Failed to create EGLContext

Issue

You would likely (and hopefully only) encounter this problem when using an emulator. Local Desktop will crash immediately, and the log will show Failed to create EGLContext with an error variant, such as EGL_BAD_MATCH or EGL_BAD_ATTRIBUTE.

Khronos EGL documentation points out these errors very clearly. It seems like the cause of our specific case is:

If context does not support being bound without read and draw surfaces, and both draw and read are EGL_NO_SURFACE, an EGL_BAD_MATCH error is generated.

info

It's hard to find these documentations on your own, that's why this Bug Cheat Sheet will prove to be very useful.

So remember: whenever you get stuck, come back here! And don't just read - please contribute whatever you find.

Solution

EGL_BAD_MATCH

Local Desktop patched this portion of Smithay to create a dummy 1x1 pbuffer surface and use it as both the draw and read surface when calling eglMakeCurrent to avoid the EGL_BAD_MATCH error.

Dear EGL experts, does the above hack make sense?

EGL_BAD_ATTRIBUTE

If the error variant is EGL_BAD_ATTRIBUTE, you must toggle the Experimental: Enable ANGLE setting in Developer options:

Hint: Initially, this setting appears greyed out (the reason is unclear). To enable toggling, first turn off the Use developer options toggle, then turn it back on. Note that the device will reboot when the ANGLE setting is changed.