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[LUG] Running two independent instances of X (including two window managers) on one PC

 

Hi folks,

I'm hoping someone might be able to help with an issue I'm having trying 
to run two independent copies of X on my PC.

Basically I've recently got a new LCD TV which has HDMI input. 
Eventually I'd like to build a MythTV box but I haven't got the funds 
for that at the moment (my other half won the telly in a competition). 
I thought for now I'd just use my PC as a Media Player for the telly.

So, I'm running Ubuntu 7.10 (AMD64) on my desktop PC.  I have an ATI 
Radeon X300 graphics card in the PC which has dual DVI output.  The 
first connection is going to my desktop's monitor via a DVI to VGA 
adaptor, and the second output it going to the TV via a DVI to HDMI cable.

With a lot of messing around and shouting at the PC I managed to get a 
mirrored output on both connections, so I could display the PC on the TV 
and PC monitor at the same time, although a drawback of this was that 
the monitor stretches the image (it appears to be trying to run at 
1280x768, although the monitor is a 1280x1024 display). It looks fine on 
the TV (which happily runs at 1280x768).  This is using the open source 
ati driver.

After much fiddling I managed to get two desktops working.  My desktop 
PC now has the main desktop on it, and I can move the mouse over to the 
left to the TV screen (what I don't get is the fact that the TV also has 
the Gnome bars at the top and bottom of the screen on it).  This also 
works fairly well, but the desktop PC monitor again is running at 
1280x768.  This is using the proprietary ATI Catalyst (fglrx) driver, I 
can't get this far using the open source ATI driver.

Now I've tried going through some instructions (sorry haven't got the 
link to hand) which explains how to setup the xorg.conf to use two 
different graphics cards as two different X displays using both a PS2 
Keyboard and Mouse and a USB Keyboard and Mouse.  Trying this just 
brings up the standard Ubuntu (un)helpful X failsafe mode which allows 
me to choose my video card etc (which I guess is handy when it works but 
I've had nothing but bad experiences with it).

So, I wondered, is there anyone out there who's managed to get two 
independent X screens running.  Ideally I'd like to be able to have two 
X screens running two different window managers (maybe Gnome/Metacity 
and possibly a lightwight one such as FWM) and have them behave as if 
they're completely independent using a pair of USB keyboards and mice.

I'd ideally like to stick with the ATI card (I have two of these cards 
installed at the moment which isn't really what I want but I can live 
with it if need be) but I'd be willing to move over to an NVidia card if 
I had to, although I chose ATI on the basis that it can use an Open 
Source driver (I really don't like running the FGLRX driver as Compiz 
doesn't work and playing video in a window is very slow).

If anyone can advise on how I can get this working I'd be really grateful.

Thanks in advance.

Rob

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