MergedFB not working on radeon X700

Hans-Jürgen Koch hjk at
Wed Apr 25 14:09:42 PDT 2007

Am Mittwoch 25 April 2007 22:41 schrieb Ricardo Ribalda Delgado:
> Hi all
>   I'm trying to have dual head support with a radeon X700 using the
> open source driver.  With Xinerama works perfectly, but when I try to
> make it work using MergedFB I get exactly the same image on both
> monitors (One connected to dvi and the other to vga). I have readed
> the man, I have tryied many options, googled and.. I don't know what
> else to do :(.

Well, your log says that mergedfb is actually not enabled:

(EE) RADEON(0): No valid mode found for CRTC2, disabling MergedFB

I had similar effects with my X300. My problem was that I connected
one of my monitors through a DVI-VGA adaptor. As soon as I used a
direct connection with a DVI cable, it started working.
I also noticed that both monitors MUST be connected during X server
startup. Furthermore, I cannot use radeonfb or radeon drm in my 
kernel (2.6.21-rc7). Consequently, I have DRI disabled in my
xorg.conf (hope to get it one day, though).

I use Option "MonitorLayout" "TMDS,TMDS" instead of your "TMDS,CRT".

My X300 now works in MergedFB mode, with two 1680x1050 monitors,
one connected with a DVI cable, one with a VGA cable.

Please report about your progress, I'm very much interested in
getting these Radeon problems solved, in the kernel AND in


More information about the xorg mailing list