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Old 05-11-2009, 06:43 AM   #1
5555collier
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No display with KVM


I'm running RHEL4 and just installed a dual-dvi KVM from Linkskey. From previous experience I've noticed that Linux will not display with Windows booted first on my other machine that is connected to the KVM. I also skip the part where kudzu detects the KVM, but on this particular one no display comes up at all. I can ssh into the machine and the xorg.conf seems fine, but no display. Anyone have experience with this???
 
Old 05-11-2009, 01:47 PM   #2
watcher69b
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in the /etc/X11/xorg.conf look to see how many screens are listed.

ie
Screen 0
mode 800x600

screen 1
mode 800x600


also check that the color depth, resolution and refresh rate are supported.
ie 800x600 depth 16 60htz
 
Old 05-11-2009, 02:08 PM   #3
5555collier
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I'm pretty sure that I have a hardware compatability issue. I actually got Linux to come up and work with the KVM and Windows to come up and work at the same time (the other machine connected to the KVM). Then the user rebooted. Now the Windows machine comes up fine and the Linux will not display. This rules out a .conf problem, monitor/cable problem and everything else. I have a similar setup on my Windows/ Linux switched by the KVM and I have to boot up the Linux box first before the Windows one, but then it works fine. I have never tried to configure the KVM on Linux because once I got it working, I didn't want to screw anything else up, but maybe that's what I need to do. Where do you configure for a KVM in Linux?
 
Old 05-11-2009, 02:12 PM   #4
farslayer
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Please only post your questions in One forum This is a duplicate

http://www.linuxquestions.org/questi...ey-kvm-725176/
 
Old 05-11-2009, 02:16 PM   #5
5555collier
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Got it. further posts this same subject in
"hardware" forum.
 
Old 05-12-2009, 06:59 AM   #6
5555collier
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Continuing the thread from "Hardware forum and "farslayer's" answer:
(the other thread got closed --duplicate {sorry, didn't know})


My guess would be the Video card is unable to detect the Display settings through the KVM, because the KVM is blocking the DDC Probe. Hardcode the Resolution and refresh rate in the xorg.conf using a Modeline.
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Acer Aspire One - Resource Links

Wikia Acer Aspire One wiki

I tried the "cvt" command and it isn't found in Rhel4 (not in man pages and "command not found" when I try it). What does it do? Is there something similar in Rhel4?
 
Old 05-12-2009, 07:43 AM   #7
farslayer
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You can always use one of the online Modeline Calculators.

http://xtiming.sourceforge.net/cgi-bin/xtiming.pl
 
Old 05-13-2009, 10:07 AM   #8
5555collier
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I tried the modeline and still no workie, so I looked in the xorg.conf file and noticed that two separate video cards were referenced, one for one monitor and one for the other (in the screen seciton). I checked on a different machine with the same setup and both monitors referenced the same video card (I thought it might have just been a mechanism for the dual-DVI output). I commented out the second video card reference and had the second monitor reference the correct video card. Then I rebooted (I was ssh'd into the machine) and went to the Linux box and my display was there. I rebooted again to verify and the display was blank again. When I first switched over to the Linux box the KVM was switched to the Windows box, so, I switched to the Windows box on the KVM, rebooted the Linux box, waited and everything came up fine. I did this twice more and it works every time now but only when the KVM is not switched to the rebooting Linux box. I guess it has something to do with the hierarchy and not finding a monitor through the KVM (since it is switched to the Windows box), it defaults then to the modeline or other configuration in the xorg.conf file. Thanks again to farslayer for starting me in the right direction. Man pages on xorg.conf helped out a lot too. It's still not perfect, but it works every time now and the user is happy.
 
Old 05-13-2009, 11:56 AM   #9
farslayer
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OK so it sounds like you might want ot modify one more item in your xorg.conf.. you want to set it to NOT probe the monitor at boot time. then it shouldn't matter which PC is selected on the KVM. .


Code:
Section "Device"

	# Override DDC 
	Option		"NoDDC" "1"
	Option		"IgnoreEDID" "1"
May or may not work, but it's worth a shot.
 
  


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