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Old 12-13-2007, 02:41 PM   #1
MonsterMaxx
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Dual Head, Twin view, separate X window - things you can do with multi displays


It seems I may not be translating my terms from windows very well and perhaps I'm just not understanding what Linux can do. Could I please get a little education on the subject?

I have Mythdora4 on a p4-3.4 Quadro 3400, (2x DVI + S-Vid) and a PVR 350 (s-vid) I'd like to be able to use dual or even triple output if possible.

When I enable Twinview, it does what I'd call in Windows 'Spanning', either I'm not understanding how to use it or it is no good for this. What I was trying to do is (in windows speak) 'Dual Head'. This is where both screens are separate.

I've tried the setting in the nVidia 9755 control panel to set it to 'separate X window' but the setting won't take, even with a reboot. Yes, I did save to the file, but watching it in both states didn't reveal any obvious changes. Looking at some examples of the X11 file on the net has my eyes going in circles, I hardly know where to begin

Then it occurs to me that Linux was developed in a multi user world, so perhaps 'separate X window' means a whole different log in. on the separate screen. That would be even better. I'd leave mythtv running on a TV and have a separate desktop running a separate log in. That'd be great! I could simply dedicate the S-Video (and remote control) output on either the PVR350 or the one on the vid card to be a whole separate login just for Myth.

I guess the questions are
Can multiple users be logged into and using Fedora at the same time? ie: one user's input the keyboard/mouse and the other the remote control output on two different displays?
Can the screen be run in 'dual head' mode? if so, could I get some hints/links on how to do this and Linux speak terms to search?
Any other hints/links to get something like this working would be appriciated, like tying the remote's input to one user. Thanks in advance

Last edited by MonsterMaxx; 12-13-2007 at 02:43 PM.
 
Old 12-14-2007, 07:42 AM   #2
Simon Bridge
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Seperate X-Window is somewhat different from windows "dual head" you are correct.

In the unix world, more than one monitor for a single system is called "multi-head" regardless of how the monitors are used.

The most common configuration seems to be the "big desktop" effect, where a single desktop spans several heads. Gamers seem to like this and now I've started playing FPSs I can sort of see the point. I still think an actual bigger screen is nicer.

But this is technically what twinview is designed for - works in linux this way too. The main advantage for a workspace is that you can drag windows from one monitor to another.

MS-Windows, being somewhat backward, only supports multi-head as a kind of added hack. X-Windows was designed to allow more than one monitor in a server/client relationship.

The standard, or Xorg, multi-head starts a different x-session on each monitor and is set up in /etc/X11/xorg.conf (though major distros usually have a gui for this). You'll want to switch twinview off for this (or use twinview across two monitors and have X handle the switch to the third... whatever.)

I'll walk you through basic dual-head the xorg way:

Code:
# Device Definitions:
Section "Device"
        Identifier      "nVidia L"
        Driver          "nvidia"
        Busid           "PCI:1:0:0"
        Screen          "0"
EndSection
Section "Device"
        Identifier      "nVidia R"
        Driver          "nvidia"
        Busid           "PCI:1:0:0"
        Screen          "1"
EndSection

# Monitor Definitions
Section "Monitor"
        Identifier      "LMonitor"
        Option          "DPMS"
        Horizsync       30-70
        Vertrefresh     50-160
EndSection
Section "Monitor"
        Identifier      "RMonitor"
        Option          "DPMS"
        Horizsync       30-70
        Vertrefresh     50-160
EndSection

# Screen Definitions
Section "Screen"
        Identifier      "LeftScreen"
        Device          "nVidia L"
        Monitor         "LMonitor"
        Defaultdepth    24
        Subsection "Display"
                Depth        24
                Mode         "1024x768"
        EndSubsection
EndSection
Section "Screen"
        Identifier      "RightScreen"
        Device          "nVidia R"
        Monitor         "RMonitor"
        Defaultdepth    24
        Subsection "Display"
                Depth        24
                Mode         "1024x768"
        EndSubsection
EndSection

# Server Definition - lay out the screens
Section "ServerLayout"
        Identifier      "Simple Layout"
        Screen          "LeftScreen"
        Screen          "RightScreen" RightOf "LeftScreen"
        Inputdevice     "Generic Keyboard"
        Inputdevice     "Configured Mouse"
EndSection
There's also a LeftOf, Above, and Below.
For most of that, it is the Identifier that is important. You should modify the entries to reflect your setup.

