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)