I use Ubuntu 14.04, no X Windows, I have installed the driver as for the installation guide, I have installed the OpenCL sdk as for the installation guide, I have installed the patched kernel 4.4 as for the installation guide, and everything worked a charm when I tested.
After the test of OpenCL, I did not use OpenCL for a while, and after few days, I tried again with several applications, and what I got is just hangs, nothing happens, apart from the cursor blinking.
I checked if the kernel was still the patched one, and it is, I re-installed the modules, but still the same.
How do I troubleshoot the issue? Can apt update and upgrade broke the OpenCL system?
I have attached a strace log file
Yes, it is possible that components have been overwritten. Some first steps you can try:
This system analyzer script may help you diagnose: https://software.intel.com/en-us/articles/mss-sys-analyzer-linux
Thanks, yes I have already done all that, kernel is the same, i915 is loaded, I have re-installed the OpenCL components.
As for libdrm, it is the only installed (libdrm2).
As I said, it was working when I finished installing driver, patched kernel and sdk, but after few days when I tried again to run several OpenCL program, Platform/Device Capabilities Viewer Sample included, it hangs.
The strace file you've attached is missing an open for /dev/dri/renderD###. On your system, what do you see with ls /dev/dri?
Without being able to open that interface, your strace shows your app is also missing all the startup steps expected after that.
In case you'd like to try again, I've updated the system analyzer to hopefully work better for OpenCL-only installs. https://software.intel.com/en-us/articles/mss-sys-analyzer-linux
Glad to hear your system works again! For others who might run into similar issues, re-installing just the OpenCL SDK and runtime/driver components may also be effective.