dual Radeon graphics cards and Xrandr 1.4

[Alex Deucher]

On Sat, Oct 17, 2015 at 8:18 PM, J. Hart <jfhart085 at gmail.com> wrote:
> I have two old Radeon HD 4850 graphics cards in a 4 head monitor
> configuration I'd like to get working with Xrandr 1.4 if possible. I built
> my linux system entirely from source code, so I am not using any particular
> premade linux distribution. I am presently running linux kernel 3.14. The
> X11 system (Xorg) is also built entirely from the latest release source code
> (no prerelease), and so is post-"xorg 7.7". (Xorg 7.7 is the latest Katamari
> release - June 6, 2012).
>
> I am using the following :
> Mesa 10.6.5
> randrproto 1.5.0
> libXrandr 1.5.0
> xrandr 1.4.3
> xf86-video-ati 7.5.0
>
> The two Radeon cards have a crossfire cable connected between them. They are
> presently working well in a 4 head Xinerama configuration using the open
> source driver listed above (xf86-video-ati 7.5.0)
>
> I have tried starting X without any xorg.config files so that Xinerama is
> not in
> effect. After starting the X server, I did the following:
>
> xrandr --listproviders # saw two providers
> xrandr --setprovideroutputsource 1 0
> clear;xrandr | grep DVI # saw only DVI-0 and DVI-1
>
> The others should have been DVI-2 and DVI-3, but they do not appear in the
> report. Any ideas would be most appreciated.
>

Please attach your xorg log and dmesg output.  Also, what desktop
environment are you using?  IIRC, you need to be using a compositor.

Alex