Linux on Mac doesn't recognise 2nd display.
 

There is further problem that my system has dual displays (identical) which work perfectly in MAC OS and Windows. But Linux detects only one of them. Is it because of lack of proper graphics driver? Any possible way to diagnose or solve it?

P.S. Should I start a new thread?

You should have, but I took care of that and split the new post out. ;}

What does "lspci" tell you about the video hardware, which drivers did
X choose? Have a look at /var/log/Xorg.0.log

Thanks Tinkster :)

lspci shows the following graphics adapters (I think, I am not experienced in these things)

05:00.0 VGA compatible controller: ATI Technologies Inc Juniper [Radeon HD 5700 Series]
05:00.1 Audio device: ATI Technologies Inc Juniper HDMI Audio [Radeon HD 5700 Series]
06:00.0 VGA compatible controller: ATI Technologies Inc Juniper [Radeon HD 5700 Series]
06:00.1 Audio device: ATI Technologies Inc Juniper HDMI Audio [Radeon HD 5700 Series]

Not sure what to look for in Xorg.0.log (there is a Xorg.1.log as well)? These are long files. Could anyone direct me? Just in case, I am attaching the two files here.

Wild hand-waving gesture ... does this help?

=o)


I don't know much about Ubuntu, so I just did some googling

Thanks for the link. It didn't help though. In the Control Center it shows the second one as an "Unknown adapter". I am surprised because in lspci it simply shows two ATI Radeon.

Any brute force way to tell linux that it is the same adapter and should use the same driver? (I am not sure if that is the right way to put it though).

How is it connected? I had this issue with a new monitor. It worked with my Macbook (using a stock Ubuntu 10.4 LTS install), but didn't take a signal from my Android tablet.

I went back to the shop, checked the wires and did lots of head scratching. Eventually, I checked my tablet on another brand of monitor with my cabling. Bingo! Worked perfectly. Apparently it was something to do with cheap and nasty parts on a cheap monitor's HDMI set-up.

Linux might be working fine, check your system on another monitor first if you can.

I am pretty sure that the connections are OK, because both monitors work with MAC OS and Windows. Only in Linux just one works.

Its possible with xorg options. Sorry, but I dont know the way that the xorg needs to be parsed to make dual video cards work. You might get a few hints from this page-

http://en.gentoo-wiki.com/wiki/X.Org...Graphics_Cards