Re: on current GNU Guix System, eglGetDisplay returned EGL_NO_DISPLAY.

[Ian Eure]

Andy Tai <atai@atai.org> writes:

> Hi, in an up to date GNU  Guix system that I have running in a 
> VM on a
> Fedora host (via KVM), the eglGetDisplay() call always returned
> EGL_NO_DISPLAY.  Note OpenGL is working; for example  glxgears 
> runs
> fine.

glxgears will fall back to software rendering, and CPUs are fast 
enough these days that the difference between software and 
hardware rendering of its relatively simple can be hard to see.

Running:

 guix shell mesa-utils -- glxinfo -B

Is the best way to tell if you’re getting hardware acceleration or 
not.  You’re looking for lines like:

   OpenGL vendor string: Intel
   OpenGL renderer string: Mesa Intel(R) UHD Graphics 620 (WHL 
   GT2)

and:

   Extended renderer info (GLX_MESA_query_renderer):
       Vendor: Intel (0x8086)
       Device: Mesa Intel(R) UHD Graphics 620 (WHL GT2) (0x3ea0)


> On recent releases of Fedora or Ubuntu 24.04, the same code, I 
> have no
> such problem.
>
> I wonder if the graphics stack on GNU Guix system is behind the 
> other
> distributions. The version shows the Mesa driver at 24.0.2 so it 
> is
> fairly up to date.
> Any info or clue is appreciated.

I’m not sure how KVM works, but it’s been my experience that 
virtualized guests usually need drivers to talk to the hypervisor 
for things like this.  Perhaps your guest configuration is missing 
this.

 -- Ian