startx permissions problem

[pgater]

Hi,

I am unable to start X windows after logging into my board. I have tried using WinSCP, PuTTY and have Xming installed on Windows Vista 64 bit ultimate. As an alternative I have Unbuntu 14.04LTS on vmplayer. The output from Putty and Ubuntu is in the attached file along with the board hardware details. This is using the headless kernel and Fred's tree. I have tried the headed kernel and tree with similar results, but when sudo startx is used it gets locked into a loop which can only be cleared by switching off the board.

I have looked on the net at this error message, but all the remedies on there do not work.

Can you advise on what I am doing wrong?

Regards,

Paul

[9600]

Hi Paul,

If you're running headless and connecting over SSH I assume that you would like to use a remote display, i.e. your workstation. In which case I don't think PuTTY alone will be much use as you need an X server. If you were running Linux on your local machine you would do 'ssh -Y nnn.nnn.nnn.nnn' from a terminal, so that your X11 connection gets forwarded. Also making sure that the xauth package is installed on the Parallella (should be by default).

Cheers,

Andrew

[sebraa]

Hi,

you need to differentiate between X Server (connected to a display) and X Client (the application).

If you connect your Parallella to an HDMI screen, then you start the X Server on the Parallella (that is what "startx" is for, or by default, the display manager). If you connect your Parallella to a network and want to use e.g. SSH, then you run the X Server on your PC (Xming for Windows, or Xorg for Linux). If you use PuTTY, you need to enable X Forwarding before connecting (this also sets $DISPLAY). From Linux, you use "ssh -X" or "ssh -Y".

In both cases you run the graphical application on the Parallella. Graphical applications always use the DISPLAY variable to find the X Server. Try "echo $DISPLAY" on the Parallella after connecting to it, if it is empty, then you made a mistake and should try again (via SSH it should be "localhost:10.0" or similar). Then try to run an application (e.g. "xterm" or "x-terminal-emulator" or "gedit").

It requires a bit of book-keeping about "what happens where", but you get used to it as soon as you see how things work together.

Best Regards,
sebraa

[9600]

D'oh! Of course and the clue was in the title :/ I was reading xterm for some reason.

Cheers,

Andrew

[pgater]

Hi,

Many thanks to you both for your advice. My bookeeping is not right

Regards,

Paul

[pgater]

Hi,

Nothing worked until I spotted another post on a different forum. If you get this error message then delete the existing Xauthority file and everything will work!

Regards,

Paul