EGL related issues

[ailzhang]

This is a bit confusing so I'm opening an issue to track here:

1. Linux On linux I found out that if DISPLAY is set (e.g localhost:10.0) in my ssh window, EGL will use that and can only load up to EGL1.0. But if I do unset DISPLAY then EGL can correctly find 1.5 and pass all tests.

Maybe relevant:

• https://www.khronos.org/registry/EGL/extensions/EXT/EGL_EXT_platform_xcb.txt
• https://github.com/apptainer/singularity/issues/1635

2. Windows Does windows require special installation for EGL, sshing into a windows powershell cannot find a EGLDisplay.

[bobcao3]

Don't think there's a good way to fix this. The true-headless EGL support is a feature of Nvidia's linux driver as a server visualization package. When DISPLAY is set, the driver will try to find a proper display output that matches the env settings. (Maybe it's because the terminal have X over SSH support and it set up the X DISPLAY settings?)

[bobcao3]

X11 is a huge mess of spaghetti, I think the best we can do is try to unset DISPLAY if we failed to initialize EGL and retry?

[ailzhang]

Yea for Linux one we can simply try unsetting DISPLAY to workaround. I'm not sure about whether it's expected to work on windows tho (it didn't work when I tested but maybe I did it wrong?

[ailzhang]

@bobcao3 Do you happen to have any idea why our EGL setup doesn't work on windows? :D