[2013-12-29 23:33:00] Started cgminer 3.4.0
[2013-12-29 23:33:00] Loaded configuration file cgm0
[2013-12-29 23:33:00] clDevicesNum returned error, no GPUs usable
[2013-12-29 23:33:00] Command line options set a device that doesn't exist
Also, if this helps:
[2013-12-29 23:33:22] CL Platform 0 vendor: Intel(R) Corporation
[2013-12-29 23:33:22] CL Platform 0 name: Intel(R) OpenCL
[2013-12-29 23:33:22] CL Platform 0 version: OpenCL 1.1
[2013-12-29 23:33:22] Error -1: Getting Device IDs (num)
[2013-12-29 23:33:22] CL Platform 1 vendor: Advanced Micro Devices, Inc.
[2013-12-29 23:33:22] CL Platform 1 name: AMD Accelerated Parallel Processing
[2013-12-29 23:33:22] CL Platform 1 version: OpenCL 1.2 AMD-APP (1348.5)
[2013-12-29 23:33:22] Platform 1 devices: 1
[2013-12-29 23:33:22] 0 Pitcairn
[2013-12-29 23:33:23] Failed to ADL_Adapter_ID_Get. Error -1
[2013-12-29 23:33:23] Failed to ADL_Adapter_ID_Get. Error -1
[2013-12-29 23:33:23] Failed to ADL_Adapter_ID_Get. Error -1
[2013-12-29 23:33:23] GPU 0 AMD Radeon HD 7800 Series hardware monitoring enabl
ed
[2013-12-29 23:33:23] 1 GPU devices max detected
[2013-12-29 23:33:23] USB all: found 6 devices - listing known devices
[2013-12-29 23:33:23] No known USB devices
EDIT: Solved by changing the gpu-platform setting in cgm0 from 0 to 1.