Now, to use it, you have to tell applications which screen to load onto. The main screen is :0.0 and the second screen is :0.1 (and so on). If you want to run an application on the second screen, you have to pass the "-display :0.1"parameter to it.

firefox -display :0.1

... puts the browser on the right-hand screen.

IIRC - this gives two logins as well. Though I imagine you can rig the login script to :0.0 to log you into :0.1 as well.
 
Old 12-14-2007, 07:46 AM   #3
Simon Bridge
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Remote Desktop in linux you are going to love!
You use VNC just like in windows. Unlike Windows, linux vnc server creates a seperate X session by default.

In other words, it is already multi-head. In this case, the other head is the vnc client window on the remote computer. You won't be bothered by some other user grabbing your mouse a messing with the desktop while you're trying to work.

And, yes, you can get a copy of the client's window to open on a spare head on your own machine if you want to see what he's doing.
 
Old 12-20-2007, 07:32 AM   #4
ffilc7373
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Hi Simon Bridge, I hope you are still reading the mail on this thread as I would like to ask you a couple of questions on Server configuration??
Cliff
 
Old 12-20-2007, 10:54 PM   #5
Simon Bridge
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And those questions are? ...
You don't need my permission to ask questions... fire away!
 
Old 12-21-2007, 04:01 AM   #6
ffilc7373
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Hi,
I didn't want to start a new thread on something that was so closely related to this.
I have been looking at the various examples of the xorg.conf file in an attempt to achieve an xorg multi head configuration with my Fujitsu Lifebook.
Under the heading ;
Section "ServerLayout"
There are several identifiers used in the examples which include "Simple Layout", "Dual Head" and in one case this section is omitted altogether.
I assume it does not matter what you call it the name is only an identifier for example it could be called "Aardvark";;or is there a set of rules on this?
I can easily achieve the Left screen /Right Screen/Both screens using Fn + F10 to switch, but I want to be able to use the extended desktop and slide a window from the left screen onto the right screen, can this be done in xorg.conf?.
Thanks Cliff
 
Old 12-21-2007, 05:47 AM   #7
Simon Bridge
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Quote:
I assume it does not matter what you call it the name is only an identifier
... that is correct. It helps to have sane names for your identifiers though.

Quote:
I want to be able to use the extended desktop and slide a window from the left screen onto the right screen, can this be done in xorg.conf?
... no.

Believe me, this is much discussed. The problems with implimenting even something like rt-click on a window and select "send to other head" is fraught with difficulty related to the way the xserver works.

To do that you need one of the "big desktop" options... xrandr or twinview. The xorg multi-head is excellent when you want specific roles for each head.
 
Old 01-13-2008, 02:39 PM   #8
MonsterMaxx
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Great info. Sorry I didn't follow this sooner, but I guess the question was ahead of my abilities and I had other stuff to learn first.
Now that I have 2x Linux boxes running (FC6 F&B Myth) VNC running (yes, you are right, I like it a lot better than windoze), VMware, samba and some other stuff working I'm ready to tackle getting the TV running the mythtv user.


is there an easier way to restart X other than init 3, init 5? that don't work so good in VNC. Some sort of root command that'll restart X, like: service vncserver restart does for the VNC server?

When I use nVidia's applett to config the file here's what I get - it looks a lot like your's, but when I restart I get the 'X server will not start' error and it deletes all this and resets it to stock.

