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Old 11-13-2007, 10:28 AM   #1
pellgarlic
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kvm switch preventing monitor detection = low resolution


i posted this same problem at debian forums, but haven't had any response so far, so i thought i'd try my luck here...

basically, i'm running debian testing, with an nvidia graphics card, using the nvidia binary blob drivers. my 19" lcd monitor is detected accurately, and everything works fine - 3d, glx, compiz etc.

recently, i had cause to hook up a kvm switch (belkin F1DJ102P-B) so i can run a windows pc alongside my debian pc for work commitments. when i reboot my debian pc with the kvm attached, it doesnt detect the lcd monitor properly (just as "CRT-0"), and boots into 640x480, with no other available resolutions (well, except for 320x240!). as a side-effect of the monitor not being detected, glx no longer works either.

what i'm wondering is - is there any way to force x to consider that monitor attached, whether it detects it or not? even if i could force the resolution higher, that would be a start, but i still wouldnt be able to play doom3 with no glx... can anyone offer any suggestions?
 
Old 11-13-2007, 11:53 AM   #2
David1357
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Quote:
Originally Posted by pellgarlic View Post
what i'm wondering is - is there any way to force x to consider that monitor attached, whether it detects it or not? even if i could force the resolution higher, that would be a start, but i still wouldnt be able to play doom3 with no glx... can anyone offer any suggestions?
To get X to recognize your monitor, switch the KVM to the Linux box and press [Ctrl][Alt][Backspace]. This will restart X and it will be able to detect your monitor's capabilities.
 
Old 11-13-2007, 12:32 PM   #3
forrestt
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Another possibility is that your kernel got updated but the nvidia module didn't and it happened to occur at about the same time you attached your kvm switch. Try reinstalling the nvidia driver.

HTH

Forrest
 
Old 01-12-2009, 07:36 AM   #4
pellgarlic
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hi, sorry i didnt acknowledge those replies before - ended up going just had to deal with it by physically swapping the connections over each time i wanted to use a different pc :P

as it was, when i plugged my monitor directly back in again, it was fine - it was only when the connection between computer and monitor was intersected by the kvm that i had the problem. it's like the kvm was preventing the graphics card from being able to detect the monitor's capabilities.

never did find a solution to this, and as i still have to do this from time to time, am still looking for a solution... it may just be that the cheap belkin kvm i am using is the problem. perhaps a more expensive kvm would function better?
 
Old 01-12-2009, 09:25 AM   #5
David1357
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Quote:
Originally Posted by pellgarlic View Post
it may just be that the cheap belkin kvm i am using is the problem.
I am using a Belkin Omniview F1DS104T. It has the problem that I mentioned above where I have to press [Ctrl][Alt][Backspace] when I switch to a Linux box that booted up while I was looking at another screen.

It also has a problem where you have to switch to the desired display, then back to your previous display, and finally to the desired display, or the mouse does not track properly.

Other than that, it works great...
 
Old 01-12-2009, 10:08 AM   #6
johnsfine
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I don't have my xorg.conf file handy (I'm posting from a Windows computer) so I can't give you details now. But it is fairly easy in the xorg.conf file to tell X not to interrogate the monitor for its capabilities, but instead trust the values coded in the xorg.conf file itself.

I have not managed to find the xorg.conf lines (if they even exist) for my own similar but slightly harder problem: My nVidia chipset on Gigabyte motherboard has a digital-only dvi connector and an analog-only vga connector. It can operate either or both together when the devices are present at boot up. But it initializes only the VGA when neither is present. I usually want to use just the DVI. It doesn't work if the DVI LCD was off at boot up. I can make xorg.conf override any timing or resolution regardless of what was present at either BIOS startup or X startup. But I haven't figured out how to override the fact that only the VGA connector is live if no monitor was present at BIOS startup. IIUC, the problems described earlier in this thread are the simpler cases that can be fully covered in xorg.conf
 
  


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