[Buildroot] Buildroot + Rpi4 + Accelerated OpenGL + X11

[David Corbeil]

Hi Giulio,

I'm pretty new to this so thanks for your reply. I had to add libepoxy and
then glamor was automatically added. I think I made progress thanks to your
help but I'm still having errors. It seems like X is capable of loading the
OpenGL drivers correctly. I don't see any errors in the xorg log file and
glxinfo is able to extract information. Now the problem is that nothing can
render. I keep getting the error: "Failed to open bo 1: Permission
Denied" whenever
I run glxgears or any flavors of glmark2. I tried changing the permission
in the xorg.conf file or directly through chmod but nothing changed. I feel
like the error message is misleading and that it's not really a permissions
issue.

I used the link you share to create a new xorg.conf
<https://pastebin.com/kwsC63Q5>.

Here are the output of glxinfo -B <https://pastebin.com/PzLbk2cH> and
glmark2 <https://pastebin.com/wd3S6YGe>.

I will now try with systemd init system instead of busybox. We'll see that
happens.


On Tue, Aug 31, 2021 at 3:53 PM Giulio Benetti <
giulio.benetti at benettiengineering.com> wrote:

> Hi David,
>
> > Il giorno 1 set 2021, alle ore 00:36, Giulio Benetti <
> giulio.benetti at benettiengineering.com> ha scritto:
> >
> > Hi David,
> >
> >> On 9/1/21 12:05 AM, David Corbeil wrote:
> >> Hi,
> >> Using Buildroot, I’m trying to build an OS that can run my OpenGL (not
> ES) app with accelerated 3D graphics. I also want it to use X11 as a
> display server. So far I haven’t tried my app directly on my built OS
> because it has many dependencies but I’m using glmark2, kmscube and glxgear
> to debug and try out different Buildroot configurations.
> >> I tried the /vc4-kms-v3d-pi4/ and /vc4-kms-v3d/ overlays in the
> config.txt, but I’ve had better results using the former.
> >> So far I was able to get glmark2 to run but it was using a software
> OpenGL renderer (swrast). Although performance is abysmal so that’s a no go.
> >> I have 4 flavors of glmark2 in my OS, glmark2, glmark2-es2,
> glmark-es2-drm and glmark2-drm. The only ones that run are glmark2-drm and
> glmark2-es2-drm. They run really well at 60fps. kmscube runs really well as
> well.
> >> The problem comes when I try to run glxgears and glxinfo when X11 is
> running. I get the following errors:
> >>  *
> >>    Glxgears
> >>        Error: Couldn’t get an RGB, Doubled-bufferedvisual
> >>  *
> >>    Glxinfo:
> >>        name of display: :0
> >>        Error: couldn’t find RGB GLX visual or fbconfig >   *
> >>    Glmark2:
> >>        Error: GLX version >= 1.3 is required
> >>        Error: Error: Couldn’t get GL visual config
> >>        Error: main: Could not initialize canvas
> >> I’d like to get the regular glmark2 to run since, from my
> understanding, it uses regular OpenGL?
> >
> > It depends on your OpenGL implementation, and here you have an ES
> implementation, so it's only a subset, but considering your defconfig below
> X tries to use the ES one but doesn't succeed because of fbturbo doesn't
> support your broadcom gpu.
> >
> >> I’m pretty convinced my end goal is possible because I was able to get
> my app to run flawlessly in Raspberry Pi OS using regular OpenGL. Just need
> to find all the necessary packages and configure the OS correctly. Easy to
> say, easy to do right?
> >
> > It is possible
> >
> >> I linked my defconfig, the xorg configuration file and xorg log file.
> >> buidlroot Rpi4_32_defconfig_eudev: https://pastebin.com/xfJ9WbdQ <
> https://pastebin.com/xfJ9WbdQ>
> >> xorg.conf: https://pastebin.com/vewDwmtD <https://pastebin.com/vewDwmtD
> >
> >> xorg log: https://pastebin.com/0yDXGDr7 <https://pastebin.com/0yDXGDr7>
> >> Maybe the xorg configuration file needs to be modified? But how?
> According to this <https://github.com/raspberrypi/linux/issues/4526>, I
> should not be using fbturbo but I don’t know what to replace it with.
> >
> > Yes, you need to use glamor as I recall, so you need to enable it in
> Buildroot and 'make clean; make'.
>
> Pardon, glamor should already been built.
> Please check it. You should not need to rebuild Buildroot.
>
> Giulio
>
> >
> > Try to take a look here for xorg.conf example:
> >
> https://www.mindwerks.net/2014/09/videocoreiv-glamor-on-your-raspberry-pi/
> >
> > That way you tell X11 to use glamor and force Gallium(the Broadcom mesa
> driver). But you need to do some attempt, I don't know if it will work as
> it is.
> >
> > Some time passed since I've had my hands on X11 on a Rockchip. But
> glamor should be the way.
> >
> > I didn't check everything I've written above, so take it with a grain of
> salt.
> >
> > Best regards
> > --
> > Giulio Benetti
> > Benetti Engineering sas
>
>

-- 
*David Corbeil-Stroombergen*
Software development engineer
Dynon
425-402-0433 Main
www.dynon.aero <http://www.dynonavionics.com/>
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