Bug#798317: xserver-xorg-video-radeon: Strange interaction of radeon config, screenshot and x11vnc

[Michel Dänzer]

On 08.09.2015 09:58, Luis Mochan wrote:
> Package: xserver-xorg-video-radeon
> Version: 1:7.5.0-1+b1
> Severity: normal
> 
> For some time I have found a strange behavior in the behavior of my radeon
> under X. After a fresh bootstrap I can start an X session without problem,
> except that if I make a screen shot it turns out completely black and if I
> access my computer by running x11vnc locally and vncviewer remotely, the screen
> is also completely black and unusable from the remote location. If I logout and
> login again, the behavior doesn't change.
> 
> If I uncomment the line
>   #       Option  "EXAPixmaps"            "on"
> in the configuration file
>   /etc/X11/xorg.conf.d/20-radeon.conf
> and restart my display manager (lightdm) X tries to run repeatedly and
> unsuccesfully. Thus, it seems that option doesn't work with my card. The
> strange behavior is the following. When I comment back that line, I recover X
> and furthermore, screenshot and magically x11vnc start working normally!
> 
> Thus, it seems that something good happens irreversibly after I turn on the
> invalid option and then turn it off. Whatever happens, should have happened
> normally without me having to perform this magic, accidentaly discovered step.
> 
> Please let me know what additional information I can provide that may prove
> useful.

[...]

> [   542.255] (**) RADEON(0): Option "SWcursor" "off"
> [   542.255] (**) RADEON(0): Option "EnablePageFlip" "on"
> [   542.255] (**) RADEON(0): Option "RenderAccel" "on"
> [   542.255] (**) RADEON(0): Option "AccelMethod" "EXA"
> [   542.255] (**) RADEON(0): Option "EXAVSync" "off"

I don't know what the problem is, but FWIW you shouldn't enable Option
"RenderAccel", because RENDER acceleration uses the 3D engine, which
isn't validated on RN100 GPUs. That might explain at least the issue
with Option "EXAPixmaps" enabled.


-- 
Earthling Michel Dänzer               |               http://www.amd.com
Libre software enthusiast             |             Mesa and X developer