
> > just picks the first visual matching the current bit depth at startup
> > (sorry I'm a GLX novice here)?
>
> Yes, that's it basically.
>
> The xserver only knows about X11 visuals and not GLX fb configs, so it
> can't intelligently choose a 'good' default visual that also exposes
> useful features to OpenGL clients. So it's up to the driver to order the
> visuals in a way to make the xserver choose a reasonable default visual.
>
> I'd say the driver should make sure that the most featureful visual gets
> selected as the default (but make sure the visual is not flagged as SLOW
> or NON_CONFORMING, 16bpp visuals with stencil buffer are flagged as SLOW
> by the i830 driver for example, hence the patch only changes the
> ordering for 32bpp visuals).

Ok, thanks.  Let me know if you see the need for other changes in the future.

> Thanks for looking at the patch.

I pushed it upstream too since it seems fine.  Sorry it took so long.

Thanks,
Jesse



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