LIBOPENCL(7)LIBOPENCL(7)NAME
libOpenCL, libOpenCL.so - OCL-ICD implementation of OpenCL ICD loader
DESCRIPTIONlibOpenCL.so is the library linked by OpenCL programs. It does not
contains any OpenCL implementation itself, but merly 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 /usr/local/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.
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 look
for into the standard dynamic loader paths.
ENVIRONMENT
Some environment variables can be used modify the default behavior of
libOpenCL.
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 "/usr/local/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 slash into $OCL_ICD_VENDORS, libOpenCL.so will
first try to use
/usr/local/etc/OpenCL/vendors/$OCL_ICD_VENDORS. If this fail,
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, contrary the Khronos specification, the loader will not
check that the loaded ICDs declare the cl_khr_icd extension. You
may need to define this environment variable if you are using the
Intel ICD together with optirun(1). Else, a bug into the Intel ICD
will make the application crash.
OCL_ICD_PLATFORM_SORT
Allows to choose the way platforms are sorted when presented to
programs through clGetPlatformIDs(3). Current provided algorithms
are:
· 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.
· none: no sort is done and the order can very at each run.
OCL_ICD_DEFAULT_PLATFORM
Number of the platform to choose as defaut platform. Note that
using this environment variable without specifying 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:
· 1: warnings (enabled by default if debug support is present
and OCL_ICD_DEBUG is not set)
· 2: informative messages
· 4: entering/exiting for some OpenCL functions
· 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
Khronos OpenCL registry website
AUTHOR
Vincent Danjean <Vincent.Danjean@ens-lyon.org>
Author.
10/06/2015 LIBOPENCL(7)
