There's also virgl_test_server which runs the virgl protocol over a socket.

This can be used for OpenGL inside containers, by bind mount-ing the socket into the container (/tmp/.virgl_test).

Also useful for debugging with rr, even with the nvidia driver you use OpenGL over virgl with the environment vars __GLX_VENDOR_LIBRARY_NAME=mesa LIBGL_ALWAYS_SOFTWARE=1 GALLIUM_DRIVER=virpipe