When using beignet (tested 1.2.1 and 1.3.0) graphical glitches appear immediately making desktop unusable, it is even enough to run clinfo
CPU/GPU: i5-3470 with Intel® HD Graphics 2500
OS: Ubuntu 14.04 64 bit:
Kernels: Same behavior on both 4.4 and 3.13
Some of the clinfo output:
Some of clinfo output on Kernel 4.4:
Platform Profile: FULL_PROFILE
Platform Version: OpenCL 1.2 beignet 1.3
Platform Name: Intel Gen OCL Driver
Platform Vendor: Intel
Local memory type: Global
Local memory size: 65536
Unified memory for Host and Device: 1
Name: Intel(R) HD Graphics
Device OpenCL C version: OpenCL C 1.2 beignet 1.3
Driver version: 1.3
I can observe the same behavior on ubuntu 16.04 64bit, beignet/xenial,now 1.1.1-2 amd64 and the same processor as the OP.
This happens e.g. when running `clinfo` or `gimp`, when running without opencl support, `gimp --gegl-disable-opencl`, everything works fine.
searching https://www.intel.com/content/dam/www/public/us/en/documents/specification-updates/3rd-gen-core-desktop-specification-update.pdf on page 48 you can find that this seems to be a known and unfixed bug:
Specific source-copy blitter instructions in Intel® HD Graphics 2500 and 4000 processor may result in unpredictable behavior when a blit source and destination overlap.
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