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I upgrade to 16.04 LTS (from 14.04 LTS) yesterday. I have two monitors, and when I rebooted after the upgrade, I could see the X windows and Gnome in both monitors. However, they were not two separate displays: they were cloned. I had a key combination (Super+P) that worked in separating the two monitors when this happened on boot in 14.04, but it doesn't work anymore. It only shows numbers over each display.

Then after 2 minutes or so, the monitors went black, and I had no mouse or keyboard access anymore. The computer ran, rather high, with the fan blasting away, but I could do nothing. I had to kill it with power button.

  1. I tried booting with one monitor (the second unplugged from the computer), and
  2. I switched to tty1 after booting (with Ctrl-Alt-F1) to see if it was Gnome or something.

Neither helped.

I have two machines hooked to my monitor/keyboard/mouse with a KVM switch, and this was connected, and the other machine was on while doing the upgrade.

I have killed the machine the hard way now several times, and the system displayed some fsck-related messages on boot. One error message appeared regarding the video card: No UMS support in radeon module.

Once, when booting with just the right monitor, I got a popup window with the message:

Could not apply the stored configuration for monitors, none of the selected modes were compatible with the possible modes:
Trying modes for CRTC 618
CRTC 618: trying mode 1400x1050 @ 77HZ with output at 1600x1200 @ 77Hz (pass 0)
[...]

While I was using Ubuntu 14.04, I installed a driver for the video card that helped to reduce the temperature and the fan noise.

My system has the following specs:

  • Dell Studio XPS 7100
  • AMD Phenom II X6 1045T Processor
  • 8 GB RAM
  • ATI Radeon HD 5700 Series video card

How can I fix the issue without reinstalling?

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excyberlabber
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1 Answers1

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I got a lot of help from Andrea Lazzarotto (thanks, Andrea!), but in the end I found the answer myself. I searched for "No UMS support in radeon module" on google. It turned up this link:

https://bbs.archlinux.org/viewtopic.php?id=166037

which referred to the grub config. So I ran the command:

sudo gedit /etc/default/grub

and saw that it referred to my radeon card:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash radeon.modeset=0"

I removed the reference to the modeset, per the post listed above, so it read:

GRUB_CMDLINE_LINUX_DEFAULT="quiet splash"

After editing the grub config, you must run: 

sudo update-grub

This saves the config changes in the file itself. I did this and then rebooted. This fixed the problem with the black screen/crash, and it also fixed the problem with the dual screens being cloned.

excyberlabber
  • 431