bug in nvidia gpu detection logic

[ireed]

The method for GPU detection does not handle all cases.
From the code in moonray/moonray/lib/rendering/rt/gpu/GPUUtils.cc:

    FILE *fp = fopen("/proc/driver/nvidia/version", "r");
    if (fp != NULL) 
        if (fscanf(fp, "NVRM version: NVIDIA UNIX x86_64 Kernel Module  %d.%d", major, minor) == 2)

The issue with this method is the output in /proc/driver/nvidia/version may not match this particular string. In my case, it does not:

  # cat /proc/driver/nvidia/version
  NVRM version: NVIDIA UNIX Open Kernel Module for x86_64  535.86.10  Release Build  (dvs-builder@U16-I2-C05-14-2)  Wed Jul 26 23:15:31 UTC 2023
  GCC version:  gcc version 4.8.5 20150623 (Red Hat 4.8.5-44) (GCC)

Note the 'for x86_64', which results in a string mismatch. This causes Moonray to incorrectly claim that i do not have a GPU:

  # moonray -in /openmoonray/testdata/rectangle.rdla -out /tmp/rectangle.exr -exec_mode xpu
     Loading Scene File(s): /openmoonray/testdata/rectangle.rdla
     Warning (lib.render): GPU: Unable to query NVIDIA driver version   ...falling back to CPU vectorized mode
     Error: GPU: Unable to query NVIDIA driver version   ...falling back to CPU vectorized mode
     Render prep time = 00:00:00.296

Of course, i can work around this by using root to manually edit that file.
A possible resolution would be to use nvidia-smi instead of parsing that file, which can change format. Maybe something like
$> nvidia-smi --query-gpu=driver_version --format=csv

[jmahovsky-dwa]

Thank you for the detailed bug report!

We have created an internal ticket for this issue and are investigating a fix.

[jmahovsky-dwa]

This has been fixed and the fix will appear in the next OpenMoonRay release.