[yocto] [meta-raspberrypi] gles2 on raspi3

[Trevor Woerner]

w00T! \O/

Swapping out meta-raspberrypi for your meta-raspi-light works!!! I now have
accelerated glmark2-es2 ~40FPS :-D

Now I have to figure out why...

Also, chromium wouldn't build with meta-raspi2-light, but that's probably a
quick fix, GL/glx.h was missing.

Adding 'MACHINE_FEATURES_append = " vc4graphics"' to local.conf with
meta-raspberrypi caused a kernel Oops. The system continues to run, but
graphics/X doesn't work.

One thing I've noticed about both meta-raspberrypi and meta-raspi-light are
that in both cases (using vc4) the boot colour square (firmware?), processor
core count berries, and kernel splash screen are missing. But that's not too
important.

Thank you very much for your explanations, they really cleared up a lot of
stuff in my head. Already I'm 10x smarter on this stuff (which doesn't say
much about where I started!) ;-) It was probably a good thing I spent the last
couple days grinding away, your explanations were perfect for where I'm at.

Any idea how mesa and mesa-gl differ? That one's still an outlier for me; they
both come from the same source base!

On Sat 2017-04-15 @ 08:09:02 PM, Andreas Müller wrote:
> In the long run I would start a discussion:
> 
> * Mesa/VC4 is not a machine feature only available on 64Bit Pi3 only:
> It is common to all version of RaspberryPi. Using mesa should be a
> decision easily selected by a setting somewhere. The only reason 64Bit
> Pi3 gets VC4 by default is that userland is not working for 64Bit -
> see commit 9d418db5ed2962821987ac90c07c3a61e40c0814)
> * Why still use userland? Dropping it would make things MUCH easier:
> All the decisions based vc4graphics in MACHINE_FEATURES could be
> removed (that's what my fork does)

Agreed! Maybe a new thread? I'd want to do more experiments wrt 32 vs 64 and
vc4 vs userland before being able to contribute.

On a related topic, I wasn't able to get any graphics to work when I did a
raspberrypi3-64 build, which (presumably) already pulled in and configured the
build for vc4. I'll dig in a bit more on that topic to see if I can reduce it
to some succinct issue.