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X server configuration for two monitors

sealord
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Hello,

here is a problem concerning the configuration of the X server

I use the openSUSE Linux Version 11.1 with the KDE 4.1.3. on a computer with a GeForce GTX 280 an two monitors attached to that graphics board.

Now I'm looking for a possibility to use this two monitors separately. Actually both monitors show the same workspace of the KDE so that both monitors change their display when I switch the workspace. But often it's necessary to switch one display and the second should continue to show the

The two display are configured as TwinView in the NVIDIA X Servers Setup. When I configure them as "Separate X screen", only the left monitor shows any picture. The X server for the right monitor is running but only the mouse pointer is displayed, when I move with the mouse to the right display.

And now, here is my question: is there any possible solution for this problem? What I want is, that I can use the two displays separately. There is no need to push a window from one display to the other. But it should be useable with one mouse and one keyboard.

I tried to configure a second instance of the kdm on the second display :0.1 but that won't work. Also I tried to startup a second KDE environment ... the result was the same. So now I'm at the end of my knowledge. :-(

Thanks a lot in advance for any assistance.

Best regards.
sealord
User avatar Zarin
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Unfortunately KDE 4 multihead X is unmaintained and therefore doesn't work at all. The last KDE version that did work in that mode was 3.5.
egandt
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Zarin wrote:Unfortunately KDE 4 multihead X is unmaintained and therefore doesn't work at all. The last KDE version that did work in that mode was 3.5.


If I fully understand this, then with 3 monitors each setup as a separate display ie :0.0, :0.1, :0.2 I can not get KDE 4.X to allow me to load the KDE Windows Manager on more than one of these desktops?

If so that is a bummer, as I've always preferred KDE to gnome, but I also need this functionality for day to day operations (with openSUSE 10.2 and KDE 3.2?, I use it constantly), but without this KDE become almost useless on a multi-monitor setup, as the desktop must work across all the monitors, (regardless of whether it is twinview or separate desktops) not just on the very first one.


Please correct me if this is wrong, or confirm that this is correct, so I can make an informed decision about switching desktop Window Managers
ERIC
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KDE 3.5 is still available in OpenSUSE 11.1, it is under the other desktops section when you select your Desktop Environment in the DVD Installer.


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jcwren
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This sounds like the problem I'm experiencing. I have KDE 4.1 up on one monitor, and X sees the second monitor, but KDE does not (cursor switches from KDE arrow to the X 'X' cursor when moving from the KDE monitor to the X monitor to the other).

Given that dual and triple head systems are more common than ever before, why would this functionality not be supported in 4.1? I would have imagined that to be fairly high up on the list.

I *really* like KDE 4.1, but without the multi-monitor support, I'm going to have to roll back to 3.5. And I really don't like that idea.
User avatar Zarin
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Xinerama/TwinView/Big Desktop/MergedFB multi-monitor modes are all supported by KDE 4. I use TwinView no problem.
cknite
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Zarin wrote:Xinerama/TwinView/Big Desktop/MergedFB multi-monitor modes are all supported by KDE 4. I use TwinView no problem.


This is not an option for those of us with 4 monitors seeing that the travesty of a mockery of sham that is randr 1.2 removed the ability for a single screen to span multiple GPUs, something that was supported w/ xgl. Now, KDE removes support for multiple screens. The only option for those wanting more than 2 monitors and KDE 4 is to go without composite support.

When is multiple x screen support planned on being re-added to kde?
User avatar Zarin
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cknite wrote:When is multiple x screen support planned on being re-added to kde?


Whenever someone volunteers to do it. If someone gets it working it will happily be added and be made available to everyone else.

Last edited by Zarin on Sun Mar 01, 2009 11:09 am, edited 1 time in total.
cknite
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Zarin wrote:
cknite wrote:When is multiple x screen support planned on being re-added to kde?


Whenever someone volunteers to do it. If someone gets it working it will happily be added and be made available to everyone else.


While the optimal solution would be support for SingleLogicalScreen across GPU's with composite, damage and glx support that works with both open and closed X11 drivers, such prospects seem incredibly dim for a number of reasons. Indeed, even Accelerated-X from Xig with its commercial development resources does not support SLS across multiple GPUs with acceleration.

