$ darktable-cltest 
[opencl_init] opencl related configuration options:
[opencl_init] 
[opencl_init] opencl: 1
[opencl_init] opencl_library: ''
[opencl_init] opencl_memory_requirement: 512
[opencl_init] opencl_memory_headroom: 0
[opencl_init] opencl_device_priority: '*/!0,*/*/*'
[opencl_init] opencl_size_roundup: 16
[opencl_init] opencl_async_pixelpipe: 0
[opencl_init] opencl_synch_cache: 0
[opencl_init] opencl_number_event_handles: 100
[opencl_init] opencl_micro_nap: 500
[opencl_init] opencl_use_pinned_memory: 0
[opencl_init] opencl_use_cpu_devices: 0
[opencl_init] opencl_avoid_atomics: 0
[opencl_init] opencl_enable_markesteijn: 1
[opencl_init] 
[opencl_init] found opencl runtime library 'libOpenCL'
[opencl_init] opencl library 'libOpenCL' found on your system and loaded
[opencl_init] found 1 platform
[opencl_init] found 1 device
[opencl_init] device 0 `Capeverde' supports image sizes of 16384 x 16384
[opencl_init] device 0 `Capeverde' allows GPU memory allocations of up to 428MB
[opencl_init] device 0: Capeverde 
     GLOBAL_MEM_SIZE:          809MB
     MAX_WORK_GROUP_SIZE:      256
     MAX_WORK_ITEM_DIMENSIONS: 3
     MAX_WORK_ITEM_SIZES:      [ 256 256 256 ]
     DRIVER_VERSION:           2442.7
     DEVICE_VERSION:           OpenCL 1.2 AMD-APP (2442.7)
[opencl_init] could not create command queue for device 0: -6
[opencl_init] FINALLY: opencl is NOT AVAILABLE on this system.
[opencl_init] initial status of opencl enabled flag is OFF.