OpenCL not working with Intel Arc

Is there an existing issue for this?

• I checked and did not find my issue in the already reported ones

Describe the bug

OpenCL is not working/enabled.

Just updated to Ubuntu 26.04 LTS, but issue existed in 24.04 LTS

Steps to reproduce

Run Darktable with

darktable -d opencl

Expected behavior

OpenCL should work

Logfile | Screenshot | Screencast

0.0001 [dt starting]
 darktable --cachedir /media/seth/Cache/darktable -d opencl
     0.2905 [opencl_init] opencl disabled via darktable preferences
     0.3105 [opencl_init] opencl library 'libOpenCL' found on your system and loaded, preference 'default path'
     0.4620 [opencl_init] found 2 platforms
     0.4620 [check platform] platform 'Intel(R) OpenCL' with key 'clplatform_intelropencl' is NOT active
[opencl_init] found 1 device

[dt_opencl_device_init]
   DEVICE:                   0: 'Intel(R) Arc(TM) Graphics'
   CONF KEY:                 cldevice_v5_intelropenclgraphicsintelrarctmgraphics
   PLATFORM, VENDOR & ID:    Intel(R) OpenCL Graphics, Intel(R) Corporation, ID=32902
   CANONICAL NAME:           intelropenclgraphicsintelrarctmgraphics
   DRIVER VERSION:           26.18.38308.1
   DEVICE VERSION:           OpenCL 3.0 NEO
   DEVICE_TYPE:              GPU, unified mem
   GLOBAL MEM SIZE:          28656 MB
   MAX MEM ALLOC:            4096 MB
   MAX IMAGE SIZE:           16384 x 16384
   MAX CONSTANT BUFFER:      4194296 KB
   ADDRESS ALIGN:            128
   COMPUTE UNITS:            128
   MAX WORK GROUP SIZE:      1024
   MAX WORK ITEM DIMENSIONS: 3
   MAX WORK ITEM SIZES:      [ 1024 1024 1024 ]
   ASYNC PIXELPIPE:          NO
   PINNED MEMORY TRANSFER:   NO
   AVOID ATOMICS:            NO
   MICRO NAP:                250
   ROUNDUP WIDTH & HEIGHT    16x16
   CHECK EVENT HANDLES:      128
   TILING ADVANTAGE:         0.000
   DEFAULT DEVICE:           NO
   KERNEL BUILD DIRECTORY:   /usr/share/darktable/kernels
   KERNEL DIRECTORY:         /media/seth/Cache/darktable/cached_v5_kernels_for_IntelROpenCLGraphicsIntelRArcTMGraphics_2618383081
   CL COMPILER OPTION:
   CL COMPILER COMMAND:      -w  -DINTEL=1 -I"/usr/share/darktable/kernels"
     0.4673 [opencl_build_program] could not build program: CL_OUT_OF_HOST_MEMORY
     0.4673 [dt_opencl_device_init] failed to compile program `demosaic_ppg.cl'!
[opencl_init] no suitable devices found.
     0.4674 [opencl_init] FINALLY: opencl PREFERENCE=OFF is NOT AVAILABLE and NOT ENABLED.
     0.9488 [iop_load_module] failed to open `lut3d': libavcodec.so.60: cannot open shared object file: No such file or directory

Commit

No response

Where did you obtain darktable from?

distro packaging

darktable version

darktable 5.4.1

What OS are you using?

Linux

What is the version of your OS?

Ubuntu 26.04 LTS

Describe your system

32GB RAM

Installed Intel GPU Drivers, libva, gmmlib.

Are you using OpenCL GPU in darktable?

Yes

If yes, what is the GPU card and driver?

Intel Corporation Arrow Lake-P [Arc Pro 130T/140T] (Intel® Arc™ 140T GPU), 32GB shared RAM, i915

Please provide additional context if applicable. You can attach files too, but might need to rename to .txt or .zip

No response

Start by reproducing the failure with darktable -d opencl and review the OpenCL initialization output, especially the Intel Arc device and CL_OUT_OF_HOST_MEMORY while compiling demosaic_ppg.cl. Trace the OpenCL initialization and kernel compilation path, accounting for the distro-packaged darktable, Intel driver, and Ubuntu versions; done means the device is accepted and the OpenCL kernels compile successfully.