Cuda driver initialization failed

Question

I have a two gpu system, a Geforce 8400 GS and Geforce GT 520. I am able to run my cuda programs on both the gpus. But when I use cuda-gdb to debug them I get an error saying that the Cuda driver initialization failed. Also, when I run the program with cuda-gdb, the cudaGetDeviceCount says I have only 1 gpu. I am able to run the programs on either of the gpus if I am not using cuda-gdb. Can somebody help me with this?

I am running Ubuntu 11.04.

Answer 1

1. It looks like you have a display driver version older than the one required by the CUDA Toolkit. Make sure you installed the display driver downloaded from the same download page you got your toolkit from.
2. cuda-gdb will hide from the application being debugged GPUs used to run your desktop environment. Otherwise the desktop environment might've hanged when the application is suspended on the breakpoint. To see both GPUs in cuda-gdb you need to run without desktop environment.