could not open the device file /dev/nvidiactl


I’m new on cuda…I’m trying to install it on my ubuntu 8.04 64bit-distro with a gf8800 using the nvidia driver 64-180.06 … after the installation steps , without problems, i tried to run NVIDIA_CUDA_SDK/bin/linux/release/deviceQuery as user and as root but i get the message:

I’ve checked the /dev/nv* permissions:

Any ideas?

thanks :)

You listed the permission. Only root and the video group can access the card. Add your user to the video group and all should be well.

i’ve added myself (raffo) to the video group

but the message is still the same…

Does this problem go away if you start X?

no, the problem remain. I can’t understand what is going wrong…i’ve spent all morning on this…

easy way: sudo chmod 0666 /dev/nvidia*

Another something simple. Did you log out and back in after adding yourself to the group?

i’ve modified the permissions on the device using chmod but nothing happened. Log-off, x-server and system restart are useless…I worked around udev rules without results…

I had the same issue some time ago. I took the “easy way” pointed out by tmurray.

sudo chmod 666 /dev/nvidia*

It was working for me, but you have to repeat it after every reboot

make sure that you are actually chamging the permissions after chmod. Maybe a wrong sudo password or something can avoid them to be changed

another possibility to try is to directly run the executable using sudo

sudo ./your_program


i had tried everything but nothing worked for me…i solved my problems simply replacing the new 64-180.06 driver with the older 64-177.67 and downgrading cuda to 2.0… all seems to be ok now without additional “tuning” phase

thanks to all :)

absolutely do not use 177.67. use 177.73 or 177.80 if you’re going to use a 177.xx driver.

ok, now i’m using a 177.82 driver, thanks

Try adding the following section to xorg.conf:

Section “DRI”
Mode 0666

It worked for me!

I had exactly the same issues with the driver 340.29.

Tried changing permissions:

chmod 666 /dev/nvidia*

nvidia-smi was working for root but not for any other user. so eventually I had to modify /etc/modprobe.d/50-nvidia.conf

options nvidia NVreg_DeviceFileUID=0 NVreg_DeviceFileGID=33 NVreg_DeviceFileMode=0666 NVreg_ModifyDeviceFiles=1

The problem was resolved with the last variable.

Remember to delete the files /dev/nvidia*

Then it works for all users

That was perfect, thanks!.. To me the problem was that I had NVreg_DeviceFileMode=0660, so I just changed to 666.