OpenCL backend problems 
Hi, 

I have 3 gpus, however I want to run XMRig on just one of them, specifically gpu #2. When I go to pass the OpenCL devices argument in the command line,
$ sudo ./xmrig --opencl-devices=2  
XMRig still uses all 3 of my gpus. Using v6.15.2 on Ubuntu. 

Am I passing this argument incorrectly? How do I select a single gpu? 

Thanks