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[jholewinski]

I originally had a Ubuntu 9.10 x64 system set up with a Radeon 5870 and a GeForce GTX 280 running Stream SDK 2.2 and CUDA 3.2.  I recently re-installed the OS and migrated to Ubuntu 10.04 server x64.  After installing Stream SDK 2.3, I am only able to run CAL and OpenCL programs (on the Radeon) as root and not as a regular user.  CUDA works fine on user accounts.

I followed the same Stream SDK setup procedure as before, including the additions to /etc/gdm/Init/Default to enable access over SSH (the machine is headless).  However, I noticed that the device node is now /dev/ati/card0 instead of /dev/dri/card0.

User Account Example:

$ ./OpenCloseDevice
Supported CAL Runtime Version: 1.3.185
Found CAL Runtime Version: 1.4.900
Use -? for help
No protocol specified
Opening Device : 0
There was an error opening device 0.

Press enter to exit...

Root Example:

$ sudo ./OpenCloseDevice 

Supported CAL Runtime Version: 1.3.185

Found CAL Runtime Version: 1.4.900

Use -? for help

Opening Device : 0

Device Handle = 268435456

== Device Info ==

Target Device              : Unknown            

Maximum resource 1D width  : 16384            

Maximum resource 2D width  : 16384            

Maximum resource 2D height : 16384            

Press enter to exit...

Running strace seems to indicate the problem is that a call to ioctl() on /dev/ati/card0 is failing:

open("/dev/ati/card0", O_RDWR)          = 3
ioctl(3, 0xc0506450, 0x7fff07a283c0)    = -1 EACCES (Permission denied)

This error does not occur when running as root.  However, the permissions on that device are world readable/writable:

$ ll /dev/ati/card0 
crw-rw-rw- 1 root root 251, 0 2011-01-19 11:35 /dev/ati/card0

Any clues as to what the problem may be?

[jholewinski]

For those interested, I finally found the solution.

According to the AMD developer site, GDM must be configured to allow remote X connections across SSH directly into the local :0 display (if using Stream SDK over SSH).  The xhost program is used to configure these permissions through a GDM configuration file.  The problem was that xhost was not installed on the system.  

Being a Ubuntu Server installation, X was not installed by default and a basic gnome environment was installed with aptitude.  The minimal Gnome installation for Ubuntu Server does *not* include the xhost program.  Unfortunately, the call to xhost in the GDM configuration file referenced by the AMD developer documentation fails silently, so there is no indication of a problem, other than Stream SDK apps not running without root.

The solution is to install the x11-server-utils package on Ubuntu (other distributions should have a similar package, if xhost is not installed by default).  Now xhost will properly run when GDM starts and Stream SDK applications can be used without root permissions.

I believe the Remote Access documentation on the AMD developer site should be updated to reflect two points:

1. Ensure xhost is installed on the local system
2. Newer AMD drivers seem to use /dev/ati/card* instead of /dev/dri/card* as mentioned in the documentation.