libOpenCL(7)

LIBOPENCL(7)                                                      LIBOPENCL(7)

NAME
       libOpenCL, libOpenCL.so - OCL-ICD implementation of OpenCL ICD loader

DESCRIPTION
       libOpenCL.so is the library linked by OpenCL programs. It does not
       contains any OpenCL implementation itself, but merely act as a
       dispatcher to real OpenCL implementations provided as OpenCL
       Installable Client Driver (ICD). An ICD loader should be able to load
       ICDs provided by any vendors.

       According to OpenCL specifications from Khronos (see [Khronos]), the
       ICD Loader looks for files into /etc/OpenCL/vendors directory and, for
       each file whose name ends with .icd, the ICD Loader loads with
       dlopen(3) the shared library whose name is on the first line of the
       .icd file.

       Each shared library name in ".icd" files can have its path, or it can
       be a plain filename. In the latter case, the ICD shared library will be
       looked for into the standard dynamic library loader paths.

ENVIRONMENT
       Some environment variables can be used modify the default behavior of
       libOpenCL.

       OPENCL_VENDOR_PATH
           This variable allows one to modify the default /etc/OpenCL/vendors
           path. It is compatible with some other ICD loaders (but not all of
           them, as the variable is not part of the standard). Note that
           $OCL_ICD_VENDORS (see below) is used in priority if defined and not
           empty.

       OCL_ICD_VENDORS
           This variable allows one to change the way ICD are searched on the
           system. Several cases are considered:

            1. if $OCL_ICD_VENDORS is a directory path, then this path
               replaces the "/etc/OpenCL/vendors" path in the standard
               behavior: the loader will use the .icd files in this directory;

            2. else, if $OCL_ICD_VENDORS ends with .icd, libOpenCL.so will
               only load the ICD whose shared library name is wrote into the
               specified ".icd" file;

               If there is no slashes into $OCL_ICD_VENDORS, libOpenCL.so will
               first try to use /etc/OpenCL/vendors$OCL_ICD_VENDORS (or
               $OPENCL_VENDOR_PATH/$OCL_ICD_VENDORS if OPENCL_VENDOR_PATH is
               defined). If this fail or if there are shashes, it uses
               $OCL_ICD_VENDORS (as a relative or absolute file name path).

            3. else libOpenCL.so will try to load $OCL_ICD_VENDORS as the ICD
               shared library itself (i.e. to load it directly with
               dlopen(3)).

       OCL_ICD_ASSUME_ICD_EXTENSION
           If set to an non-empty value, contrary the Khronos specification,
           the loader will not check that the loaded ICDs declare the
           cl_khr_icd extension. It will also use the clGetPlatformInfo from
           the dispatch table if no such function is globally available. You
           may need to define this environment variable if you are using not
           (fully) compliant ICD, or if you are using the Intel ICD together
           with optirun(1). In the latter case, a bug into the Intel ICD will
           make the application crash.

       If set to the debug value, some additional messages will be printed in
       debug mode (see OCL_ICD_DEBUG below).

       OCL_ICD_PLATFORM_SORT
           Allows one to choose the way platforms are sorted when presented to
           programs through clGetPlatformIDs(3). Current provided algorithms
           are:

           o   devices: first, list platforms that support most GPU, then most
               CPU then most accelerators. If OCL_ICD_PLATFORM_SORT is not set
               or set to an unknown value, this algorithm is used.

           o   none: no sort is done and the order can change at each run.

       OCL_ICD_DEFAULT_PLATFORM
           Number of the platform to choose as default platform. Note that
           using this environment variable without ensuring the use of a sort
           algorithm for platforms is not really useful.

       OCL_ICD_DEBUG
           If ocl-icd has been compiled with debug support, you can set this
           environment variable to a value where each bit display some kind of
           informations. Defined values are:

           o   1: warnings (enabled by default if debug support is present and
               OCL_ICD_DEBUG is not set)

           o   2: informative messages

           o   4: entering/exiting for some OpenCL functions

           o   8: dump of the internal structure of loaded ICDs

           OCL_ICD_DEBUG is mainly useful for ocl-icd development itself
           and/or for ICD development.

SEE ALSO
       http://www.khronos.org/registry/cl/[Khronos OpenCL registry website]

AUTHOR
       Vincent Danjean <Vincent.Danjean@ens-lyon.org>
           Author.

                                  2015-06-08                      LIBOPENCL(7)