Question about Render System?

GL on x86, GLES on the others.

LE10 and older Generic and all Generic-legacy images use GL + x11.

LE11/12/13 use GLES + GBM.

It is currently possible to build GL + GBM image (Generic-gl). LE14 would probably use that.

GL is interesting for gamers, so it has a constant value on x86.

On ARM platforms the chips usually only support GLES, and GL without hardware acceleration would be way too slow on them.

GL is generally better for x86. Kodi's GL renderer has an improved HQ upscaling compared to GLES. It also allows using high quality BWDIF sw deinterlacing when VAAPI hw decoding is used. This is important for devices that lack advanced VAAPI deinterlacing capabilities (eg. Intel Jasper Lake). In GLES renderer this is broken/not implemented.

5 years ago LE had to switch to GLES because HDR passthrough is not possible when x11 windowing system is used. LE needed to go with Kodi-GBM. Back then it was only possible to build Kodi-GBM with GLES.

Since then there were changes in Mesa that allowed using libglvnd GL library instead of x11 GL libraries. Also, there were changes in Kodi's GL renderer that made HDR passthrough possible.

Quote from ubuntuuser

I am after true 4k or as close to true 4k as I can get in Linux.

4K is nothing more than the dimensions of the image. Both GLES and GL support 4K output. Current LE releases use GLES and there is nothing wrong with GLES. Future LE images will probably switch to GL, and there's nothing wrong with that either. Two different code-paths that use slightly different technologies to basically achieve the same thing.

If you mean 'HDR' output? HDR is only supported on GBM images (Generic) not X11 (Generic Legacy); and it is supported whether the image is LE12 (GLES) or LE13 (could be GLES or GL) as the rendering method isn't important.