KMS error while trying to switch user in KDE

[Toomas Aas]

Hello!

I have installed a new desktop machine with FreeBSD 10-STABLE amd64,  
xorg 1.12.4 and KDE 4.12.5. The system has ATI Radeon X1300/X1550  
video card. Graphics is configured WITH_NEW_XORG (the default), vt and  
radeonkms are in use, video driver is xf86-video-ati-7.2.0_3 built  
WITH_GALLIUM.

One thing that does not work is 'switch user' functionality in KDE.  
When attempting to start new session, the screen flashes briefly and  
then I am returned to active session with screen locked, which I can  
unlock and continue working.

When looking at /var/log/kdm.log during the switch, it says that  
something is wrong with X.org:

------------------------------------------------------------------------------
Fatal server error:
no screens found

Please consult the The X.Org Foundation support
          at http://wiki.x.org
  for help.
Please also check the log file at "/var/log/Xorg.1.log" for additional  
information.

Server terminated with error (1). Closing log file.
------------------------------------------------------------------------------

So I look at Xorg.1.log and it seems to indicate a problem related to KMS:

------------------------------------------------------------------------------
[   431.280] (--) Using syscons driver with X support (version 2.0)
[   431.280] (--) using VT number 10

[   431.282] (II) [KMS] Kernel modesetting enabled.
[   431.282] (WW) VGA arbiter: cannot open kernel arbiter, no  
multi-card support
[   431.282] (==) RADEON(0): Depth 24, (--) framebuffer bpp 32
[   431.282] (II) RADEON(0): Pixel depth = 24 bits stored in 4 bytes  
(32 bpp pixmaps)
[   431.282] (==) RADEON(0): Default visual is TrueColor
[   431.282] (==) RADEON(0): RGB weight 888
[   431.282] (II) RADEON(0): Using 8 bits per RGB (8 bit DAC)
[   431.282] (--) RADEON(0): Chipset: "ATI Radeon X1300/X1550" (ChipID  
= 0x7142)
[   431.283] drmOpenDevice: node name is /dev/dri/card0
[   431.283] drmOpenDevice: open result is 7, (OK)
[   431.283] drmOpenByBusid: Searching for BusID pci:0000:02:00.0
[   431.283] drmOpenDevice: node name is /dev/dri/card0
[   431.283] drmOpenDevice: open result is 7, (OK)
[   431.283] drmOpenByBusid: drmOpenMinor returns 7
[   431.283] drmOpenByBusid: Interface 1.4 failed, trying 1.1
[   431.283] drmOpenByBusid: drmGetBusid reports pci:0000:02:00.0
[   431.283] (EE) RADEON(0): [drm] failed to set drm interface version.
[   431.283] (EE) RADEON(0): Kernel modesetting setup failed
[   431.283] (II) UnloadModule: "radeon"
[   431.283] (EE) Screen(s) found, but none have a usable configuration.
[   431.283]
Fatal server error:
[   431.283] no screens found
[   431.283]
Please consult the The X.Org Foundation support
          at http://wiki.x.org
  for help.
[   431.283] Please also check the log file at "/var/log/Xorg.1.log"  
for additional information.
[   431.283]
[   431.283] Server terminated with error (1). Closing log file.
------------------------------------------------------------------------------

Can this problem be solved?

-- 
Toomas Aas