This was quite difficult for me to understand as I recalled this working with Xgl back in 2006 when I last was running a multi card setup. After some research, numerous causes seem to be at play. Amongst closed drivers, ATI seems ok with xrandr and its latest drivers support randr 1.3. Nvidia however has signalled no desire to play along and continues to only support Xinerama for multi-GPU screen glueing, however they currently do not support Composite with Xinerama and to my knowledge have not signalled any intention to do so. It seems the binary driver vendors are content with sitting back and waiting for the open source community to provide a solution.

As for the open source drivers, currently they lack 3d acceleration for many of the latest cards as well as that little problem that no one can get a straight answer out of xorg as to which version of xrandr might actually gain multi-gpu support. In fact, xorg has apparently been reduced to asking for and not receiving, bequeathed code from google supported summer of code interns. Of course, I'm not quite sure why Packard believes summer interns might be successful where he has clearly failed... But, I digress. Regardless, this leaves no clear path to SLS and thus firm need for multihead support, lest KDE be the only desktop that can not run on more than 2 monitors and "do compiz".

I'll admit that as a developer for real time/fault tolerant messaging systems, I'm not in a position to truly question the technical wisdom of removing Xgl's method of abstracting the drawing area and the x screens in a manner that allowed for 3d acceleration across multiple gpus that seemed to be driver independent. I'll simply leave it as a statement of fact that in the commercial world, companies find that glibly removing features for purely technical minutiae is a good way to be out of customers. It's really unfortunate that Gnome, KDE, XFCE, et al must all implement multiscreen support when that in itself is a poor substitute for true SingleLogicalScreen + Composite + Damage + Glx.

Where am I going with this? ROI. To fully support multi-head in KDE is somewhat complex. Full MH support would entail dragging of windows between screens. IMHO anything less is useless, as separate X servers (:0.0 and :1.0) and x2x is actually ~better~ than separate X screens (:0.1 and 0.0) as windows are essentially trapped on one screen and additional instances of the app can't be easily started elsewhere. It leaves one with glorified copy/paste AND the crippling inability to spawn applications on multiple screens...

In the past 2 weeks I've gone thru 2 ATI 3850HD's, 1 ATI 4850X2 and 2 NVIDIA 9800GT's in an attempt to get a 4 screen desktop to work. While I don't completely have that, I can now swap out any of these 3 solutions, relink xorg.conf and use drivers 'nvidia', 'fglrx', 'radeon', 'radeonhd' and 'vesa'. The bottom two monitors are configured via twinview/mergedfb/big desktop with the second card configured as 2 separate screens with one of them rotated to the side. I figure that's about as good an environment for this work as any.

So a quick list of pertinent wiki pages and a list of libraries you reckon would be affected would help to get me running.

Thanks,
Chris
User avatar Zarin
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cknite wrote: Nvidia however has signalled no desire to play along and continues to only support Xinerama for multi-GPU screen glueing, however they currently do not support Composite with Xinerama and to my knowledge have not signalled any intention to do so.


Compositing is supported with their TwinView Xinerama implementation.

To get multihead mode supported I believe all that needs to done is make KWin and Plasma multi-instance friendly. KWin supported it in KDE 3 and I keep seeing code relating to it in the core so there's most likely just a small bug somewhere that prevents the second instance from starting automatically (Most likely the check to see if another WM is already running). As for Plasma I have no idea what would be required.

Last edited by Zarin on Tue Mar 03, 2009 9:43 am, edited 1 time in total.
cknite
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Compositing is supported with their TwinView Xinerama implementation.


Unfortunately TwinView doesn't support card spanning and Nvidia doesn't support Compiz w/ the standard Xinerama extension.

To get multihead mode supported I believe all that needs to done is make KWin and Plasma multi-instance friendly. KWin supported it in KDE 3 and I keep seeing code relating to it in the core so there's most likely just a small bug somewhere that prevents the second instance from starting automatically (Most likely the check to see if another WM is already running). As for Plasma I have no idea what would be required.


Will kwin run without plasma? I believe it should. Also, care to suggest a good starting breakpoint in kwin for stepping through the screen initialization routines?

Thanks,
Chris
User avatar Zarin
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cknite wrote:Will kwin run without plasma? I believe it should. Also, care to suggest a good starting breakpoint in kwin for stepping through the screen initialization routines?


The only dependencies KWin has is kdelibs and kdebase-runtime, this is identical to all other KDE applications so will work fine even if kdebase-workspace-plasma isn't installed.

As for where to start all I can suggest is main().

 
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