Dual Monitors - but identical images!
 

I have not run Linux/Unix for several years. I have installed Red Hat Enterprise (free demo) on my old desktopm and it runs. I have added a second monitor, as there two video cards installed. I get two identical screens in spite of trying 'Individual Desktops' and also 'Spanning Desktops' under Display Settings-Dual Head. Reboots don't help. (Sorry, I'm using Gnome). I want the 'Extend desktop' effect u-know-who offers.

Thanks.

Hi, welcome to LQ!

Slackware?! :}

Sorry, just kidding. Which graphics chipset are you using in that machine?



Cheers,
Tink

Tinkster OP is using demo can you install anything in demo as redhat is not free?

I wouldn't have a clue. If he's using a dualhead intel chipset, however, he
won't need to install anything.



Cheers,
Tink

Answering Tinkster
 

(Is this the right way to annswer?)

System-Administration-Display reports that BOTH cards are "ATi Technologies Inc Radeon RV100 QY (Radeon 7000/VE". I doubt that is correct: the output plugging options are visibly different, and I seem to be getting only 800 X 600.

It seems to me the problem is not video chips (the screens look fine), but what linux is choosing to send down the wires. Does that make sense?

How long is the demo good for as Redhat is not free, but I believe Centos is the free version of Redhat.
I would install Centos and have a fully functional version. Then you may be able to get the dual-monitor setup without configuring.

Not sure I follow your logic; it's all important which hardware
you're using because it determines whether or not you can easily
enough do the "extended desktop" thing or not. Looking at your
post, and googling for it with linux and dual-head thrown in
gives a few hits: this one, while geared at Ubuntu, seems
quite promising.



Cheers,
Tink

Bring up a terminal and show us the output of 'xrandr'.

Adam

Redhat Dual Screens with ATI CCC
 

Update: As adamk75 stated, the VGA card Radeon 7000 is not supported by the current ATI driver.

I was able to have dual screens (with spanning desktops) with redhat using the ATI Catalyst Control Center.
As in your post, you have ATI cards, so go to the ATI Driver Download page, and download your driver.
Usually, just with a single reboot after successfully installing the drivers, it should detect the two screens...

This is bad advice. If you look at the OPs posts, you'll see that the video card in question is a Radeon 7000, which has never been supported by the proprietary drivers from AMD/ATI.

Adam

One could try the ATI open source drivers:
http://cgit.freedesktop.org/xorg/dri...video-radeonhd
http://cgit.freedesktop.org/xorg/driver/xf86-video-ati
I hope this helps...

radeonhd is also for much newer video cards. xf86-video-ati should be used by default for that video card on any distribution from the last 10 years.

Perhaps, before recommending someone install different drivers, we try to figure out what's wrong with their current setup?

Adam

Monitors - the status
 

Hi Paul, Tink, ...,
I abandoned the second monitor as a distraction. Then 'xrandr' showed a list of resolutions, (one *'ed) and something, now lost.

Now reconnected, and xrandr says:- Xlib: extension "RANDR" missing on display ":0.0" Rather different.

Correction/additions to previous input:
The video cards are one, dual-head Radeon 7000/VE (not two cards)
I have two Sharp monitors: a LL-T19D1-B and a LL=191A-B. No Sharp monitors are listed in the cofiguration screen, so I called out generic LCD at 1024x768.

Thanks all of you.

Please show us your /var/log/Xorg.0.log file.

Adam

Log file
 

I'm on my Windows machine, and I don't know how to get a file from the Linux box to here. I have looked briefly at the file (it is very long), and I did notice 'Failed to detect second monitor'. I'll work on getting the whole file across,

Dick

The Log File
 

Got it here. Now to attach it ...

Honestly, your on a linux distribution with a version of Xorg that is over 5 years old. The chances of getting useful support with such an old version of Xorg is small. All I can really say is that the driver does not support xrandr 1.2, so you'll have to use MergedFB. I suggest checking the 'radeon' man page for information about MergedFB. But, again, bear in mind that the driver has changed a lot in 5 years. It's quite possible that the error about not detecting a secondary monitor is a bug in the driver back then, and has been fixed in newer versions.

Is there any reason why you're returning to Linux by installing such an ancient version?

Adam

I'm trying to simulate what a customer is doing; they run Red Hat linux, but will be paying for current versions. 5.7 is the latest I could download and burn to CD's as a 30-day trial. What do you mean by Xorg and MergedFB? Maybe I just have to bite the bullet and buy the current version. I'll try for a driver update for the Radeon video card first.

Thanks, Dick

Xorg is the X server. MergedFB is a feature of the radeon driver that extends one screen across multiple monitors. It's deprecated and no longer supported, having been replaced by xrandr 1.2.