What's wrong with this picture?
Code:
Section "Monitor"
    Identifier     "Monitor0"
    VendorName     "Unknown"
    ModelName      "CRT-0"
    HorizSync       30.0 - 110.0
    VertRefresh     50.0 - 150.0
    Option         "DPMS"
EndSection

Section "Monitor"
    Identifier     "Monitor1"
    VendorName     "Unknown"
    ModelName      "TV-0"
    HorizSync       28.0 - 33.0
    VertRefresh     43.0 - 72.0
EndSection

Section "Device"
    Identifier     "Videocard0"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce 7800 GS"
    BusID          "PCI:2:0:0"
    Screen          0
EndSection

Section "Device"
    Identifier     "Videocard1"
    Driver         "nvidia"
    VendorName     "NVIDIA Corporation"
    BoardName      "GeForce 7800 GS"
    BusID          "PCI:2:0:0"
    Screen          1
EndSection

Section "Screen"
    Identifier     "Screen0"
    Device         "Videocard0"
    Monitor        "Monitor0"
    DefaultDepth    24
    Option         "TwinView" "0"
    Option         "TwinViewXineramaInfoOrder" "CRT-0"
    Option         "metamodes" "CRT: 1600x1200 +0+0"
    SubSection     "Display"
        Depth       24
    EndSubSection
EndSection

Section "Screen"
    Identifier     "Screen1"
    Device         "Videocard1"
    Monitor        "Monitor1"
    DefaultDepth    24
    Option         "TwinView" "0"
    Option         "metamodes" "TV: 1024x768 +0+0"
EndSection

Last edited by MonsterMaxx; 01-13-2008 at 02:46 PM.
 
Old 01-13-2008, 02:56 PM   #9
MonsterMaxx
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POP!

I commented out the 'option' items on the last two sections and it started.

But when I log in, it starts one session normally on the main screen and there's another log in on the TV, but with the default KDE (no tweaks like I've done normally with this user.)
The mouse will slide from one screen to the other and I can operate both.
Sort of feels like 2 sessions of KDE have been started, but that I can access both.

hmmmmm
confused

When I log in, I only want the main screen. As a user that is.

The TV will be totally dedicated to the Myth user, which I guess should just start up, log itself in and be running on the TV.

?

Last edited by MonsterMaxx; 01-13-2008 at 03:11 PM.
 
Old 01-16-2008, 10:17 PM   #10
MonsterMaxx
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bump
 
Old 01-16-2008, 11:07 PM   #11
Simon Bridge
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Unfortunately I know very little about mythtv.
Your last post seems to indicate that everything is working pretty much like it should - have you tried autologging the mythtv user to the TV session?
 
Old 01-17-2008, 10:05 PM   #12
MonsterMaxx
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Quote:
Originally Posted by Simon Bridge View Post
have you tried autologging the mythtv user to the TV session?
umm...I think that's what I'm trying to find out how to do...isn't it?
 
Old 01-17-2008, 11:28 PM   #13
Simon Bridge
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I'm sorry, I thought that autologin methods were well known... ish.
Here's some specific to mythtv though:
http://www.mythtv.org/wiki/index.php...end_Auto_Login
http://wilsonet.com/mythtv/fcmyth.php

Normally, autologin is done from gdm.conf (though gnome has a dialog box to help). Set automatic login to "True" and the first screen gets autologged. Make sure screen 0 is the TV and you are set.
 
Old 01-18-2008, 12:58 AM   #14
MonsterMaxx
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OK, read the wiki, but I still don't get it. I feel like I'm just not speaking the language sometimes.

Basicly what I want is two users, two stations. One uses the keyboard and the monitor, the other (mythtv) the remote and TV - this user should autologin. I think I've seen the bits on autologin, what I'm not seeing is which files to edit and what to do to them so that the mythtv user is seperate and leaves the monitor and keyboard alone. I figure if mythtv needs a keyboard it'll get there thru VNC.

Is what I want possible (two users, one machine)? I think I can follow the wiki thing if I knew the kind of changes to make.

{I'm really not very good at this stuff}
 
Old 01-18-2008, 01:48 AM   #15
Simon Bridge
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Yes... two users are allowed on one machine.
Don't you need two logins as it stands?
 
  


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