Question regarding OpenGL 2.1 support and Xorg

[Wladimir J. van der Laan]

On Wed, Nov 01, 2017 at 11:59:16AM +0100, Lucas Stach wrote:
> Am Dienstag, den 31.10.2017, 09:43 +0000 schrieb Luís Mendes:
> > Hi,
> > 
> > I've read that Open GL 2.1 support is available through latest
> > patches for mesa etnaviv:
> > [PATCH] etnaviv: add ext_texture_srgb support
> > https://lists.freedesktop.org/archives/etnaviv/2017-October/001193.ht
> > ml
> > 
> > Could this mean that it is possible to run Xorg without the xf86-
> > video-armada driver?
> > It wouldn't make use of the GC320 unit, but it could allow another
> > option for running X.
> > 
> > Currently the problem seems just to be that etnaviv doesn't support
> > openGL 2.1 causing glamor to fail with:
> > [    41.867] Require OpenGL version 2.1 or later.
> > [    41.867] (EE) modeset(0): Failed to initialize glamor at
> > ScreenInit() time.
> > 
> > as detailed in the log below.
> > Or I am getting something wrong?
> 
> I don't know if anyone has tested glamor on our GL stack, but in any
> case it will be horribly slow with the big GPUs like GC2000, which
> can't texture from their own render format.

It might still be slower too on other chips, but isn't GC2000 specifically an
anomaly in that regard, in requiring the split-tiled formats?

Pre-GC2000 (even its smaller brother, GC880) can texture from their own render
format for sake of having only one pixel pipe.

GC3000+ can texture from their own render format because it implements the
SINGLE_BUFFER feature, which allows the 2 (or however many) pixel pipes to
interleave to one buffer.

Regards,
Wladimir