I think I was affected by this issue , which lead me to this error message after unloading Xorg :
sudo modprobe radeon [ 301.718377] [drm:radeon_init] *ERROR* No UMS support in radeon module!
I had to force kms by :
grep radeon /etc/default/grub GRUB_CMDLINE_LINUX_DEFAULT="radeon.modeset=1"
As suggested I updated kernel :
Linux version 3.16.0-29-generic (buildd@toyol) (gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #39-Ubuntu SMP Tue Dec 16 20:53:40 UTC 2014
So to move foreward Isnt modeset module arg supposed to be enabled by default ? how to check ?
modinfo radeon | grep modeset parm: modeset:Disable/Enable modesetting (int)
vermagic: 3.16.0-29-generic SMP mod_unload modversions 686
Linux version 3.13.0-44-generic (buildd@komainu) (gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #73-Ubuntu SMP Tue Dec 16 00:23:46 UTC 2014
dmesg | egrep 'drm|radeon'
[ 4.620260] [drm] Initialized drm 1.1.0 20060810
[ 5.231024] [drm] radeon userspace modesetting enabled.
[ 5.260424] [drm] Supports vblank timestamp caching Rev 2 (21.10.2013).
[ 5.288641] [drm] No driver support for vblank timestamp query.
[ 5.316515] [drm] Initialized radeon 1.34.0 20080528 for 0000:01:00.0 on minor 0
http://askubuntu.com/questions/456060/drmno-driver-support-for-vblank-timestamp-query
sudo lshw -c video
[sudo] password for default:
Sorry, try again.
[sudo] password for default:
*-display UNCLAIMED
description: VGA compatible controller
product: RV100 [Radeon 7000 / Radeon VE]
vendor: Advanced Micro Devices, Inc. [AMD/ATI]
physical id: 0
bus info: pci@0000:01:00.0
version: 00
width: 32 bits
clock: 66MHz
capabilities: agp agp-2.0 pm vga_controller bus_master cap_list
configuration: latency=64 mingnt=8
resources: memory:f0000000-f7ffffff ioport:ec00(size=256) memory:ff8f0000-ff8fffff memory:ff800000-ff81ffff
lspci -vnn
01:00.0 VGA compatible controller [0300]: Advanced Micro Devices, Inc. [AMD/ATI] RV100 [Radeon 7000 / Radeon VE] [1002:5159] (prog-if 00 [VGA controller])
Subsystem: Palit Microsystems Inc. Device [1569:5159]
Flags: bus master, stepping, 66MHz, medium devsel, latency 64, IRQ 16
Memory at f0000000 (32-bit, prefetchable) [size=128M]
I/O ports at ec00 [size=256]
Memory at ff8f0000 (32-bit, non-prefetchable) [size=64K]
Expansion ROM at ff800000 [disabled] [size=128K]
Capabilities: [58] AGP version 2.0
Capabilities: [50] Power Management version 2
Kernel modules: radeon, radeonfb
lsmod | grep radeon
radeon 742155 0
i2c_algo_bit 13199 1 radeon
ttm 65371 1 radeon
drm_kms_helper 45466 1 radeon
drm 197641 3 drm_kms_helper,ttm,radeon
sudo apt-get install linux-headers-generic-lts-trusty xserver-xorg-video-radeon-lts-trusty linux-generic-lts-trusty linux-image-generic-lts-trusty
01:00.0 0300: 1002:5159
sudo modprobe radeon [ 301.718377] [drm:radeon_init] *ERROR* No UMS support in radeon module!
(II) [KMS] drm report modesetting isn't supported.
sudo apt-get install linux-generic-lts-utopic
grep radeon /etc/default/grub GRUB_CMDLINE_LINUX_DEFAULT="radeon.modeset=1"
VERSION="14.04.1 LTS, Trusty Tahr" ID=ubuntu
cat /proc/version Linux version 3.16.0-29-generic (buildd@toyol) (gcc version 4.8.2 (Ubuntu 4.8.2-19ubuntu1) ) #39-Ubuntu SMP Tue Dec 16 20:53:40 UTC 2014