[Mesa-dev] [PATCH] intel: Don't expose XRGB8888 visuals any more

[Kenneth Graunke]

On 01/20/2013 05:49 PM, Ian Romanick wrote:
> From: Ian Romanick <ian.d.romanick at intel.com>
>
> There really isn't any point.  There is no resource savings, and we have
> to do gymnastics in the driver to make it work.
>
> There are also bad interactions with multisampling and OpenGL ES 3.0.
> In ES3, a multisample-to-singlesample blit must have identical source
> and destination format.  This means a multisample RGBA8 to singlesample
> RGB8 (window) blit will generate an error.  Also in ES3, RGB8 is not a
> renderable format.  This means that the application CANNOT make an RGB8
> multisample renderbuffer.
>
> As a result, if an application gets an RGB8 window and wants to do
> multisample FBO rendering, it will probably break.
>
> "Fixes" gles3conform
> framebuffer_blit_functionality_multisampled_to_singlesampled_blit test
> on RGB8 visuals.
>
> Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
> ---
> There are a couple alternative ways to fix this problem, but they all
> involve a lot more owrk with little imaginable benefit.  We should also
> add a piglit test that checks that there are no RGB8 visuals that are
> marked as conformant and ES3 capable.
>
>   src/mesa/drivers/dri/intel/intel_screen.c | 1 -
>   1 file changed, 1 deletion(-)
>
> diff --git a/src/mesa/drivers/dri/intel/intel_screen.c b/src/mesa/drivers/dri/intel/intel_screen.c
> index 347b3dd..8609572 100644
> --- a/src/mesa/drivers/dri/intel/intel_screen.c
> +++ b/src/mesa/drivers/dri/intel/intel_screen.c
> @@ -906,7 +906,6 @@ intel_screen_make_configs(__DRIscreen *dri_screen)
>   {
>      static const gl_format formats[3] = {
>         MESA_FORMAT_RGB565,
> -      MESA_FORMAT_XRGB8888,
>         MESA_FORMAT_ARGB8888
>      };

You need to reduce the array size as well, or else the loop below (using 
ARRAY_SIZE(formats)) will use undefined values.  I would just remove the 
explicit size and let the compiler figure it out.

I agree with removing XRGB visuals.  There's no benefit at all.  Feel 
free to add by R-b on Acked-by.

--Ken