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Re: Upcoming Qt switch to OpenGL ES on arm64




Hey Scott,


On Sat, Nov 24, 2018 at 9:01 PM Scott Kitterman <debian@xxxxxxxxxxxxx> wrote:
>
> On Saturday, November 24, 2018 08:36:11 PM bret curtis wrote:
>
> We have a Rasberry Pi working as a desktop here at my house.  It's quite
> usable as long as you only try to do a few things at a time, but it's not by
> any means zippy.  I strongly suspect that moving back from GLES would move it
> from "reasonable for limited use" to "pointless".  Please don't do anything to
> make things even slower.
>
> Scott K
>

It's because of the VC4 mesa driver that the RPi is usable for you,
reasonable for limited use. Not using VC4, but the CPU based llvmpipe,
is what makes it pointless and almost too slow to use as a desktop. If
you don't have VC4 enabled, I suggest you give it a try, it's a world
of difference.

Moving Qt back to using Desktop GL from GLES is going to have zero
impact performance on the RPi since the VC4 supports up to OpenGL 2.1
and and GLES 2.0 [1]

The problem is that there are applications that make use of Qt that do
not support GLES while Qt can support both. So these things can't be
shipped on armel and armhf and now possibly arm64.

What applications does Debian have in its repo that only support GLES?

Cheers,
Bret

[1] https://github.com/anholt/mesa/wiki/VC4-OpenGL-support