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Daniel Rikowski
Asked: 2010-06-06 04:43:18 +0800 CST

How can I start an X11 session on my headless Fedora 13 server?

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I have a small home server using Fedora 13 as operating system.

Since the upgrade to Fedora 13 I cannot start the X11 server. (I need it to use vnc)

When I try to start the server, both the nouveau and the original NVIDIA driver claim that there's no physical monitor attached (which is true) and that the X server cannot start because the initial display modes cannot be probed.

I tried to manually add the display modes to xorg.conf but they seem to be ignored.

Some forums suggest to simply use the VESA driver in this situation, but since I can't get it run either (different, more obscure message) I want to get it working with the nouveau driver as a matter of principle.

Temporarily attaching a monitor would mean a lot of work for me (> 1 hour and currently it's almost 35°C/95°F in my home) I want to try that only if that definitely fixes the problem and stays that way if I remove the monitor again)

How can I make the driver work without having a physical monitor attached?

Thank you for your time and your help!

fedora headless x11

4 Answers

  1. One option would be to set up X forwarding over ssh and run an X server on your local machine with the apps running on the server.

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  2. Another option is running GDM over VNC, which will give you a GDM login window over VNC. See Vnc & Gdm

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  3. Found it here, credits to Ata Roboubi.

    Using the official nvidia driver, with "ConnectedMonitor" and "UseEDID"=False options as below, the driver will be forced to use the CRT-0 output without checking any EDID data.

    Even if you let a configured mode string into the file, it will fall back to 1024x768.

    /etc/X11/xorg.conf:

    Section "Device"
        Identifier     "Configured Video Device"
        Driver         "nvidia"
        Option         "ConnectedMonitor" "CRT-0"
        Option         "UseEDID"     "FALSE"
EndSection

    Resulting Xorg.0.log:

    (**) Aug 12 19:35:46 NVIDIA(0): ConnectedMonitor string: "CRT-0"
(**) Aug 12 19:35:46 NVIDIA(0): Ignoring EDIDs
(II) Aug 12 19:35:47 NVIDIA(GPU-0): Not probing EDID on CRT-0.
(II) Aug 12 19:35:47 NVIDIA(0): NVIDIA GPU GeForce GTS 450 (GF116) at PCI:3:0:0 (GPU-0)
(--) Aug 12 19:35:47 NVIDIA(0): Memory: 1048576 kBytes
(--) Aug 12 19:35:47 NVIDIA(0): VideoBIOS: 70.26.26.00.01
(II) Aug 12 19:35:47 NVIDIA(0): Detected PCI Express Link width: 16X
(--) Aug 12 19:35:47 NVIDIA(0): Interlaced video modes are supported on this GPU
(--) Aug 12 19:35:47 NVIDIA(0): Connected display device(s) on GeForce GTS 450 at PCI:3:0:0
(--) Aug 12 19:35:47 NVIDIA(0):     CRT-0
(--) Aug 12 19:35:47 NVIDIA(0): CRT-0: 400.0 MHz maximum pixel clock
(II) Aug 12 19:35:47 NVIDIA(0): Display Device found referenced in MetaMode: CRT-0
(II) Aug 12 19:35:47 NVIDIA(0): Assigned Display Device: CRT-0
(WW) Aug 12 19:35:47 NVIDIA(0): No valid modes for "CRT-0:1280x1024"; removing.
(WW) Aug 12 19:35:47 NVIDIA(0):
(WW) Aug 12 19:35:47 NVIDIA(0): Unable to validate any modes; falling back to the default mode
(WW) Aug 12 19:35:47 NVIDIA(0):     "nvidia-auto-select".
(WW) Aug 12 19:35:47 NVIDIA(0):
(II) Aug 12 19:35:47 NVIDIA(0): Validated modes:
(II) Aug 12 19:35:47 NVIDIA(0):     "nvidia-auto-select"
(II) Aug 12 19:35:47 NVIDIA(0): Virtual screen size determined to be 1024 x 768
(WW) Aug 12 19:35:47 NVIDIA(0): Unable to get display device CRT-0's EDID; cannot compute DPI
(WW) Aug 12 19:35:47 NVIDIA(0):     from CRT-0's EDID.
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  4. If you want a persistent session that's there even when you're not connected over SSH, you can use Xpra.

    You can also use Xvnc, which will give you something similar, but probably a bit simpler, with the usual "virtual desktop".

    You can also use Xvfb. This is a bit more versatile than Xvnc since you can decide yourself how to connect (Xvnc implies VNC usage).

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