Multiple cards and xinerama/twinview
I've been running triple monitor using two seperate video cards for a while, but still haven't come up with a setup that really makes me happy. I've got a GF4 ti4600 with 2 crts (monitors #1 and #2), and a gf4 mx440 pci with 1 crt for the secondary card (monitor #3). The problems I'm having are related to twinview/xinerama: twinview doesn't work across multiple cards, so I have to use xinerama in order to include the third monitor in my setup. I would like to have all three monitors as one continuous expanse, so there's two ways to do this:
1) TwinView to link #1 and #2, and xinerama to link the resulting display with #3
2) Treat each output as a seperate screen and link them all with xinerama
Currently I'm going with solution 2, which is less than ideal because I'm limited to using gl apps on only one monitor - and even this has shown to be problematic with certain apps ( there are some annoyances when using fullscreen apps, and the fact that a lot of apps don't have a way to specify what area of the screen to start on means a lot of dragging around every time I start an app).
The main problem with solution 1 is that when you enable xinerama in XF86Config, the twinview screen (ie, #1+#2) stop reporting as seperate screens in xinerama, so I end up with what appears to my windowmanager to be one 1600x1200 monitor, and one 3200x1200 monitor.
The way I see it, there are three "possibilities" which would make me happy (I put that in quotes because there may be some technical reasons these haven't already be implemented):
1) make TwinView cooperate with xinerama (ie, even if xinerama is in use, still report two seperate screens for the twinview screen)
2) make TwinView handle multiple cards as well as single multiheaded cards
3) make it so opengl apps work on any of the screens when using the dualheaded card as seperate screens instead of twinview
I'm assuming #3 is a limitation with X, but what about 1 and 2? Would either of these be possible? Is there currently anything planned to make multi-card more usable, or is this something that won't get much support because of the relatively small number of people using it? Unfortunately most of the posts I've seen on the forums regarding triple monitor and above don't seem to get many responses : |
Re: Multiple cards and xinerama/twinview
Excellent post Bai.
I am in the same situation and haven't figured out how to make it work properly.
I have a Geforce 4 ti4200 dual head, and for the 3rd monitor I'm using an old ati rage pro.
They all work fine in winblows, but making it happen in linux is another story :\
Here you can find a good example for using 3 screens and 2 cards :
In case anyone is still interested:
I've had the same problem. The nvidia internal xinerama gets deactivated if you use the server wide xinerama extension.
Basically all what xinerama aware programs (like kde) care about for their screen alignment is the reply of the XineramaQueryScreens procedure of the xinerama extension.
So what I've done is to fake the reply in the xinerama extension to match my real monitor layout - and indeed this works quite well :-).
I'm currently working on making this a config option, but if you'd like to have a preliminary patch with hard coded values, drop me a private note.
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