I'm using the default open source driver and when I run

  # cat /sys/kernel/debug/vgaswitcheroo/switch

I always have my discrete AMD adapter as DynOff. I tried

  echo ON > /sys/kernel/debug/vgaswitcheroo/switch

But nothing happens. What should I do?


3 Answers 3


On my Ubuntu 18.04, I solved it this way. There is no need to edit /etc/default/grub file.

  1. Check that the integrated GPU is used by default by running glxheads

    $ glxheads                                                              
       GL_VERSION:  3.0 Mesa 18.0.5                                            
       GL_VENDOR:   Intel Open Source Technology Center                        
       GL_RENDERER: Mesa DRI Intel(R) Sandybridge Mobile
  2. Check that the discrete GPU is visible but DynOff

    $ sudo cat /sys/kernel/debug/vgaswitcheroo/switch                       
      0:DIS: :DynOff:0000:01:00.0                                             
  3. Enable the discrete GPU for the glxheads and run it again. You can see that the renderer has changed.

    $ DRI_PRIME=1 glxheads                                                  
      GL_VERSION:  3.0 Mesa 18.0.5                                            
      GL_VENDOR:   X.Org                                                      
      GL_RENDERER: AMD TURKS (DRM 2.50.0 / 4.15.0-32-generic, LLVM 6.0.0)
  4. Additionally, while running DRI_PRIME=1 glxheads, in the different window check that now the discrete GPU is DynPwr instead of DynOff

    $ sudo cat /sys/kernel/debug/vgaswitcheroo/switch                         
      0:DIS: :DynPwr:0000:01:00.0                                             
  5. So you need to run each application with DRI_PRIME=1 in order to use discrete GPU. Also, you can set this environmental variable permanently https://unix.stackexchange.com/questions/117467/how-to-permanently-set-environmental-variables

  1. Set kernel parameter:

    sudo nano /etc/default/grub
  2. Find GRUB_CMDLINE_LINUX_DEFAULT, append radeon.runpm=0 like this

    GRUB_CMDLINE_LINUX_DEFAULT="quiet splash radeon.runpm=0"
  3. Update config

    sudo update-grub
  4. To /etc/rc.local add

    echo OFF > /sys/kernel/debug/vgaswitcheroo/switch
  5. Restart machine

    sudo shutdown -r now
  6. PROFIT!

    sudo cat /sys/kernel/debug/vgaswitcheroo/switch 
    1:DIS: :Off:0000:01:00.0

My set to ATI discrete hybrid works.

# lspci | grep VGA
00:02.0 VGA compatible controller: Intel Corporation 3rd Gen Core processor Graphics Controller (rev 09)
01:00.0 VGA compatible controller: Advanced Micro Devices, Inc. [AMD/ATI] Thames [Radeon HD 7500M/7600M Series]

gedit /etc/default/grub 
#GRUB_CMDLINE_LINUX_DEFAULT="quiet splash radeon.runpm=0"

cat /sys/kernel/debug/vgaswitcheroo/switch 
0:DIS: :Pwr:0000:01:00.0

Add DRI_PRIME=1 string in files env to work with ATI graphics card in apps.

gedit /etc/bash.bashrc 
gedit /etc/environment 
gedit /etc/profile

At the end it's used with all apps by default.

# glxheads 
glxheads: exercise multiple GLX connections (any key = exit)
  glxheads xdisplayname ...
  glxheads :0 mars:0 venus:1
Name: :0.0
  Display:     0x55a68ea5b670
  Window:      0x4200002
  Context:     0x55a68ea6cd80
  GL_VERSION:  3.0 Mesa 17.2.2
  GL_VENDOR:   X.Org
  GL_RENDERER: AMD TURKS (DRM 2.50.0 / 4.13.0-25-generic, LLVM 5.0.0)

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