I’ve recently installed Cuda 5.5 on a Fedora 18 box. When I run nvidia-smi as root, everything works perfectly. When I use nvidia-smi as a normal user, I receive the error message:
NVIDIA: could not open the device file /dev/nvidiaactl (no such file or directory).
NVIDIA-SMI has failed because it couldn’t communicate with NVIDIA driver. Make sure the latest NVIDIA driver is installed and running.
If I log back in as root, things still work just fine. Other support resources around the internet say that I should add my user to the “video” group. I’ve done that, but it doesn’t seem to have fixed anything. I’m officially stumped.
Once you run nvidia-smi as a root user, the device files should be created, and thereafter (until the next reboot), you should not have the problem, even if you are an ordinary user. If that is what you observe, that is expected behavior.
If you are not observing that, then the device control files are getting created with a set of permissions that are not compatible with your “ordinary” user. That would be difficult to fix without knowing the exact set of permissions as well as the specifics of your “ordinary” user and groups.
The getting started guide makes reference to this: