FYI, glxgears requires OpenGL.
- In a simple case, when running glxgears locally and displaying locally, the OpenGL must be supported on the local computer.
- In a remote case with X event forwarding the remote host must instead provide the OpenGL support.
- In a case of a virtual desktop server which is being remotely monitored, then it is the local virtual server which must provide the OpenGL support despite the remote location seeing the result.
If you log in locally to the Jetson, not via VNC, and run this command, do you see OpenGL support?
glxinfo | egrep -i 'glx.*(vendor|version)'
Assuming you see GLX when you run via VNC, and from the local login scenario, then it should work if versions are not in conflict. If you see this only on local login, then it means your virtual server is different than the local server and may not support OpenGL.
About this:
…one has to have an X instance to run anything. For a regular server you have to log in to create that server instance. A virtual server is indistinguishable from a regular server so far as software is concerned, but a virtual server does not require an attached monitor. Virtual servers still must log in, but most likely this is set up to occur automatically. After this remote software can associate with that virtual server. If that virtual server has OpenGL support of the proper release, then it should just work right even without a regular monitor attached.
Someone else may be able to help with virtual server install and/or setup, but basically it sounds like you are looking for a virtual server to run automatically on boot which your remote desktop software can associate with, and where that server uses the NVIDIA hardware accelerated GPU driver.
A dummy HDMI plug would work too, but it is a hardware solution to fake having a monitor attached. A virtual server is the same thing, but done without extra hardware.