Ubuntu

No display when attaching monitor post-boot to server

Asked by J. Scott Berg

I have a machine running Ubuntu-server 12.04.5. I ordinarily boot it without a monitor and keyboard. If I try to attach a monitor at a later point, I see nothing on the display, and the display does not indicate that it is receiving any signal. I did try to wake it by pressing keys on the keyboard (USB). I tried booting with and without the keyboard, and saw the same result either way. If I boot with the monitor, everything is fine. To be clear, this is text-only, no X server is running. The motherboard has no built-in video, so I have an NVidia GeForce 210 installed. I have tried setting GRUB_TERMINAL=console in /etc/default/grub and adding nouveau to /etc/modprobe.d/blacklist-framebuffer, and neither of these solved the problem.

I would like to be able to boot the machine without the monitor and keyboard, then attach them at a later time and be able to make use of them. Is this possible, and if so what do I need to do?

Thanks.

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J. Scott Berg
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actionparsnip (andrew-woodhead666) said : 		#1

Does the server have a make and model?

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J. Scott Berg (jsberg) said : 		#2

The motherboard is a SuperMicro X9SRA-O.

But I've been doing some debugging in the meantime, and I got it working: the video card was outputting a signal on the DVI connector, but I was using a DVI->VGA cable, and the monitor saw no signal. Replacing the cable with a DVI->DVI cable, everything works (at least with either the nouveau driver disabled or the nomodeset kernel parameter).

Unfortunately, the same trick doesn't seem to work on a different system, Intel DG45ID motherboard with onboard video (DVI connector only).

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J. Scott Berg (jsberg) said : 		#3

In the end I found a solution for the Intel DG45ID as well: adding the kernel boot parameter "video=HDMI-A-2:D", which forces the output on. One cannot use nomodeset in this case (KMS is required). The HDMI-A-2 is apparently a quirk of the intel drm drivers, it's really a DVI connection.